view src/option.c @ 34854:97b5457962ed v9.1.0296

patch 9.1.0296: regexp: engines do not handle case-folding well Commit: https://github.com/vim/vim/commit/7a27c108e0509f3255ebdcb6558e896c223e4d23 Author: Christian Brabandt <cb@256bit.org> Date: Tue Apr 9 22:53:19 2024 +0200 patch 9.1.0296: regexp: engines do not handle case-folding well Problem: Regex engines do not handle case-folding well Solution: Correctly calculate byte length of characters to skip When the regexp engine compares two utf-8 codepoints case insensitively it may match an adjacent character, because it assumes it can step over as many bytes as the pattern contains. This however is not necessarily true because of case-folding, a multi-byte UTF-8 character can be considered equal to some single-byte value. Let's consider the pattern '?' and the string 's'. When comparing and ignoring case, the single character 's' matches, and since it matches Vim will try to step over the match (by the amount of bytes of the pattern), assuming that since it matches, the length of both strings is the same. However in that case, it should only step over the single byte value 's' so by 1 byte and try to start matching after it again. So for the backtracking engine we need to ensure: - we try to match the correct length for the pattern and the text - in case of a match, we step over it correctly The same thing can happen for the NFA engine, when skipping to the next character to test for a match. We are skipping over the regstart pointer, however we do not consider the case that because of case-folding we may need to adjust the number of bytes to skip over. So this needs to be adjusted in find_match_text() as well. A related issue turned out, when prog->match_text is actually empty. In that case we should try to find the next match and skip this condition. fixes: #14294 closes: #14433 Signed-off-by: Christian Brabandt <cb@256bit.org>
author Christian Brabandt <cb@256bit.org>
date Tue, 09 Apr 2024 23:00:08 +0200
parents 159d598e6781
children 2d7721a4d213
line wrap: on
line source

/* vi:set ts=8 sts=4 sw=4 noet:
 *
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * Code to handle user-settable options. This is all pretty much table-
 * driven. Checklist for adding a new option:
 * - Put it in the options array in optiondefs.h (copy an existing entry).
 * - For a global option: Add a variable for it in option.h.
 * - For a buffer or window local option:
 *   - Add a PV_XX macro definition to the optiondefs.h file.
 *   - Add a variable to the window or buffer struct in structs.h.
 *   - For a window option, add some code to copy_winopt().
 *   - For a window string option, add code to check_win_options() and
 *     clear_winopt().
 *   - For a buffer option, add some code to buf_copy_options().
 *   - For a buffer string option, add code to check_buf_options().
 * - If it's a numeric option, add any necessary bounds checks to
 *   set_num_option().
 * - If it's a list of flags, add some code in did_set_string_option(), search
 *   for WW_ALL.
 * - When adding an option with expansion (P_EXPAND), but with a different
 *   default for Vi and Vim (no P_VI_DEF), add some code at VIMEXP.
 * - Add documentation!  One line in doc/quickref.txt, full description in
 *   options.txt, and any other related places.
 * - Add an entry in runtime/optwin.vim.
 * When making changes:
 * - Adjust the help for the option in doc/option.txt.
 * - When an entry has the P_VIM flag, or is lacking the P_VI_DEF flag, add a
 *   comment at the help for the 'compatible' option.
 */

#define IN_OPTION_C
#include "vim.h"
#include "optiondefs.h"

static void set_options_default(int opt_flags);
static void set_string_default_esc(char *name, char_u *val, int escape);
static char_u *find_dup_item(char_u *origval, char_u *newval, long_u flags);
static char_u *option_expand(int opt_idx, char_u *val);
static void didset_options(void);
static void didset_options2(void);
#if defined(FEAT_EVAL) || defined(PROTO)
static long_u *insecure_flag(int opt_idx, int opt_flags);
#else
# define insecure_flag(opt_idx, opt_flags) (&options[opt_idx].flags)
#endif
static char *set_bool_option(int opt_idx, char_u *varp, int value, int opt_flags);
static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf, size_t errbuflen, int opt_flags);
static int find_key_option(char_u *arg_arg, int has_lt);
static void showoptions(int all, int opt_flags);
static int optval_default(struct vimoption *, char_u *varp, int compatible);
static void showoneopt(struct vimoption *, int opt_flags);
static int put_setstring(FILE *fd, char *cmd, char *name, char_u **valuep, long_u flags);
static int put_setnum(FILE *fd, char *cmd, char *name, long *valuep);
static int put_setbool(FILE *fd, char *cmd, char *name, int value);
static int istermoption(struct vimoption *p);
static char_u *get_varp_scope(struct vimoption *p, int scope);
static char_u *get_varp(struct vimoption *);
static void check_win_options(win_T *win);
static void option_value2string(struct vimoption *, int scope);
static void check_winopt(winopt_T *wop);
static int wc_use_keyname(char_u *varp, long *wcp);
static void compatible_set(void);

#if defined(FEAT_EVAL) || defined(PROTO)
static char *(p_bin_dep_opts[])    = {"textwidth", "wrapmargin", "modeline", "expandtab", NULL};
static char *(p_paste_dep_opts[])  = {"autoindent", "expandtab", "ruler", "showmatch", "smarttab",
    "softtabstop", "textwidth", "wrapmargin",
#ifdef FEAT_RIGHTLEFT
    "hkmap", "revins",
#endif
#ifdef FEAT_VARTABS
    "varsofttabstop",
#endif
    NULL};
static void didset_options_sctx(int opt_flags, char **buf);
#endif


/*
 * Initialize the 'shell' option to a default value.
 */
    static void
set_init_default_shell(void)
{
    char_u	*p;

    // Find default value for 'shell' option.
    // Don't use it if it is empty.
    if (((p = mch_getenv((char_u *)"SHELL")) != NULL && *p != NUL)
#if defined(MSWIN)
	    || ((p = mch_getenv((char_u *)"COMSPEC")) != NULL && *p != NUL)
	    || ((p = (char_u *)default_shell()) != NULL && *p != NUL)
#endif
	    )
#if defined(MSWIN)
    {
	// For MS-Windows put the path in quotes instead of escaping spaces.
	char_u	    *cmd;
	size_t	    len;

	if (vim_strchr(p, ' ') != NULL)
	{
	    len = STRLEN(p) + 3;  // two quotes and a trailing NUL
	    cmd = alloc(len);
	    if (cmd != NULL)
	    {
		vim_snprintf((char *)cmd, len, "\"%s\"", p);
		set_string_default("sh", cmd);
		vim_free(cmd);
	    }
	}
	else
	    set_string_default("sh", p);
    }
#else
	set_string_default_esc("sh", p, TRUE);
#endif
}

/*
 * Set the default for 'backupskip' to include environment variables for
 * temp files.
 */
    static void
set_init_default_backupskip(void)
{
    int		opt_idx;
    long_u	n;
    char_u	*p;
#ifdef UNIX
    static char	*(names[4]) = {"", "TMPDIR", "TEMP", "TMP"};
#else
    static char	*(names[3]) = {"TMPDIR", "TEMP", "TMP"};
#endif
    int		len;
    garray_T	ga;
    char_u	*item;

    opt_idx = findoption((char_u *)"backupskip");

    ga_init2(&ga, 1, 100);
    for (n = 0; n < (long)ARRAY_LENGTH(names); ++n)
    {
	int		mustfree = FALSE;
#ifdef UNIX
	if (*names[n] == NUL)
# ifdef MACOS_X
	    p = (char_u *)"/private/tmp";
# else
	p = (char_u *)"/tmp";
# endif
	else
#endif
	    p = vim_getenv((char_u *)names[n], &mustfree);
	if (p != NULL && *p != NUL)
	{
	    // First time count the NUL, otherwise count the ','.
	    len = (int)STRLEN(p) + 3;
	    item = alloc(len);
	    if (item != NULL)
	    {
		STRCPY(item, p);
		add_pathsep(item);
		STRCAT(item, "*");
		if (find_dup_item(ga.ga_data, item, options[opt_idx].flags)
									== NULL
			&& ga_grow(&ga, len) == OK)
		{
		    if (ga.ga_len > 0)
			STRCAT(ga.ga_data, ",");
		    STRCAT(ga.ga_data, item);
		    ga.ga_len += len;
		}
		vim_free(item);
	    }
	}
	if (mustfree)
	    vim_free(p);
    }
    if (ga.ga_data != NULL)
    {
	set_string_default("bsk", ga.ga_data);
	vim_free(ga.ga_data);
    }
}

/*
 * Initialize the 'maxmemtot' and 'maxmem' options to a default value.
 * 'maxmemtot' and 'maxmem' may have to be adjusted for available memory.
 */
    static void
set_init_default_maxmemtot(void)
{
    int		opt_idx;
    long_u	n;

    opt_idx = findoption((char_u *)"maxmemtot");
    if (opt_idx < 0)
	return;

#if !defined(HAVE_AVAIL_MEM) && !defined(HAVE_TOTAL_MEM)
    if (options[opt_idx].def_val[VI_DEFAULT] == (char_u *)0L)
#endif
    {
#if defined(HAVE_AVAIL_MEM)
	// Use amount of memory available at this moment.
	n = (mch_avail_mem(FALSE) >> 1);
#elif defined(HAVE_TOTAL_MEM)
	// Use amount of memory available to Vim.
	n = (mch_total_mem(FALSE) >> 1);
#else
	n = (0x7fffffff >> 11);
#endif
	options[opt_idx].def_val[VI_DEFAULT] = (char_u *)n;
	opt_idx = findoption((char_u *)"maxmem");
	if (opt_idx >= 0)
	{
#if !defined(HAVE_AVAIL_MEM) && !defined(HAVE_TOTAL_MEM)
	    if ((long)(long_i)options[opt_idx].def_val[VI_DEFAULT] > (long)n
		    || (long)(long_i)options[opt_idx].def_val[VI_DEFAULT] == 0L)
#endif
		options[opt_idx].def_val[VI_DEFAULT] = (char_u *)n;
	}
    }
}

/*
 * Initialize the 'cdpath' option to a default value.
 */
    static void
set_init_default_cdpath(void)
{
    int		opt_idx;
    char_u	*cdpath;
    char_u	*buf;
    int	i;
    int	j;
    int	mustfree = FALSE;

    cdpath = vim_getenv((char_u *)"CDPATH", &mustfree);
    if (cdpath == NULL)
	return;

    buf = alloc((STRLEN(cdpath) << 1) + 2);
    if (buf != NULL)
    {
	buf[0] = ',';	    // start with ",", current dir first
	j = 1;
	for (i = 0; cdpath[i] != NUL; ++i)
	{
	    if (vim_ispathlistsep(cdpath[i]))
		buf[j++] = ',';
	    else
	    {
		if (cdpath[i] == ' ' || cdpath[i] == ',')
		    buf[j++] = '\\';
		buf[j++] = cdpath[i];
	    }
	}
	buf[j] = NUL;
	opt_idx = findoption((char_u *)"cdpath");
	if (opt_idx >= 0)
	{
	    options[opt_idx].def_val[VI_DEFAULT] = buf;
	    options[opt_idx].flags |= P_DEF_ALLOCED;
	}
	else
	    vim_free(buf); // cannot happen
    }
    if (mustfree)
	vim_free(cdpath);
}

/*
 * Initialize the 'printencoding' option to a default value.
 */
    static void
set_init_default_printencoding(void)
{
#if defined(FEAT_POSTSCRIPT) && \
    (defined(MSWIN) || defined(VMS) || defined(MAC) || defined(hpux))
    // Set print encoding on platforms that don't default to latin1
    set_string_default("penc",
# if defined(MSWIN)
	    (char_u *)"cp1252"
# elif defined(VMS)
	    (char_u *)"dec-mcs"
# elif defined(MAC)
	    (char_u *)"mac-roman"
# else // HPUX
	    (char_u *)"hp-roman8"
# endif
	    );
#endif
}

#ifdef FEAT_POSTSCRIPT
/*
 * Initialize the 'printexpr' option to a default value.
 */
    static void
set_init_default_printexpr(void)
{
    // 'printexpr' must be allocated to be able to evaluate it.
    set_string_default("pexpr",
# if defined(MSWIN)
	    (char_u *)"system('copy' . ' ' . v:fname_in . (&printdevice == '' ? ' LPT1:' : (' \"' . &printdevice . '\"'))) . delete(v:fname_in)"
# elif defined(VMS)
	    (char_u *)"system('print/delete' . (&printdevice == '' ? '' : ' /queue=' . &printdevice) . ' ' . v:fname_in)"

# else
	    (char_u *)"system('lpr' . (&printdevice == '' ? '' : ' -P' . &printdevice) . ' ' . v:fname_in) . delete(v:fname_in) + v:shell_error"
# endif
	    );
}
#endif

#ifdef UNIX
/*
 * Force restricted-mode on for "nologin" or "false" $SHELL
 */
    static void
set_init_restricted_mode(void)
{
    char_u	*p;

    p = get_isolated_shell_name();
    if (p == NULL)
	return;
    if (fnamecmp(p, "nologin") == 0 || fnamecmp(p, "false") == 0)
	restricted = TRUE;
    vim_free(p);
}
#endif

#ifdef CLEAN_RUNTIMEPATH
/*
 * When Vim is started with the "--clean" argument, set the default value
 * for the 'runtimepath' and 'packpath' options.
 */
    static void
set_init_clean_rtp(void)
{
    int		opt_idx;

    opt_idx = findoption((char_u *)"runtimepath");
    if (opt_idx >= 0)
    {
	options[opt_idx].def_val[VI_DEFAULT] = (char_u *)CLEAN_RUNTIMEPATH;
	p_rtp = (char_u *)CLEAN_RUNTIMEPATH;
    }
    opt_idx = findoption((char_u *)"packpath");
    if (opt_idx < 0)
	return;
    options[opt_idx].def_val[VI_DEFAULT] = (char_u *)CLEAN_RUNTIMEPATH;
    p_pp = (char_u *)CLEAN_RUNTIMEPATH;
}
#endif

/*
 * Expand environment variables and things like "~" for the defaults.
 * If option_expand() returns non-NULL the variable is expanded.  This can
 * only happen for non-indirect options.
 * Also set the default to the expanded value, so ":set" does not list
 * them.
 * Don't set the P_ALLOCED flag, because we don't want to free the
 * default.
 */
    static void
set_init_expand_env(void)
{
    int		opt_idx;
    char_u	*p;

    for (opt_idx = 0; !istermoption_idx(opt_idx); opt_idx++)
    {
	if ((options[opt_idx].flags & P_GETTEXT)
		&& options[opt_idx].var != NULL)
	    p = (char_u *)_(*(char **)options[opt_idx].var);
	else
	    p = option_expand(opt_idx, NULL);
	if (p != NULL && (p = vim_strsave(p)) != NULL)
	{
	    *(char_u **)options[opt_idx].var = p;
	    // VIMEXP
	    // Defaults for all expanded options are currently the same for Vi
	    // and Vim.  When this changes, add some code here!  Also need to
	    // split P_DEF_ALLOCED in two.
	    if (options[opt_idx].flags & P_DEF_ALLOCED)
		vim_free(options[opt_idx].def_val[VI_DEFAULT]);
	    options[opt_idx].def_val[VI_DEFAULT] = p;
	    options[opt_idx].flags |= P_DEF_ALLOCED;
	}
    }
}

/*
 * Initialize the 'LANG' environment variable to a default value.
 */
    static void
set_init_lang_env(void)
{
#if defined(MSWIN) && defined(FEAT_GETTEXT)
    // If $LANG isn't set, try to get a good value for it.  This makes the
    // right language be used automatically.  Don't do this for English.
    if (mch_getenv((char_u *)"LANG") == NULL)
    {
	char	buf[20];
	long_u	n;

	// Could use LOCALE_SISO639LANGNAME, but it's not in Win95.
	// LOCALE_SABBREVLANGNAME gives us three letters, like "enu", we use
	// only the first two.
	n = GetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_SABBREVLANGNAME,
							     (LPTSTR)buf, 20);
	if (n >= 2 && STRNICMP(buf, "en", 2) != 0)
	{
	    // There are a few exceptions (probably more)
	    if (STRNICMP(buf, "cht", 3) == 0 || STRNICMP(buf, "zht", 3) == 0)
		STRCPY(buf, "zh_TW");
	    else if (STRNICMP(buf, "chs", 3) == 0
					      || STRNICMP(buf, "zhc", 3) == 0)
		STRCPY(buf, "zh_CN");
	    else if (STRNICMP(buf, "jp", 2) == 0)
		STRCPY(buf, "ja");
	    else
		buf[2] = NUL;		// truncate to two-letter code
	    vim_setenv((char_u *)"LANG", (char_u *)buf);
	}
    }
#elif defined(MACOS_CONVERT)
    // Moved to os_mac_conv.c to avoid dependency problems.
    mac_lang_init();
#endif
}

/*
 * Initialize the 'encoding' option to a default value.
 */
    static void
set_init_default_encoding(void)
{
    char_u	*p;
    int		opt_idx;

# if defined(MSWIN) || defined(__MVS__)
    // MS-Windows has builtin support for conversion to and from Unicode, using
    // "utf-8" for 'encoding' should work best for most users.
    // z/OS built should default to UTF-8 mode as setlocale does not respect utf-8 environment variable locales
    p = vim_strsave((char_u *)ENC_DFLT);
# else
    // enc_locale() will try to find the encoding of the current locale.
    // This works best for properly configured systems, old and new.
    p = enc_locale();
# endif
    if (p == NULL)
	return;

    // Try setting 'encoding' and check if the value is valid.
    // If not, go back to the default encoding.
    char_u *save_enc = p_enc;
    p_enc = p;
    if (STRCMP(p_enc, "gb18030") == 0)
    {
	// We don't support "gb18030", but "cp936" is a good substitute
	// for practical purposes, thus use that.  It's not an alias to
	// still support conversion between gb18030 and utf-8.
	p_enc = vim_strsave((char_u *)"cp936");
	vim_free(p);
    }
    if (mb_init() == NULL)
    {
	opt_idx = findoption((char_u *)"encoding");
	if (opt_idx >= 0)
	{
	    options[opt_idx].def_val[VI_DEFAULT] = p_enc;
	    options[opt_idx].flags |= P_DEF_ALLOCED;
	}

#if defined(MSWIN) || defined(MACOS_X) || defined(VMS)
	if (STRCMP(p_enc, "latin1") == 0 || enc_utf8)
	{
	    // Adjust the default for 'isprint' and 'iskeyword' to match
	    // latin1.  Also set the defaults for when 'nocompatible' is
	    // set.
	    set_string_option_direct((char_u *)"isp", -1,
		    ISP_LATIN1, OPT_FREE, SID_NONE);
	    set_string_option_direct((char_u *)"isk", -1,
		    ISK_LATIN1, OPT_FREE, SID_NONE);
	    opt_idx = findoption((char_u *)"isp");
	    if (opt_idx >= 0)
		options[opt_idx].def_val[VIM_DEFAULT] = ISP_LATIN1;
	    opt_idx = findoption((char_u *)"isk");
	    if (opt_idx >= 0)
		options[opt_idx].def_val[VIM_DEFAULT] = ISK_LATIN1;
	    (void)init_chartab();
	}
#endif

#if defined(MSWIN) && (!defined(FEAT_GUI) || defined(VIMDLL))
	// Win32 console: When GetACP() returns a different value from
	// GetConsoleCP() set 'termencoding'.
	if (
# ifdef VIMDLL
		(!gui.in_use && !gui.starting) &&
# endif
		GetACP() != GetConsoleCP())
	{
	    char	buf[50];

	    // Win32 console: In ConPTY, GetConsoleCP() returns zero.
	    // Use an alternative value.
	    if (GetConsoleCP() == 0)
		sprintf(buf, "cp%ld", (long)GetACP());
	    else
		sprintf(buf, "cp%ld", (long)GetConsoleCP());
	    p_tenc = vim_strsave((char_u *)buf);
	    if (p_tenc != NULL)
	    {
		opt_idx = findoption((char_u *)"termencoding");
		if (opt_idx >= 0)
		{
		    options[opt_idx].def_val[VI_DEFAULT] = p_tenc;
		    options[opt_idx].flags |= P_DEF_ALLOCED;
		}
		convert_setup(&input_conv, p_tenc, p_enc);
		convert_setup(&output_conv, p_enc, p_tenc);
	    }
	    else
		p_tenc = empty_option;
	}
#endif
#if defined(MSWIN)
	// $HOME may have characters in active code page.
	init_homedir();
#endif
    }
    else
    {
	vim_free(p_enc);
	p_enc = save_enc;
    }
}

/*
 * Initialize the options, first part.
 *
 * Called only once from main(), just after creating the first buffer.
 * If "clean_arg" is TRUE Vim was started with --clean.
 */
    void
set_init_1(int clean_arg)
{
#ifdef FEAT_LANGMAP
    langmap_init();
#endif

    // Be Vi compatible by default
    p_cp = TRUE;

    // Use POSIX compatibility when $VIM_POSIX is set.
    if (mch_getenv((char_u *)"VIM_POSIX") != NULL)
    {
	set_string_default("cpo", (char_u *)CPO_ALL);
	set_string_default("shm", (char_u *)SHM_POSIX);
    }

    set_init_default_shell();
    set_init_default_backupskip();
    set_init_default_maxmemtot();
    set_init_default_cdpath();
    set_init_default_printencoding();
#ifdef FEAT_POSTSCRIPT
    set_init_default_printexpr();
#endif

    /*
     * Set all the options (except the terminal options) to their default
     * value.  Also set the global value for local options.
     */
    set_options_default(0);

#ifdef UNIX
    set_init_restricted_mode();
#endif

#ifdef CLEAN_RUNTIMEPATH
    if (clean_arg)
	set_init_clean_rtp();
#endif

#ifdef FEAT_GUI
    if (found_reverse_arg)
	set_option_value_give_err((char_u *)"bg", 0L, (char_u *)"dark", 0);
#endif

    curbuf->b_p_initialized = TRUE;
    curbuf->b_p_ar = -1;	// no local 'autoread' value
    curbuf->b_p_ul = NO_LOCAL_UNDOLEVEL;
    check_buf_options(curbuf);
    check_win_options(curwin);
    check_options();

    // Must be before option_expand(), because that one needs vim_isIDc()
    didset_options();

#ifdef FEAT_SPELL
    // Use the current chartab for the generic chartab. This is not in
    // didset_options() because it only depends on 'encoding'.
    init_spell_chartab();
#endif

    set_init_default_encoding();

    // Expand environment variables and things like "~" for the defaults.
    set_init_expand_env();

    save_file_ff(curbuf);	// Buffer is unchanged

#if defined(FEAT_ARABIC)
    // Detect use of mlterm.
    // Mlterm is a terminal emulator akin to xterm that has some special
    // abilities (bidi namely).
    // NOTE: mlterm's author is being asked to 'set' a variable
    //       instead of an environment variable due to inheritance.
    if (mch_getenv((char_u *)"MLTERM") != NULL)
	set_option_value_give_err((char_u *)"tbidi", 1L, NULL, 0);
#endif

    didset_options2();

    set_init_lang_env();

#ifdef FEAT_MULTI_LANG
    // Set the default for 'helplang'.
    set_helplang_default(get_mess_lang());
#endif
}

static char_u *fencs_utf8_default = (char_u *)"ucs-bom,utf-8,default,latin1";

/*
 * Set the "fileencodings" option to the default value for when 'encoding' is
 * utf-8.
 */
    void
set_fencs_unicode(void)
{
    set_string_option_direct((char_u *)"fencs", -1, fencs_utf8_default,
								  OPT_FREE, 0);
}

/*
 * Set an option to its default value.
 * This does not take care of side effects!
 */
    static void
set_option_default(
    int		opt_idx,
    int		opt_flags,	// OPT_FREE, OPT_LOCAL and/or OPT_GLOBAL
    int		compatible)	// use Vi default value
{
    char_u	*varp;		// pointer to variable for current option
    int		dvi;		// index in def_val[]
    long_u	flags;
    long_u	*flagsp;
    int		both = (opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0;

    varp = get_varp_scope(&(options[opt_idx]), both ? OPT_LOCAL : opt_flags);
    flags = options[opt_idx].flags;
    if (varp != NULL)	    // skip hidden option, nothing to do for it
    {
	dvi = ((flags & P_VI_DEF) || compatible) ? VI_DEFAULT : VIM_DEFAULT;
	if (flags & P_STRING)
	{
	    // 'fencs' default value depends on 'encoding'
	    if (options[opt_idx].var == (char_u *)&p_fencs && enc_utf8)
		set_fencs_unicode();
	    // Use set_string_option_direct() for local options to handle
	    // freeing and allocating the value.
	    else if (options[opt_idx].indir != PV_NONE)
		set_string_option_direct(NULL, opt_idx,
				 options[opt_idx].def_val[dvi], opt_flags, 0);
	    else
	    {
		if ((opt_flags & OPT_FREE) && (flags & P_ALLOCED))
		    free_string_option(*(char_u **)(varp));
		*(char_u **)varp = options[opt_idx].def_val[dvi];
		options[opt_idx].flags &= ~P_ALLOCED;
	    }
	}
	else if (flags & P_NUM)
	{
	    if (options[opt_idx].indir == PV_SCROLL)
		win_comp_scroll(curwin);
	    else
	    {
		long def_val = (long)(long_i)options[opt_idx].def_val[dvi];

		if ((long *)varp == &curwin->w_p_so
			|| (long *)varp == &curwin->w_p_siso)
		    // 'scrolloff' and 'sidescrolloff' local values have a
		    // different default value than the global default.
		    *(long *)varp = -1;
		else
		    *(long *)varp = def_val;
		// May also set global value for local option.
		if (both)
		    *(long *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL) =
								def_val;
	    }
	}
	else	// P_BOOL
	{
	    // the cast to long is required for Manx C, long_i is needed for
	    // MSVC
	    *(int *)varp = (int)(long)(long_i)options[opt_idx].def_val[dvi];
#ifdef UNIX
	    // 'modeline' defaults to off for root
	    if (options[opt_idx].indir == PV_ML && getuid() == ROOT_UID)
		*(int *)varp = FALSE;
#endif
	    // May also set global value for local option.
	    if (both)
		*(int *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL) =
								*(int *)varp;
	}

	// The default value is not insecure.
	flagsp = insecure_flag(opt_idx, opt_flags);
	*flagsp = *flagsp & ~P_INSECURE;
    }

#ifdef FEAT_EVAL
    set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
#endif
}

/*
 * Set all options (except terminal options) to their default value.
 * When "opt_flags" is non-zero skip 'encoding'.
 */
    static void
set_options_default(
    int		opt_flags)	// OPT_FREE, OPT_LOCAL and/or OPT_GLOBAL
{
    int		i;
    win_T	*wp;
    tabpage_T	*tp;

    for (i = 0; !istermoption_idx(i); i++)
	if (!(options[i].flags & P_NODEFAULT)
		&& (opt_flags == 0
		    || (options[i].var != (char_u *)&p_enc
# if defined(FEAT_CRYPT)
			&& options[i].var != (char_u *)&p_cm
			&& options[i].var != (char_u *)&p_key
# endif
			)))
	    set_option_default(i, opt_flags, p_cp);

    // The 'scroll' option must be computed for all windows.
    FOR_ALL_TAB_WINDOWS(tp, wp)
	win_comp_scroll(wp);
    parse_cino(curbuf);
}

/*
 * Set the Vi-default value of a string option.
 * Used for 'sh', 'backupskip' and 'term'.
 * When "escape" is TRUE escape spaces with a backslash.
 */
    static void
set_string_default_esc(char *name, char_u *val, int escape)
{
    char_u	*p;
    int		opt_idx;

    if (escape && vim_strchr(val, ' ') != NULL)
	p = vim_strsave_escaped(val, (char_u *)" ");
    else
	p = vim_strsave(val);
    if (p == NULL)		// we don't want a NULL
	return;

    opt_idx = findoption((char_u *)name);
    if (opt_idx < 0)
	return;

    if (options[opt_idx].flags & P_DEF_ALLOCED)
	vim_free(options[opt_idx].def_val[VI_DEFAULT]);
    options[opt_idx].def_val[VI_DEFAULT] = p;
    options[opt_idx].flags |= P_DEF_ALLOCED;
}

    void
set_string_default(char *name, char_u *val)
{
    set_string_default_esc(name, val, FALSE);
}

/*
 * For an option value that contains comma separated items, find "newval" in
 * "origval".  Return NULL if not found.
 */
    static char_u *
find_dup_item(char_u *origval, char_u *newval, long_u flags)
{
    int	    bs = 0;
    size_t  newlen;
    char_u  *s;

    if (origval == NULL)
	return NULL;

    newlen = STRLEN(newval);
    for (s = origval; *s != NUL; ++s)
    {
	if ((!(flags & P_COMMA)
		    || s == origval
		    || (s[-1] == ',' && !(bs & 1)))
		&& STRNCMP(s, newval, newlen) == 0
		&& (!(flags & P_COMMA)
		    || s[newlen] == ','
		    || s[newlen] == NUL))
	    return s;
	// Count backslashes.  Only a comma with an even number of backslashes
	// or a single backslash preceded by a comma before it is recognized as
	// a separator.
	if ((s > origval + 1
		    && s[-1] == '\\'
		    && s[-2] != ',')
		|| (s == origval + 1
		    && s[-1] == '\\'))
	    ++bs;
	else
	    bs = 0;
    }
    return NULL;
}

/*
 * Set the Vi-default value of a number option.
 * Used for 'lines' and 'columns'.
 */
    void
set_number_default(char *name, long val)
{
    int		opt_idx;

    opt_idx = findoption((char_u *)name);
    if (opt_idx >= 0)
	options[opt_idx].def_val[VI_DEFAULT] = (char_u *)(long_i)val;
}

#if defined(FEAT_PROP_POPUP) || defined(PROTO)
/*
 * Set all window-local and buffer-local options to the Vim default.
 * local-global options will use the global value.
 * When "do_buffer" is FALSE don't set buffer-local options.
 */
    void
set_local_options_default(win_T *wp, int do_buffer)
{
    win_T	*save_curwin = curwin;
    int		i;

    curwin = wp;
    curbuf = curwin->w_buffer;
    block_autocmds();

    for (i = 0; !istermoption_idx(i); i++)
    {
	struct vimoption    *p = &(options[i]);
	char_u		    *varp = get_varp_scope(p, OPT_LOCAL);

	if (p->indir != PV_NONE
		&& (do_buffer || (p->indir & PV_BUF) == 0)
		&& !(options[i].flags & P_NODEFAULT)
		&& !optval_default(p, varp, FALSE))
	    set_option_default(i, OPT_FREE|OPT_LOCAL, FALSE);
    }

    unblock_autocmds();
    curwin = save_curwin;
    curbuf = curwin->w_buffer;
}
#endif

#if defined(EXITFREE) || defined(PROTO)
/*
 * Free all options.
 */
    void
free_all_options(void)
{
    int		i;

    for (i = 0; !istermoption_idx(i); i++)
    {
	if (options[i].indir == PV_NONE)
	{
	    // global option: free value and default value.
	    if ((options[i].flags & P_ALLOCED) && options[i].var != NULL)
		free_string_option(*(char_u **)options[i].var);
	    if (options[i].flags & P_DEF_ALLOCED)
		free_string_option(options[i].def_val[VI_DEFAULT]);
	}
	else if (options[i].var != VAR_WIN
		&& (options[i].flags & P_STRING))
	    // buffer-local option: free global value
	    clear_string_option((char_u **)options[i].var);
    }
    free_operatorfunc_option();
    free_tagfunc_option();
}
#endif


/*
 * Initialize the options, part two: After getting Rows and Columns and
 * setting 'term'.
 */
    void
set_init_2(void)
{
    int		idx;

    // 'scroll' defaults to half the window height. The stored default is zero,
    // which results in the actual value computed from the window height.
    idx = findoption((char_u *)"scroll");
    if (idx >= 0 && !(options[idx].flags & P_WAS_SET))
	set_option_default(idx, OPT_LOCAL, p_cp);
    comp_col();

    // 'window' is only for backwards compatibility with Vi.
    // Default is Rows - 1.
    if (!option_was_set((char_u *)"window"))
	p_window = Rows - 1;
    set_number_default("window", Rows - 1);

    // For DOS console the default is always black.
#if !((defined(MSWIN)) && !defined(FEAT_GUI))
    // If 'background' wasn't set by the user, try guessing the value,
    // depending on the terminal name.  Only need to check for terminals
    // with a dark background, that can handle color.
    idx = findoption((char_u *)"bg");
    if (idx >= 0 && !(options[idx].flags & P_WAS_SET)
						 && *term_bg_default() == 'd')
    {
	set_string_option_direct(NULL, idx, (char_u *)"dark", OPT_FREE, 0);
	// don't mark it as set, when starting the GUI it may be
	// changed again
	options[idx].flags &= ~P_WAS_SET;
    }
#endif

#ifdef CURSOR_SHAPE
    parse_shape_opt(SHAPE_CURSOR);	// set cursor shapes from 'guicursor'
#endif
#ifdef FEAT_MOUSESHAPE
    parse_shape_opt(SHAPE_MOUSE);	// set mouse shapes from 'mouseshape'
#endif
#ifdef FEAT_PRINTER
    (void)parse_printoptions(NULL);	// parse 'printoptions' default value
#endif
}

/*
 * Initialize the options, part three: After reading the .vimrc
 */
    void
set_init_3(void)
{
#if defined(UNIX) || defined(MSWIN)
/*
 * Set 'shellpipe' and 'shellredir', depending on the 'shell' option.
 * This is done after other initializations, where 'shell' might have been
 * set, but only if they have not been set before.
 */
    char_u  *p;
    int	    idx_srr;
    int	    do_srr;
# ifdef FEAT_QUICKFIX
    int	    idx_sp;
    int	    do_sp;
# endif

    idx_srr = findoption((char_u *)"srr");
    if (idx_srr < 0)
	do_srr = FALSE;
    else
	do_srr = !(options[idx_srr].flags & P_WAS_SET);
# ifdef FEAT_QUICKFIX
    idx_sp = findoption((char_u *)"sp");
    if (idx_sp < 0)
	do_sp = FALSE;
    else
	do_sp = !(options[idx_sp].flags & P_WAS_SET);
# endif
    p = get_isolated_shell_name();
    if (p != NULL)
    {
	// Default for p_sp is "| tee", for p_srr is ">".
	// For known shells it is changed here to include stderr.
	if (	   fnamecmp(p, "csh") == 0
		|| fnamecmp(p, "tcsh") == 0
# if defined(MSWIN)	// also check with .exe extension
		|| fnamecmp(p, "csh.exe") == 0
		|| fnamecmp(p, "tcsh.exe") == 0
# endif
	   )
	{
# if defined(FEAT_QUICKFIX)
	    if (do_sp)
	    {
#  ifdef MSWIN
		p_sp = (char_u *)">&";
#  else
		p_sp = (char_u *)"|& tee";
#  endif
		options[idx_sp].def_val[VI_DEFAULT] = p_sp;
	    }
# endif
	    if (do_srr)
	    {
		p_srr = (char_u *)">&";
		options[idx_srr].def_val[VI_DEFAULT] = p_srr;
	    }
	}
# ifdef MSWIN
	// Windows PowerShell output is UTF-16 with BOM so re-encode to the
	// current codepage.
	else if (   fnamecmp(p, "powershell") == 0
		    || fnamecmp(p, "powershell.exe") == 0
		)
	{
# if defined(FEAT_QUICKFIX)
		if (do_sp)
		{
		    p_sp = (char_u *)"2>&1 | Out-File -Encoding default";
		    options[idx_sp].def_val[VI_DEFAULT] = p_sp;
		}
# endif
		if (do_srr)
		{
		    p_srr = (char_u *)"2>&1 | Out-File -Encoding default";
		    options[idx_srr].def_val[VI_DEFAULT] = p_srr;
		}
	}
#endif
	else
	    // Always use POSIX shell style redirection if we reach this
	    if (       fnamecmp(p, "sh") == 0
		    || fnamecmp(p, "ksh") == 0
		    || fnamecmp(p, "mksh") == 0
		    || fnamecmp(p, "pdksh") == 0
		    || fnamecmp(p, "zsh") == 0
		    || fnamecmp(p, "zsh-beta") == 0
		    || fnamecmp(p, "bash") == 0
		    || fnamecmp(p, "fish") == 0
		    || fnamecmp(p, "ash") == 0
		    || fnamecmp(p, "dash") == 0
		    || fnamecmp(p, "pwsh") == 0
# ifdef MSWIN
		    || fnamecmp(p, "cmd") == 0
		    || fnamecmp(p, "sh.exe") == 0
		    || fnamecmp(p, "ksh.exe") == 0
		    || fnamecmp(p, "mksh.exe") == 0
		    || fnamecmp(p, "pdksh.exe") == 0
		    || fnamecmp(p, "zsh.exe") == 0
		    || fnamecmp(p, "zsh-beta.exe") == 0
		    || fnamecmp(p, "bash.exe") == 0
		    || fnamecmp(p, "cmd.exe") == 0
		    || fnamecmp(p, "dash.exe") == 0
		    || fnamecmp(p, "pwsh.exe") == 0
# endif
		    )
	    {
# if defined(FEAT_QUICKFIX)
		if (do_sp)
		{
#  ifdef MSWIN
		    p_sp = (char_u *)">%s 2>&1";
#  else
		    if (fnamecmp(p, "pwsh") == 0)
			p_sp = (char_u *)">%s 2>&1";
		    else
			p_sp = (char_u *)"2>&1| tee";
#  endif
		    options[idx_sp].def_val[VI_DEFAULT] = p_sp;
		}
# endif
		if (do_srr)
		{
		    p_srr = (char_u *)">%s 2>&1";
		    options[idx_srr].def_val[VI_DEFAULT] = p_srr;
		}
	    }
	vim_free(p);
    }
#endif

#if defined(MSWIN)
    /*
     * Set 'shellcmdflag', 'shellxquote', and 'shellquote' depending on the
     * 'shell' option.
     * This is done after other initializations, where 'shell' might have been
     * set, but only if they have not been set before.
     * Default values depend on shell (cmd.exe is default shell):
     *
     *			    p_shcf	p_sxq
     * cmd.exe		-   "/c"	"("
     * powershell.exe   -   "-Command"	"\""
     * pwsh.exe		-   "-c"	"\""
     * "sh" like shells -   "-c"	"\""
     *
     * For Win32 p_sxq is set instead of p_shq to include shell redirection.
     */
    if (strstr((char *)gettail(p_sh), "powershell") != NULL)
    {
	int	idx_opt;

	idx_opt = findoption((char_u *)"shcf");
	if (idx_opt >= 0 && !(options[idx_opt].flags & P_WAS_SET))
	{
	    p_shcf = (char_u*)"-Command";
	    options[idx_opt].def_val[VI_DEFAULT] = p_shcf;
	}

	idx_opt = findoption((char_u *)"sxq");
	if (idx_opt >= 0 && !(options[idx_opt].flags & P_WAS_SET))
	{
	    p_sxq = (char_u*)"\"";
	    options[idx_opt].def_val[VI_DEFAULT] = p_sxq;
	}
    }
    else if (strstr((char *)gettail(p_sh), "sh") != NULL)
    {
	int	idx3;

	idx3 = findoption((char_u *)"shcf");
	if (idx3 >= 0 && !(options[idx3].flags & P_WAS_SET))
	{
	    p_shcf = (char_u *)"-c";
	    options[idx3].def_val[VI_DEFAULT] = p_shcf;
	}

	// Somehow Win32 requires the quotes around the redirection too
	idx3 = findoption((char_u *)"sxq");
	if (idx3 >= 0 && !(options[idx3].flags & P_WAS_SET))
	{
	    p_sxq = (char_u *)"\"";
	    options[idx3].def_val[VI_DEFAULT] = p_sxq;
	}
    }
    else if (strstr((char *)gettail(p_sh), "cmd.exe") != NULL)
    {
	int	idx3;

	/*
	 * cmd.exe on Windows will strip the first and last double quote given
	 * on the command line, e.g. most of the time things like:
	 *   cmd /c "my path/to/echo" "my args to echo"
	 * become:
	 *   my path/to/echo" "my args to echo
	 * when executed.
	 *
	 * To avoid this, set shellxquote to surround the command in
	 * parenthesis.  This appears to make most commands work, without
	 * breaking commands that worked previously, such as
	 * '"path with spaces/cmd" "a&b"'.
	 */
	idx3 = findoption((char_u *)"sxq");
	if (idx3 >= 0 && !(options[idx3].flags & P_WAS_SET))
	{
	    p_sxq = (char_u *)"(";
	    options[idx3].def_val[VI_DEFAULT] = p_sxq;
	}

	idx3 = findoption((char_u *)"shcf");
	if (idx3 >= 0 && !(options[idx3].flags & P_WAS_SET))
	{
	    p_shcf = (char_u *)"/c";
	    options[idx3].def_val[VI_DEFAULT] = p_shcf;
	}
    }
#endif

    if (BUFEMPTY())
    {
	int idx_ffs = findoption((char_u *)"ffs");

	// Apply the first entry of 'fileformats' to the initial buffer.
	if (idx_ffs >= 0 && (options[idx_ffs].flags & P_WAS_SET))
	    set_fileformat(default_fileformat(), OPT_LOCAL);
    }

    set_title_defaults();
}

#if defined(FEAT_MULTI_LANG) || defined(PROTO)
/*
 * When 'helplang' is still at its default value, set it to "lang".
 * Only the first two characters of "lang" are used.
 */
    void
set_helplang_default(char_u *lang)
{
    int		idx;

    if (lang == NULL || STRLEN(lang) < 2)	// safety check
	return;
    idx = findoption((char_u *)"hlg");
    if (idx < 0 || (options[idx].flags & P_WAS_SET))
	return;

    if (options[idx].flags & P_ALLOCED)
	free_string_option(p_hlg);
    p_hlg = vim_strsave(lang);
    if (p_hlg == NULL)
	p_hlg = empty_option;
    else
    {
	// zh_CN becomes "cn", zh_TW becomes "tw"
	if (STRNICMP(p_hlg, "zh_", 3) == 0 && STRLEN(p_hlg) >= 5)
	{
	    p_hlg[0] = TOLOWER_ASC(p_hlg[3]);
	    p_hlg[1] = TOLOWER_ASC(p_hlg[4]);
	}
	// any C like setting, such as C.UTF-8, becomes "en"
	else if (STRLEN(p_hlg) >= 1 && *p_hlg == 'C')
	{
	    p_hlg[0] = 'e';
	    p_hlg[1] = 'n';
	}
	p_hlg[2] = NUL;
    }
    options[idx].flags |= P_ALLOCED;
}
#endif

/*
 * 'title' and 'icon' only default to true if they have not been set or reset
 * in .vimrc and we can read the old value.
 * When 'title' and 'icon' have been reset in .vimrc, we won't even check if
 * they can be reset.  This reduces startup time when using X on a remote
 * machine.
 */
    void
set_title_defaults(void)
{
    int	    idx1;
    long    val;

    // If GUI is (going to be) used, we can always set the window title and
    // icon name.  Saves a bit of time, because the X11 display server does
    // not need to be contacted.
    idx1 = findoption((char_u *)"title");
    if (idx1 >= 0 && !(options[idx1].flags & P_WAS_SET))
    {
#ifdef FEAT_GUI
	if (gui.starting || gui.in_use)
	    val = TRUE;
	else
#endif
	    val = mch_can_restore_title();
	options[idx1].def_val[VI_DEFAULT] = (char_u *)(long_i)val;
	p_title = val;
    }
    idx1 = findoption((char_u *)"icon");
    if (idx1 < 0 || (options[idx1].flags & P_WAS_SET))
    {
	return;
    }

#ifdef FEAT_GUI
    if (gui.starting || gui.in_use)
	val = TRUE;
    else
#endif
	val = mch_can_restore_icon();
    options[idx1].def_val[VI_DEFAULT] = (char_u *)(long_i)val;
    p_icon = val;
}

    void
ex_set(exarg_T *eap)
{
    int		flags = 0;

    if (eap->cmdidx == CMD_setlocal)
	flags = OPT_LOCAL;
    else if (eap->cmdidx == CMD_setglobal)
	flags = OPT_GLOBAL;
#if defined(FEAT_EVAL) && defined(FEAT_BROWSE)
    if ((cmdmod.cmod_flags & CMOD_BROWSE) && flags == 0)
	ex_options(eap);
    else
#endif
    {
	if (eap->forceit)
	    flags |= OPT_ONECOLUMN;
	(void)do_set(eap->arg, flags);
    }
}

/*
 * :set boolean option prefix
 */
typedef enum {
    PREFIX_NO = 0,	// "no" prefix
    PREFIX_NONE,	// no prefix
    PREFIX_INV,		// "inv" prefix
} set_prefix_T;

/*
 * Return the prefix type for the option name in *argp.
 */
    static set_prefix_T
get_option_prefix(char_u **argp)
{
    int		prefix = PREFIX_NONE;
    char_u	*arg = *argp;

    if (STRNCMP(arg, "no", 2) == 0 && STRNCMP(arg, "novice", 6) != 0)
    {
	prefix = PREFIX_NO;
	arg += 2;
    }
    else if (STRNCMP(arg, "inv", 3) == 0)
    {
	prefix = PREFIX_INV;
	arg += 3;
    }

    *argp = arg;
    return prefix;
}

/*
 * Parse the option name in "arg" and return the option index in "*opt_idxp",
 * and the option name length in "*lenp".  For a <t_xx> option, return the key
 * number in "*keyp".
 *
 * Returns FAIL if an option starting with "<" doesn't end with a ">",
 * otherwise returns OK.
 */
    static int
parse_option_name(char_u *arg, int *opt_idxp, int *lenp, int *keyp)
{
    int	key = 0;
    int	len;
    int	opt_idx;

    if (*arg == '<')
    {
	opt_idx = -1;
	// look out for <t_>;>
	if (arg[1] == 't' && arg[2] == '_' && arg[3] && arg[4])
	    len = 5;
	else
	{
	    len = 1;
	    while (arg[len] != NUL && arg[len] != '>')
		++len;
	}
	if (arg[len] != '>')
	    return FAIL;

	arg[len] = NUL;			    // put NUL after name
	if (arg[1] == 't' && arg[2] == '_') // could be term code
	    opt_idx = findoption(arg + 1);
	arg[len++] = '>';		    // restore '>'
	if (opt_idx == -1)
	    key = find_key_option(arg + 1, TRUE);
    }
    else
    {
	int	nextchar;   // next non-white char after option name

	len = 0;
	// The two characters after "t_" may not be alphanumeric.
	if (arg[0] == 't' && arg[1] == '_' && arg[2] && arg[3])
	    len = 4;
	else
	    while (ASCII_ISALNUM(arg[len]) || arg[len] == '_')
		++len;
	nextchar = arg[len];
	arg[len] = NUL;			    // put NUL after name
	opt_idx = findoption(arg);
	arg[len] = nextchar;		    // restore nextchar
	if (opt_idx == -1)
	    key = find_key_option(arg, FALSE);
    }

    *keyp = key;
    *lenp = len;
    *opt_idxp = opt_idx;

    return OK;
}

/*
 * Get the option operator (+=, ^=, -=).
 */
    static set_op_T
get_opt_op(char_u *arg)
{
    set_op_T op = OP_NONE;

    if (*arg != NUL && *(arg + 1) == '=')
    {
	if (*arg == '+')
	    op = OP_ADDING;		// "+="
	else if (*arg == '^')
	    op = OP_PREPENDING;		// "^="
	else if (*arg == '-')
	    op = OP_REMOVING;		// "-="
    }

    return op;
}

/*
 * Validate whether the value of the option in "opt_idx" can be changed.
 * Returns FAIL if the option can be skipped or cannot be changed. Returns OK
 * if it can be changed.
 */
    static int
validate_opt_idx(int opt_idx, int opt_flags, long_u flags, char **errmsg)
{
    // Skip all options that are not window-local (used when showing
    // an already loaded buffer in a window).
    if ((opt_flags & OPT_WINONLY)
	    && (opt_idx < 0 || options[opt_idx].var != VAR_WIN))
	return FAIL;

    // Skip all options that are window-local (used for :vimgrep).
    if ((opt_flags & OPT_NOWIN) && opt_idx >= 0
	    && options[opt_idx].var == VAR_WIN)
	return FAIL;

    // Disallow changing some options from modelines.
    if (opt_flags & OPT_MODELINE)
    {
	if (flags & (P_SECURE | P_NO_ML))
	{
	    *errmsg = e_not_allowed_in_modeline;
	    return FAIL;
	}
	if ((flags & P_MLE) && !p_mle)
	{
	    *errmsg = e_not_allowed_in_modeline_when_modelineexpr_is_off;
	    return FAIL;
	}
#ifdef FEAT_DIFF
	// In diff mode some options are overruled.  This avoids that
	// 'foldmethod' becomes "marker" instead of "diff" and that
	// "wrap" gets set.
	if (curwin->w_p_diff
		&& opt_idx >= 0  // shut up coverity warning
		&& (
# ifdef FEAT_FOLDING
		    options[opt_idx].indir == PV_FDM ||
# endif
		    options[opt_idx].indir == PV_WRAP))
	    return FAIL;
#endif
    }

#ifdef HAVE_SANDBOX
    // Disallow changing some options in the sandbox
    if (sandbox != 0 && (flags & P_SECURE))
    {
	*errmsg = e_not_allowed_in_sandbox;
	return FAIL;
    }
#endif

    return OK;
}

/*
 * Get the Vim/Vi default value for a string option.
 */
    static char_u *
stropt_get_default_val(
    int		opt_idx,
    char_u	*varp,
    int		flags,
    int		cp_val)
{
    char_u	*newval;

    newval = options[opt_idx].def_val[((flags & P_VI_DEF) || cp_val)
	? VI_DEFAULT : VIM_DEFAULT];
    if ((char_u **)varp == &p_bg)
    {
	// guess the value of 'background'
#ifdef FEAT_GUI
	if (gui.in_use)
	    newval = gui_bg_default();
	else
#endif
	    newval = term_bg_default();
    }
    else if ((char_u **)varp == &p_fencs && enc_utf8)
	newval = fencs_utf8_default;

    // expand environment variables and ~ since the default value was
    // already expanded, only required when an environment variable was set
    // later
    if (newval == NULL)
	newval = empty_option;
    else
    {
	char_u *s = option_expand(opt_idx, newval);
	if (s == NULL)
	    s = newval;
	newval = vim_strsave(s);
    }

    return newval;
}

/*
 * Convert the 'backspace' option number value to a string: for adding,
 * prepending and removing string.
 */
    static void
opt_backspace_nr2str(
    char_u	*varp,
    char_u	**origval_p,
    char_u	**origval_l_p,
    char_u	**origval_g_p,
    char_u	**oldval_p)
{
    int		i = getdigits((char_u **)varp);

    switch (i)
    {
	case 0:
	    *(char_u **)varp = empty_option;
	    break;
	case 1:
	    *(char_u **)varp = vim_strsave((char_u *)"indent,eol");
	    break;
	case 2:
	    *(char_u **)varp = vim_strsave((char_u *)"indent,eol,start");
	    break;
	case 3:
	    *(char_u **)varp = vim_strsave((char_u *)"indent,eol,nostop");
	    break;
    }
    vim_free(*oldval_p);
    if (*origval_p == *oldval_p)
	*origval_p = *(char_u **)varp;
    if (*origval_l_p == *oldval_p)
	*origval_l_p = *(char_u **)varp;
    if (*origval_g_p == *oldval_p)
	*origval_g_p = *(char_u **)varp;
    *oldval_p = *(char_u **)varp;
}

/*
 * Convert the 'whichwrap' option number value to a string, for backwards
 * compatibility with Vim 3.0.
 * Note: 'argp' is a pointer to a char_u pointer and is updated.
 */
    static char_u *
opt_whichwrap_nr2str(char_u **argp, char_u *whichwrap)
{
    *whichwrap = NUL;
    int i = getdigits(argp);
    if (i & 1)
	STRCAT(whichwrap, "b,");
    if (i & 2)
	STRCAT(whichwrap, "s,");
    if (i & 4)
	STRCAT(whichwrap, "h,l,");
    if (i & 8)
	STRCAT(whichwrap, "<,>,");
    if (i & 16)
	STRCAT(whichwrap, "[,],");
    if (*whichwrap != NUL)	// remove trailing ,
	whichwrap[STRLEN(whichwrap) - 1] = NUL;

    return whichwrap;
}

/*
 * Copy the new string value into allocated memory for the option.
 * Can't use set_string_option_direct(), because we need to remove the
 * backslashes.
 */
    static char_u *
stropt_copy_value(
    char_u	*origval,
    char_u	**argp,
    set_op_T	op,
    int		flags UNUSED)
{
    char_u	*arg = *argp;
    unsigned	newlen;
    char_u	*newval;
    char_u	*s = NULL;

    // get a bit too much
    newlen = (unsigned)STRLEN(arg) + 1;
    if (op != OP_NONE)
	newlen += (unsigned)STRLEN(origval) + 1;
    newval = alloc(newlen);
    if (newval == NULL)  // out of mem, don't change
	return NULL;
    s = newval;

    // Copy the string, skip over escaped chars.
    // For MS-DOS and WIN32 backslashes before normal file name characters
    // are not removed, and keep backslash at start, for "\\machine\path",
    // but do remove it for "\\\\machine\\path".
    // The reverse is found in escape_option_str_cmdline().
    while (*arg != NUL && !VIM_ISWHITE(*arg))
    {
	int i;

	if (*arg == '\\' && arg[1] != NUL
#ifdef BACKSLASH_IN_FILENAME
		&& !((flags & P_EXPAND)
		    && vim_isfilec(arg[1])
		    && !VIM_ISWHITE(arg[1])
		    && (arg[1] != '\\'
			|| (s == newval && arg[2] != '\\')))
#endif
	   )
	    ++arg;	// remove backslash
	if (has_mbyte && (i = (*mb_ptr2len)(arg)) > 1)
	{
	    // copy multibyte char
	    mch_memmove(s, arg, (size_t)i);
	    arg += i;
	    s += i;
	}
	else
	    *s++ = *arg++;
    }
    *s = NUL;

    *argp = arg;
    return newval;
}

/*
 * Expand environment variables and ~ in string option value 'newval'.
 */
    static char_u *
stropt_expand_envvar(
    int		opt_idx,
    char_u	*origval,
    char_u	*newval,
    set_op_T	op)
{
    char_u *s = option_expand(opt_idx, newval);
    if (s == NULL)
	return newval;

    vim_free(newval);
    unsigned newlen = (unsigned)STRLEN(s) + 1;
    if (op != OP_NONE)
	newlen += (unsigned)STRLEN(origval) + 1;

    newval = alloc(newlen);
    if (newval == NULL)
	return NULL;

    STRCPY(newval, s);

    return newval;
}

/*
 * Concatenate the original and new values of a string option, adding a "," if
 * needed.
 */
    static void
stropt_concat_with_comma(
    char_u	*origval,
    char_u	*newval,
    set_op_T	op,
    int		flags)
{
    int		len = 0;

    int comma = ((flags & P_COMMA) && *origval != NUL && *newval != NUL);
    if (op == OP_ADDING)
    {
	len = (int)STRLEN(origval);
	// strip a trailing comma, would get 2
	if (comma && len > 1
		&& (flags & P_ONECOMMA) == P_ONECOMMA
		&& origval[len - 1] == ','
		&& origval[len - 2] != '\\')
	    len--;
	mch_memmove(newval + len + comma, newval, STRLEN(newval) + 1);
	mch_memmove(newval, origval, (size_t)len);
    }
    else
    {
	len = (int)STRLEN(newval);
	STRMOVE(newval + len + comma, origval);
    }
    if (comma)
	newval[len] = ',';
}

/*
 * Remove a value from a string option.  Copy string option value in "origval"
 * to "newval" and then remove the string "strval" of length "len".
 */
    static void
stropt_remove_val(
    char_u	*origval,
    char_u	*newval,
    int		flags,
    char_u	*strval,
    int		len)
{
    // Remove newval[] from origval[]. (Note: "len" has been set above
    // and is used here).
    STRCPY(newval, origval);
    if (*strval)
    {
	// may need to remove a comma
	if (flags & P_COMMA)
	{
	    if (strval == origval)
	    {
		// include comma after string
		if (strval[len] == ',')
		    ++len;
	    }
	    else
	    {
		// include comma before string
		--strval;
		++len;
	    }
	}
	STRMOVE(newval + (strval - origval), strval + len);
    }
}

/*
 * Remove flags that appear twice in the string option value 'newval'.
 */
    static void
stropt_remove_dupflags(char_u *newval, int flags)
{
    char_u	*s = newval;

    // Remove flags that appear twice.
    while (*s)
    {
	// if options have P_FLAGLIST and P_ONECOMMA such as 'whichwrap'
	if (flags & P_ONECOMMA)
	{
	    if (*s != ',' && *(s + 1) == ',' && vim_strchr(s + 2, *s) != NULL)
	    {
		// Remove the duplicated value and the next comma.
		STRMOVE(s, s + 2);
		continue;
	    }
	}
	else
	{
	    if ((!(flags & P_COMMA) || *s != ',')
		    && vim_strchr(s + 1, *s) != NULL)
	    {
		STRMOVE(s, s + 1);
		continue;
	    }
	}
	++s;
    }
}

/*
 * Get the string value specified for a ":set" command.  The following set
 * options are supported:
 *	set {opt}&
 *	set {opt}<
 *	set {opt}={val}
 *	set {opt}:{val}
 */
    static char_u *
stropt_get_newval(
    int		nextchar,
    int		opt_idx,
    char_u	**argp,
    char_u	*varp,
    char_u	**origval_arg,
    char_u	**origval_l_arg,
    char_u	**origval_g_arg,
    char_u	**oldval_arg,
    set_op_T    *op_arg,
    int		flags,
    int		cp_val)
{
    char_u	*arg = *argp;
    char_u	*origval = *origval_arg;
    char_u	*origval_l = *origval_l_arg;
    char_u	*origval_g = *origval_g_arg;
    char_u	*oldval = *oldval_arg;
    set_op_T    op = *op_arg;
    char_u	*save_arg = NULL;
    char_u	*newval;
    char_u	*s = NULL;
    char_u	whichwrap[80];

    if (nextchar == '&')	// set to default val
	newval = stropt_get_default_val(opt_idx, varp, flags, cp_val);
    else if (nextchar == '<')	// set to global val
	newval = vim_strsave(*(char_u **)get_varp_scope(
					     &(options[opt_idx]), OPT_GLOBAL));
    else
    {
	++arg;	// jump to after the '=' or ':'

	// Set 'keywordprg' to ":help" if an empty
	// value was passed to :set by the user.
	if (varp == (char_u *)&p_kp && (*arg == NUL || *arg == ' '))
	{
	    save_arg = arg;
	    arg = (char_u *)":help";
	}
	// Convert 'backspace' number to string
	else if (varp == (char_u *)&p_bs && VIM_ISDIGIT(**(char_u **)varp))
	    opt_backspace_nr2str(varp, &origval, &origval_l, &origval_g,
								&oldval);
	else if (varp == (char_u *)&p_ww && VIM_ISDIGIT(*arg))
	{
	    // Convert 'whichwrap' number to string, for backwards
	    // compatibility with Vim 3.0.
	    char_u *t = opt_whichwrap_nr2str(&arg, whichwrap);
	    save_arg = arg;
	    arg = t;
	}
	// Remove '>' before 'dir' and 'bdir', for backwards compatibility with
	// version 3.0
	else if (*arg == '>' && (varp == (char_u *)&p_dir
		    || varp == (char_u *)&p_bdir))
	    ++arg;

	// Copy the new string into allocated memory.
	newval = stropt_copy_value(origval, &arg, op, flags);
	if (newval == NULL)
	    goto done;

	// Expand environment variables and ~.
	// Don't do it when adding without inserting a comma.
	if (op == OP_NONE || (flags & P_COMMA))
	{
	    newval = stropt_expand_envvar(opt_idx, origval, newval, op);
	    if (newval == NULL)
		goto done;
	}

	// locate newval[] in origval[] when removing it and when adding to
	// avoid duplicates
	int len = 0;
	if (op == OP_REMOVING || (flags & P_NODUP))
	{
	    len = (int)STRLEN(newval);
	    s = find_dup_item(origval, newval, flags);

	    // do not add if already there
	    if ((op == OP_ADDING || op == OP_PREPENDING) && s != NULL)
	    {
		op = OP_NONE;
		STRCPY(newval, origval);
	    }

	    // if no duplicate, move pointer to end of original value
	    if (s == NULL)
		s = origval + (int)STRLEN(origval);
	}

	// concatenate the two strings; add a ',' if needed
	if (op == OP_ADDING || op == OP_PREPENDING)
	    stropt_concat_with_comma(origval, newval, op, flags);
	else if (op == OP_REMOVING)
	    // Remove newval[] from origval[]. (Note: "len" has been set above
	    // and is used here).
	    stropt_remove_val(origval, newval, flags, s, len);

	if (flags & P_FLAGLIST)
	    // Remove flags that appear twice.
	    stropt_remove_dupflags(newval, flags);
    }

done:
    if (save_arg != NULL)
	arg = save_arg;  // arg was temporarily changed, restore it
    *argp = arg;
    *origval_arg = origval;
    *origval_l_arg = origval_l;
    *origval_g_arg = origval_g;
    *oldval_arg = oldval;
    *op_arg = op;

    return newval;
}

/*
 * Part of do_set() for string options.
 * Returns FAIL on failure, do not process further options.
 */
    static int
do_set_option_string(
	int	    opt_idx,
	int	    opt_flags,
	char_u	    **argp,
	int	    nextchar,
	set_op_T    op_arg,
	long_u	    flags,
	int	    cp_val,
	char_u	    *varp_arg,
	char	    *errbuf,
	size_t	    errbuflen,
	int	    *value_checked,
	char	    **errmsg)
{
    char_u	*arg = *argp;
    set_op_T    op = op_arg;
    char_u	*varp = varp_arg;
    char_u	*oldval = NULL; // previous value if *varp
    char_u	*newval;
    char_u	*origval = NULL;
    char_u	*origval_l = NULL;
    char_u	*origval_g = NULL;
#if defined(FEAT_EVAL)
    char_u	*saved_origval = NULL;
    char_u	*saved_origval_l = NULL;
    char_u	*saved_origval_g = NULL;
    char_u	*saved_newval = NULL;
#endif

    // When using ":set opt=val" for a global option
    // with a local value the local value will be
    // reset, use the global value here.
    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0
	    && ((int)options[opt_idx].indir & PV_BOTH))
	varp = options[opt_idx].var;

    // The old value is kept until we are sure that the new value is valid.
    oldval = *(char_u **)varp;

    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
    {
	origval_l = *(char_u **)get_varp_scope(
			   &(options[opt_idx]), OPT_LOCAL);
	origval_g = *(char_u **)get_varp_scope(
			  &(options[opt_idx]), OPT_GLOBAL);

	// A global-local string option might have an empty option as value to
	// indicate that the global value should be used.
	if (((int)options[opt_idx].indir & PV_BOTH)
						  && origval_l == empty_option)
	    origval_l = origval_g;
    }

    // When setting the local value of a global option, the old value may be
    // the global value.
    if (((int)options[opt_idx].indir & PV_BOTH) && (opt_flags & OPT_LOCAL))
	origval = *(char_u **)get_varp(&options[opt_idx]);
    else
	origval = oldval;

    // Get the new value for the option
    newval = stropt_get_newval(nextchar, opt_idx, &arg, varp, &origval,
				&origval_l, &origval_g, &oldval, &op, flags,
				cp_val);

    // Set the new value.
    *(char_u **)(varp) = newval;
    if (newval == NULL)
	*(char_u **)(varp) = empty_option;

#if defined(FEAT_EVAL)
    if (!starting
# ifdef FEAT_CRYPT
	    && options[opt_idx].indir != PV_KEY
# endif
		      && origval != NULL && newval != NULL)
    {
	// origval may be freed by did_set_string_option(), make a copy.
	saved_origval = vim_strsave(origval);
	// newval (and varp) may become invalid if the buffer is closed by
	// autocommands.
	saved_newval = vim_strsave(newval);
	if (origval_l != NULL)
	    saved_origval_l = vim_strsave(origval_l);
	if (origval_g != NULL)
	    saved_origval_g = vim_strsave(origval_g);
    }
#endif

    {
	long_u	*p = insecure_flag(opt_idx, opt_flags);
	int	secure_saved = secure;

	// When an option is set in the sandbox, from a modeline or in secure
	// mode, then deal with side effects in secure mode.  Also when the
	// value was set with the P_INSECURE flag and is not completely
	// replaced.
	if ((opt_flags & OPT_MODELINE)
#ifdef HAVE_SANDBOX
	      || sandbox != 0
#endif
	      || (op != OP_NONE && (*p & P_INSECURE)))
	    secure = 1;

	// Handle side effects, and set the global value for ":set" on local
	// options. Note: when setting 'syntax' or 'filetype' autocommands may
	// be triggered that can cause havoc.
	*errmsg = did_set_string_option(
			opt_idx, (char_u **)varp, oldval, newval, errbuf,
			errbuflen, opt_flags, op, value_checked);

	secure = secure_saved;
    }

#if defined(FEAT_EVAL)
    if (*errmsg == NULL)
	trigger_optionset_string(opt_idx, opt_flags, saved_origval,
			       saved_origval_l, saved_origval_g, saved_newval);
    vim_free(saved_origval);
    vim_free(saved_origval_l);
    vim_free(saved_origval_g);
    vim_free(saved_newval);
#endif

    *argp = arg;
    return *errmsg == NULL ? OK : FAIL;
}

/*
 * Set a boolean option.
 * Returns an untranslated error message or NULL.
 */
    static char *
do_set_option_bool(
    int		opt_idx,
    int		opt_flags,
    set_prefix_T prefix,
    long_u	flags,
    char_u	*varp,
    int		nextchar,
    int		afterchar,
    int		cp_val)

{
    varnumber_T	value;

    if (nextchar == '=' || nextchar == ':')
	return e_invalid_argument;
    if (opt_idx < 0 || varp == NULL)
	return NULL;  // "cannot happen"

    // ":set opt!": invert
    // ":set opt&": reset to default value
    // ":set opt<": reset to global value
    if (nextchar == '!')
	value = *(int *)(varp) ^ 1;
    else if (nextchar == '&')
	value = (int)(long)(long_i)options[opt_idx].def_val[
	    ((flags & P_VI_DEF) || cp_val) ? VI_DEFAULT : VIM_DEFAULT];
    else if (nextchar == '<')
    {
	// For 'autoread' -1 means to use global value.
	if ((int *)varp == &curbuf->b_p_ar && opt_flags == OPT_LOCAL)
	    value = -1;
	else
	    value = *(int *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
    }
    else
    {
	// ":set invopt": invert
	// ":set opt" or ":set noopt": set or reset
	if (nextchar != NUL && !VIM_ISWHITE(afterchar))
	    return e_trailing_characters;
	if (prefix == PREFIX_INV)
	    value = *(int *)(varp) ^ 1;
	else
	    value = prefix == PREFIX_NO ? 0 : 1;
    }

    return set_bool_option(opt_idx, varp, (int)value, opt_flags);
}

/*
 * Set a numeric option.
 * Returns an untranslated error message or NULL.
 */
    static char *
do_set_option_numeric(
    int		opt_idx,
    int		opt_flags,
    char_u	**argp,
    int		nextchar,
    set_op_T	op,
    long_u	flags,
    int		cp_val,
    char_u	*varp,
    char	*errbuf,
    size_t	errbuflen)
{
    char_u		*arg = *argp;
    varnumber_T		value;
    int			i;
    char		*errmsg = NULL;

    if (opt_idx < 0 || varp == NULL)
	return NULL;  // "cannot happen"
		      //
    /*
     * Different ways to set a number option:
     * &	    set to default value
     * <	    set to global value
     * <xx>	    accept special key codes for 'wildchar'
     * c	    accept any non-digit for 'wildchar'
     * [-]0-9   set number
     * other    error
     */
    ++arg;
    if (nextchar == '&')
	value = (long)(long_i)options[opt_idx].def_val[
	    ((flags & P_VI_DEF) || cp_val) ? VI_DEFAULT : VIM_DEFAULT];
    else if (nextchar == '<')
    {
	if ((long *)varp == &curbuf->b_p_ul && opt_flags == OPT_LOCAL)
	    // for 'undolevels' NO_LOCAL_UNDOLEVEL means using the global value
	    value = NO_LOCAL_UNDOLEVEL;
	else if (opt_flags == OPT_LOCAL
		    && ((long *)varp == &curwin->w_p_siso
		     || (long *)varp == &curwin->w_p_so))
	    // for 'scrolloff'/'sidescrolloff' -1 means using the global value
	    value = -1;
	else
	    value = *(long *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
    }
    else if (((long *)varp == &p_wc || (long *)varp == &p_wcm)
	    && (*arg == '<'
		|| *arg == '^'
		|| (*arg != NUL
		    && (!arg[1] || VIM_ISWHITE(arg[1]))
		    && !VIM_ISDIGIT(*arg))))
    {
	value = string_to_key(arg, FALSE);
	if (value == 0 && (long *)varp != &p_wcm)
	{
	    errmsg = e_invalid_argument;
	    goto skip;
	}
    }
    else if (*arg == '-' || VIM_ISDIGIT(*arg))
    {
	// Allow negative (for 'undolevels'), octal and hex numbers.
	vim_str2nr(arg, NULL, &i, STR2NR_ALL, &value, NULL, 0, TRUE, NULL);
	if (i == 0 || (arg[i] != NUL && !VIM_ISWHITE(arg[i])))
	{
	    errmsg = e_number_required_after_equal;
	    goto skip;
	}
    }
    else
    {
	errmsg = e_number_required_after_equal;
	goto skip;
    }

    if (op == OP_ADDING)
	value = *(long *)varp + value;
    else if (op == OP_PREPENDING)
	value = *(long *)varp * value;
    else if (op == OP_REMOVING)
	value = *(long *)varp - value;

    errmsg = set_num_option(opt_idx, varp, value, errbuf, errbuflen,
								opt_flags);

skip:
    *argp = arg;
    return errmsg;
}

/*
 * Set a key code (t_xx) option
 */
    static char *
do_set_option_keycode(char_u **argp, char_u *key_name, int nextchar)
{
    char_u	*arg = *argp;
    char_u	*p;

    if (nextchar == '&')
    {
	if (add_termcap_entry(key_name, TRUE) == FAIL)
	    return e_not_found_in_termcap;
    }
    else
    {
	++arg; // jump to after the '=' or ':'
	for (p = arg; *p && !VIM_ISWHITE(*p); ++p)
	    if (*p == '\\' && p[1] != NUL)
		++p;
	nextchar = *p;
	*p = NUL;
	add_termcode(key_name, arg, FALSE);
	*p = nextchar;
    }
    if (full_screen)
	ttest(FALSE);
    redraw_all_later(UPD_CLEAR);

    *argp = arg;
    return NULL;
}

/*
 * Set an option to a new value.
 */
    static char *
do_set_option_value(
    int		opt_idx,
    int		opt_flags,
    char_u	**argp,
    set_prefix_T prefix,
    set_op_T	op,
    long_u	flags,
    char_u	*varp,
    char_u	*key_name,
    int		nextchar,
    int		afterchar,
    int		cp_val,
    int		*stopopteval,
    char	*errbuf,
    size_t	errbuflen)
{
    int		value_checked = FALSE;
    char	*errmsg = NULL;
    char_u	*arg = *argp;

    if (flags & P_BOOL)
    {
	// boolean option
	errmsg = do_set_option_bool(opt_idx, opt_flags, prefix, flags, varp,
						nextchar, afterchar, cp_val);
	if (errmsg != NULL)
	    goto skip;
    }
    else
    {
	// numeric or string option
	if (vim_strchr((char_u *)"=:&<", nextchar) == NULL
		|| prefix != PREFIX_NONE)
	{
	    errmsg = e_invalid_argument;
	    goto skip;
	}

	if (flags & P_NUM)
	{
	    // numeric option
	    errmsg = do_set_option_numeric(opt_idx, opt_flags, &arg, nextchar,
						op, flags, cp_val, varp,
						errbuf, errbuflen);
	    if (errmsg != NULL)
		goto skip;
	}
	else if (opt_idx >= 0)
	{
	    // string option
	    if (do_set_option_string(opt_idx, opt_flags, &arg, nextchar, op,
					flags, cp_val, varp, errbuf, errbuflen,
					&value_checked, &errmsg) == FAIL)
	    {
		if (errmsg != NULL)
		    goto skip;
		*stopopteval = TRUE;
		goto skip;
	    }
	}
	else
	{
	    // key code option
	    errmsg = do_set_option_keycode(&arg, key_name, nextchar);
	    if (errmsg != NULL)
		goto skip;
	}
    }

    if (opt_idx >= 0)
	did_set_option(opt_idx, opt_flags, op == OP_NONE, value_checked);

skip:
    *argp = arg;
    return errmsg;
}

/*
 * Set an option to a new value.
 * Return NULL if OK, return an untranslated error message when something is
 * wrong.  "errbuf[errbuflen]" can be used to create the error message.
 */
    static char *
do_set_option(
    int		opt_flags,
    char_u	**argp,
    char_u	*arg_start,
    char_u	**startarg,
    int		*did_show,
    int		*stopopteval,
    char	*errbuf,
    size_t	errbuflen)
{
    int		opt_idx;
    char_u	*arg;
    set_prefix_T prefix;	// no prefix, "no" prefix or "inv" prefix
    set_op_T	op;
    long_u	flags;		// flags for current option
    char_u	*varp;		// pointer to variable for current option
    char_u	key_name[2];
    int		nextchar;	// next non-white char after option name
    int		afterchar;	// character just after option name
    char	*errmsg = NULL;
    int		key;
    int		len;

    prefix = get_option_prefix(argp);
    arg = *argp;

    // find end of name
    key = 0;
    if (parse_option_name(arg, &opt_idx, &len, &key) == FAIL)
	return e_invalid_argument;

    // remember character after option name
    afterchar = arg[len];

    if (in_vim9script())
    {
	char_u *p = skipwhite(arg + len);

	// disallow white space before =val, +=val, -=val, ^=val
	if (p > arg + len && (p[0] == '='
		    || (vim_strchr((char_u *)"+-^", p[0]) != NULL
			&& p[1] == '=')))
	{
	    errmsg = e_no_white_space_allowed_between_option_and;
	    arg = p;
	    *startarg = p;
	    goto skip;
	}
    }
    else
	// skip white space, allow ":set ai  ?", ":set hlsearch  !"
	while (VIM_ISWHITE(arg[len]))
	    ++len;

    op = get_opt_op(arg + len);
    if (op != OP_NONE)
	len++;

    nextchar = arg[len];

    if (opt_idx == -1 && key == 0)	// found a mismatch: skip
    {
	if (in_vim9script() && arg > arg_start
		&& vim_strchr((char_u *)"!&<", *arg) != NULL)
	    errmsg = e_no_white_space_allowed_between_option_and;
	else
	    errmsg = e_unknown_option;
	goto skip;
    }

    if (opt_idx >= 0)
    {
	if (options[opt_idx].var == NULL)   // hidden option: skip
	{
	    // Only give an error message when requesting the value of
	    // a hidden option, ignore setting it.
	    if (vim_strchr((char_u *)"=:!&<", nextchar) == NULL
		    && (!(options[opt_idx].flags & P_BOOL)
			|| nextchar == '?'))
		errmsg = e_option_not_supported;
	    goto skip;
	}

	flags = options[opt_idx].flags;
	varp = get_varp_scope(&(options[opt_idx]), opt_flags);
    }
    else
    {
	flags = P_STRING;
	varp = NULL;
	if (key < 0)
	{
	    key_name[0] = KEY2TERMCAP0(key);
	    key_name[1] = KEY2TERMCAP1(key);
	}
	else
	{
	    key_name[0] = KS_KEY;
	    key_name[1] = (key & 0xff);
	}
    }

    // Make sure the option value can be changed.
    if (validate_opt_idx(opt_idx, opt_flags, flags, &errmsg) == FAIL)
	goto skip;

    int cp_val = p_cp;
    if (vim_strchr((char_u *)"?=:!&<", nextchar) != NULL)
    {
	arg += len;
	if (nextchar == '&' && arg[1] == 'v' && arg[2] == 'i')
	{
	    if (arg[3] == 'm')	// "opt&vim": set to Vim default
	    {
		cp_val = FALSE;
		arg += 3;
	    }
	    else		// "opt&vi": set to Vi default
	    {
		cp_val = TRUE;
		arg += 2;
	    }
	}
	if (vim_strchr((char_u *)"?!&<", nextchar) != NULL
		&& arg[1] != NUL && !VIM_ISWHITE(arg[1]))
	{
	    errmsg = e_trailing_characters;
	    goto skip;
	}
    }

    // Allow '=' and ':' for historical reasons (MSDOS command.com).
    // Allows only one '=' character per "set" command line. grrr. (jw)
    if (nextchar == '?'
	    || (prefix == PREFIX_NONE
		&& vim_strchr((char_u *)"=:&<", nextchar) == NULL
		&& !(flags & P_BOOL)))
    {
	// print value
	if (*did_show)
	    msg_putchar('\n');	    // cursor below last one
	else
	{
	    gotocmdline(TRUE);	    // cursor at status line
	    *did_show = TRUE;	    // remember that we did a line
	}
	if (opt_idx >= 0)
	{
	    showoneopt(&options[opt_idx], opt_flags);
#ifdef FEAT_EVAL
	    if (p_verbose > 0)
	    {
		// Mention where the option was last set.
		if (varp == options[opt_idx].var)
		    last_set_msg(options[opt_idx].script_ctx);
		else if ((int)options[opt_idx].indir & PV_WIN)
		    last_set_msg(curwin->w_p_script_ctx[
			    (int)options[opt_idx].indir & PV_MASK]);
		else if ((int)options[opt_idx].indir & PV_BUF)
		    last_set_msg(curbuf->b_p_script_ctx[
			    (int)options[opt_idx].indir & PV_MASK]);
	    }
#endif
	}
	else
	{
	    char_u	    *p;

	    p = find_termcode(key_name);
	    if (p == NULL)
	    {
		errmsg = e_key_code_not_set;
		goto skip;
	    }
	    else
		(void)show_one_termcode(key_name, p, TRUE);
	}
	if (nextchar != '?'
		&& nextchar != NUL && !VIM_ISWHITE(afterchar))
	    errmsg = e_trailing_characters;
    }
    else
    {
	errmsg = do_set_option_value(opt_idx, opt_flags, &arg, prefix, op,
					flags, varp, key_name, nextchar,
					afterchar, cp_val, stopopteval, errbuf,
					errbuflen);
    }

skip:
    *argp = arg;
    return errmsg;
}

/*
 * Parse 'arg' for option settings.
 *
 * 'arg' may be IObuff, but only when no errors can be present and option
 * does not need to be expanded with option_expand().
 * "opt_flags":
 * 0 for ":set"
 * OPT_GLOBAL     for ":setglobal"
 * OPT_LOCAL      for ":setlocal" and a modeline
 * OPT_MODELINE   for a modeline
 * OPT_WINONLY    to only set window-local options
 * OPT_NOWIN	  to skip setting window-local options
 * OPT_ONECOLUMN  do not use multiple columns
 *
 * Returns FAIL if an error is detected, OK otherwise.
 */
    int
do_set(
    char_u	*arg_start,	// option string (may be written to!)
    int		opt_flags)
{
    char_u	*arg = arg_start;
    int		i;
    int		did_show = FALSE;   // already showed one value

    if (*arg == NUL)
    {
	showoptions(0, opt_flags);
	did_show = TRUE;
	goto theend;
    }

    while (*arg != NUL)		// loop to process all options
    {
	if (STRNCMP(arg, "all", 3) == 0 && !ASCII_ISALPHA(arg[3])
						&& !(opt_flags & OPT_MODELINE))
	{
	    // ":set all"  show all options.
	    // ":set all&" set all options to their default value.
	    arg += 3;
	    if (*arg == '&')
	    {
		++arg;
		// Only for :set command set global value of local options.
		set_options_default(OPT_FREE | opt_flags);
		didset_options();
		didset_options2();
		redraw_all_later(UPD_CLEAR);
	    }
	    else
	    {
		showoptions(1, opt_flags);
		did_show = TRUE;
	    }
	}
	else if (STRNCMP(arg, "termcap", 7) == 0 && !(opt_flags & OPT_MODELINE))
	{
	    showoptions(2, opt_flags);
	    show_termcodes(opt_flags);
	    did_show = TRUE;
	    arg += 7;
	}
	else
	{
	    int		stopopteval = FALSE;
	    char	*errmsg = NULL;
	    char	errbuf[ERR_BUFLEN];
	    char_u	*startarg = arg;

	    errmsg = do_set_option(opt_flags, &arg, arg_start, &startarg,
					&did_show, &stopopteval, errbuf,
					ERR_BUFLEN);
	    if (stopopteval)
		break;

	    // Advance to next argument.
	    // - skip until a blank found, taking care of backslashes
	    // - skip blanks
	    // - skip one "=val" argument (for hidden options ":set gfn =xx")
	    for (i = 0; i < 2 ; ++i)
	    {
		while (*arg != NUL && !VIM_ISWHITE(*arg))
		    if (*arg++ == '\\' && *arg != NUL)
			++arg;
		arg = skipwhite(arg);
		if (*arg != '=')
		    break;
	    }

	    if (errmsg != NULL)
	    {
		vim_strncpy(IObuff, (char_u *)_(errmsg), IOSIZE - 1);
		i = (int)STRLEN(IObuff) + 2;
		if (i + (arg - startarg) < IOSIZE)
		{
		    // append the argument with the error
		    STRCAT(IObuff, ": ");
		    mch_memmove(IObuff + i, startarg, (arg - startarg));
		    IObuff[i + (arg - startarg)] = NUL;
		}
		// make sure all characters are printable
		trans_characters(IObuff, IOSIZE);

		++no_wait_return;		// wait_return() done later
		emsg((char *)IObuff);	// show error highlighted
		--no_wait_return;

		return FAIL;
	    }
	}

	arg = skipwhite(arg);
    }

theend:
    if (silent_mode && did_show)
    {
	// After displaying option values in silent mode.
	silent_mode = FALSE;
	info_message = TRUE;	// use mch_msg(), not mch_errmsg()
	msg_putchar('\n');
	cursor_on();		// msg_start() switches it off
	out_flush();
	silent_mode = TRUE;
	info_message = FALSE;	// use mch_msg(), not mch_errmsg()
    }

    return OK;
}

/*
 * Call this when an option has been given a new value through a user command.
 * Sets the P_WAS_SET flag and takes care of the P_INSECURE flag.
 */
    void
did_set_option(
    int	    opt_idx,
    int	    opt_flags,	    // possibly with OPT_MODELINE
    int	    new_value,	    // value was replaced completely
    int	    value_checked)  // value was checked to be safe, no need to set the
			    // P_INSECURE flag.
{
    long_u	*p;

    options[opt_idx].flags |= P_WAS_SET;

    // When an option is set in the sandbox, from a modeline or in secure mode
    // set the P_INSECURE flag.  Otherwise, if a new value is stored reset the
    // flag.
    p = insecure_flag(opt_idx, opt_flags);
    if (!value_checked && (secure
#ifdef HAVE_SANDBOX
	    || sandbox != 0
#endif
	    || (opt_flags & OPT_MODELINE)))
	*p = *p | P_INSECURE;
    else if (new_value)
	*p = *p & ~P_INSECURE;
}

/*
 * Convert a key name or string into a key value.
 * Used for 'wildchar' and 'cedit' options.
 * When "multi_byte" is TRUE allow for multi-byte characters.
 */
    int
string_to_key(char_u *arg, int multi_byte)
{
    if (*arg == '<')
	return find_key_option(arg + 1, TRUE);
    if (*arg == '^')
	return Ctrl_chr(arg[1]);
    if (multi_byte)
	return PTR2CHAR(arg);
    return *arg;
}

/*
 * When changing 'title', 'titlestring', 'icon' or 'iconstring', call
 * maketitle() to create and display it.
 * When switching the title or icon off, call mch_restore_title() to get
 * the old value back.
 */
    void
did_set_title(void)
{
    if (starting != NO_SCREEN
#ifdef FEAT_GUI
	    && !gui.starting
#endif
				)
	maketitle();
}

/*
 * set_options_bin -  called when 'bin' changes value.
 */
    void
set_options_bin(
    int		oldval,
    int		newval,
    int		opt_flags)	// OPT_LOCAL and/or OPT_GLOBAL
{
    // The option values that are changed when 'bin' changes are
    // copied when 'bin is set and restored when 'bin' is reset.
    if (newval)
    {
	if (!oldval)		// switched on
	{
	    if (!(opt_flags & OPT_GLOBAL))
	    {
		curbuf->b_p_tw_nobin = curbuf->b_p_tw;
		curbuf->b_p_wm_nobin = curbuf->b_p_wm;
		curbuf->b_p_ml_nobin = curbuf->b_p_ml;
		curbuf->b_p_et_nobin = curbuf->b_p_et;
	    }
	    if (!(opt_flags & OPT_LOCAL))
	    {
		p_tw_nobin = p_tw;
		p_wm_nobin = p_wm;
		p_ml_nobin = p_ml;
		p_et_nobin = p_et;
	    }
	}

	if (!(opt_flags & OPT_GLOBAL))
	{
	    curbuf->b_p_tw = 0;	// no automatic line wrap
	    curbuf->b_p_wm = 0;	// no automatic line wrap
	    curbuf->b_p_ml = 0;	// no modelines
	    curbuf->b_p_et = 0;	// no expandtab
	}
	if (!(opt_flags & OPT_LOCAL))
	{
	    p_tw = 0;
	    p_wm = 0;
	    p_ml = FALSE;
	    p_et = FALSE;
	    p_bin = TRUE;	// needed when called for the "-b" argument
	}
    }
    else if (oldval)		// switched off
    {
	if (!(opt_flags & OPT_GLOBAL))
	{
	    curbuf->b_p_tw = curbuf->b_p_tw_nobin;
	    curbuf->b_p_wm = curbuf->b_p_wm_nobin;
	    curbuf->b_p_ml = curbuf->b_p_ml_nobin;
	    curbuf->b_p_et = curbuf->b_p_et_nobin;
	}
	if (!(opt_flags & OPT_LOCAL))
	{
	    p_tw = p_tw_nobin;
	    p_wm = p_wm_nobin;
	    p_ml = p_ml_nobin;
	    p_et = p_et_nobin;
	}
    }
#if defined(FEAT_EVAL) || defined(PROTO)
    // Remember where the dependent option were reset
    didset_options_sctx(opt_flags, p_bin_dep_opts);
#endif
}

/*
 * Expand environment variables for some string options.
 * These string options cannot be indirect!
 * If "val" is NULL expand the current value of the option.
 * Return pointer to NameBuff, or NULL when not expanded.
 */
    static char_u *
option_expand(int opt_idx, char_u *val)
{
    // if option doesn't need expansion nothing to do
    if (!(options[opt_idx].flags & P_EXPAND) || options[opt_idx].var == NULL)
	return NULL;

    // If val is longer than MAXPATHL no meaningful expansion can be done,
    // expand_env() would truncate the string.
    if (val != NULL && STRLEN(val) > MAXPATHL)
	return NULL;

    if (val == NULL)
	val = *(char_u **)options[opt_idx].var;

    /*
     * Expanding this with NameBuff, expand_env() must not be passed IObuff.
     * Escape spaces when expanding 'tags', they are used to separate file
     * names.
     * For 'spellsuggest' expand after "file:".
     */
    expand_env_esc(val, NameBuff, MAXPATHL,
	    (char_u **)options[opt_idx].var == &p_tags, FALSE,
#ifdef FEAT_SPELL
	    (char_u **)options[opt_idx].var == &p_sps ? (char_u *)"file:" :
#endif
				  NULL);
    if (STRCMP(NameBuff, val) == 0)   // they are the same
	return NULL;

    return NameBuff;
}

/*
 * After setting various option values: recompute variables that depend on
 * option values.
 */
    static void
didset_options(void)
{
    // initialize the table for 'iskeyword' et.al.
    (void)init_chartab();

    didset_string_options();

#ifdef FEAT_SPELL
    (void)spell_check_msm();
    (void)spell_check_sps();
    (void)compile_cap_prog(curwin->w_s);
    (void)did_set_spell_option(TRUE);
#endif
    // set cedit_key
    (void)did_set_cedit(NULL);
#ifdef FEAT_LINEBREAK
    // initialize the table for 'breakat'.
    did_set_breakat(NULL);
#endif
    after_copy_winopt(curwin);
}

/*
 * More side effects of setting options.
 */
    static void
didset_options2(void)
{
    // Initialize the highlight_attr[] table.
    (void)highlight_changed();

    // Parse default for 'wildmode'
    check_opt_wim();

    // Parse default for 'listchars'.
    (void)set_listchars_option(curwin, curwin->w_p_lcs, TRUE, NULL, 0);

    // Parse default for 'fillchars'.
    (void)set_fillchars_option(curwin, curwin->w_p_fcs, TRUE, NULL, 0);

#ifdef FEAT_CLIPBOARD
    // Parse default for 'clipboard'
    (void)did_set_clipboard(NULL);
#endif
#ifdef FEAT_VARTABS
    vim_free(curbuf->b_p_vsts_array);
    (void)tabstop_set(curbuf->b_p_vsts, &curbuf->b_p_vsts_array);
    vim_free(curbuf->b_p_vts_array);
    (void)tabstop_set(curbuf->b_p_vts,  &curbuf->b_p_vts_array);
#endif
}

/*
 * Check for string options that are NULL (normally only termcap options).
 */
    void
check_options(void)
{
    int		opt_idx;

    for (opt_idx = 0; options[opt_idx].fullname != NULL; opt_idx++)
	if ((options[opt_idx].flags & P_STRING) && options[opt_idx].var != NULL)
	    check_string_option((char_u **)get_varp(&(options[opt_idx])));
}

/*
 * Return the option index found by a pointer into term_strings[].
 * Return -1 if not found.
 */
    int
get_term_opt_idx(char_u **p)
{
    int opt_idx;

    for (opt_idx = 1; options[opt_idx].fullname != NULL; opt_idx++)
	if (options[opt_idx].var == (char_u *)p)
	    return opt_idx;
    return -1; // cannot happen: didn't find it!
}

/*
 * Mark a terminal option as allocated, found by a pointer into term_strings[].
 * Return the option index or -1 if not found.
 */
    int
set_term_option_alloced(char_u **p)
{
    int		opt_idx = get_term_opt_idx(p);

    if (opt_idx >= 0)
	options[opt_idx].flags |= P_ALLOCED;
    return opt_idx;
}

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * Return TRUE when option "opt" was set from a modeline or in secure mode.
 * Return FALSE when it wasn't.
 * Return -1 for an unknown option.
 */
    int
was_set_insecurely(char_u *opt, int opt_flags)
{
    int	    idx = findoption(opt);
    long_u  *flagp;

    if (idx >= 0)
    {
	flagp = insecure_flag(idx, opt_flags);
	return (*flagp & P_INSECURE) != 0;
    }
    internal_error("was_set_insecurely()");
    return -1;
}

/*
 * Get a pointer to the flags used for the P_INSECURE flag of option
 * "opt_idx".  For some local options a local flags field is used.
 * NOTE: Caller must make sure that "curwin" is set to the window from which
 * the option is used.
 */
    static long_u *
insecure_flag(int opt_idx, int opt_flags)
{
    if (opt_flags & OPT_LOCAL)
	switch ((int)options[opt_idx].indir)
	{
#ifdef FEAT_STL_OPT
	    case PV_STL:	return &curwin->w_p_stl_flags;
#endif
#ifdef FEAT_EVAL
# ifdef FEAT_FOLDING
	    case PV_FDE:	return &curwin->w_p_fde_flags;
	    case PV_FDT:	return &curwin->w_p_fdt_flags;
# endif
# ifdef FEAT_BEVAL
	    case PV_BEXPR:	return &curbuf->b_p_bexpr_flags;
# endif
	    case PV_INDE:	return &curbuf->b_p_inde_flags;
	    case PV_FEX:	return &curbuf->b_p_fex_flags;
# ifdef FEAT_FIND_ID
	    case PV_INEX:	return &curbuf->b_p_inex_flags;
# endif
#endif
	}

    // Nothing special, return global flags field.
    return &options[opt_idx].flags;
}
#endif

/*
 * Redraw the window title and/or tab page text later.
 */
    void
redraw_titles(void)
{
    need_maketitle = TRUE;
    redraw_tabline = TRUE;
}

/*
 * Return TRUE if "val" is a valid name: only consists of alphanumeric ASCII
 * characters or characters in "allowed".
 */
    int
valid_name(char_u *val, char *allowed)
{
    char_u *s;

    for (s = val; *s != NUL; ++s)
	if (!ASCII_ISALNUM(*s) && vim_strchr((char_u *)allowed, *s) == NULL)
	    return FALSE;
    return TRUE;
}

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * Set the script_ctx for an option, taking care of setting the buffer- or
 * window-local value.
 */
    void
set_option_sctx_idx(int opt_idx, int opt_flags, sctx_T script_ctx)
{
    int		both = (opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0;
    int		indir = (int)options[opt_idx].indir;
    sctx_T	new_script_ctx = script_ctx;

    // Modeline already has the line number set.
    if (!(opt_flags & OPT_MODELINE))
	new_script_ctx.sc_lnum += SOURCING_LNUM;

    // Remember where the option was set.  For local options need to do that
    // in the buffer or window structure.
    if (both || (opt_flags & OPT_GLOBAL) || (indir & (PV_BUF|PV_WIN)) == 0)
	options[opt_idx].script_ctx = new_script_ctx;
    if (both || (opt_flags & OPT_LOCAL))
    {
	if (indir & PV_BUF)
	    curbuf->b_p_script_ctx[indir & PV_MASK] = new_script_ctx;
	else if (indir & PV_WIN)
	{
	    curwin->w_p_script_ctx[indir & PV_MASK] = new_script_ctx;
	    if (both)
		// also setting the "all buffers" value
		curwin->w_allbuf_opt.wo_script_ctx[indir & PV_MASK] =
								new_script_ctx;
	}
    }
}

/*
 * Get the script context of global option "name".
 *
 */
    sctx_T *
get_option_sctx(char *name)
{
    int idx = findoption((char_u *)name);

    if (idx >= 0)
	return &options[idx].script_ctx;
    siemsg("no such option: %s", name);
    return NULL;
}

/*
 * Set the script_ctx for a termcap option.
 * "name" must be the two character code, e.g. "RV".
 * When "name" is NULL use "opt_idx".
 */
    void
set_term_option_sctx_idx(char *name, int opt_idx)
{
    char_u  buf[5];
    int	    idx;

    if (name == NULL)
	idx = opt_idx;
    else
    {
	buf[0] = 't';
	buf[1] = '_';
	buf[2] = name[0];
	buf[3] = name[1];
	buf[4] = 0;
	idx = findoption(buf);
    }
    if (idx >= 0)
	set_option_sctx_idx(idx, OPT_GLOBAL, current_sctx);
}
#endif

#if defined(FEAT_EVAL)
/*
 * Apply the OptionSet autocommand.
 */
    static void
apply_optionset_autocmd(
	int	opt_idx,
	long	opt_flags,
	long	oldval,
	long	oldval_g,
	long	newval,
	char	*errmsg)
{
    char_u buf_old[12], buf_old_global[12], buf_new[12], buf_type[12];

    // Don't do this while starting up, failure or recursively.
    if (starting || errmsg != NULL || *get_vim_var_str(VV_OPTION_TYPE) != NUL)
	return;

    vim_snprintf((char *)buf_old, sizeof(buf_old), "%ld", oldval);
    vim_snprintf((char *)buf_old_global, sizeof(buf_old_global), "%ld",
							oldval_g);
    vim_snprintf((char *)buf_new, sizeof(buf_new), "%ld", newval);
    vim_snprintf((char *)buf_type, sizeof(buf_type), "%s",
				(opt_flags & OPT_LOCAL) ? "local" : "global");
    set_vim_var_string(VV_OPTION_NEW, buf_new, -1);
    set_vim_var_string(VV_OPTION_OLD, buf_old, -1);
    set_vim_var_string(VV_OPTION_TYPE, buf_type, -1);
    if (opt_flags & OPT_LOCAL)
    {
	set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"setlocal", -1);
	set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
    }
    if (opt_flags & OPT_GLOBAL)
    {
	set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"setglobal", -1);
	set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old, -1);
    }
    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
    {
	set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"set", -1);
	set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
	set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old_global, -1);
    }
    if (opt_flags & OPT_MODELINE)
    {
	set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"modeline", -1);
	set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
    }
    apply_autocmds(EVENT_OPTIONSET, (char_u *)options[opt_idx].fullname,
	    NULL, FALSE, NULL);
    reset_v_option_vars();
}
#endif

#if defined(FEAT_ARABIC) || defined(PROTO)
/*
 * Process the updated 'arabic' option value.
 */
    char *
did_set_arabic(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (curwin->w_p_arab)
    {
	// 'arabic' is set, handle various sub-settings.
	if (!p_tbidi)
	{
	    // set rightleft mode
	    if (!curwin->w_p_rl)
	    {
		curwin->w_p_rl = TRUE;
		changed_window_setting();
	    }

	    // Enable Arabic shaping (major part of what Arabic requires)
	    if (!p_arshape)
	    {
		p_arshape = TRUE;
		redraw_later_clear();
	    }
	}

	// Arabic requires a utf-8 encoding, inform the user if it's not
	// set.
	if (STRCMP(p_enc, "utf-8") != 0)
	{
	    static char *w_arabic = N_("W17: Arabic requires UTF-8, do ':set encoding=utf-8'");

	    msg_source(HL_ATTR(HLF_W));
	    msg_attr(_(w_arabic), HL_ATTR(HLF_W));
#ifdef FEAT_EVAL
	    set_vim_var_string(VV_WARNINGMSG, (char_u *)_(w_arabic), -1);
#endif
	}

	// set 'delcombine'
	p_deco = TRUE;

# ifdef FEAT_KEYMAP
	// Force-set the necessary keymap for arabic
	errmsg = set_option_value((char_u *)"keymap", 0L, (char_u *)"arabic",
								OPT_LOCAL);
# endif
    }
    else
    {
	// 'arabic' is reset, handle various sub-settings.
	if (!p_tbidi)
	{
	    // reset rightleft mode
	    if (curwin->w_p_rl)
	    {
		curwin->w_p_rl = FALSE;
		changed_window_setting();
	    }

	    // 'arabicshape' isn't reset, it is a global option and
	    // another window may still need it "on".
	}

	// 'delcombine' isn't reset, it is a global option and another
	// window may still want it "on".

# ifdef FEAT_KEYMAP
	// Revert to the default keymap
	curbuf->b_p_iminsert = B_IMODE_NONE;
	curbuf->b_p_imsearch = B_IMODE_USE_INSERT;
# endif
    }

    return errmsg;
}
#endif

#if defined(FEAT_AUTOCHDIR) || defined(PROTO)
/*
 * Process the updated 'autochdir' option value.
 */
    char *
did_set_autochdir(optset_T *args UNUSED)
{
    // Change directories when the 'acd' option is set now.
    DO_AUTOCHDIR;
    return NULL;
}
#endif

#if defined(FEAT_BEVAL_GUI) || defined(PROTO)
/*
 * Process the updated 'ballooneval' option value.
 */
    char *
did_set_ballooneval(optset_T *args)
{
    if (balloonEvalForTerm)
	return NULL;

    if (p_beval && !args->os_oldval.boolean)
	gui_mch_enable_beval_area(balloonEval);
    else if (!p_beval && args->os_oldval.boolean)
	gui_mch_disable_beval_area(balloonEval);

    return NULL;
}
#endif

#if defined(FEAT_BEVAL_TERM) || defined(PROTO)
/*
 * Process the updated 'balloonevalterm' option value.
 */
    char *
did_set_balloonevalterm(optset_T *args UNUSED)
{
    mch_bevalterm_changed();
    return NULL;
}
#endif

/*
 * Process the updated 'binary' option value.
 */
    char *
did_set_binary(optset_T *args)
{
    // when 'bin' is set also set some other options
    set_options_bin(args->os_oldval.boolean, curbuf->b_p_bin, args->os_flags);
    redraw_titles();

    return NULL;
}

/*
 * Process the updated 'buflisted' option value.
 */
    char *
did_set_buflisted(optset_T *args)
{
    // when 'buflisted' changes, trigger autocommands
    if (args->os_oldval.boolean != curbuf->b_p_bl)
	apply_autocmds(curbuf->b_p_bl ? EVENT_BUFADD : EVENT_BUFDELETE,
						NULL, NULL, TRUE, curbuf);
    return NULL;
}

/*
 * Process the new 'cmdheight' option value.
 */
    char *
did_set_cmdheight(optset_T *args)
{
    long old_value = args->os_oldval.number;
    char *errmsg = NULL;

    // if p_ch changed value, change the command line height
    if (p_ch < 1)
    {
	errmsg = e_argument_must_be_positive;
	p_ch = 1;
    }
    if (p_ch > Rows - min_rows() + 1)
	p_ch = Rows - min_rows() + 1;

    // Only compute the new window layout when startup has been
    // completed. Otherwise the frame sizes may be wrong.
    if ((p_ch != old_value
		|| tabline_height() + topframe->fr_height != Rows - p_ch)
	    && full_screen
#ifdef FEAT_GUI
	    && !gui.starting
#endif
       )
	command_height();

    return errmsg;
}

/*
 * Process the updated 'compatible' option value.
 */
    char *
did_set_compatible(optset_T *args UNUSED)
{
    compatible_set();
    return NULL;
}

#if defined(FEAT_CONCEAL) || defined(PROTO)
/*
 * Process the new 'conceallevel' option value.
 */
    char *
did_set_conceallevel(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (curwin->w_p_cole < 0)
    {
	errmsg = e_argument_must_be_positive;
	curwin->w_p_cole = 0;
    }
    else if (curwin->w_p_cole > 3)
    {
	errmsg = e_invalid_argument;
	curwin->w_p_cole = 3;
    }

    return errmsg;
}
#endif

#if defined(FEAT_DIFF) || defined(PROTO)
/*
 * Process the updated 'diff' option value.
 */
    char *
did_set_diff(optset_T *args UNUSED)
{
    // May add or remove the buffer from the list of diff buffers.
    diff_buf_adjust(curwin);
# ifdef FEAT_FOLDING
    if (foldmethodIsDiff(curwin))
	foldUpdateAll(curwin);
# endif
    return NULL;
}
#endif

/*
 * Process the updated 'endoffile' or 'endofline' or 'fixendofline' or 'bomb'
 * option value.
 */
    char *
did_set_eof_eol_fixeol_bomb(optset_T *args UNUSED)
{
    // redraw the window title and tab page text
    redraw_titles();
    return NULL;
}

/*
 * Process the updated 'equalalways' option value.
 */
    char *
did_set_equalalways(optset_T *args)
{
    if (p_ea && !args->os_oldval.boolean)
	win_equal(curwin, FALSE, 0);

    return NULL;
}

#if defined(FEAT_FOLDING) || defined(PROTO)
/*
 * Process the new 'foldcolumn' option value.
 */
    char *
did_set_foldcolumn(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (curwin->w_p_fdc < 0)
    {
	errmsg = e_argument_must_be_positive;
	curwin->w_p_fdc = 0;
    }
    else if (curwin->w_p_fdc > 12)
    {
	errmsg = e_invalid_argument;
	curwin->w_p_fdc = 12;
    }

    return errmsg;
}

/*
 * Process the new 'foldlevel' option value.
 */
    char *
did_set_foldlevel(optset_T *args UNUSED)
{
    if (curwin->w_p_fdl < 0)
	curwin->w_p_fdl = 0;
    newFoldLevel();
    return NULL;
}

/*
 * Process the new 'foldminlines' option value.
 */
    char *
did_set_foldminlines(optset_T *args UNUSED)
{
    foldUpdateAll(curwin);
    return NULL;
}

/*
 * Process the new 'foldnestmax' option value.
 */
    char *
did_set_foldnestmax(optset_T *args UNUSED)
{
    if (foldmethodIsSyntax(curwin) || foldmethodIsIndent(curwin))
	foldUpdateAll(curwin);
    return NULL;
}
#endif

#if defined(FEAT_SEARCH_EXTRA) || defined(PROTO)
/*
 * Process the updated 'hlsearch' option value.
 */
    char *
did_set_hlsearch(optset_T *args UNUSED)
{
    // when 'hlsearch' is set or reset: reset no_hlsearch
    set_no_hlsearch(FALSE);
    return NULL;
}
#endif

/*
 * Process the updated 'ignorecase' option value.
 */
    char *
did_set_ignorecase(optset_T *args UNUSED)
{
    // when 'ignorecase' is set or reset and 'hlsearch' is set, redraw
    if (p_hls)
	redraw_all_later(UPD_SOME_VALID);
    return NULL;
}

#if defined(HAVE_INPUT_METHOD) || defined(PROTO)
/*
 * Process the updated 'imdisable' option value.
 */
    char *
did_set_imdisable(optset_T *args UNUSED)
{
    // Only de-activate it here, it will be enabled when changing mode.
    if (p_imdisable)
	im_set_active(FALSE);
    else if (State & MODE_INSERT)
	// When the option is set from an autocommand, it may need to take
	// effect right away.
	im_set_active(curbuf->b_p_iminsert == B_IMODE_IM);
    return NULL;
}
#endif

/*
 * Process the new 'iminsert' option value.
 */
    char *
did_set_iminsert(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (curbuf->b_p_iminsert < 0 || curbuf->b_p_iminsert > B_IMODE_LAST)
    {
	errmsg = e_invalid_argument;
	curbuf->b_p_iminsert = B_IMODE_NONE;
    }
    p_iminsert = curbuf->b_p_iminsert;
    if (termcap_active)	// don't do this in the alternate screen
	showmode();
#if defined(FEAT_KEYMAP)
    // Show/unshow value of 'keymap' in status lines.
    status_redraw_curbuf();
#endif

    return errmsg;
}

/*
 * Process the new 'imsearch' option value.
 */
    char *
did_set_imsearch(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (curbuf->b_p_imsearch < -1 || curbuf->b_p_imsearch > B_IMODE_LAST)
    {
	errmsg = e_invalid_argument;
	curbuf->b_p_imsearch = B_IMODE_NONE;
    }
    p_imsearch = curbuf->b_p_imsearch;

    return errmsg;
}

#if (defined(FEAT_XIM) && defined(FEAT_GUI_GTK)) || defined(PROTO)
/*
 * Process the new 'imstyle' option value.
 */
    char *
did_set_imstyle(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (p_imst != IM_ON_THE_SPOT && p_imst != IM_OVER_THE_SPOT)
	errmsg = e_invalid_argument;

    return errmsg;
}
#endif

/*
 * Process the updated 'insertmode' option value.
 */
    char *
did_set_insertmode(optset_T *args)
{
    // when 'insertmode' is set from an autocommand need to do work here
    if (p_im)
    {
	if ((State & MODE_INSERT) == 0)
	    need_start_insertmode = TRUE;
	stop_insert_mode = FALSE;
    }
    // only reset if it was set previously
    else if (args->os_oldval.boolean)
    {
	need_start_insertmode = FALSE;
	stop_insert_mode = TRUE;
	if (restart_edit != 0 && mode_displayed)
	    clear_cmdline = TRUE;	// remove "(insert)"
	restart_edit = 0;
    }

    return NULL;
}

#if defined(FEAT_LANGMAP) || defined(PROTO)
/*
 * Process the updated 'langnoremap' option value.
 */
    char *
did_set_langnoremap(optset_T *args UNUSED)
{
    // 'langnoremap' -> !'langremap'
    p_lrm = !p_lnr;
    return NULL;
}

/*
 * Process the updated 'langremap' option value.
 */
    char *
did_set_langremap(optset_T *args UNUSED)
{
    // 'langremap' -> !'langnoremap'
    p_lnr = !p_lrm;
    return NULL;
}
#endif

/*
 * Process the new 'laststatus' option value.
 */
    char *
did_set_laststatus(optset_T *args UNUSED)
{
    last_status(FALSE);	// (re)set last window status line
    return NULL;
}

#if defined(FEAT_GUI) || defined(PROTO)
/*
 * Process the new 'linespace' option value.
 */
    char *
did_set_linespace(optset_T *args UNUSED)
{
    // Recompute gui.char_height and resize the Vim window to keep the
    // same number of lines.
    if (gui.in_use && gui_mch_adjust_charheight() == OK)
	gui_set_shellsize(FALSE, FALSE, RESIZE_VERT);
    return NULL;
}
#endif

/*
 * Process the updated 'lisp' option value.
 */
    char *
did_set_lisp(optset_T *args UNUSED)
{
    // When 'lisp' option changes include/exclude '-' in keyword characters.
    (void)buf_init_chartab(curbuf, FALSE);	    // ignore errors
    return NULL;
}

/*
 * Process the new 'maxcombine' option value.
 */
    char *
did_set_maxcombine(optset_T *args UNUSED)
{
    if (p_mco > MAX_MCO)
	p_mco = MAX_MCO;
    else if (p_mco < 0)
	p_mco = 0;
    screenclear();	    // will re-allocate the screen
    return NULL;
}

/*
 * Process the updated 'modifiable' option value.
 */
    char *
did_set_modifiable(optset_T *args UNUSED)
{
    // when 'modifiable' is changed, redraw the window title

# ifdef FEAT_TERMINAL
    // Cannot set 'modifiable' when in Terminal mode.
    if (curbuf->b_p_ma && (term_in_normal_mode() || (bt_terminal(curbuf)
		    && curbuf->b_term != NULL && !term_is_finished(curbuf))))
    {
	curbuf->b_p_ma = FALSE;
	return e_cannot_make_terminal_with_running_job_modifiable;
    }
# endif
    redraw_titles();

    return NULL;
}

/*
 * Process the updated 'modified' option value.
 */
    char *
did_set_modified(optset_T *args)
{
    if (!args->os_newval.boolean)
	save_file_ff(curbuf);	// Buffer is unchanged
    redraw_titles();
    curbuf->b_modified_was_set = args->os_newval.boolean;
    return NULL;
}

#if defined(FEAT_GUI) || defined(PROTO)
/*
 * Process the updated 'mousehide' option value.
 */
    char *
did_set_mousehide(optset_T *args UNUSED)
{
    if (!p_mh)
	gui_mch_mousehide(FALSE);
    return NULL;
}
#endif

/*
 * Process the updated 'number' or 'relativenumber' option value.
 */
    char *
did_set_number_relativenumber(optset_T *args UNUSED)
{
#if (defined(FEAT_SIGNS) && defined(FEAT_GUI)) || defined(PROTO)
    if (gui.in_use
	    && (*curwin->w_p_scl == 'n' && *(curwin->w_p_scl + 1) == 'u')
	    && curbuf->b_signlist != NULL)
    {
	// If the 'number' or 'relativenumber' options are modified and
	// 'signcolumn' is set to 'number', then clear the screen for a full
	// refresh. Otherwise the sign icons are not displayed properly in the
	// number column.  If the 'number' option is set and only the
	// 'relativenumber' option is toggled, then don't refresh the screen
	// (optimization).
	if (!(curwin->w_p_nu && ((int *)args->os_varp == &curwin->w_p_rnu)))
	    redraw_all_later(UPD_CLEAR);
    }
#endif
    return NULL;
}

#if defined(FEAT_LINEBREAK) || defined(PROTO)
/*
 * Process the new 'numberwidth' option value.
 */
    char *
did_set_numberwidth(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    // 'numberwidth' must be positive
    if (curwin->w_p_nuw < 1)
    {
	errmsg = e_argument_must_be_positive;
	curwin->w_p_nuw = 1;
    }
    if (curwin->w_p_nuw > 20)
    {
	errmsg = e_invalid_argument;
	curwin->w_p_nuw = 20;
    }
    curwin->w_nrwidth_line_count = 0; // trigger a redraw

    return errmsg;
}
#endif

/*
 * Process the updated 'paste' option value.  Called after p_paste was set or
 * reset.  When 'paste' is set or reset also change other options.
 */
    char *
did_set_paste(optset_T *args UNUSED)
{
    static int	old_p_paste = FALSE;
    static int	save_sm = 0;
    static int	save_sta = 0;
    static int	save_ru = 0;
#ifdef FEAT_RIGHTLEFT
    static int	save_ri = 0;
    static int	save_hkmap = 0;
#endif
    buf_T	*buf;

    if (p_paste)
    {
	// Paste switched from off to on.
	// Save the current values, so they can be restored later.
	if (!old_p_paste)
	{
	    // save options for each buffer
	    FOR_ALL_BUFFERS(buf)
	    {
		buf->b_p_tw_nopaste = buf->b_p_tw;
		buf->b_p_wm_nopaste = buf->b_p_wm;
		buf->b_p_sts_nopaste = buf->b_p_sts;
		buf->b_p_ai_nopaste = buf->b_p_ai;
		buf->b_p_et_nopaste = buf->b_p_et;
#ifdef FEAT_VARTABS
		if (buf->b_p_vsts_nopaste)
		    vim_free(buf->b_p_vsts_nopaste);
		buf->b_p_vsts_nopaste =
			buf->b_p_vsts && buf->b_p_vsts != empty_option
					   ? vim_strsave(buf->b_p_vsts) : NULL;
#endif
	    }

	    // save global options
	    save_sm = p_sm;
	    save_sta = p_sta;
	    save_ru = p_ru;
#ifdef FEAT_RIGHTLEFT
	    save_ri = p_ri;
	    save_hkmap = p_hkmap;
#endif
	    // save global values for local buffer options
	    p_ai_nopaste = p_ai;
	    p_et_nopaste = p_et;
	    p_sts_nopaste = p_sts;
	    p_tw_nopaste = p_tw;
	    p_wm_nopaste = p_wm;
#ifdef FEAT_VARTABS
	    if (p_vsts_nopaste)
		vim_free(p_vsts_nopaste);
	    p_vsts_nopaste = p_vsts && p_vsts != empty_option
						  ? vim_strsave(p_vsts) : NULL;
#endif
	}

	// Always set the option values, also when 'paste' is set when it is
	// already on.  Set options for each buffer.
	FOR_ALL_BUFFERS(buf)
	{
	    buf->b_p_tw = 0;	    // textwidth is 0
	    buf->b_p_wm = 0;	    // wrapmargin is 0
	    buf->b_p_sts = 0;	    // softtabstop is 0
	    buf->b_p_ai = 0;	    // no auto-indent
	    buf->b_p_et = 0;	    // no expandtab
#ifdef FEAT_VARTABS
	    if (buf->b_p_vsts)
		free_string_option(buf->b_p_vsts);
	    buf->b_p_vsts = empty_option;
	    VIM_CLEAR(buf->b_p_vsts_array);
#endif
	}

	// set global options
	p_sm = 0;		    // no showmatch
	p_sta = 0;		    // no smarttab
	if (p_ru)
	    status_redraw_all();    // redraw to remove the ruler
	p_ru = 0;		    // no ruler
#ifdef FEAT_RIGHTLEFT
	p_ri = 0;		    // no reverse insert
	p_hkmap = 0;		    // no Hebrew keyboard
#endif
	// set global values for local buffer options
	p_tw = 0;
	p_wm = 0;
	p_sts = 0;
	p_ai = 0;
	p_et = 0;
#ifdef FEAT_VARTABS
	if (p_vsts)
	    free_string_option(p_vsts);
	p_vsts = empty_option;
#endif
    }

    // Paste switched from on to off: Restore saved values.
    else if (old_p_paste)
    {
	// restore options for each buffer
	FOR_ALL_BUFFERS(buf)
	{
	    buf->b_p_tw = buf->b_p_tw_nopaste;
	    buf->b_p_wm = buf->b_p_wm_nopaste;
	    buf->b_p_sts = buf->b_p_sts_nopaste;
	    buf->b_p_ai = buf->b_p_ai_nopaste;
	    buf->b_p_et = buf->b_p_et_nopaste;
#ifdef FEAT_VARTABS
	    if (buf->b_p_vsts)
		free_string_option(buf->b_p_vsts);
	    buf->b_p_vsts = buf->b_p_vsts_nopaste
			 ? vim_strsave(buf->b_p_vsts_nopaste) : empty_option;
	    vim_free(buf->b_p_vsts_array);
	    if (buf->b_p_vsts && buf->b_p_vsts != empty_option)
		(void)tabstop_set(buf->b_p_vsts, &buf->b_p_vsts_array);
	    else
		buf->b_p_vsts_array = NULL;
#endif
	}

	// restore global options
	p_sm = save_sm;
	p_sta = save_sta;
	if (p_ru != save_ru)
	    status_redraw_all();    // redraw to draw the ruler
	p_ru = save_ru;
#ifdef FEAT_RIGHTLEFT
	p_ri = save_ri;
	p_hkmap = save_hkmap;
#endif
	// set global values for local buffer options
	p_ai = p_ai_nopaste;
	p_et = p_et_nopaste;
	p_sts = p_sts_nopaste;
	p_tw = p_tw_nopaste;
	p_wm = p_wm_nopaste;
#ifdef FEAT_VARTABS
	if (p_vsts)
	    free_string_option(p_vsts);
	p_vsts = p_vsts_nopaste ? vim_strsave(p_vsts_nopaste) : empty_option;
#endif
    }

    old_p_paste = p_paste;

#if defined(FEAT_EVAL) || defined(PROTO)
    // Remember where the dependent options were reset
    didset_options_sctx((OPT_LOCAL | OPT_GLOBAL), p_paste_dep_opts);
#endif

    return NULL;
}


#ifdef FEAT_QUICKFIX
/*
 * Process the updated 'previewwindow' option value.
 */
    char *
did_set_previewwindow(optset_T *args UNUSED)
{
    if (!curwin->w_p_pvw)
	return NULL;

    // There can be only one window with 'previewwindow' set.
    win_T	*win;

    FOR_ALL_WINDOWS(win)
	if (win->w_p_pvw && win != curwin)
	{
	    curwin->w_p_pvw = FALSE;
	    return e_preview_window_already_exists;
	}

    return NULL;
}
#endif

#if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3) || defined(PROTO)
/*
 * Process the new 'pyxversion' option value.
 */
    char *
did_set_pyxversion(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (p_pyx != 0 && p_pyx != 2 && p_pyx != 3)
	errmsg = e_invalid_argument;

    return errmsg;
}
#endif

/*
 * Process the updated 'readonly' option value.
 */
    char *
did_set_readonly(optset_T *args)
{
    // when 'readonly' is reset globally, also reset readonlymode
    if (!curbuf->b_p_ro && (args->os_flags & OPT_LOCAL) == 0)
	readonlymode = FALSE;

    // when 'readonly' is set may give W10 again
    if (curbuf->b_p_ro)
	curbuf->b_did_warn = FALSE;

    redraw_titles();

    return NULL;
}

/*
 * Process the updated 'scrollbind' option value.
 */
    char *
did_set_scrollbind(optset_T *args UNUSED)
{
    // when 'scrollbind' is set: snapshot the current position to avoid a jump
    // at the end of normal_cmd()
    if (!curwin->w_p_scb)
	return NULL;

    do_check_scrollbind(FALSE);
    curwin->w_scbind_pos = curwin->w_topline;
    return NULL;
}

#if defined(BACKSLASH_IN_FILENAME) || defined(PROTO)
/*
 * Process the updated 'shellslash' option value.
 */
    char *
did_set_shellslash(optset_T *args UNUSED)
{
    if (p_ssl)
    {
	psepc = '/';
	psepcN = '\\';
	pseps[0] = '/';
    }
    else
    {
	psepc = '\\';
	psepcN = '/';
	pseps[0] = '\\';
    }

    // need to adjust the file name arguments and buffer names.
    buflist_slash_adjust();
    alist_slash_adjust();
# ifdef FEAT_EVAL
    scriptnames_slash_adjust();
# endif
    return NULL;
}
#endif

/*
 * Process the new 'shiftwidth' or the 'tabstop' option value.
 */
    char *
did_set_shiftwidth_tabstop(optset_T *args)
{
    long	*pp = (long *)args->os_varp;
    char	*errmsg = NULL;

    if (curbuf->b_p_sw < 0)
    {
	errmsg = e_argument_must_be_positive;
#ifdef FEAT_VARTABS
	// Use the first 'vartabstop' value, or 'tabstop' if vts isn't in use.
	curbuf->b_p_sw = tabstop_count(curbuf->b_p_vts_array) > 0
		       ? tabstop_first(curbuf->b_p_vts_array)
		       : curbuf->b_p_ts;
#else
	curbuf->b_p_sw = curbuf->b_p_ts;
#endif
    }

#ifdef FEAT_FOLDING
    if (foldmethodIsIndent(curwin))
	foldUpdateAll(curwin);
#endif
    // When 'shiftwidth' changes, or it's zero and 'tabstop' changes:
    // parse 'cinoptions'.
    if (pp == &curbuf->b_p_sw || curbuf->b_p_sw == 0)
	parse_cino(curbuf);

    return errmsg;
}

/*
 * Process the new 'showtabline' option value.
 */
    char *
did_set_showtabline(optset_T *args UNUSED)
{
    shell_new_rows();	// recompute window positions and heights
    return NULL;
}

/*
 * Process the updated 'smoothscroll' option value.
 */
    char *
did_set_smoothscroll(optset_T *args UNUSED)
{
    if (!curwin->w_p_sms)
	curwin->w_skipcol = 0;

    return NULL;
}

#if defined(FEAT_SPELL) || defined(PROTO)
/*
 * Process the updated 'spell' option value.
 */
    char *
did_set_spell(optset_T *args UNUSED)
{
    if (curwin->w_p_spell)
	return parse_spelllang(curwin);

    return NULL;
}
#endif

/*
 * Process the updated 'swapfile' option value.
 */
    char *
did_set_swapfile(optset_T *args UNUSED)
{
    // when 'swf' is set, create swapfile, when reset remove swapfile
    if (curbuf->b_p_swf && p_uc)
	ml_open_file(curbuf);		// create the swap file
    else
	// no need to reset curbuf->b_may_swap, ml_open_file() will check
	// buf->b_p_swf
	mf_close_file(curbuf, TRUE);	// remove the swap file
    return NULL;
}

#if defined(FEAT_TERMGUICOLORS) || defined(PROTO)
    char *
did_set_termguicolors(optset_T *args UNUSED)
{
# ifdef FEAT_VTP
    // Do not turn on 'tgc' when 24-bit colors are not supported.
    if (
#  ifdef VIMDLL
	    !gui.in_use && !gui.starting &&
#  endif
	    !has_vtp_working())
    {
	p_tgc = 0;
	return e_24_bit_colors_are_not_supported_on_this_environment;
    }
    if (is_term_win32())
	swap_tcap();
# endif
# ifdef FEAT_GUI
    if (!gui.in_use && !gui.starting)
# endif
	highlight_gui_started();
# ifdef FEAT_VTP
    // reset t_Co
    if (is_term_win32())
    {
	control_console_color_rgb();
	set_termname(T_NAME);
	init_highlight(TRUE, FALSE);
    }
# endif
# ifdef FEAT_TERMINAL
    term_update_colors_all();
    term_update_palette_all();
    term_update_wincolor_all();
# endif

    return NULL;
}
#endif

/*
 * Process the updated 'terse' option value.
 */
    char *
did_set_terse(optset_T *args UNUSED)
{
    char_u	*p;

    // when 'terse' is set change 'shortmess'
    p = vim_strchr(p_shm, SHM_SEARCH);

    // insert 's' in p_shm
    if (p_terse && p == NULL)
    {
	STRCPY(IObuff, p_shm);
	STRCAT(IObuff, "s");
	set_string_option_direct((char_u *)"shm", -1, IObuff, OPT_FREE, 0);
    }
    // remove 's' from p_shm
    else if (!p_terse && p != NULL)
	STRMOVE(p, p + 1);
    return NULL;
}

/*
 * Process the updated 'textauto' option value.
 */
    char *
did_set_textauto(optset_T *args)
{
    // when 'textauto' is set or reset also change 'fileformats'
    set_string_option_direct((char_u *)"ffs", -1,
				p_ta ? (char_u *)DFLT_FFS_VIM : (char_u *)"",
				OPT_FREE | args->os_flags, 0);

    return NULL;
}

/*
 * Process the updated 'textmode' option value.
 */
    char *
did_set_textmode(optset_T *args)
{
    // when 'textmode' is set or reset also change 'fileformat'
    set_fileformat(curbuf->b_p_tx ? EOL_DOS : EOL_UNIX, args->os_flags);

    return NULL;
}

/*
 * Process the new 'textwidth' option value.
 */
    char *
did_set_textwidth(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (curbuf->b_p_tw < 0)
    {
	errmsg = e_argument_must_be_positive;
	curbuf->b_p_tw = 0;
    }
#ifdef FEAT_SYN_HL
    {
	win_T	*wp;
	tabpage_T	*tp;

	FOR_ALL_TAB_WINDOWS(tp, wp)
	    check_colorcolumn(wp);
    }
#endif

    return errmsg;
}

/*
 * Process the updated 'title' or the 'icon' option value.
 */
    char *
did_set_title_icon(optset_T *args UNUSED)
{
    // when 'title' changed, may need to change the title; same for 'icon'
    did_set_title();
    return NULL;
}

/*
 * Process the new 'titlelen' option value.
 */
    char *
did_set_titlelen(optset_T *args)
{
    long old_value = args->os_oldval.number;
    char *errmsg = NULL;

    // if 'titlelen' has changed, redraw the title
    if (p_titlelen < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_titlelen = 85;
    }
    if (starting != NO_SCREEN && old_value != p_titlelen)
	need_maketitle = TRUE;

    return errmsg;
}

#if defined(FEAT_PERSISTENT_UNDO) || defined(PROTO)
/*
 * Process the updated 'undofile' option value.
 */
    char *
did_set_undofile(optset_T *args)
{
    // Only take action when the option was set.
    if (!curbuf->b_p_udf && !p_udf)
	return NULL;

    // When reset we do not delete the undo file, the option may be set again
    // without making any changes in between.
    char_u	hash[UNDO_HASH_SIZE];
    buf_T	*save_curbuf = curbuf;

    FOR_ALL_BUFFERS(curbuf)
    {
	// When 'undofile' is set globally: for every buffer, otherwise
	// only for the current buffer: Try to read in the undofile,
	// if one exists, the buffer wasn't changed and the buffer was
	// loaded
	if ((curbuf == save_curbuf
		    || (args->os_flags & OPT_GLOBAL)
		    || args->os_flags == 0)
		&& !curbufIsChanged() && curbuf->b_ml.ml_mfp != NULL)
	{
#ifdef FEAT_CRYPT
	    if (crypt_method_is_sodium(crypt_get_method_nr(curbuf)))
		continue;
#endif
	    u_compute_hash(hash);
	    u_read_undo(NULL, hash, curbuf->b_fname);
	}
    }
    curbuf = save_curbuf;

    return NULL;
}
#endif

/*
 * Process the new global 'undolevels' option value.
 */
    static void
update_global_undolevels(long value, long old_value)
{
    // sync undo before 'undolevels' changes

    // use the old value, otherwise u_sync() may not work properly
    p_ul = old_value;
    u_sync(TRUE);
    p_ul = value;
}

/*
 * Process the new buffer local 'undolevels' option value.
 */
    static void
update_buflocal_undolevels(long value, long old_value)
{
    // use the old value, otherwise u_sync() may not work properly
    curbuf->b_p_ul = old_value;
    u_sync(TRUE);
    curbuf->b_p_ul = value;
}

/*
 * Process the new 'undolevels' option value.
 */
    char *
did_set_undolevels(optset_T *args)
{
    long *pp = (long *)args->os_varp;

    if (pp == &p_ul)			// global 'undolevels'
	update_global_undolevels(args->os_newval.number,
						       args->os_oldval.number);
    else if (pp == &curbuf->b_p_ul)	// buffer local 'undolevels'
	update_buflocal_undolevels(args->os_newval.number,
						       args->os_oldval.number);

    return NULL;
}

/*
 * Process the new 'updatecount' option value.
 */
    char *
did_set_updatecount(optset_T *args)
{
    long old_value = args->os_oldval.number;
    char *errmsg = NULL;

    // when 'updatecount' changes from zero to non-zero, open swap files
    if (p_uc < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_uc = 100;
    }
    if (p_uc && !old_value)
	ml_open_files();

    return errmsg;
}

/*
 * Process the updated 'weirdinvert' option value.
 */
    char *
did_set_weirdinvert(optset_T *args)
{
    // When 'weirdinvert' changed, set/reset 't_xs'.
    // Then set 'weirdinvert' according to value of 't_xs'.
    if (p_wiv && !args->os_oldval.boolean)
	T_XS = (char_u *)"y";
    else if (!p_wiv && args->os_oldval.boolean)
	T_XS = empty_option;
    p_wiv = (*T_XS != NUL);

    return NULL;
}

/*
 * Process the new 'wildchar' / 'wildcharm' option value.
 */
    char *
did_set_wildchar(optset_T *args)
{
    long c = *(long *)args->os_varp;

    // Don't allow key values that wouldn't work as wildchar.
    if (c == Ctrl_C || c == '\n' || c == '\r' || c == K_KENTER)
	return e_invalid_argument;

    return NULL;
}

/*
 * Process the new 'window' option value.
 */
    char *
did_set_window(optset_T *args UNUSED)
{
    if (p_window < 1)
	p_window = 1;
    else if (p_window >= Rows)
	p_window = Rows - 1;
    return NULL;
}

/*
 * Process the new 'winheight' or the 'helpheight' option value.
 */
    char *
did_set_winheight_helpheight(optset_T *args)
{
    long	*pp = (long *)args->os_varp;
    char	*errmsg = NULL;

    if (p_wh < 1)
    {
	errmsg = e_argument_must_be_positive;
	p_wh = 1;
    }
    if (p_wmh > p_wh)
    {
	errmsg = e_winheight_cannot_be_smaller_than_winminheight;
	p_wh = p_wmh;
    }
    if (p_hh < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_hh = 0;
    }

    // Change window height NOW
    if (!ONE_WINDOW)
    {
	if (pp == &p_wh && curwin->w_height < p_wh)
	    win_setheight((int)p_wh);
	if (pp == &p_hh && curbuf->b_help && curwin->w_height < p_hh)
	    win_setheight((int)p_hh);
    }

    return errmsg;
}

/*
 * Process the new 'winminheight' option value.
 */
    char *
did_set_winminheight(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (p_wmh < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_wmh = 0;
    }
    if (p_wmh > p_wh)
    {
	errmsg = e_winheight_cannot_be_smaller_than_winminheight;
	p_wmh = p_wh;
    }
    win_setminheight();

    return errmsg;
}

/*
 * Process the new 'winminwidth' option value.
 */
    char *
did_set_winminwidth(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (p_wmw < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_wmw = 0;
    }
    if (p_wmw > p_wiw)
    {
	errmsg = e_winwidth_cannot_be_smaller_than_winminwidth;
	p_wmw = p_wiw;
    }
    win_setminwidth();

    return errmsg;
}

/*
 * Process the new 'winwidth' option value.
 */
    char *
did_set_winwidth(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (p_wiw < 1)
    {
	errmsg = e_argument_must_be_positive;
	p_wiw = 1;
    }
    if (p_wmw > p_wiw)
    {
	errmsg = e_winwidth_cannot_be_smaller_than_winminwidth;
	p_wiw = p_wmw;
    }

    // Change window width NOW
    if (!ONE_WINDOW && curwin->w_width < p_wiw)
	win_setwidth((int)p_wiw);

    return errmsg;
}

/*
 * Process the updated 'wrap' option value.
 */
    char *
did_set_wrap(optset_T *args UNUSED)
{
    // Set w_leftcol or w_skipcol to zero.
    if (curwin->w_p_wrap)
	curwin->w_leftcol = 0;
    else
	curwin->w_skipcol = 0;

    return NULL;
}

/*
 * Set the value of a boolean option, and take care of side effects.
 * Returns NULL for success, or an error message for an error.
 */
    static char *
set_bool_option(
    int		opt_idx,		// index in options[] table
    char_u	*varp,			// pointer to the option variable
    int		value,			// new value
    int		opt_flags)		// OPT_LOCAL and/or OPT_GLOBAL
{
    int		old_value = *(int *)varp;
#if defined(FEAT_EVAL)
    int		old_global_value = 0;
#endif
    char	*errmsg = NULL;

    // Disallow changing some options from secure mode
    if ((secure
#ifdef HAVE_SANDBOX
		|| sandbox != 0
#endif
		) && (options[opt_idx].flags & P_SECURE))
	return e_not_allowed_here;

#if defined(FEAT_EVAL)
    // Save the global value before changing anything. This is needed as for
    // a global-only option setting the "local value" in fact sets the global
    // value (since there is only one value).
    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
	old_global_value = *(int *)get_varp_scope(&(options[opt_idx]),
								   OPT_GLOBAL);
#endif

    *(int *)varp = value;	    // set the new value
#ifdef FEAT_EVAL
    // Remember where the option was set.
    set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
#endif

#ifdef FEAT_GUI
    need_mouse_correct = TRUE;
#endif

    // May set global value for local option.
    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
	*(int *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL) = value;

    // Handle side effects of changing a bool option.
    if (options[opt_idx].opt_did_set_cb != NULL)
    {
	optset_T args;

	CLEAR_FIELD(args);
	args.os_varp = varp;
	args.os_flags = opt_flags;
	args.os_oldval.boolean = old_value;
	args.os_newval.boolean = value;
	args.os_errbuf = NULL;
	errmsg = options[opt_idx].opt_did_set_cb(&args);
	if (errmsg != NULL)
	    return errmsg;
    }

    // after handling side effects, call autocommand

    options[opt_idx].flags |= P_WAS_SET;

#if defined(FEAT_EVAL)
    apply_optionset_autocmd(opt_idx, opt_flags,
				(long)(old_value ? TRUE : FALSE),
				(long)(old_global_value ? TRUE : FALSE),
				(long)(value ? TRUE : FALSE), NULL);
#endif

    comp_col();			    // in case 'ruler' or 'showcmd' changed

    if (curwin->w_curswant != MAXCOL
		     && (options[opt_idx].flags & (P_CURSWANT | P_RALL)) != 0
				   && (options[opt_idx].flags & P_HLONLY) == 0)
	curwin->w_set_curswant = TRUE;

    if ((opt_flags & OPT_NO_REDRAW) == 0)
	check_redraw(options[opt_idx].flags);

    return errmsg;
}

/*
 * Check the bounds of numeric options.
 */
    static char *
check_num_option_bounds(
    long	*pp,
    long	old_value,
    long	old_Rows,
    long	old_Columns,
    char	*errbuf,
    size_t	errbuflen,
    char	*errmsg)
{
    if (Rows < min_rows() && full_screen)
    {
	if (errbuf != NULL)
	{
	    vim_snprintf(errbuf, errbuflen,
		    _(e_need_at_least_nr_lines), min_rows());
	    errmsg = errbuf;
	}
	Rows = min_rows();
    }
    if (Columns < MIN_COLUMNS && full_screen)
    {
	if (errbuf != NULL)
	{
	    vim_snprintf(errbuf, errbuflen,
		    _(e_need_at_least_nr_columns), MIN_COLUMNS);
	    errmsg = errbuf;
	}
	Columns = MIN_COLUMNS;
    }
    limit_screen_size();

    // If the screen (shell) height has been changed, assume it is the
    // physical screenheight.
    if (old_Rows != Rows || old_Columns != Columns)
    {
	// Changing the screen size is not allowed while updating the screen.
	if (updating_screen)
	    *pp = old_value;
	else if (full_screen
#ifdef FEAT_GUI
		&& !gui.starting
#endif
		)
	    set_shellsize((int)Columns, (int)Rows, TRUE);
	else
	{
	    // Postpone the resizing; check the size and cmdline position for
	    // messages.
	    check_shellsize();
	    if (cmdline_row > Rows - p_ch && Rows > p_ch)
		cmdline_row = Rows - p_ch;
	}
	if (p_window >= Rows || !option_was_set((char_u *)"window"))
	    p_window = Rows - 1;
    }

    if (curbuf->b_p_ts <= 0)
    {
	errmsg = e_argument_must_be_positive;
	curbuf->b_p_ts = 8;
    }
    else if (curbuf->b_p_ts > TABSTOP_MAX)
    {
	errmsg = e_invalid_argument;
	curbuf->b_p_ts = 8;
    }
    if (p_tm < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_tm = 0;
    }
    if ((curwin->w_p_scr <= 0
		|| (curwin->w_p_scr > curwin->w_height
		    && curwin->w_height > 0))
	    && full_screen)
    {
	if (pp == &(curwin->w_p_scr))
	{
	    if (curwin->w_p_scr != 0)
		errmsg = e_invalid_scroll_size;
	    win_comp_scroll(curwin);
	}
	// If 'scroll' became invalid because of a side effect silently adjust
	// it.
	else if (curwin->w_p_scr <= 0)
	    curwin->w_p_scr = 1;
	else // curwin->w_p_scr > curwin->w_height
	    curwin->w_p_scr = curwin->w_height;
    }
    if (p_hi < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_hi = 0;
    }
    else if (p_hi > 10000)
    {
	errmsg = e_invalid_argument;
	p_hi = 10000;
    }
    if (p_re < 0 || p_re > 2)
    {
	errmsg = e_invalid_argument;
	p_re = 0;
    }
    if (p_report < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_report = 1;
    }
    if ((p_sj < -100 || p_sj >= Rows) && full_screen)
    {
	if (Rows != old_Rows)	// Rows changed, just adjust p_sj
	    p_sj = Rows / 2;
	else
	{
	    errmsg = e_invalid_scroll_size;
	    p_sj = 1;
	}
    }
    if (p_so < 0 && full_screen)
    {
	errmsg = e_argument_must_be_positive;
	p_so = 0;
    }
    if (p_siso < 0 && full_screen)
    {
	errmsg = e_argument_must_be_positive;
	p_siso = 0;
    }
    if (p_cwh < 1)
    {
	errmsg = e_argument_must_be_positive;
	p_cwh = 1;
    }
    if (p_ut < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_ut = 2000;
    }
    if (p_ss < 0)
    {
	errmsg = e_argument_must_be_positive;
	p_ss = 0;
    }

    return errmsg;
}

/*
 * Set the value of a number option, and take care of side effects.
 * Returns NULL for success, or an error message for an error.
 */
    static char *
set_num_option(
    int		opt_idx,		// index in options[] table
    char_u	*varp,			// pointer to the option variable
    long	value,			// new value
    char	*errbuf,		// buffer for error messages
    size_t	errbuflen,		// length of "errbuf"
    int		opt_flags)		// OPT_LOCAL, OPT_GLOBAL,
					// OPT_MODELINE, etc.
{
    char	*errmsg = NULL;
    long	old_value = *(long *)varp;
#if defined(FEAT_EVAL)
    long	old_global_value = 0;	// only used when setting a local and
					// global option
#endif
    long	old_Rows = Rows;	// remember old Rows
    long	old_Columns = Columns;	// remember old Columns
    long	*pp = (long *)varp;

    // Disallow changing some options from secure mode.
    if ((secure
#ifdef HAVE_SANDBOX
		|| sandbox != 0
#endif
		) && (options[opt_idx].flags & P_SECURE))
	return e_not_allowed_here;

#if defined(FEAT_EVAL)
    // Save the global value before changing anything. This is needed as for
    // a global-only option setting the "local value" in fact sets the global
    // value (since there is only one value).
    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
	old_global_value = *(long *)get_varp_scope(&(options[opt_idx]),
								   OPT_GLOBAL);
#endif

    *pp = value;
#ifdef FEAT_EVAL
    // Remember where the option was set.
    set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
#endif
#ifdef FEAT_GUI
    need_mouse_correct = TRUE;
#endif

    // Invoke the option specific callback function to validate and apply the
    // new value.
    if (options[opt_idx].opt_did_set_cb != NULL)
    {
	optset_T args;

	CLEAR_FIELD(args);
	args.os_varp = varp;
	args.os_flags = opt_flags;
	args.os_oldval.number = old_value;
	args.os_newval.number = value;
	args.os_errbuf = NULL;
	errmsg = options[opt_idx].opt_did_set_cb(&args);
    }

    // Check the bounds for numeric options here
    errmsg = check_num_option_bounds(pp, old_value, old_Rows, old_Columns,
						errbuf, errbuflen, errmsg);

    // May set global value for local option.
    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
	*(long *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL) = *pp;

    options[opt_idx].flags |= P_WAS_SET;

#if defined(FEAT_EVAL)
    apply_optionset_autocmd(opt_idx, opt_flags, old_value, old_global_value,
								value, errmsg);
#endif

    comp_col();			    // in case 'columns' or 'ls' changed

    if (curwin->w_curswant != MAXCOL
		     && (options[opt_idx].flags & (P_CURSWANT | P_RALL)) != 0
				   && (options[opt_idx].flags & P_HLONLY) == 0)
	curwin->w_set_curswant = TRUE;

    if ((opt_flags & OPT_NO_REDRAW) == 0)
	check_redraw(options[opt_idx].flags);

    return errmsg;
}

/*
 * Called after an option changed: check if something needs to be redrawn.
 */
    void
check_redraw(long_u flags)
{
    // Careful: P_RCLR and P_RALL are a combination of other P_ flags
    int		doclear = (flags & P_RCLR) == P_RCLR;
    int		all = ((flags & P_RALL) == P_RALL || doclear);

    if ((flags & P_RSTAT) || all)	// mark all status lines dirty
	status_redraw_all();

    if ((flags & P_RBUF) || (flags & P_RWIN) || all)
    {
	if (flags & P_HLONLY)
	    redraw_later(UPD_NOT_VALID);
	else
	    changed_window_setting();
    }
    if (flags & P_RBUF)
	redraw_curbuf_later(UPD_NOT_VALID);
    if (doclear)
	redraw_all_later(UPD_CLEAR);
    else if (all)
	redraw_all_later(UPD_NOT_VALID);
}

/*
 * Find index for option 'arg'.
 * Return -1 if not found.
 */
    int
findoption(char_u *arg)
{
    int		    opt_idx;
    char	    *s, *p;
    static short    quick_tab[27] = {0, 0};	// quick access table
    int		    is_term_opt;

    // For first call: Initialize the quick-access table.
    // It contains the index for the first option that starts with a certain
    // letter.  There are 26 letters, plus the first "t_" option.
    if (quick_tab[1] == 0)
    {
	p = options[0].fullname;
	for (opt_idx = 1; (s = options[opt_idx].fullname) != NULL; opt_idx++)
	{
	    if (s[0] != p[0])
	    {
		if (s[0] == 't' && s[1] == '_')
		    quick_tab[26] = opt_idx;
		else
		    quick_tab[CharOrdLow(s[0])] = opt_idx;
	    }
	    p = s;
	}
    }

    // Check for name starting with an illegal character.
    if (arg[0] < 'a' || arg[0] > 'z')
	return -1;

    is_term_opt = (arg[0] == 't' && arg[1] == '_');
    if (is_term_opt)
	opt_idx = quick_tab[26];
    else
	opt_idx = quick_tab[CharOrdLow(arg[0])];
    for (; (s = options[opt_idx].fullname) != NULL && s[0] == arg[0]; opt_idx++)
    {
	if (STRCMP(arg, s) == 0)		    // match full name
	    break;
    }
    if (s != NULL && s[0] != arg[0])
	s = NULL;
    if (s == NULL && !is_term_opt)
    {
	opt_idx = quick_tab[CharOrdLow(arg[0])];
	for ( ; options[opt_idx].fullname != NULL; opt_idx++)
	{
	    s = options[opt_idx].shortname;
	    if (s != NULL && STRCMP(arg, s) == 0)   // match short name
		break;
	    s = NULL;
	}
    }
    if (s == NULL)
	opt_idx = -1;
    return opt_idx;
}

#if defined(FEAT_EVAL) || defined(FEAT_TCL) || defined(FEAT_MZSCHEME) \
	|| defined(FEAT_SPELL) || defined(PROTO)
/*
 * Get the value for an option.
 *
 * Returns:
 * Number option: gov_number, *numval gets value.
 * Toggle option: gov_bool,   *numval gets value.
 * String option: gov_string, *stringval gets allocated string.
 * Hidden Number option: gov_hidden_number.
 * Hidden Toggle option: gov_hidden_bool.
 * Hidden String option: gov_hidden_string.
 * Unknown option: gov_unknown.
 *
 * "flagsp" (if not NULL) is set to the option flags (P_xxxx).
 */
    getoption_T
get_option_value(
    char_u	*name,
    long	*numval,
    char_u	**stringval,	    // NULL when only checking existence
    int		*flagsp,
    int		scope)
{
    int		opt_idx;
    char_u	*varp;

    opt_idx = findoption(name);
    if (opt_idx < 0)		    // option not in the table
    {
	int key;

	if (STRLEN(name) == 4 && name[0] == 't' && name[1] == '_'
				  && (key = find_key_option(name, FALSE)) != 0)
	{
	    char_u key_name[2];
	    char_u *p;

	    if (flagsp != NULL)
		*flagsp = 0;  // terminal option has no flags

	    // check for a terminal option
	    if (key < 0)
	    {
		key_name[0] = KEY2TERMCAP0(key);
		key_name[1] = KEY2TERMCAP1(key);
	    }
	    else
	    {
		key_name[0] = KS_KEY;
		key_name[1] = (key & 0xff);
	    }
	    p = find_termcode(key_name);
	    if (p != NULL)
	    {
		if (stringval != NULL)
		    *stringval = vim_strsave(p);
		return gov_string;
	    }
	}
	return gov_unknown;
    }

    varp = get_varp_scope(&(options[opt_idx]), scope);

    if (flagsp != NULL)
	// Return the P_xxxx option flags.
	*flagsp = options[opt_idx].flags;

    if (options[opt_idx].flags & P_STRING)
    {
	if (varp == NULL)		    // hidden option
	    return gov_hidden_string;
	if (stringval != NULL)
	{
	    if ((char_u **)varp == &p_pt)	// 'pastetoggle'
		*stringval = str2special_save(*(char_u **)(varp), FALSE,
									FALSE);
#ifdef FEAT_CRYPT
	    // never return the value of the crypt key
	    else if ((char_u **)varp == &curbuf->b_p_key
						&& **(char_u **)(varp) != NUL)
		*stringval = vim_strsave((char_u *)"*****");
#endif
	    else
		*stringval = vim_strsave(*(char_u **)(varp));
	}
	return gov_string;
    }

    if (varp == NULL)		    // hidden option
	return (options[opt_idx].flags & P_NUM)
					 ? gov_hidden_number : gov_hidden_bool;
    if (options[opt_idx].flags & P_NUM)
	*numval = *(long *)varp;
    else
    {
	// Special case: 'modified' is b_changed, but we also want to consider
	// it set when 'ff' or 'fenc' changed.
	if ((int *)varp == &curbuf->b_changed)
	    *numval = curbufIsChanged();
	else
	    *numval = (long) *(int *)varp;
    }
    return (options[opt_idx].flags & P_NUM) ? gov_number : gov_bool;
}
#endif

#if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3) || defined(PROTO)
/*
 * Returns the option attributes and its value. Unlike the above function it
 * will return either global value or local value of the option depending on
 * what was requested, but it will never return global value if it was
 * requested to return local one and vice versa. Neither it will return
 * buffer-local value if it was requested to return window-local one.
 *
 * Pretends that option is absent if it is not present in the requested scope
 * (i.e. has no global, window-local or buffer-local value depending on
 * opt_type). Uses
 *
 * Returned flags:
 *       0 hidden or unknown option, also option that does not have requested
 *	   type (see SREQ_* in vim.h)
 *  see SOPT_* in vim.h for other flags
 *
 * Possible opt_type values: see SREQ_* in vim.h
 */
    int
get_option_value_strict(
    char_u	*name,
    long	*numval,
    char_u	**stringval,	    // NULL when only obtaining attributes
    int		opt_type,
    void	*from)
{
    int		opt_idx;
    char_u	*varp = NULL;
    struct vimoption *p;
    int		r = 0;

    opt_idx = findoption(name);
    if (opt_idx < 0)
	return 0;

    p = &(options[opt_idx]);

    // Hidden option
    if (p->var == NULL)
	return 0;

    if (p->flags & P_BOOL)
	r |= SOPT_BOOL;
    else if (p->flags & P_NUM)
	r |= SOPT_NUM;
    else if (p->flags & P_STRING)
	r |= SOPT_STRING;

    if (p->indir == PV_NONE)
    {
	if (opt_type == SREQ_GLOBAL)
	    r |= SOPT_GLOBAL;
	else
	    return 0; // Did not request global-only option
    }
    else
    {
	if (p->indir & PV_BOTH)
	    r |= SOPT_GLOBAL;
	else if (opt_type == SREQ_GLOBAL)
	    return 0; // Requested global option

	if (p->indir & PV_WIN)
	{
	    if (opt_type == SREQ_BUF)
		return 0; // Did not request window-local option
	    else
		r |= SOPT_WIN;
	}
	else if (p->indir & PV_BUF)
	{
	    if (opt_type == SREQ_WIN)
		return 0; // Did not request buffer-local option
	    else
		r |= SOPT_BUF;
	}
    }

    if (stringval == NULL)
	return r;

    if (opt_type == SREQ_GLOBAL)
	varp = p->var;
    else
    {
	if (opt_type == SREQ_BUF)
	{
	    // Special case: 'modified' is b_changed, but we also want to
	    // consider it set when 'ff' or 'fenc' changed.
	    if (p->indir == PV_MOD)
	    {
		*numval = bufIsChanged((buf_T *)from);
		varp = NULL;
	    }
# ifdef FEAT_CRYPT
	    else if (p->indir == PV_KEY)
	    {
		// never return the value of the crypt key
		*stringval = NULL;
		varp = NULL;
	    }
# endif
	    else
	    {
		buf_T *save_curbuf = curbuf;

		// only getting a pointer, no need to use aucmd_prepbuf()
		curbuf = (buf_T *)from;
		curwin->w_buffer = curbuf;
		varp = get_varp(p);
		curbuf = save_curbuf;
		curwin->w_buffer = curbuf;
	    }
	}
	else if (opt_type == SREQ_WIN)
	{
	    win_T	*save_curwin = curwin;

	    curwin = (win_T *)from;
	    curbuf = curwin->w_buffer;
	    varp = get_varp(p);
	    curwin = save_curwin;
	    curbuf = curwin->w_buffer;
	}
	if (varp == p->var)
	    return (r | SOPT_UNSET);
    }

    if (varp != NULL)
    {
	if (p->flags & P_STRING)
	    *stringval = vim_strsave(*(char_u **)(varp));
	else if (p->flags & P_NUM)
	    *numval = *(long *) varp;
	else
	    *numval = *(int *)varp;
    }

    return r;
}

/*
 * Iterate over options. First argument is a pointer to a pointer to a
 * structure inside options[] array, second is option type like in the above
 * function.
 *
 * If first argument points to NULL it is assumed that iteration just started
 * and caller needs the very first value.
 * If first argument points to the end marker function returns NULL and sets
 * first argument to NULL.
 *
 * Returns full option name for current option on each call.
 */
    char_u *
option_iter_next(void **option, int opt_type)
{
    struct vimoption	*ret = NULL;
    do
    {
	if (*option == NULL)
	    *option = (void *) options;
	else if (((struct vimoption *) (*option))->fullname == NULL)
	{
	    *option = NULL;
	    return NULL;
	}
	else
	    *option = (void *) (((struct vimoption *) (*option)) + 1);

	ret = ((struct vimoption *) (*option));

	// Hidden option
	if (ret->var == NULL)
	{
	    ret = NULL;
	    continue;
	}

	switch (opt_type)
	{
	    case SREQ_GLOBAL:
		if (!(ret->indir == PV_NONE || ret->indir & PV_BOTH))
		    ret = NULL;
		break;
	    case SREQ_BUF:
		if (!(ret->indir & PV_BUF))
		    ret = NULL;
		break;
	    case SREQ_WIN:
		if (!(ret->indir & PV_WIN))
		    ret = NULL;
		break;
	    default:
		internal_error("option_iter_next()");
		return NULL;
	}
    }
    while (ret == NULL);

    return (char_u *)ret->fullname;
}
#endif

/*
 * Return the flags for the option at 'opt_idx'.
 */
    long_u
get_option_flags(int opt_idx)
{
    return options[opt_idx].flags;
}

/*
 * Set a flag for the option at 'opt_idx'.
 */
    void
set_option_flag(int opt_idx, long_u flag)
{
    options[opt_idx].flags |= flag;
}

/*
 * Returns TRUE if the option at 'opt_idx' is a global option
 */
    int
is_global_option(int opt_idx)
{
    return options[opt_idx].indir == PV_NONE;
}

/*
 * Returns TRUE if the option at 'opt_idx' is a global option which also has a
 * local value.
 */
    int
is_global_local_option(int opt_idx)
{
    return options[opt_idx].indir & PV_BOTH;
}

/*
 * Returns TRUE if the option at 'opt_idx' is a window-local option
 */
    int
is_window_local_option(int opt_idx)
{
    return options[opt_idx].var == VAR_WIN;
}

/*
 * Returns TRUE if the option at 'opt_idx' is a hidden option
 */
    int
is_hidden_option(int opt_idx)
{
    return options[opt_idx].var == NULL;
}

#if defined(FEAT_CRYPT) || defined(PROTO)
/*
 * Returns TRUE if the option at 'opt_idx' is a crypt key option
 */
    int
is_crypt_key_option(int opt_idx)
{
    return options[opt_idx].indir == PV_KEY;
}
#endif

/*
 * Set the value of option "name".
 * Use "string" for string options, use "number" for other options.
 *
 * Returns NULL on success or an untranslated error message on error.
 */
    char *
set_option_value(
    char_u	*name,
    long	number,
    char_u	*string,
    int		opt_flags)	// OPT_LOCAL or 0 (both)
{
    int		opt_idx;
    char_u	*varp;
    long_u	flags;
    static char	errbuf[ERR_BUFLEN];
    int		errbuflen = ERR_BUFLEN;

    opt_idx = findoption(name);
    if (opt_idx < 0)
    {
	int key;

	if (STRLEN(name) == 4 && name[0] == 't' && name[1] == '_'
		&& (key = find_key_option(name, FALSE)) != 0)
	{
	    char_u key_name[2];

	    if (key < 0)
	    {
		key_name[0] = KEY2TERMCAP0(key);
		key_name[1] = KEY2TERMCAP1(key);
	    }
	    else
	    {
		key_name[0] = KS_KEY;
		key_name[1] = (key & 0xff);
	    }
	    add_termcode(key_name, string, FALSE);
	    if (full_screen)
		ttest(FALSE);
	    redraw_all_later(UPD_CLEAR);
	    return NULL;
	}

	semsg(_(e_unknown_option_str_2), name);
    }
    else
    {
	flags = options[opt_idx].flags;
#ifdef HAVE_SANDBOX
	// Disallow changing some options in the sandbox
	if (sandbox > 0 && (flags & P_SECURE))
	{
	    emsg(_(e_not_allowed_in_sandbox));
	    return NULL;
	}
#endif
	if (flags & P_STRING)
	    return set_string_option(opt_idx, string, opt_flags, errbuf, errbuflen);

	varp = get_varp_scope(&(options[opt_idx]), opt_flags);
	if (varp != NULL)	// hidden option is not changed
	{
	    if (number == 0 && string != NULL)
	    {
		int idx;

		// Either we are given a string or we are setting option
		// to zero.
		for (idx = 0; string[idx] == '0'; ++idx)
		    ;
		if (string[idx] != NUL || idx == 0)
		{
		    // There's another character after zeros or the string
		    // is empty.  In both cases, we are trying to set a
		    // num option using a string.
		    semsg(_(e_number_required_after_str_equal_str),
								 name, string);
		    return NULL;     // do nothing as we hit an error

		}
	    }
	    if (flags & P_NUM)
	    {
		return set_num_option(opt_idx, varp, number,
					   errbuf, sizeof(errbuf), opt_flags);
	    }
	    else
		return set_bool_option(opt_idx, varp, (int)number, opt_flags);
	}

    }
    return NULL;
}

/*
 * Call set_option_value() and when an error is returned report it.
 */
    void
set_option_value_give_err(
    char_u	*name,
    long	number,
    char_u	*string,
    int		opt_flags)	// OPT_LOCAL or 0 (both)
{
    char *errmsg = set_option_value(name, number, string, opt_flags);

    if (errmsg != NULL)
	emsg(_(errmsg));
}

/*
 * Get the terminal code for a terminal option.
 * Returns NULL when not found.
 */
    char_u *
get_term_code(char_u *tname)
{
    int	    opt_idx;
    char_u  *varp;

    if (tname[0] != 't' || tname[1] != '_' ||
	    tname[2] == NUL || tname[3] == NUL)
	return NULL;
    if ((opt_idx = findoption(tname)) >= 0)
    {
	varp = get_varp(&(options[opt_idx]));
	if (varp != NULL)
	    varp = *(char_u **)(varp);
	return varp;
    }
    return find_termcode(tname + 2);
}

    char_u *
get_highlight_default(void)
{
    int i;

    i = findoption((char_u *)"hl");
    if (i >= 0)
	return options[i].def_val[VI_DEFAULT];
    return (char_u *)NULL;
}

    char_u *
get_encoding_default(void)
{
    int i;

    i = findoption((char_u *)"enc");
    if (i >= 0)
	return options[i].def_val[VI_DEFAULT];
    return (char_u *)NULL;
}

#if defined(FEAT_QUICKFIX) || defined(PROTO)
    int
is_option_allocated(char *name)
{
    int idx = findoption((char_u *)name);

    return idx >= 0 && (options[idx].flags & P_ALLOCED);
}
#endif

/*
 * Translate a string like "t_xx", "<t_xx>" or "<S-Tab>" to a key number.
 * When "has_lt" is true there is a '<' before "*arg_arg".
 * Returns 0 when the key is not recognized.
 */
    static int
find_key_option(char_u *arg_arg, int has_lt)
{
    int		key = 0;
    int		modifiers;
    char_u	*arg = arg_arg;

    // Don't use get_special_key_code() for t_xx, we don't want it to call
    // add_termcap_entry().
    if (arg[0] == 't' && arg[1] == '_' && arg[2] && arg[3])
	key = TERMCAP2KEY(arg[2], arg[3]);
    else if (has_lt)
    {
	--arg;			    // put arg at the '<'
	modifiers = 0;
	key = find_special_key(&arg, &modifiers,
			    FSK_KEYCODE | FSK_KEEP_X_KEY | FSK_SIMPLIFY, NULL);
	if (modifiers)		    // can't handle modifiers here
	    key = 0;
    }
    return key;
}

/*
 * if 'all' == 0: show changed options
 * if 'all' == 1: show all normal options
 * if 'all' == 2: show all terminal options
 */
    static void
showoptions(
    int		all,
    int		opt_flags)	// OPT_LOCAL and/or OPT_GLOBAL
{
    struct vimoption	*p;
    int			col;
    int			isterm;
    char_u		*varp;
    struct vimoption	**items;
    int			item_count;
    int			run;
    int			row, rows;
    int			cols;
    int			i;
    int			len;

#define INC 20
#define GAP 3

    items = ALLOC_MULT(struct vimoption *, OPTION_COUNT);
    if (items == NULL)
	return;

    // Highlight title
    if (all == 2)
	msg_puts_title(_("\n--- Terminal codes ---"));
    else if (opt_flags & OPT_GLOBAL)
	msg_puts_title(_("\n--- Global option values ---"));
    else if (opt_flags & OPT_LOCAL)
	msg_puts_title(_("\n--- Local option values ---"));
    else
	msg_puts_title(_("\n--- Options ---"));

    // Do the loop two times:
    // 1. display the short items
    // 2. display the long items (only strings and numbers)
    // When "opt_flags" has OPT_ONECOLUMN do everything in run 2.
    for (run = 1; run <= 2 && !got_int; ++run)
    {
	// collect the items in items[]
	item_count = 0;
	for (p = &options[0]; p->fullname != NULL; p++)
	{
	    // apply :filter /pat/
	    if (message_filtered((char_u *)p->fullname))
		continue;

	    varp = NULL;
	    isterm = istermoption(p);
	    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) != 0)
	    {
		if (p->indir != PV_NONE && !isterm)
		    varp = get_varp_scope(p, opt_flags);
	    }
	    else
		varp = get_varp(p);
	    if (varp != NULL
		    && ((all == 2 && isterm)
			|| (all == 1 && !isterm)
			|| (all == 0 && !optval_default(p, varp, p_cp))))
	    {
		if (opt_flags & OPT_ONECOLUMN)
		    len = Columns;
		else if (p->flags & P_BOOL)
		    len = 1;		// a toggle option fits always
		else
		{
		    option_value2string(p, opt_flags);
		    len = (int)STRLEN(p->fullname) + vim_strsize(NameBuff) + 1;
		}
		if ((len <= INC - GAP && run == 1) ||
						(len > INC - GAP && run == 2))
		    items[item_count++] = p;
	    }
	}

	// display the items
	if (run == 1)
	{
	    cols = (Columns + GAP - 3) / INC;
	    if (cols == 0)
		cols = 1;
	    rows = (item_count + cols - 1) / cols;
	}
	else	// run == 2
	    rows = item_count;
	for (row = 0; row < rows && !got_int; ++row)
	{
	    msg_putchar('\n');			// go to next line
	    if (got_int)			// 'q' typed in more
		break;
	    col = 0;
	    for (i = row; i < item_count; i += rows)
	    {
		msg_col = col;			// make columns
		showoneopt(items[i], opt_flags);
		col += INC;
	    }
	    out_flush();
	    ui_breakcheck();
	}
    }
    vim_free(items);
}

/*
 * Return TRUE if option "p" has its default value.
 */
    static int
optval_default(struct vimoption *p, char_u *varp, int compatible)
{
    int		dvi;

    if (varp == NULL)
	return TRUE;	    // hidden option is always at default
    dvi = ((p->flags & P_VI_DEF) || compatible) ? VI_DEFAULT : VIM_DEFAULT;
    if (p->flags & P_NUM)
	return (*(long *)varp == (long)(long_i)p->def_val[dvi]);
    if (p->flags & P_BOOL)
			// the cast to long is required for Manx C, long_i is
			// needed for MSVC
	return (*(int *)varp == (int)(long)(long_i)p->def_val[dvi]);
    // P_STRING
    return (STRCMP(*(char_u **)varp, p->def_val[dvi]) == 0);
}

/*
 * showoneopt: show the value of one option
 * must not be called with a hidden option!
 */
    static void
showoneopt(
    struct vimoption	*p,
    int			opt_flags)	// OPT_LOCAL or OPT_GLOBAL
{
    char_u	*varp;
    int		save_silent = silent_mode;

    silent_mode = FALSE;
    info_message = TRUE;	// use mch_msg(), not mch_errmsg()

    varp = get_varp_scope(p, opt_flags);

    // for 'modified' we also need to check if 'ff' or 'fenc' changed.
    if ((p->flags & P_BOOL) && ((int *)varp == &curbuf->b_changed
					? !curbufIsChanged() : !*(int *)varp))
	msg_puts("no");
    else if ((p->flags & P_BOOL) && *(int *)varp < 0)
	msg_puts("--");
    else
	msg_puts("  ");
    msg_puts(p->fullname);
    if (!(p->flags & P_BOOL))
    {
	msg_putchar('=');
	// put value string in NameBuff
	option_value2string(p, opt_flags);
	msg_outtrans(NameBuff);
    }

    silent_mode = save_silent;
    info_message = FALSE;
}

/*
 * Write modified options as ":set" commands to a file.
 *
 * There are three values for "opt_flags":
 * OPT_GLOBAL:		   Write global option values and fresh values of
 *			   buffer-local options (used for start of a session
 *			   file).
 * OPT_GLOBAL + OPT_LOCAL: Idem, add fresh values of window-local options for
 *			   curwin (used for a vimrc file).
 * OPT_LOCAL:		   Write buffer-local option values for curbuf, fresh
 *			   and local values for window-local options of
 *			   curwin.  Local values are also written when at the
 *			   default value, because a modeline or autocommand
 *			   may have set them when doing ":edit file" and the
 *			   user has set them back at the default or fresh
 *			   value.
 *			   When "local_only" is TRUE, don't write fresh
 *			   values, only local values (for ":mkview").
 * (fresh value = value used for a new buffer or window for a local option).
 *
 * Return FAIL on error, OK otherwise.
 */
    int
makeset(FILE *fd, int opt_flags, int local_only)
{
    struct vimoption	*p;
    char_u		*varp;			// currently used value
    char_u		*varp_fresh;		// local value
    char_u		*varp_local = NULL;	// fresh value
    char		*cmd;
    int			round;
    int			pri;

    /*
     * The options that don't have a default (terminal name, columns, lines)
     * are never written.  Terminal options are also not written.
     * Do the loop over "options[]" twice: once for options with the
     * P_PRI_MKRC flag and once without.
     */
    for (pri = 1; pri >= 0; --pri)
    {
      for (p = &options[0]; !istermoption(p); p++)
	if (!(p->flags & P_NO_MKRC)
		&& !istermoption(p)
		&& ((pri == 1) == ((p->flags & P_PRI_MKRC) != 0)))
	{
	    // skip global option when only doing locals
	    if (p->indir == PV_NONE && !(opt_flags & OPT_GLOBAL))
		continue;

	    // Do not store options like 'bufhidden' and 'syntax' in a vimrc
	    // file, they are always buffer-specific.
	    if ((opt_flags & OPT_GLOBAL) && (p->flags & P_NOGLOB))
		continue;

	    // Global values are only written when not at the default value.
	    varp = get_varp_scope(p, opt_flags);
	    if ((opt_flags & OPT_GLOBAL) && optval_default(p, varp, p_cp))
		continue;

	    if ((opt_flags & OPT_SKIPRTP) && (p->var == (char_u *)&p_rtp
						 || p->var == (char_u *)&p_pp))
		continue;

	    round = 2;
	    if (p->indir != PV_NONE)
	    {
		if (p->var == VAR_WIN)
		{
		    // skip window-local option when only doing globals
		    if (!(opt_flags & OPT_LOCAL))
			continue;
		    // When fresh value of window-local option is not at the
		    // default, need to write it too.
		    if (!(opt_flags & OPT_GLOBAL) && !local_only)
		    {
			varp_fresh = get_varp_scope(p, OPT_GLOBAL);
			if (!optval_default(p, varp_fresh, p_cp))
			{
			    round = 1;
			    varp_local = varp;
			    varp = varp_fresh;
			}
		    }
		}
	    }

	    // Round 1: fresh value for window-local options.
	    // Round 2: other values
	    for ( ; round <= 2; varp = varp_local, ++round)
	    {
		if (round == 1 || (opt_flags & OPT_GLOBAL))
		    cmd = "set";
		else
		    cmd = "setlocal";

		if (p->flags & P_BOOL)
		{
		    if (put_setbool(fd, cmd, p->fullname, *(int *)varp) == FAIL)
			return FAIL;
		}
		else if (p->flags & P_NUM)
		{
		    if (put_setnum(fd, cmd, p->fullname, (long *)varp) == FAIL)
			return FAIL;
		}
		else    // P_STRING
		{
		    int		do_endif = FALSE;

		    // Don't set 'syntax' and 'filetype' again if the value is
		    // already right, avoids reloading the syntax file.
		    if (
#if defined(FEAT_SYN_HL)
			    p->indir == PV_SYN ||
#endif
			    p->indir == PV_FT)
		    {
			if (fprintf(fd, "if &%s != '%s'", p->fullname,
						       *(char_u **)(varp)) < 0
				|| put_eol(fd) < 0)
			    return FAIL;
			do_endif = TRUE;
		    }
		    if (put_setstring(fd, cmd, p->fullname, (char_u **)varp,
							     p->flags) == FAIL)
			return FAIL;
		    if (do_endif)
		    {
			if (put_line(fd, "endif") == FAIL)
			    return FAIL;
		    }
		}
	    }
	}
    }
    return OK;
}

#if defined(FEAT_FOLDING) || defined(PROTO)
/*
 * Generate set commands for the local fold options only.  Used when
 * 'sessionoptions' or 'viewoptions' contains "folds" but not "options".
 */
    int
makefoldset(FILE *fd)
{
    if (put_setstring(fd, "setlocal", "fdm", &curwin->w_p_fdm, 0) == FAIL
# ifdef FEAT_EVAL
	    || put_setstring(fd, "setlocal", "fde", &curwin->w_p_fde, 0)
								       == FAIL
# endif
	    || put_setstring(fd, "setlocal", "fmr", &curwin->w_p_fmr, 0)
								       == FAIL
	    || put_setstring(fd, "setlocal", "fdi", &curwin->w_p_fdi, 0)
								       == FAIL
	    || put_setnum(fd, "setlocal", "fdl", &curwin->w_p_fdl) == FAIL
	    || put_setnum(fd, "setlocal", "fml", &curwin->w_p_fml) == FAIL
	    || put_setnum(fd, "setlocal", "fdn", &curwin->w_p_fdn) == FAIL
	    || put_setbool(fd, "setlocal", "fen", curwin->w_p_fen) == FAIL
	    )
	return FAIL;

    return OK;
}
#endif

    static int
put_setstring(
    FILE	*fd,
    char	*cmd,
    char	*name,
    char_u	**valuep,
    long_u	flags)
{
    char_u	*s;
    char_u	*buf = NULL;
    char_u	*part = NULL;
    char_u	*p;

    if (fprintf(fd, "%s %s=", cmd, name) < 0)
	return FAIL;
    if (*valuep != NULL)
    {
	// Output 'pastetoggle' as key names.  For other
	// options some characters have to be escaped with
	// CTRL-V or backslash
	if (valuep == &p_pt)
	{
	    s = *valuep;
	    while (*s != NUL)
		if (put_escstr(fd, str2special(&s, FALSE, FALSE), 2) == FAIL)
		    return FAIL;
	}
	// expand the option value, replace $HOME by ~
	else if ((flags & P_EXPAND) != 0)
	{
	    int  size = (int)STRLEN(*valuep) + 1;

	    // replace home directory in the whole option value into "buf"
	    buf = alloc(size);
	    if (buf == NULL)
		goto fail;
	    home_replace(NULL, *valuep, buf, size, FALSE);

	    // If the option value is longer than MAXPATHL, we need to append
	    // each comma separated part of the option separately, so that it
	    // can be expanded when read back.
	    if (size >= MAXPATHL && (flags & P_COMMA) != 0
					   && vim_strchr(*valuep, ',') != NULL)
	    {
		part = alloc(size);
		if (part == NULL)
		    goto fail;

		// write line break to clear the option, e.g. ':set rtp='
		if (put_eol(fd) == FAIL)
		    goto fail;

		p = buf;
		while (*p != NUL)
		{
		    // for each comma separated option part, append value to
		    // the option, :set rtp+=value
		    if (fprintf(fd, "%s %s+=", cmd, name) < 0)
			goto fail;
		    (void)copy_option_part(&p, part, size,  ",");
		    if (put_escstr(fd, part, 2) == FAIL || put_eol(fd) == FAIL)
			goto fail;
		}
		vim_free(buf);
		vim_free(part);
		return OK;
	    }
	    if (put_escstr(fd, buf, 2) == FAIL)
	    {
		vim_free(buf);
		return FAIL;
	    }
	    vim_free(buf);
	}
	else if (put_escstr(fd, *valuep, 2) == FAIL)
	    return FAIL;
    }
    if (put_eol(fd) < 0)
	return FAIL;
    return OK;
fail:
    vim_free(buf);
    vim_free(part);
    return FAIL;
}

    static int
put_setnum(
    FILE	*fd,
    char	*cmd,
    char	*name,
    long	*valuep)
{
    long	wc;

    if (fprintf(fd, "%s %s=", cmd, name) < 0)
	return FAIL;
    if (wc_use_keyname((char_u *)valuep, &wc))
    {
	// print 'wildchar' and 'wildcharm' as a key name
	if (fputs((char *)get_special_key_name((int)wc, 0), fd) < 0)
	    return FAIL;
    }
    else if (fprintf(fd, "%ld", *valuep) < 0)
	return FAIL;
    if (put_eol(fd) < 0)
	return FAIL;
    return OK;
}

    static int
put_setbool(
    FILE	*fd,
    char	*cmd,
    char	*name,
    int		value)
{
    if (value < 0)	// global/local option using global value
	return OK;
    if (fprintf(fd, "%s %s%s", cmd, value ? "" : "no", name) < 0
	    || put_eol(fd) < 0)
	return FAIL;
    return OK;
}

/*
 * Clear all the terminal options.
 * If the option has been allocated, free the memory.
 * Terminal options are never hidden or indirect.
 */
    void
clear_termoptions(void)
{
    // Reset a few things before clearing the old options. This may cause
    // outputting a few things that the terminal doesn't understand, but the
    // screen will be cleared later, so this is OK.
    mch_setmouse(FALSE);	    // switch mouse off
    mch_restore_title(SAVE_RESTORE_BOTH);    // restore window titles
#if defined(FEAT_XCLIPBOARD) && defined(FEAT_GUI)
    // When starting the GUI close the display opened for the clipboard.
    // After restoring the title, because that will need the display.
    if (gui.starting)
	clear_xterm_clip();
#endif
    stoptermcap();			// stop termcap mode

    free_termoptions();
}

    void
free_termoptions(void)
{
    struct vimoption   *p;

    for (p = options; p->fullname != NULL; p++)
	if (istermoption(p))
	{
	    if (p->flags & P_ALLOCED)
		free_string_option(*(char_u **)(p->var));
	    if (p->flags & P_DEF_ALLOCED)
		free_string_option(p->def_val[VI_DEFAULT]);
	    *(char_u **)(p->var) = empty_option;
	    p->def_val[VI_DEFAULT] = empty_option;
	    p->flags &= ~(P_ALLOCED|P_DEF_ALLOCED);
#ifdef FEAT_EVAL
	    // remember where the option was cleared
	    set_option_sctx_idx((int)(p - options), OPT_GLOBAL, current_sctx);
#endif
	}
    clear_termcodes();
}

/*
 * Free the string for one term option, if it was allocated.
 * Set the string to empty_option and clear allocated flag.
 * "var" points to the option value.
 */
    void
free_one_termoption(char_u *var)
{
    struct vimoption   *p;

    for (p = &options[0]; p->fullname != NULL; p++)
	if (p->var == var)
	{
	    if (p->flags & P_ALLOCED)
		free_string_option(*(char_u **)(p->var));
	    *(char_u **)(p->var) = empty_option;
	    p->flags &= ~P_ALLOCED;
	    break;
	}
}

/*
 * Set the terminal option defaults to the current value.
 * Used after setting the terminal name.
 */
    void
set_term_defaults(void)
{
    struct vimoption   *p;

    for (p = &options[0]; p->fullname != NULL; p++)
    {
	if (istermoption(p) && p->def_val[VI_DEFAULT] != *(char_u **)(p->var))
	{
	    if (p->flags & P_DEF_ALLOCED)
	    {
		free_string_option(p->def_val[VI_DEFAULT]);
		p->flags &= ~P_DEF_ALLOCED;
	    }
	    p->def_val[VI_DEFAULT] = *(char_u **)(p->var);
	    if (p->flags & P_ALLOCED)
	    {
		p->flags |= P_DEF_ALLOCED;
		p->flags &= ~P_ALLOCED;	 // don't free the value now
	    }
	}
    }
}

/*
 * return TRUE if 'p' starts with 't_'
 */
    static int
istermoption(struct vimoption *p)
{
    return (p->fullname[0] == 't' && p->fullname[1] == '_');
}

/*
 * Returns TRUE if the option at 'opt_idx' starts with 't_'
 */
    int
istermoption_idx(int opt_idx)
{
    return istermoption(&options[opt_idx]);
}

#if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3) || defined(PROTO)
/*
 * Unset local option value, similar to ":set opt<".
 */
    void
unset_global_local_option(char_u *name, void *from)
{
    struct vimoption *p;
    int		opt_idx;
    buf_T	*buf = (buf_T *)from;

    opt_idx = findoption(name);
    if (opt_idx < 0)
	return;
    p = &(options[opt_idx]);

    switch ((int)p->indir)
    {
	// global option with local value: use local value if it's been set
	case PV_EP:
	    clear_string_option(&buf->b_p_ep);
	    break;
	case PV_KP:
	    clear_string_option(&buf->b_p_kp);
	    break;
	case PV_PATH:
	    clear_string_option(&buf->b_p_path);
	    break;
	case PV_AR:
	    buf->b_p_ar = -1;
	    break;
	case PV_BKC:
	    clear_string_option(&buf->b_p_bkc);
	    buf->b_bkc_flags = 0;
	    break;
	case PV_TAGS:
	    clear_string_option(&buf->b_p_tags);
	    break;
	case PV_TC:
	    clear_string_option(&buf->b_p_tc);
	    buf->b_tc_flags = 0;
	    break;
	case PV_SISO:
	    curwin->w_p_siso = -1;
	    break;
	case PV_SO:
	    curwin->w_p_so = -1;
	    break;
# ifdef FEAT_FIND_ID
	case PV_DEF:
	    clear_string_option(&buf->b_p_def);
	    break;
	case PV_INC:
	    clear_string_option(&buf->b_p_inc);
	    break;
# endif
	case PV_DICT:
	    clear_string_option(&buf->b_p_dict);
	    break;
	case PV_TSR:
	    clear_string_option(&buf->b_p_tsr);
	    break;
# ifdef FEAT_COMPL_FUNC
	case PV_TSRFU:
	    clear_string_option(&buf->b_p_tsrfu);
	    break;
# endif
	case PV_FP:
	    clear_string_option(&buf->b_p_fp);
	    break;
# ifdef FEAT_QUICKFIX
	case PV_EFM:
	    clear_string_option(&buf->b_p_efm);
	    break;
	case PV_GP:
	    clear_string_option(&buf->b_p_gp);
	    break;
	case PV_MP:
	    clear_string_option(&buf->b_p_mp);
	    break;
# endif
# if defined(FEAT_BEVAL) && defined(FEAT_EVAL)
	case PV_BEXPR:
	    clear_string_option(&buf->b_p_bexpr);
	    break;
# endif
# if defined(FEAT_CRYPT)
	case PV_CM:
	    clear_string_option(&buf->b_p_cm);
	    break;
# endif
# ifdef FEAT_LINEBREAK
	case PV_SBR:
	    clear_string_option(&((win_T *)from)->w_p_sbr);
	    break;
# endif
# ifdef FEAT_STL_OPT
	case PV_STL:
	    clear_string_option(&((win_T *)from)->w_p_stl);
	    break;
# endif
	case PV_UL:
	    buf->b_p_ul = NO_LOCAL_UNDOLEVEL;
	    break;
	case PV_LW:
	    clear_string_option(&buf->b_p_lw);
	    break;
	case PV_MENC:
	    clear_string_option(&buf->b_p_menc);
	    break;
	case PV_LCS:
	    clear_string_option(&((win_T *)from)->w_p_lcs);
	    set_listchars_option((win_T *)from, ((win_T *)from)->w_p_lcs, TRUE,
								      NULL, 0);
	    redraw_later(UPD_NOT_VALID);
	    break;
	case PV_FCS:
	    clear_string_option(&((win_T *)from)->w_p_fcs);
	    set_fillchars_option((win_T *)from, ((win_T *)from)->w_p_fcs, TRUE,
								      NULL, 0);
	    redraw_later(UPD_NOT_VALID);
	    break;
	case PV_VE:
	    clear_string_option(&((win_T *)from)->w_p_ve);
	    ((win_T *)from)->w_ve_flags = 0;
	    break;
    }
}
#endif

/*
 * Get pointer to option variable, depending on local or global scope.
 * "scope" can be OPT_LOCAL, OPT_GLOBAL or a combination.
 */
    static char_u *
get_varp_scope(struct vimoption *p, int scope)
{
    if ((scope & OPT_GLOBAL) && p->indir != PV_NONE)
    {
	if (p->var == VAR_WIN)
	    return (char_u *)GLOBAL_WO(get_varp(p));
	return p->var;
    }
    if ((scope & OPT_LOCAL) && ((int)p->indir & PV_BOTH))
    {
	switch ((int)p->indir)
	{
	    case PV_FP:   return (char_u *)&(curbuf->b_p_fp);
#ifdef FEAT_QUICKFIX
	    case PV_EFM:  return (char_u *)&(curbuf->b_p_efm);
	    case PV_GP:   return (char_u *)&(curbuf->b_p_gp);
	    case PV_MP:   return (char_u *)&(curbuf->b_p_mp);
#endif
	    case PV_EP:   return (char_u *)&(curbuf->b_p_ep);
	    case PV_KP:   return (char_u *)&(curbuf->b_p_kp);
	    case PV_PATH: return (char_u *)&(curbuf->b_p_path);
	    case PV_AR:   return (char_u *)&(curbuf->b_p_ar);
	    case PV_TAGS: return (char_u *)&(curbuf->b_p_tags);
	    case PV_TC:   return (char_u *)&(curbuf->b_p_tc);
	    case PV_SISO: return (char_u *)&(curwin->w_p_siso);
	    case PV_SO:   return (char_u *)&(curwin->w_p_so);
#ifdef FEAT_FIND_ID
	    case PV_DEF:  return (char_u *)&(curbuf->b_p_def);
	    case PV_INC:  return (char_u *)&(curbuf->b_p_inc);
#endif
	    case PV_DICT: return (char_u *)&(curbuf->b_p_dict);
	    case PV_TSR:  return (char_u *)&(curbuf->b_p_tsr);
#ifdef FEAT_COMPL_FUNC
	    case PV_TSRFU: return (char_u *)&(curbuf->b_p_tsrfu);
#endif
#if defined(FEAT_BEVAL) && defined(FEAT_EVAL)
	    case PV_BEXPR: return (char_u *)&(curbuf->b_p_bexpr);
#endif
#if defined(FEAT_CRYPT)
	    case PV_CM:	  return (char_u *)&(curbuf->b_p_cm);
#endif
#ifdef FEAT_LINEBREAK
	    case PV_SBR:  return (char_u *)&(curwin->w_p_sbr);
#endif
#ifdef FEAT_STL_OPT
	    case PV_STL:  return (char_u *)&(curwin->w_p_stl);
#endif
	    case PV_UL:   return (char_u *)&(curbuf->b_p_ul);
	    case PV_LW:   return (char_u *)&(curbuf->b_p_lw);
	    case PV_BKC:  return (char_u *)&(curbuf->b_p_bkc);
	    case PV_MENC: return (char_u *)&(curbuf->b_p_menc);
	    case PV_LCS:  return (char_u *)&(curwin->w_p_lcs);
	    case PV_FCS:  return (char_u *)&(curwin->w_p_fcs);
	    case PV_VE:	  return (char_u *)&(curwin->w_p_ve);

	}
	return NULL; // "cannot happen"
    }
    return get_varp(p);
}

/*
 * Get pointer to option variable at 'opt_idx', depending on local or global
 * scope.
 */
    char_u *
get_option_varp_scope(int opt_idx, int scope)
{
    return get_varp_scope(&(options[opt_idx]), scope);
}

/*
 * Get pointer to option variable.
 */
    static char_u *
get_varp(struct vimoption *p)
{
    // hidden option, always return NULL
    if (p->var == NULL)
	return NULL;

    switch ((int)p->indir)
    {
	case PV_NONE:	return p->var;

	// global option with local value: use local value if it's been set
	case PV_EP:	return *curbuf->b_p_ep != NUL
				    ? (char_u *)&curbuf->b_p_ep : p->var;
	case PV_KP:	return *curbuf->b_p_kp != NUL
				    ? (char_u *)&curbuf->b_p_kp : p->var;
	case PV_PATH:	return *curbuf->b_p_path != NUL
				    ? (char_u *)&(curbuf->b_p_path) : p->var;
	case PV_AR:	return curbuf->b_p_ar >= 0
				    ? (char_u *)&(curbuf->b_p_ar) : p->var;
	case PV_TAGS:	return *curbuf->b_p_tags != NUL
				    ? (char_u *)&(curbuf->b_p_tags) : p->var;
	case PV_TC:	return *curbuf->b_p_tc != NUL
				    ? (char_u *)&(curbuf->b_p_tc) : p->var;
	case PV_BKC:	return *curbuf->b_p_bkc != NUL
				    ? (char_u *)&(curbuf->b_p_bkc) : p->var;
	case PV_SISO:	return curwin->w_p_siso >= 0
				    ? (char_u *)&(curwin->w_p_siso) : p->var;
	case PV_SO:	return curwin->w_p_so >= 0
				    ? (char_u *)&(curwin->w_p_so) : p->var;
#ifdef FEAT_FIND_ID
	case PV_DEF:	return *curbuf->b_p_def != NUL
				    ? (char_u *)&(curbuf->b_p_def) : p->var;
	case PV_INC:	return *curbuf->b_p_inc != NUL
				    ? (char_u *)&(curbuf->b_p_inc) : p->var;
#endif
	case PV_DICT:	return *curbuf->b_p_dict != NUL
				    ? (char_u *)&(curbuf->b_p_dict) : p->var;
	case PV_TSR:	return *curbuf->b_p_tsr != NUL
				    ? (char_u *)&(curbuf->b_p_tsr) : p->var;
#ifdef FEAT_COMPL_FUNC
	case PV_TSRFU:	return *curbuf->b_p_tsrfu != NUL
				    ? (char_u *)&(curbuf->b_p_tsrfu) : p->var;
#endif
	case PV_FP:	return *curbuf->b_p_fp != NUL
				    ? (char_u *)&(curbuf->b_p_fp) : p->var;
#ifdef FEAT_QUICKFIX
	case PV_EFM:	return *curbuf->b_p_efm != NUL
				    ? (char_u *)&(curbuf->b_p_efm) : p->var;
	case PV_GP:	return *curbuf->b_p_gp != NUL
				    ? (char_u *)&(curbuf->b_p_gp) : p->var;
	case PV_MP:	return *curbuf->b_p_mp != NUL
				    ? (char_u *)&(curbuf->b_p_mp) : p->var;
#endif
#if defined(FEAT_BEVAL) && defined(FEAT_EVAL)
	case PV_BEXPR:	return *curbuf->b_p_bexpr != NUL
				    ? (char_u *)&(curbuf->b_p_bexpr) : p->var;
#endif
#if defined(FEAT_CRYPT)
	case PV_CM:	return *curbuf->b_p_cm != NUL
				    ? (char_u *)&(curbuf->b_p_cm) : p->var;
#endif
#ifdef FEAT_LINEBREAK
	case PV_SBR:	return *curwin->w_p_sbr != NUL
				    ? (char_u *)&(curwin->w_p_sbr) : p->var;
#endif
#ifdef FEAT_STL_OPT
	case PV_STL:	return *curwin->w_p_stl != NUL
				    ? (char_u *)&(curwin->w_p_stl) : p->var;
#endif
	case PV_UL:	return curbuf->b_p_ul != NO_LOCAL_UNDOLEVEL
				    ? (char_u *)&(curbuf->b_p_ul) : p->var;
	case PV_LW:	return *curbuf->b_p_lw != NUL
				    ? (char_u *)&(curbuf->b_p_lw) : p->var;
	case PV_MENC:	return *curbuf->b_p_menc != NUL
				    ? (char_u *)&(curbuf->b_p_menc) : p->var;
#ifdef FEAT_ARABIC
	case PV_ARAB:	return (char_u *)&(curwin->w_p_arab);
#endif
	case PV_LIST:	return (char_u *)&(curwin->w_p_list);
	case PV_LCS:	return *curwin->w_p_lcs != NUL
				    ? (char_u *)&(curwin->w_p_lcs) : p->var;
	case PV_FCS:	return *curwin->w_p_fcs != NUL
				    ? (char_u *)&(curwin->w_p_fcs) : p->var;
	case PV_VE:	return *curwin->w_p_ve != NUL
				    ? (char_u *)&(curwin->w_p_ve) : p->var;
#ifdef FEAT_SPELL
	case PV_SPELL:	return (char_u *)&(curwin->w_p_spell);
#endif
#ifdef FEAT_SYN_HL
	case PV_CUC:	return (char_u *)&(curwin->w_p_cuc);
	case PV_CUL:	return (char_u *)&(curwin->w_p_cul);
	case PV_CULOPT:	return (char_u *)&(curwin->w_p_culopt);
	case PV_CC:	return (char_u *)&(curwin->w_p_cc);
#endif
#ifdef FEAT_DIFF
	case PV_DIFF:	return (char_u *)&(curwin->w_p_diff);
#endif
#ifdef FEAT_FOLDING
	case PV_FDC:	return (char_u *)&(curwin->w_p_fdc);
	case PV_FEN:	return (char_u *)&(curwin->w_p_fen);
	case PV_FDI:	return (char_u *)&(curwin->w_p_fdi);
	case PV_FDL:	return (char_u *)&(curwin->w_p_fdl);
	case PV_FDM:	return (char_u *)&(curwin->w_p_fdm);
	case PV_FML:	return (char_u *)&(curwin->w_p_fml);
	case PV_FDN:	return (char_u *)&(curwin->w_p_fdn);
# ifdef FEAT_EVAL
	case PV_FDE:	return (char_u *)&(curwin->w_p_fde);
	case PV_FDT:	return (char_u *)&(curwin->w_p_fdt);
# endif
	case PV_FMR:	return (char_u *)&(curwin->w_p_fmr);
#endif
	case PV_NU:	return (char_u *)&(curwin->w_p_nu);
	case PV_RNU:	return (char_u *)&(curwin->w_p_rnu);
#ifdef FEAT_LINEBREAK
	case PV_NUW:	return (char_u *)&(curwin->w_p_nuw);
#endif
	case PV_WFB:	return (char_u *)&(curwin->w_p_wfb);
	case PV_WFH:	return (char_u *)&(curwin->w_p_wfh);
	case PV_WFW:	return (char_u *)&(curwin->w_p_wfw);
#if defined(FEAT_QUICKFIX)
	case PV_PVW:	return (char_u *)&(curwin->w_p_pvw);
#endif
#ifdef FEAT_RIGHTLEFT
	case PV_RL:	return (char_u *)&(curwin->w_p_rl);
	case PV_RLC:	return (char_u *)&(curwin->w_p_rlc);
#endif
	case PV_SCROLL:	return (char_u *)&(curwin->w_p_scr);
	case PV_SMS:	return (char_u *)&(curwin->w_p_sms);
	case PV_WRAP:	return (char_u *)&(curwin->w_p_wrap);
#ifdef FEAT_LINEBREAK
	case PV_LBR:	return (char_u *)&(curwin->w_p_lbr);
	case PV_BRI:	return (char_u *)&(curwin->w_p_bri);
	case PV_BRIOPT: return (char_u *)&(curwin->w_p_briopt);
#endif
	case PV_WCR:	return (char_u *)&(curwin->w_p_wcr);
	case PV_SCBIND: return (char_u *)&(curwin->w_p_scb);
	case PV_CRBIND: return (char_u *)&(curwin->w_p_crb);
#ifdef FEAT_CONCEAL
	case PV_COCU:   return (char_u *)&(curwin->w_p_cocu);
	case PV_COLE:   return (char_u *)&(curwin->w_p_cole);
#endif
#ifdef FEAT_TERMINAL
	case PV_TWK:    return (char_u *)&(curwin->w_p_twk);
	case PV_TWS:    return (char_u *)&(curwin->w_p_tws);
	case PV_TWSL:	return (char_u *)&(curbuf->b_p_twsl);
#endif

	case PV_AI:	return (char_u *)&(curbuf->b_p_ai);
	case PV_BIN:	return (char_u *)&(curbuf->b_p_bin);
	case PV_BOMB:	return (char_u *)&(curbuf->b_p_bomb);
	case PV_BH:	return (char_u *)&(curbuf->b_p_bh);
	case PV_BT:	return (char_u *)&(curbuf->b_p_bt);
	case PV_BL:	return (char_u *)&(curbuf->b_p_bl);
	case PV_CI:	return (char_u *)&(curbuf->b_p_ci);
	case PV_CIN:	return (char_u *)&(curbuf->b_p_cin);
	case PV_CINK:	return (char_u *)&(curbuf->b_p_cink);
	case PV_CINO:	return (char_u *)&(curbuf->b_p_cino);
	case PV_CINSD:	return (char_u *)&(curbuf->b_p_cinsd);
	case PV_CINW:	return (char_u *)&(curbuf->b_p_cinw);
	case PV_COM:	return (char_u *)&(curbuf->b_p_com);
#ifdef FEAT_FOLDING
	case PV_CMS:	return (char_u *)&(curbuf->b_p_cms);
#endif
	case PV_CPT:	return (char_u *)&(curbuf->b_p_cpt);
#ifdef BACKSLASH_IN_FILENAME
	case PV_CSL:	return (char_u *)&(curbuf->b_p_csl);
#endif
#ifdef FEAT_COMPL_FUNC
	case PV_CFU:	return (char_u *)&(curbuf->b_p_cfu);
	case PV_OFU:	return (char_u *)&(curbuf->b_p_ofu);
#endif
#ifdef FEAT_EVAL
	case PV_TFU:	return (char_u *)&(curbuf->b_p_tfu);
#endif
	case PV_EOF:	return (char_u *)&(curbuf->b_p_eof);
	case PV_EOL:	return (char_u *)&(curbuf->b_p_eol);
	case PV_FIXEOL:	return (char_u *)&(curbuf->b_p_fixeol);
	case PV_ET:	return (char_u *)&(curbuf->b_p_et);
	case PV_FENC:	return (char_u *)&(curbuf->b_p_fenc);
	case PV_FF:	return (char_u *)&(curbuf->b_p_ff);
	case PV_FT:	return (char_u *)&(curbuf->b_p_ft);
	case PV_FO:	return (char_u *)&(curbuf->b_p_fo);
	case PV_FLP:	return (char_u *)&(curbuf->b_p_flp);
	case PV_IMI:	return (char_u *)&(curbuf->b_p_iminsert);
	case PV_IMS:	return (char_u *)&(curbuf->b_p_imsearch);
	case PV_INF:	return (char_u *)&(curbuf->b_p_inf);
	case PV_ISK:	return (char_u *)&(curbuf->b_p_isk);
#ifdef FEAT_FIND_ID
# ifdef FEAT_EVAL
	case PV_INEX:	return (char_u *)&(curbuf->b_p_inex);
# endif
#endif
#if defined(FEAT_EVAL)
	case PV_INDE:	return (char_u *)&(curbuf->b_p_inde);
	case PV_INDK:	return (char_u *)&(curbuf->b_p_indk);
#endif
#ifdef FEAT_EVAL
	case PV_FEX:	return (char_u *)&(curbuf->b_p_fex);
#endif
#ifdef FEAT_CRYPT
	case PV_KEY:	return (char_u *)&(curbuf->b_p_key);
#endif
	case PV_LISP:	return (char_u *)&(curbuf->b_p_lisp);
	case PV_LOP:	return (char_u *)&(curbuf->b_p_lop);
	case PV_ML:	return (char_u *)&(curbuf->b_p_ml);
	case PV_MPS:	return (char_u *)&(curbuf->b_p_mps);
	case PV_MA:	return (char_u *)&(curbuf->b_p_ma);
	case PV_MOD:	return (char_u *)&(curbuf->b_changed);
	case PV_NF:	return (char_u *)&(curbuf->b_p_nf);
	case PV_PI:	return (char_u *)&(curbuf->b_p_pi);
	case PV_QE:	return (char_u *)&(curbuf->b_p_qe);
	case PV_RO:	return (char_u *)&(curbuf->b_p_ro);
	case PV_SI:	return (char_u *)&(curbuf->b_p_si);
	case PV_SN:	return (char_u *)&(curbuf->b_p_sn);
	case PV_STS:	return (char_u *)&(curbuf->b_p_sts);
	case PV_SUA:	return (char_u *)&(curbuf->b_p_sua);
	case PV_SWF:	return (char_u *)&(curbuf->b_p_swf);
#ifdef FEAT_SYN_HL
	case PV_SMC:	return (char_u *)&(curbuf->b_p_smc);
	case PV_SYN:	return (char_u *)&(curbuf->b_p_syn);
#endif
#ifdef FEAT_SPELL
	case PV_SPC:	return (char_u *)&(curwin->w_s->b_p_spc);
	case PV_SPF:	return (char_u *)&(curwin->w_s->b_p_spf);
	case PV_SPL:	return (char_u *)&(curwin->w_s->b_p_spl);
	case PV_SPO:	return (char_u *)&(curwin->w_s->b_p_spo);
#endif
	case PV_SW:	return (char_u *)&(curbuf->b_p_sw);
	case PV_TS:	return (char_u *)&(curbuf->b_p_ts);
	case PV_TW:	return (char_u *)&(curbuf->b_p_tw);
	case PV_TX:	return (char_u *)&(curbuf->b_p_tx);
#ifdef FEAT_PERSISTENT_UNDO
	case PV_UDF:	return (char_u *)&(curbuf->b_p_udf);
#endif
	case PV_WM:	return (char_u *)&(curbuf->b_p_wm);
#ifdef FEAT_KEYMAP
	case PV_KMAP:	return (char_u *)&(curbuf->b_p_keymap);
#endif
#ifdef FEAT_SIGNS
	case PV_SCL:	return (char_u *)&(curwin->w_p_scl);
#endif
#ifdef FEAT_VARTABS
	case PV_VSTS:	return (char_u *)&(curbuf->b_p_vsts);
	case PV_VTS:	return (char_u *)&(curbuf->b_p_vts);
#endif
	default:	iemsg(e_get_varp_error);
    }
    // always return a valid pointer to avoid a crash!
    return (char_u *)&(curbuf->b_p_wm);
}

/*
 * Return a pointer to the variable for option at 'opt_idx'
 */
    char_u *
get_option_var(int opt_idx)
{
    return options[opt_idx].var;
}

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * Return the full name of the option at 'opt_idx'
 */
    char_u *
get_option_fullname(int opt_idx)
{
    return (char_u *)options[opt_idx].fullname;
}
#endif

/*
 * Return the did_set callback function for the option at 'opt_idx'
 */
    opt_did_set_cb_T
get_option_did_set_cb(int opt_idx)
{
    return options[opt_idx].opt_did_set_cb;
}

/*
 * Get the value of 'equalprg', either the buffer-local one or the global one.
 */
    char_u *
get_equalprg(void)
{
    if (*curbuf->b_p_ep == NUL)
	return p_ep;
    return curbuf->b_p_ep;
}

/*
 * Copy options from one window to another.
 * Used when splitting a window.
 */
    void
win_copy_options(win_T *wp_from, win_T *wp_to)
{
    copy_winopt(&wp_from->w_onebuf_opt, &wp_to->w_onebuf_opt);
    copy_winopt(&wp_from->w_allbuf_opt, &wp_to->w_allbuf_opt);
    after_copy_winopt(wp_to);
}

/*
 * After copying window options: update variables depending on options.
 */
    void
after_copy_winopt(win_T *wp)
{
#ifdef FEAT_LINEBREAK
    briopt_check(wp);
#endif
#ifdef FEAT_SYN_HL
    fill_culopt_flags(NULL, wp);
    check_colorcolumn(wp);
#endif
    set_listchars_option(wp, wp->w_p_lcs, TRUE, NULL, 0);
    set_fillchars_option(wp, wp->w_p_fcs, TRUE, NULL, 0);
}

    static char_u *
copy_option_val(char_u *val)
{
    if (val == empty_option)
	return empty_option;  // no need to allocate memory
    return vim_strsave(val);
}

/*
 * Copy the options from one winopt_T to another.
 * Doesn't free the old option values in "to", use clear_winopt() for that.
 * The 'scroll' option is not copied, because it depends on the window height.
 * The 'previewwindow' option is reset, there can be only one preview window.
 */
    void
copy_winopt(winopt_T *from, winopt_T *to)
{
#ifdef FEAT_ARABIC
    to->wo_arab = from->wo_arab;
#endif
    to->wo_list = from->wo_list;
    to->wo_lcs = copy_option_val(from->wo_lcs);
    to->wo_fcs = copy_option_val(from->wo_fcs);
    to->wo_nu = from->wo_nu;
    to->wo_rnu = from->wo_rnu;
    to->wo_ve = copy_option_val(from->wo_ve);
    to->wo_ve_flags = from->wo_ve_flags;
#ifdef FEAT_LINEBREAK
    to->wo_nuw = from->wo_nuw;
#endif
#ifdef FEAT_RIGHTLEFT
    to->wo_rl  = from->wo_rl;
    to->wo_rlc = copy_option_val(from->wo_rlc);
#endif
#ifdef FEAT_LINEBREAK
    to->wo_sbr = copy_option_val(from->wo_sbr);
#endif
#ifdef FEAT_STL_OPT
    to->wo_stl = copy_option_val(from->wo_stl);
#endif
    to->wo_wrap = from->wo_wrap;
#ifdef FEAT_DIFF
    to->wo_wrap_save = from->wo_wrap_save;
#endif
#ifdef FEAT_LINEBREAK
    to->wo_lbr = from->wo_lbr;
    to->wo_bri = from->wo_bri;
    to->wo_briopt = copy_option_val(from->wo_briopt);
#endif
    to->wo_wcr = copy_option_val(from->wo_wcr);
    to->wo_scb = from->wo_scb;
    to->wo_scb_save = from->wo_scb_save;
    to->wo_sms = from->wo_sms;
    to->wo_crb = from->wo_crb;
    to->wo_crb_save = from->wo_crb_save;
    to->wo_siso = from->wo_siso;
    to->wo_so = from->wo_so;
#ifdef FEAT_SPELL
    to->wo_spell = from->wo_spell;
#endif
#ifdef FEAT_SYN_HL
    to->wo_cuc = from->wo_cuc;
    to->wo_cul = from->wo_cul;
    to->wo_culopt = copy_option_val(from->wo_culopt);
    to->wo_cc = copy_option_val(from->wo_cc);
#endif
#ifdef FEAT_DIFF
    to->wo_diff = from->wo_diff;
    to->wo_diff_saved = from->wo_diff_saved;
#endif
#ifdef FEAT_CONCEAL
    to->wo_cocu = copy_option_val(from->wo_cocu);
    to->wo_cole = from->wo_cole;
#endif
#ifdef FEAT_TERMINAL
    to->wo_twk = copy_option_val(from->wo_twk);
    to->wo_tws = copy_option_val(from->wo_tws);
#endif
#ifdef FEAT_FOLDING
    to->wo_fdc = from->wo_fdc;
    to->wo_fdc_save = from->wo_fdc_save;
    to->wo_fen = from->wo_fen;
    to->wo_fen_save = from->wo_fen_save;
    to->wo_fdi = copy_option_val(from->wo_fdi);
    to->wo_fml = from->wo_fml;
    to->wo_fdl = from->wo_fdl;
    to->wo_fdl_save = from->wo_fdl_save;
    to->wo_fdm = copy_option_val(from->wo_fdm);
    to->wo_fdm_save = from->wo_diff_saved
			       ? vim_strsave(from->wo_fdm_save) : empty_option;
    to->wo_fdn = from->wo_fdn;
# ifdef FEAT_EVAL
    to->wo_fde = copy_option_val(from->wo_fde);
    to->wo_fdt = copy_option_val(from->wo_fdt);
# endif
    to->wo_fmr = copy_option_val(from->wo_fmr);
#endif
#ifdef FEAT_SIGNS
    to->wo_scl = copy_option_val(from->wo_scl);
#endif

#ifdef FEAT_EVAL
    // Copy the script context so that we know where the value was last set.
    mch_memmove(to->wo_script_ctx, from->wo_script_ctx,
						    sizeof(to->wo_script_ctx));
#endif
    check_winopt(to);		// don't want NULL pointers
}

/*
 * Check string options in a window for a NULL value.
 */
    static void
check_win_options(win_T *win)
{
    check_winopt(&win->w_onebuf_opt);
    check_winopt(&win->w_allbuf_opt);
}

/*
 * Check for NULL pointers in a winopt_T and replace them with empty_option.
 */
    static void
check_winopt(winopt_T *wop UNUSED)
{
#ifdef FEAT_FOLDING
    check_string_option(&wop->wo_fdi);
    check_string_option(&wop->wo_fdm);
    check_string_option(&wop->wo_fdm_save);
# ifdef FEAT_EVAL
    check_string_option(&wop->wo_fde);
    check_string_option(&wop->wo_fdt);
# endif
    check_string_option(&wop->wo_fmr);
#endif
#ifdef FEAT_SIGNS
    check_string_option(&wop->wo_scl);
#endif
#ifdef FEAT_RIGHTLEFT
    check_string_option(&wop->wo_rlc);
#endif
#ifdef FEAT_LINEBREAK
    check_string_option(&wop->wo_sbr);
#endif
#ifdef FEAT_STL_OPT
    check_string_option(&wop->wo_stl);
#endif
#ifdef FEAT_SYN_HL
    check_string_option(&wop->wo_culopt);
    check_string_option(&wop->wo_cc);
#endif
#ifdef FEAT_CONCEAL
    check_string_option(&wop->wo_cocu);
#endif
#ifdef FEAT_TERMINAL
    check_string_option(&wop->wo_twk);
    check_string_option(&wop->wo_tws);
#endif
#ifdef FEAT_LINEBREAK
    check_string_option(&wop->wo_briopt);
#endif
    check_string_option(&wop->wo_wcr);
    check_string_option(&wop->wo_lcs);
    check_string_option(&wop->wo_fcs);
    check_string_option(&wop->wo_ve);
}

/*
 * Free the allocated memory inside a winopt_T.
 */
    void
clear_winopt(winopt_T *wop UNUSED)
{
#ifdef FEAT_FOLDING
    clear_string_option(&wop->wo_fdi);
    clear_string_option(&wop->wo_fdm);
    clear_string_option(&wop->wo_fdm_save);
# ifdef FEAT_EVAL
    clear_string_option(&wop->wo_fde);
    clear_string_option(&wop->wo_fdt);
# endif
    clear_string_option(&wop->wo_fmr);
#endif
#ifdef FEAT_SIGNS
    clear_string_option(&wop->wo_scl);
#endif
#ifdef FEAT_LINEBREAK
    clear_string_option(&wop->wo_briopt);
#endif
    clear_string_option(&wop->wo_wcr);
#ifdef FEAT_RIGHTLEFT
    clear_string_option(&wop->wo_rlc);
#endif
#ifdef FEAT_LINEBREAK
    clear_string_option(&wop->wo_sbr);
#endif
#ifdef FEAT_STL_OPT
    clear_string_option(&wop->wo_stl);
#endif
#ifdef FEAT_SYN_HL
    clear_string_option(&wop->wo_culopt);
    clear_string_option(&wop->wo_cc);
#endif
#ifdef FEAT_CONCEAL
    clear_string_option(&wop->wo_cocu);
#endif
#ifdef FEAT_TERMINAL
    clear_string_option(&wop->wo_twk);
    clear_string_option(&wop->wo_tws);
#endif
    clear_string_option(&wop->wo_lcs);
    clear_string_option(&wop->wo_fcs);
    clear_string_option(&wop->wo_ve);
}

#ifdef FEAT_EVAL
// Index into the options table for a buffer-local option enum.
static int buf_opt_idx[BV_COUNT];
# define COPY_OPT_SCTX(buf, bv) buf->b_p_script_ctx[bv] = options[buf_opt_idx[bv]].script_ctx

/*
 * Initialize buf_opt_idx[] if not done already.
 */
    static void
init_buf_opt_idx(void)
{
    static int did_init_buf_opt_idx = FALSE;
    int i;

    if (did_init_buf_opt_idx)
	return;
    did_init_buf_opt_idx = TRUE;
    for (i = 0; !istermoption_idx(i); i++)
	if (options[i].indir & PV_BUF)
	    buf_opt_idx[options[i].indir & PV_MASK] = i;
}
#else
# define COPY_OPT_SCTX(buf, bv)
#endif

/*
 * Copy global option values to local options for one buffer.
 * Used when creating a new buffer and sometimes when entering a buffer.
 * flags:
 * BCO_ENTER	We will enter the buffer "buf".
 * BCO_ALWAYS	Always copy the options, but only set b_p_initialized when
 *		appropriate.
 * BCO_NOHELP	Don't copy the values to a help buffer.
 */
    void
buf_copy_options(buf_T *buf, int flags)
{
    int		should_copy = TRUE;
    char_u	*save_p_isk = NULL;	    // init for GCC
    int		dont_do_help;
    int		did_isk = FALSE;

    // Skip this when the option defaults have not been set yet.  Happens when
    // main() allocates the first buffer.
    if (p_cpo != NULL)
    {
	/*
	 * Always copy when entering and 'cpo' contains 'S'.
	 * Don't copy when already initialized.
	 * Don't copy when 'cpo' contains 's' and not entering.
	 * 'S'	BCO_ENTER  initialized	's'  should_copy
	 * yes	  yes	       X	 X	TRUE
	 * yes	  no	      yes	 X	FALSE
	 * no	   X	      yes	 X	FALSE
	 *  X	  no	      no	yes	FALSE
	 *  X	  no	      no	no	TRUE
	 * no	  yes	      no	 X	TRUE
	 */
	if ((vim_strchr(p_cpo, CPO_BUFOPTGLOB) == NULL || !(flags & BCO_ENTER))
		&& (buf->b_p_initialized
		    || (!(flags & BCO_ENTER)
			&& vim_strchr(p_cpo, CPO_BUFOPT) != NULL)))
	    should_copy = FALSE;

	if (should_copy || (flags & BCO_ALWAYS))
	{
#ifdef FEAT_EVAL
	    CLEAR_FIELD(buf->b_p_script_ctx);
	    init_buf_opt_idx();
#endif
	    // Don't copy the options specific to a help buffer when
	    // BCO_NOHELP is given or the options were initialized already
	    // (jumping back to a help file with CTRL-T or CTRL-O)
	    dont_do_help = ((flags & BCO_NOHELP) && buf->b_help)
						       || buf->b_p_initialized;
	    if (dont_do_help)		// don't free b_p_isk
	    {
		save_p_isk = buf->b_p_isk;
		buf->b_p_isk = NULL;
	    }
	    // Always free the allocated strings.  If not already initialized,
	    // reset 'readonly' and copy 'fileformat'.
	    if (!buf->b_p_initialized)
	    {
		free_buf_options(buf, TRUE);
		buf->b_p_ro = FALSE;		// don't copy readonly
		buf->b_p_tx = p_tx;
		buf->b_p_fenc = vim_strsave(p_fenc);
		switch (*p_ffs)
		{
		    case 'm':
			buf->b_p_ff = vim_strsave((char_u *)FF_MAC); break;
		    case 'd':
			buf->b_p_ff = vim_strsave((char_u *)FF_DOS); break;
		    case 'u':
			buf->b_p_ff = vim_strsave((char_u *)FF_UNIX); break;
		    default:
			buf->b_p_ff = vim_strsave(p_ff);
		}
		if (buf->b_p_ff != NULL)
		    buf->b_start_ffc = *buf->b_p_ff;
		buf->b_p_bh = empty_option;
		buf->b_p_bt = empty_option;
	    }
	    else
		free_buf_options(buf, FALSE);

	    buf->b_p_ai = p_ai;
	    COPY_OPT_SCTX(buf, BV_AI);
	    buf->b_p_ai_nopaste = p_ai_nopaste;
	    buf->b_p_sw = p_sw;
	    COPY_OPT_SCTX(buf, BV_SW);
	    buf->b_p_tw = p_tw;
	    COPY_OPT_SCTX(buf, BV_TW);
	    buf->b_p_tw_nopaste = p_tw_nopaste;
	    buf->b_p_tw_nobin = p_tw_nobin;
	    buf->b_p_wm = p_wm;
	    COPY_OPT_SCTX(buf, BV_WM);
	    buf->b_p_wm_nopaste = p_wm_nopaste;
	    buf->b_p_wm_nobin = p_wm_nobin;
	    buf->b_p_bin = p_bin;
	    COPY_OPT_SCTX(buf, BV_BIN);
	    buf->b_p_bomb = p_bomb;
	    COPY_OPT_SCTX(buf, BV_BOMB);
	    buf->b_p_fixeol = p_fixeol;
	    COPY_OPT_SCTX(buf, BV_FIXEOL);
	    buf->b_p_et = p_et;
	    COPY_OPT_SCTX(buf, BV_ET);
	    buf->b_p_et_nobin = p_et_nobin;
	    buf->b_p_et_nopaste = p_et_nopaste;
	    buf->b_p_ml = p_ml;
	    COPY_OPT_SCTX(buf, BV_ML);
	    buf->b_p_ml_nobin = p_ml_nobin;
	    buf->b_p_inf = p_inf;
	    COPY_OPT_SCTX(buf, BV_INF);
	    if (cmdmod.cmod_flags & CMOD_NOSWAPFILE)
		buf->b_p_swf = FALSE;
	    else
	    {
		buf->b_p_swf = p_swf;
		COPY_OPT_SCTX(buf, BV_SWF);
	    }
	    buf->b_p_cpt = vim_strsave(p_cpt);
	    COPY_OPT_SCTX(buf, BV_CPT);
#ifdef BACKSLASH_IN_FILENAME
	    buf->b_p_csl = vim_strsave(p_csl);
	    COPY_OPT_SCTX(buf, BV_CSL);
#endif
#ifdef FEAT_COMPL_FUNC
	    buf->b_p_cfu = vim_strsave(p_cfu);
	    COPY_OPT_SCTX(buf, BV_CFU);
	    set_buflocal_cfu_callback(buf);
	    buf->b_p_ofu = vim_strsave(p_ofu);
	    COPY_OPT_SCTX(buf, BV_OFU);
	    set_buflocal_ofu_callback(buf);
#endif
#ifdef FEAT_EVAL
	    buf->b_p_tfu = vim_strsave(p_tfu);
	    COPY_OPT_SCTX(buf, BV_TFU);
	    set_buflocal_tfu_callback(buf);
#endif
	    buf->b_p_sts = p_sts;
	    COPY_OPT_SCTX(buf, BV_STS);
	    buf->b_p_sts_nopaste = p_sts_nopaste;
#ifdef FEAT_VARTABS
	    buf->b_p_vsts = vim_strsave(p_vsts);
	    COPY_OPT_SCTX(buf, BV_VSTS);
	    if (p_vsts && p_vsts != empty_option)
		(void)tabstop_set(p_vsts, &buf->b_p_vsts_array);
	    else
		buf->b_p_vsts_array = NULL;
	    buf->b_p_vsts_nopaste = p_vsts_nopaste
				 ? vim_strsave(p_vsts_nopaste) : NULL;
#endif
	    buf->b_p_sn = p_sn;
	    COPY_OPT_SCTX(buf, BV_SN);
	    buf->b_p_com = vim_strsave(p_com);
	    COPY_OPT_SCTX(buf, BV_COM);
#ifdef FEAT_FOLDING
	    buf->b_p_cms = vim_strsave(p_cms);
	    COPY_OPT_SCTX(buf, BV_CMS);
#endif
	    buf->b_p_fo = vim_strsave(p_fo);
	    COPY_OPT_SCTX(buf, BV_FO);
	    buf->b_p_flp = vim_strsave(p_flp);
	    COPY_OPT_SCTX(buf, BV_FLP);
	    // NOTE: Valgrind may report a bogus memory leak for 'nrformats'
	    // when it is set to 8 bytes in defaults.vim.
	    buf->b_p_nf = vim_strsave(p_nf);
	    COPY_OPT_SCTX(buf, BV_NF);
	    buf->b_p_mps = vim_strsave(p_mps);
	    COPY_OPT_SCTX(buf, BV_MPS);
	    buf->b_p_si = p_si;
	    COPY_OPT_SCTX(buf, BV_SI);
	    buf->b_p_ci = p_ci;
	    COPY_OPT_SCTX(buf, BV_CI);

	    buf->b_p_cin = p_cin;
	    COPY_OPT_SCTX(buf, BV_CIN);
	    buf->b_p_cink = vim_strsave(p_cink);
	    COPY_OPT_SCTX(buf, BV_CINK);
	    buf->b_p_cino = vim_strsave(p_cino);
	    COPY_OPT_SCTX(buf, BV_CINO);
	    buf->b_p_cinsd = vim_strsave(p_cinsd);
	    COPY_OPT_SCTX(buf, BV_CINSD);
	    buf->b_p_lop = vim_strsave(p_lop);
	    COPY_OPT_SCTX(buf, BV_LOP);

	    // Don't copy 'filetype', it must be detected
	    buf->b_p_ft = empty_option;
	    buf->b_p_pi = p_pi;
	    COPY_OPT_SCTX(buf, BV_PI);
	    buf->b_p_cinw = vim_strsave(p_cinw);
	    COPY_OPT_SCTX(buf, BV_CINW);
	    buf->b_p_lisp = p_lisp;
	    COPY_OPT_SCTX(buf, BV_LISP);
#ifdef FEAT_SYN_HL
	    // Don't copy 'syntax', it must be set
	    buf->b_p_syn = empty_option;
	    buf->b_p_smc = p_smc;
	    COPY_OPT_SCTX(buf, BV_SMC);
	    buf->b_s.b_syn_isk = empty_option;
#endif
#ifdef FEAT_SPELL
	    buf->b_s.b_p_spc = vim_strsave(p_spc);
	    COPY_OPT_SCTX(buf, BV_SPC);
	    (void)compile_cap_prog(&buf->b_s);
	    buf->b_s.b_p_spf = vim_strsave(p_spf);
	    COPY_OPT_SCTX(buf, BV_SPF);
	    buf->b_s.b_p_spl = vim_strsave(p_spl);
	    COPY_OPT_SCTX(buf, BV_SPL);
	    buf->b_s.b_p_spo = vim_strsave(p_spo);
	    COPY_OPT_SCTX(buf, BV_SPO);
#endif
#if defined(FEAT_EVAL)
	    buf->b_p_inde = vim_strsave(p_inde);
	    COPY_OPT_SCTX(buf, BV_INDE);
	    buf->b_p_indk = vim_strsave(p_indk);
	    COPY_OPT_SCTX(buf, BV_INDK);
#endif
	    buf->b_p_fp = empty_option;
#if defined(FEAT_EVAL)
	    buf->b_p_fex = vim_strsave(p_fex);
	    COPY_OPT_SCTX(buf, BV_FEX);
#endif
#ifdef FEAT_CRYPT
	    buf->b_p_key = vim_strsave(p_key);
	    COPY_OPT_SCTX(buf, BV_KEY);
#endif
	    buf->b_p_sua = vim_strsave(p_sua);
	    COPY_OPT_SCTX(buf, BV_SUA);
#ifdef FEAT_KEYMAP
	    buf->b_p_keymap = vim_strsave(p_keymap);
	    COPY_OPT_SCTX(buf, BV_KMAP);
	    buf->b_kmap_state |= KEYMAP_INIT;
#endif
#ifdef FEAT_TERMINAL
	    buf->b_p_twsl = p_twsl;
	    COPY_OPT_SCTX(buf, BV_TWSL);
#endif
	    // This isn't really an option, but copying the langmap and IME
	    // state from the current buffer is better than resetting it.
	    buf->b_p_iminsert = p_iminsert;
	    COPY_OPT_SCTX(buf, BV_IMI);
	    buf->b_p_imsearch = p_imsearch;
	    COPY_OPT_SCTX(buf, BV_IMS);

	    // options that are normally global but also have a local value
	    // are not copied, start using the global value
	    buf->b_p_ar = -1;
	    buf->b_p_ul = NO_LOCAL_UNDOLEVEL;
	    buf->b_p_bkc = empty_option;
	    buf->b_bkc_flags = 0;
#ifdef FEAT_QUICKFIX
	    buf->b_p_gp = empty_option;
	    buf->b_p_mp = empty_option;
	    buf->b_p_efm = empty_option;
#endif
	    buf->b_p_ep = empty_option;
	    buf->b_p_kp = empty_option;
	    buf->b_p_path = empty_option;
	    buf->b_p_tags = empty_option;
	    buf->b_p_tc = empty_option;
	    buf->b_tc_flags = 0;
#ifdef FEAT_FIND_ID
	    buf->b_p_def = empty_option;
	    buf->b_p_inc = empty_option;
# ifdef FEAT_EVAL
	    buf->b_p_inex = vim_strsave(p_inex);
	    COPY_OPT_SCTX(buf, BV_INEX);
# endif
#endif
	    buf->b_p_dict = empty_option;
	    buf->b_p_tsr = empty_option;
#ifdef FEAT_COMPL_FUNC
	    buf->b_p_tsrfu = empty_option;
#endif
	    buf->b_p_qe = vim_strsave(p_qe);
	    COPY_OPT_SCTX(buf, BV_QE);
#if defined(FEAT_BEVAL) && defined(FEAT_EVAL)
	    buf->b_p_bexpr = empty_option;
#endif
#if defined(FEAT_CRYPT)
	    buf->b_p_cm = empty_option;
#endif
#ifdef FEAT_PERSISTENT_UNDO
	    buf->b_p_udf = p_udf;
	    COPY_OPT_SCTX(buf, BV_UDF);
#endif
	    buf->b_p_lw = empty_option;
	    buf->b_p_menc = empty_option;

	    // Don't copy the options set by ex_help(), use the saved values,
	    // when going from a help buffer to a non-help buffer.
	    // Don't touch these at all when BCO_NOHELP is used and going from
	    // or to a help buffer.
	    if (dont_do_help)
	    {
		buf->b_p_isk = save_p_isk;
#ifdef FEAT_VARTABS
		if (p_vts && *p_vts != NUL && !buf->b_p_vts_array)
		    (void)tabstop_set(p_vts, &buf->b_p_vts_array);
		else
		    buf->b_p_vts_array = NULL;
#endif
	    }
	    else
	    {
		buf->b_p_isk = vim_strsave(p_isk);
		COPY_OPT_SCTX(buf, BV_ISK);
		did_isk = TRUE;
		buf->b_p_ts = p_ts;
		COPY_OPT_SCTX(buf, BV_TS);
#ifdef FEAT_VARTABS
		buf->b_p_vts = vim_strsave(p_vts);
		COPY_OPT_SCTX(buf, BV_VTS);
		if (p_vts && *p_vts != NUL && !buf->b_p_vts_array)
		    (void)tabstop_set(p_vts, &buf->b_p_vts_array);
		else
		    buf->b_p_vts_array = NULL;
#endif
		buf->b_help = FALSE;
		if (buf->b_p_bt[0] == 'h')
		    clear_string_option(&buf->b_p_bt);
		buf->b_p_ma = p_ma;
		COPY_OPT_SCTX(buf, BV_MA);
	    }
	}

	// When the options should be copied (ignoring BCO_ALWAYS), set the
	// flag that indicates that the options have been initialized.
	if (should_copy)
	    buf->b_p_initialized = TRUE;
    }

    check_buf_options(buf);	    // make sure we don't have NULLs
    if (did_isk)
	(void)buf_init_chartab(buf, FALSE);
}

/*
 * Reset the 'modifiable' option and its default value.
 */
    void
reset_modifiable(void)
{
    int		opt_idx;

    curbuf->b_p_ma = FALSE;
    p_ma = FALSE;
    opt_idx = findoption((char_u *)"ma");
    if (opt_idx >= 0)
	options[opt_idx].def_val[VI_DEFAULT] = FALSE;
}

/*
 * Set the global value for 'iminsert' to the local value.
 */
    void
set_iminsert_global(void)
{
    p_iminsert = curbuf->b_p_iminsert;
}

/*
 * Set the global value for 'imsearch' to the local value.
 */
    void
set_imsearch_global(void)
{
    p_imsearch = curbuf->b_p_imsearch;
}

static int expand_option_idx = -1;
static int expand_option_start_col = 0;
static char_u expand_option_name[5] = {'t', '_', NUL, NUL, NUL};
static int expand_option_flags = 0;
static int expand_option_append = FALSE;

    void
set_context_in_set_cmd(
    expand_T	*xp,
    char_u	*arg,
    int		opt_flags)	// OPT_GLOBAL and/or OPT_LOCAL
{
    int		nextchar;
    long_u	flags = 0;	// init for GCC
    int		opt_idx = 0;	// init for GCC
    char_u	*p;
    char_u	*s;
    int		is_term_option = FALSE;
    int		key;

    expand_option_flags = opt_flags;

    xp->xp_context = EXPAND_SETTINGS;
    if (*arg == NUL)
    {
	xp->xp_pattern = arg;
	return;
    }
    p = arg + STRLEN(arg) - 1;
    if (*p == ' ' && *(p - 1) != '\\')
    {
	xp->xp_pattern = p + 1;
	return;
    }
    while (p > arg)
    {
	s = p;
	// count number of backslashes before ' ' or ','
	if (*p == ' ' || *p == ',')
	{
	    while (s > arg && *(s - 1) == '\\')
		--s;
	}
	// break at a space with an even number of backslashes
	if (*p == ' ' && ((p - s) & 1) == 0)
	{
	    ++p;
	    break;
	}
	--p;
    }
    if (STRNCMP(p, "no", 2) == 0 && STRNCMP(p, "novice", 6) != 0)
    {
	xp->xp_context = EXPAND_BOOL_SETTINGS;
	xp->xp_prefix = XP_PREFIX_NO;
	p += 2;
    }
    else if (STRNCMP(p, "inv", 3) == 0)
    {
	xp->xp_context = EXPAND_BOOL_SETTINGS;
	xp->xp_prefix = XP_PREFIX_INV;
	p += 3;
    }
    xp->xp_pattern = arg = p;
    if (*arg == '<')
    {
	while (*p != '>')
	    if (*p++ == NUL)	    // expand terminal option name
		return;
	key = get_special_key_code(arg + 1);
	if (key == 0)		    // unknown name
	{
	    xp->xp_context = EXPAND_NOTHING;
	    return;
	}
	nextchar = *++p;
	is_term_option = TRUE;
	expand_option_name[2] = KEY2TERMCAP0(key);
	expand_option_name[3] = KEY2TERMCAP1(key);
    }
    else
    {
	if (p[0] == 't' && p[1] == '_')
	{
	    p += 2;
	    if (*p != NUL)
		++p;
	    if (*p == NUL)
		return;		// expand option name
	    nextchar = *++p;
	    is_term_option = TRUE;
	    expand_option_name[2] = p[-2];
	    expand_option_name[3] = p[-1];
	}
	else
	{
	    // Allow * wildcard
	    while (ASCII_ISALNUM(*p) || *p == '_' || *p == '*')
		p++;
	    if (*p == NUL)
		return;
	    nextchar = *p;
	    *p = NUL;
	    opt_idx = findoption(arg);
	    *p = nextchar;
	    if (opt_idx == -1 || options[opt_idx].var == NULL)
	    {
		xp->xp_context = EXPAND_NOTHING;
		return;
	    }
	    flags = options[opt_idx].flags;
	    if (flags & P_BOOL)
	    {
		xp->xp_context = EXPAND_NOTHING;
		return;
	    }
	}
    }
    // handle "-=" and "+="
    expand_option_append = FALSE;
    int expand_option_subtract = FALSE;
    if ((nextchar == '-' || nextchar == '+' || nextchar == '^') && p[1] == '=')
    {
	if (nextchar == '-')
	    expand_option_subtract = TRUE;
	if (nextchar == '+' || nextchar == '^')
	    expand_option_append = TRUE;
	++p;
	nextchar = '=';
    }
    if ((nextchar != '=' && nextchar != ':')
				    || xp->xp_context == EXPAND_BOOL_SETTINGS)
    {
	xp->xp_context = EXPAND_UNSUCCESSFUL;
	return;
    }

    // Below are for handling expanding a specific option's value after the '='
    // or ':'

    if (is_term_option)
	expand_option_idx = -1;
    else
	expand_option_idx = opt_idx;

    if (!is_term_option)
    {
	if (options[opt_idx].flags & P_NO_CMD_EXPAND)
	{
	    xp->xp_context=EXPAND_UNSUCCESSFUL;
	    return;
	}
    }

    xp->xp_pattern = p + 1;
    expand_option_start_col = (int)(p + 1 - xp->xp_line);

    // Certain options currently have special case handling to reuse the
    // expansion logic with other commands.
#ifdef FEAT_SYN_HL
    if (options[opt_idx].var == (char_u *)&p_syn)
    {
	xp->xp_context = EXPAND_OWNSYNTAX;
	return;
    }
#endif
    if (options[opt_idx].var == (char_u *)&p_ft)
    {
	xp->xp_context = EXPAND_FILETYPE;
	return;
    }
#ifdef FEAT_KEYMAP
    if (options[opt_idx].var == (char_u *)&p_keymap)
    {
	xp->xp_context = EXPAND_KEYMAP;
	return;
    }
#endif

    // Now pick. If the option has a custom expander, use that. Otherwise, just
    // fill with the existing option value.
    if (expand_option_subtract)
    {
	xp->xp_context = EXPAND_SETTING_SUBTRACT;
	return;
    }
    else if (expand_option_idx >= 0 &&
	    options[expand_option_idx].opt_expand_cb != NULL)
    {
	xp->xp_context = EXPAND_STRING_SETTING;
    }
    else if (*xp->xp_pattern == NUL)
    {
	xp->xp_context = EXPAND_OLD_SETTING;
	return;
    }
    else
	xp->xp_context = EXPAND_NOTHING;

    if (is_term_option || (flags & P_NUM))
	return;

    // Only string options below

    // Options that have P_EXPAND are considered to all use file/dir expansion.
    if (flags & P_EXPAND)
    {
	p = options[opt_idx].var;
	if (p == (char_u *)&p_bdir
		|| p == (char_u *)&p_dir
		|| p == (char_u *)&p_path
		|| p == (char_u *)&p_pp
		|| p == (char_u *)&p_rtp
		|| p == (char_u *)&p_cdpath
#ifdef FEAT_SESSION
		|| p == (char_u *)&p_vdir
#endif
		)
	{
	    xp->xp_context = EXPAND_DIRECTORIES;
	    if (p == (char_u *)&p_path || p == (char_u *)&p_cdpath)
		xp->xp_backslash = XP_BS_THREE;
	    else
		xp->xp_backslash = XP_BS_ONE;
	}
	else
	{
	    xp->xp_context = EXPAND_FILES;
	    // for 'tags' need three backslashes for a space
	    if (p == (char_u *)&p_tags)
		xp->xp_backslash = XP_BS_THREE;
	    else
		xp->xp_backslash = XP_BS_ONE;
	}
	if (flags & P_COMMA)
	    xp->xp_backslash |= XP_BS_COMMA;
    }

    // For an option that is a list of file names, or comma/colon-separated
    // values, split it by the delimiter and find the start of the current
    // pattern, while accounting for backslash-escaped space/commas/colons.
    // Triple-backslashed escaped file names (e.g. 'path') can also be
    // delimited by space.
    if ((flags & P_EXPAND) || (flags & P_COMMA) || (flags & P_COLON))
    {
	for (p = arg + STRLEN(arg) - 1; p >= xp->xp_pattern; --p)
	{
	    // count number of backslashes before ' ' or ',' or ':'
	    if (*p == ' ' || *p == ',' ||
		    (*p == ':' && (flags & P_COLON)))
	    {
		s = p;
		while (s > xp->xp_pattern && *(s - 1) == '\\')
		    --s;
		if ((*p == ' ' && ((xp->xp_backslash & XP_BS_THREE) && (p - s) < 3))
#if defined(BACKSLASH_IN_FILENAME)
			|| (*p == ',' && (flags & P_COMMA) && (p - s) < 1)
#else
			|| (*p == ',' && (flags & P_COMMA) && (p - s) < 2)
#endif
			|| (*p == ':' && (flags & P_COLON)))
		{
		    xp->xp_pattern = p + 1;
		    break;
		}
	    }
	}
    }

    // An option that is a list of single-character flags should always start
    // at the end as we don't complete words.
    if (flags & P_FLAGLIST)
	xp->xp_pattern = arg + STRLEN(arg);

    // Some options can either be using file/dir expansions, or custom value
    // expansion depending on what the user typed. Unfortunately we have to
    // manually handle it here to make sure we have the correct xp_context set.
#ifdef FEAT_SPELL
    if (options[opt_idx].var == (char_u *)&p_sps)
    {
	if (STRNCMP(xp->xp_pattern, "file:", 5) == 0)
	{
	    xp->xp_pattern += 5;
	    return;
	}
	else if (options[expand_option_idx].opt_expand_cb != NULL)
	{
	    xp->xp_context = EXPAND_STRING_SETTING;
	}
    }
#endif
}

/*
 * Returns TRUE if 'str' either matches 'regmatch' or fuzzy matches 'pat'.
 *
 * If 'test_only' is TRUE and 'fuzzy' is FALSE and if 'str' matches the regular
 * expression 'regmatch', then returns TRUE.  Otherwise returns FALSE.
 *
 * If 'test_only' is FALSE and 'fuzzy' is FALSE and if 'str' matches the
 * regular expression 'regmatch', then stores the match in matches[idx] and
 * returns TRUE.
 *
 * If 'test_only' is TRUE and 'fuzzy' is TRUE and if 'str' fuzzy matches
 * 'fuzzystr', then returns TRUE. Otherwise returns FALSE.
 *
 * If 'test_only' is FALSE and 'fuzzy' is TRUE and if 'str' fuzzy matches
 * 'fuzzystr', then stores the match details in fuzmatch[idx] and returns TRUE.
 */
    static int
match_str(
	char_u		*str,
	regmatch_T	*regmatch,
	char_u		**matches,
	int		idx,
	int		test_only,
	int		fuzzy,
	char_u		*fuzzystr,
	fuzmatch_str_T  *fuzmatch)
{
    if (!fuzzy)
    {
	if (vim_regexec(regmatch, str, (colnr_T)0))
	{
	    if (!test_only)
		matches[idx] = vim_strsave(str);
	    return TRUE;
	}
    }
    else
    {
	int score;

	score = fuzzy_match_str(str, fuzzystr);
	if (score != 0)
	{
	    if (!test_only)
	    {
		fuzmatch[idx].idx = idx;
		fuzmatch[idx].str = vim_strsave(str);
		fuzmatch[idx].score = score;
	    }

	    return TRUE;
	}
    }

    return FALSE;
}

    int
ExpandSettings(
    expand_T	*xp,
    regmatch_T	*regmatch,
    char_u	*fuzzystr,
    int		*numMatches,
    char_u	***matches,
    int		can_fuzzy)
{
    int		num_normal = 0;	    // Nr of matching non-term-code settings
    int		num_term = 0;	    // Nr of matching terminal code settings
    int		opt_idx;
    int		match;
    int		count = 0;
    char_u	*str;
    int		loop;
    int		is_term_opt;
    char_u	name_buf[MAX_KEY_NAME_LEN];
    static char *(names[]) = {"all", "termcap"};
    int		ic = regmatch->rm_ic;	// remember the ignore-case flag
    int		fuzzy;
    fuzmatch_str_T  *fuzmatch = NULL;

    fuzzy = can_fuzzy && cmdline_fuzzy_complete(fuzzystr);

    // do this loop twice:
    // loop == 0: count the number of matching options
    // loop == 1: copy the matching options into allocated memory
    for (loop = 0; loop <= 1; ++loop)
    {
	regmatch->rm_ic = ic;
	if (xp->xp_context != EXPAND_BOOL_SETTINGS)
	{
	    for (match = 0; match < (int)ARRAY_LENGTH(names); ++match)
	    {
		if (match_str((char_u *)names[match], regmatch, *matches,
			    count, (loop == 0), fuzzy, fuzzystr, fuzmatch))
		{
		    if (loop == 0)
			num_normal++;
		    else
			count++;
		}
	    }
	}
	for (opt_idx = 0; (str = (char_u *)options[opt_idx].fullname) != NULL;
								    opt_idx++)
	{
	    if (options[opt_idx].var == NULL)
		continue;
	    if (xp->xp_context == EXPAND_BOOL_SETTINGS
		    && !(options[opt_idx].flags & P_BOOL))
		continue;
	    is_term_opt = istermoption_idx(opt_idx);
	    if (is_term_opt && num_normal > 0)
		continue;

	    if (match_str(str, regmatch, *matches, count, (loop == 0),
						fuzzy, fuzzystr, fuzmatch))
	    {
		if (loop == 0)
		{
		    if (is_term_opt)
			num_term++;
		    else
			num_normal++;
		}
		else
		    count++;
	    }
	    else if (!fuzzy && options[opt_idx].shortname != NULL
			&& vim_regexec(regmatch,
			     (char_u *)options[opt_idx].shortname, (colnr_T)0))
	    {
		// Compare against the abbreviated option name (for regular
		// expression match). Fuzzy matching (previous if) already
		// matches against both the expanded and abbreviated names.
		if (loop == 0)
		{
		    if (is_term_opt)
			num_term++;
		    else
			num_normal++;
		}
		else
		    (*matches)[count++] = vim_strsave(str);
	    }
	    else if (is_term_opt)
	    {
		name_buf[0] = '<';
		name_buf[1] = 't';
		name_buf[2] = '_';
		name_buf[3] = str[2];
		name_buf[4] = str[3];
		name_buf[5] = '>';
		name_buf[6] = NUL;

		if (match_str(name_buf, regmatch, *matches, count, (loop == 0),
			    fuzzy, fuzzystr, fuzmatch))
		{
		    if (loop == 0)
			num_term++;
		    else
			count++;
		}
	    }
	}

	// Check terminal key codes, these are not in the option table
	if (xp->xp_context != EXPAND_BOOL_SETTINGS  && num_normal == 0)
	{
	    for (opt_idx = 0; (str = get_termcode(opt_idx)) != NULL; opt_idx++)
	    {
		if (!SAFE_isprint(str[0]) || !SAFE_isprint(str[1]))
		    continue;

		name_buf[0] = 't';
		name_buf[1] = '_';
		name_buf[2] = str[0];
		name_buf[3] = str[1];
		name_buf[4] = NUL;

		if (match_str(name_buf, regmatch, *matches, count,
				       (loop == 0), fuzzy, fuzzystr, fuzmatch))
		{
		    if (loop == 0)
			num_term++;
		    else
			count++;
		}
		else
		{
		    name_buf[0] = '<';
		    name_buf[1] = 't';
		    name_buf[2] = '_';
		    name_buf[3] = str[0];
		    name_buf[4] = str[1];
		    name_buf[5] = '>';
		    name_buf[6] = NUL;

		    if (match_str(name_buf, regmatch, *matches, count,
					    (loop == 0), fuzzy, fuzzystr,
					    fuzmatch))
		    {
			if (loop == 0)
			    num_term++;
			else
			    count++;
		    }
		}
	    }

	    // Check special key names.
	    regmatch->rm_ic = TRUE;		// ignore case here
	    for (opt_idx = 0; (str = get_key_name(opt_idx)) != NULL; opt_idx++)
	    {
		name_buf[0] = '<';
		STRCPY(name_buf + 1, str);
		STRCAT(name_buf, ">");

		if (match_str(name_buf, regmatch, *matches, count, (loop == 0),
			    fuzzy, fuzzystr, fuzmatch))
		{
		    if (loop == 0)
			num_term++;
		    else
			count++;
		}
	    }
	}
	if (loop == 0)
	{
	    if (num_normal > 0)
		*numMatches = num_normal;
	    else if (num_term > 0)
		*numMatches = num_term;
	    else
		return OK;
	    if (!fuzzy)
	    {
		*matches = ALLOC_MULT(char_u *, *numMatches);
		if (*matches == NULL)
		{
		    *matches = (char_u **)"";
		    return FAIL;
		}
	    }
	    else
	    {
		fuzmatch = ALLOC_MULT(fuzmatch_str_T, *numMatches);
		if (fuzmatch == NULL)
		{
		    *matches = (char_u **)"";
		    return FAIL;
		}
	    }
	}
    }

    if (fuzzy &&
	fuzzymatches_to_strmatches(fuzmatch, matches, count, FALSE) == FAIL)
	return FAIL;

    return OK;
}

// Escape an option value that can be used on the command-line with :set.
// Caller needs to free the returned string, unless NULL is returned.
    static char_u*
escape_option_str_cmdline(char_u *var)
{
    char_u *buf;

    // A backslash is required before some characters.  This is the reverse of
    // what happens in do_set().
    buf = vim_strsave_escaped(var, escape_chars);
    if (buf == NULL)
	return NULL;

#ifdef BACKSLASH_IN_FILENAME
    // For MS-Windows et al. we don't double backslashes at the start and
    // before a file name character.
    // The reverse is found at stropt_copy_value().
    for (var = buf; *var != NUL; MB_PTR_ADV(var))
	if (var[0] == '\\' && var[1] == '\\'
		&& expand_option_idx >= 0
		&& (options[expand_option_idx].flags & P_EXPAND)
		&& vim_isfilec(var[2])
		&& (var[2] != '\\' || (var == buf && var[4] != '\\')))
	    STRMOVE(var, var + 1);
#endif
    return buf;
}

/*
 * Expansion handler for :set= when we just want to fill in with the existing value.
 */
    int
ExpandOldSetting(int *numMatches, char_u ***matches)
{
    char_u  *var = NULL;	// init for GCC
    char_u  *buf;

    *numMatches = 0;
    *matches = ALLOC_MULT(char_u *, 1);
    if (*matches == NULL)
	return FAIL;

    // For a terminal key code expand_option_idx is < 0.
    if (expand_option_idx < 0)
    {
	var = find_termcode(expand_option_name + 2);
	if (var == NULL)
	    expand_option_idx = findoption(expand_option_name);
    }

    if (expand_option_idx >= 0)
    {
	// put string of option value in NameBuff
	option_value2string(&options[expand_option_idx], expand_option_flags);
	var = NameBuff;
    }
    else if (var == NULL)
	var = (char_u *)"";

    buf = escape_option_str_cmdline(var);
    if (buf == NULL)
    {
	VIM_CLEAR(*matches);
	return FAIL;
    }

    (*matches)[0] = buf;
    *numMatches = 1;
    return OK;
}

/*
 * Expansion handler for :set=/:set+= when the option has a custom expansion handler.
 */
    int
ExpandStringSetting(
    expand_T	*xp,
    regmatch_T	*regmatch,
    int		*numMatches,
    char_u	***matches)
{
    char_u  *var = NULL;	// init for GCC
    char_u  *buf;

    if (expand_option_idx < 0 ||
	    options[expand_option_idx].opt_expand_cb == NULL)
    {
	// Not supposed to reach this. This function is only for options with
	// custom expansion callbacks.
	return FAIL;
    }

    optexpand_T args;
    args.oe_varp = get_varp_scope(&options[expand_option_idx], expand_option_flags);
    args.oe_append = expand_option_append;
    args.oe_regmatch = regmatch;
    args.oe_xp = xp;
    args.oe_set_arg = xp->xp_line + expand_option_start_col;
    args.oe_include_orig_val =
	!expand_option_append &&
	(*args.oe_set_arg == NUL);

    // Retrieve the existing value, but escape it as a reverse of setting it.
    // We technically only need to do this when oe_append or
    // oe_include_orig_val is true.
    option_value2string(&options[expand_option_idx], expand_option_flags);
    var = NameBuff;
    buf = escape_option_str_cmdline(var);
    if (buf == NULL)
	return FAIL;

    args.oe_opt_value = buf;

    int num_ret = options[expand_option_idx].opt_expand_cb(&args, numMatches, matches);

    vim_free(buf);
    return num_ret;
}

/*
 * Expansion handler for :set-=
 */
    int
ExpandSettingSubtract(
    expand_T	*xp,
    regmatch_T	*regmatch,
    int		*numMatches,
    char_u	***matches)
{
    if (expand_option_idx < 0)
	// term option
	return ExpandOldSetting(numMatches, matches);

    char_u *option_val = *(char_u**)get_option_varp_scope(
	expand_option_idx, expand_option_flags);

    long_u option_flags =  options[expand_option_idx].flags;

    if (option_flags & P_NUM)
	return ExpandOldSetting(numMatches, matches);
    else if (option_flags & P_COMMA)
    {
	// Split the option by comma, then present each option to the user if
	// it matches the pattern.
	// This condition needs to go first, because 'whichwrap' has both
	// P_COMMA and P_FLAGLIST.
	garray_T    ga;

	char_u	    *item;
	char_u	    *option_copy;
	char_u	    *next_val;
	char_u	    *comma;

	if (*option_val == NUL)
	    return FAIL;

	// Make a copy as we need to inject null characters destructively.
	option_copy = vim_strsave(option_val);
	if (option_copy == NULL)
	    return FAIL;
	next_val = option_copy;

	ga_init2(&ga, sizeof(char_u *), 10);

	do
	{
	    item = next_val;
	    comma = vim_strchr(next_val, ',');
	    while (comma != NULL && comma != next_val && *(comma - 1) == '\\')
	    {
		// "\," is interpreted as a literal comma rather than option
		// separator when reading options in copy_option_part(). Skip
		// it.
		comma = vim_strchr(comma + 1, ',');
	    }
	    if (comma != NULL)
	    {
		*comma = NUL; // null-terminate this value, required by later functions
		next_val = comma + 1;
	    }
	    else
		next_val = NULL;

	    if (*item == NUL)
		// empty value, don't add to list
		continue;

	    if (!vim_regexec(regmatch, item, (colnr_T)0))
		continue;

	    char_u *buf = escape_option_str_cmdline(item);
	    if (buf == NULL)
	    {
		vim_free(option_copy);
		ga_clear_strings(&ga);
		return FAIL;
	    }
	    if (ga_add_string(&ga, buf) != OK)
	    {
		vim_free(buf);
		break;
	    }
	} while (next_val != NULL);

	vim_free(option_copy);

	*matches = ga.ga_data;
	*numMatches = ga.ga_len;
	return OK;
    }
    else if (option_flags & P_FLAGLIST)
    {
	// Only present the flags that are set on the option as the other flags
	// are not meaningful to do set-= on.

	if (*xp->xp_pattern != NUL)
	{
	    // Don't suggest anything if cmdline is non-empty. Vim's set-=
	    // behavior requires consecutive strings and it's usually
	    // unintuitive to users if they try to subtract multiple flags at
	    // once.
	    return FAIL;
	}

	size_t num_flags = STRLEN(option_val);
	if (num_flags == 0)
	    return FAIL;

	*matches = ALLOC_MULT(char_u *, num_flags + 1);
	if (*matches == NULL)
	    return FAIL;

	int count = 0;
	char_u *p;

	p = vim_strsave(option_val);
	if (p == NULL)
	{
	    VIM_CLEAR(*matches);
	    return FAIL;
	}
	(*matches)[count++] = p;

	if (num_flags > 1)
	{
	    // If more than one flags, split the flags up and expose each
	    // character as individual choice.
	    for (char_u *flag = option_val; *flag != NUL; flag++)
	    {
		p = vim_strnsave(flag, 1);
		if (p == NULL)
		    break;
		(*matches)[count++] = p;
	    }
	}

	*numMatches = count;
	return OK;
    }

    return ExpandOldSetting(numMatches, matches);
}

/*
 * Get the value for the numeric or string option *opp in a nice format into
 * NameBuff[].  Must not be called with a hidden option!
 */
    static void
option_value2string(
    struct vimoption	*opp,
    int			scope)	// OPT_GLOBAL and/or OPT_LOCAL
{
    char_u	*varp;

    varp = get_varp_scope(opp, scope);

    if (opp->flags & P_NUM)
    {
	long wc = 0;

	if (wc_use_keyname(varp, &wc))
	    STRCPY(NameBuff, get_special_key_name((int)wc, 0));
	else if (wc != 0)
	    STRCPY(NameBuff, transchar((int)wc));
	else
	    sprintf((char *)NameBuff, "%ld", *(long *)varp);
    }
    else    // P_STRING
    {
	varp = *(char_u **)(varp);
	if (varp == NULL)		    // just in case
	    NameBuff[0] = NUL;
#ifdef FEAT_CRYPT
	// don't show the actual value of 'key', only that it's set
	else if (opp->var == (char_u *)&p_key && *varp)
	    STRCPY(NameBuff, "*****");
#endif
	else if (opp->flags & P_EXPAND)
	    home_replace(NULL, varp, NameBuff, MAXPATHL, FALSE);
	// Translate 'pastetoggle' into special key names
	else if ((char_u **)opp->var == &p_pt)
	    str2specialbuf(p_pt, NameBuff, MAXPATHL);
	else
	    vim_strncpy(NameBuff, varp, MAXPATHL - 1);
    }
}

/*
 * Return TRUE if "varp" points to 'wildchar' or 'wildcharm' and it can be
 * printed as a keyname.
 * "*wcp" is set to the value of the option if it's 'wildchar' or 'wildcharm'.
 */
    static int
wc_use_keyname(char_u *varp, long *wcp)
{
    if (((long *)varp == &p_wc) || ((long *)varp == &p_wcm))
    {
	*wcp = *(long *)varp;
	if (IS_SPECIAL(*wcp) || find_special_key_in_table((int)*wcp) >= 0)
	    return TRUE;
    }
    return FALSE;
}

/*
 * Return TRUE if "x" is present in 'shortmess' option, or
 * 'shortmess' contains 'a' and "x" is present in SHM_A.
 */
    int
shortmess(int x)
{
    return p_shm != NULL &&
	    (   vim_strchr(p_shm, x) != NULL
	    || (vim_strchr(p_shm, 'a') != NULL
		&& vim_strchr((char_u *)SHM_A, x) != NULL));
}

/*
 * vimrc_found() - Called when a ".vimrc" or "VIMINIT" has been found.
 *
 * Reset 'compatible' and set the values for options that didn't get set yet
 * to the Vim defaults.
 * Don't do this if the 'compatible' option has been set or reset before.
 * When "fname" is not NULL, use it to set $"envname" when it wasn't set yet.
 */
    void
vimrc_found(char_u *fname, char_u *envname)
{
    int		opt_idx;
    int		dofree = FALSE;
    char_u	*p;

    if (!option_was_set((char_u *)"cp"))
    {
	p_cp = FALSE;
	for (opt_idx = 0; !istermoption_idx(opt_idx); opt_idx++)
	    if (!(options[opt_idx].flags & (P_WAS_SET|P_VI_DEF)))
		set_option_default(opt_idx, OPT_FREE, FALSE);
	didset_options();
	didset_options2();
    }

    if (fname != NULL)
    {
	p = vim_getenv(envname, &dofree);
	if (p == NULL)
	{
	    // Set $MYVIMRC to the first vimrc file found.
	    p = FullName_save(fname, FALSE);
	    if (p != NULL)
	    {
		vim_setenv(envname, p);
		vim_free(p);
	    }
	}
	else if (dofree)
	    vim_free(p);
    }
}

/*
 * Set 'compatible' on or off.  Called for "-C" and "-N" command line arg.
 */
    void
change_compatible(int on)
{
    int	    opt_idx;

    if (p_cp != on)
    {
	p_cp = on;
	compatible_set();
    }
    opt_idx = findoption((char_u *)"cp");
    if (opt_idx >= 0)
	options[opt_idx].flags |= P_WAS_SET;
}

/*
 * Return TRUE when option "name" has been set.
 * Only works correctly for global options.
 */
    int
option_was_set(char_u *name)
{
    int idx;

    idx = findoption(name);
    if (idx < 0)	// unknown option
	return FALSE;
    if (options[idx].flags & P_WAS_SET)
	return TRUE;
    return FALSE;
}

/*
 * Reset the flag indicating option "name" was set.
 */
    int
reset_option_was_set(char_u *name)
{
    int idx = findoption(name);

    if (idx < 0)
	return FAIL;

    options[idx].flags &= ~P_WAS_SET;
    return OK;
}

/*
 * compatible_set() - Called when 'compatible' has been set or unset.
 *
 * When 'compatible' set: Set all relevant options (those that have the P_VIM)
 * flag) to a Vi compatible value.
 * When 'compatible' is unset: Set all options that have a different default
 * for Vim (without the P_VI_DEF flag) to that default.
 */
    static void
compatible_set(void)
{
    int	    opt_idx;

    for (opt_idx = 0; !istermoption_idx(opt_idx); opt_idx++)
	if (	   ((options[opt_idx].flags & P_VIM) && p_cp)
		|| (!(options[opt_idx].flags & P_VI_DEF) && !p_cp))
	    set_option_default(opt_idx, OPT_FREE, p_cp);
    didset_options();
    didset_options2();
}

/*
 * Check if backspacing over something is allowed.
 */
    int
can_bs(
    int		what)	    // BS_INDENT, BS_EOL, BS_START or BS_NOSTOP
{
#ifdef FEAT_JOB_CHANNEL
    if (what == BS_START && bt_prompt(curbuf))
	return FALSE;
#endif
    switch (*p_bs)
    {
	case '3':       return TRUE;
	case '2':	return (what != BS_NOSTOP);
	case '1':	return (what != BS_START);
	case '0':	return FALSE;
    }
    return vim_strchr(p_bs, what) != NULL;
}

/*
 * Return the effective 'scrolloff' value for the current window, using the
 * global value when appropriate.
 */
    long
get_scrolloff_value(void)
{
    return curwin->w_p_so < 0 ? p_so : curwin->w_p_so;
}

/*
 * Return the effective 'sidescrolloff' value for the current window, using the
 * global value when appropriate.
 */
    long
get_sidescrolloff_value(void)
{
    return curwin->w_p_siso < 0 ? p_siso : curwin->w_p_siso;
}

/*
 * Get the local or global value of 'backupcopy'.
 */
    unsigned int
get_bkc_value(buf_T *buf)
{
    return buf->b_bkc_flags ? buf->b_bkc_flags : bkc_flags;
}

#if defined(FEAT_LINEBREAK) || defined(PROTO)
/*
 * Get the local or global value of 'formatlistpat'.
 */
    char_u *
get_flp_value(buf_T *buf)
{
    if (buf->b_p_flp == NULL || *buf->b_p_flp == NUL)
	return p_flp;
    return buf->b_p_flp;
}
#endif

/*
 * Get the local or global value of the 'virtualedit' flags.
 */
    unsigned int
get_ve_flags(void)
{
    return (curwin->w_ve_flags ? curwin->w_ve_flags : ve_flags)
	    & ~(VE_NONE | VE_NONEU);
}

#if defined(FEAT_LINEBREAK) || defined(PROTO)
/*
 * Get the local or global value of 'showbreak'.
 */
    char_u *
get_showbreak_value(win_T *win)
{
    if (win->w_p_sbr == NULL || *win->w_p_sbr == NUL)
	return p_sbr;
    if (STRCMP(win->w_p_sbr, "NONE") == 0)
	return empty_option;
    return win->w_p_sbr;
}
#endif

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * Get window or buffer local options.
 */
    dict_T *
get_winbuf_options(int bufopt)
{
    dict_T	*d;
    int		opt_idx;

    d = dict_alloc();
    if (d == NULL)
	return NULL;

    for (opt_idx = 0; !istermoption_idx(opt_idx); opt_idx++)
    {
	struct vimoption *opt = &options[opt_idx];

	if ((bufopt && (opt->indir & PV_BUF))
					 || (!bufopt && (opt->indir & PV_WIN)))
	{
	    char_u *varp = get_varp(opt);

	    if (varp != NULL)
	    {
		if (opt->flags & P_STRING)
		    dict_add_string(d, opt->fullname, *(char_u **)varp);
		else if (opt->flags & P_NUM)
		    dict_add_number(d, opt->fullname, *(long *)varp);
		else
		    dict_add_number(d, opt->fullname, *(int *)varp);
	    }
	}
    }

    return d;
}
#endif

#if defined(FEAT_SYN_HL) || defined(PROTO)
/*
 * This is called when 'culopt' is changed
 */
    int
fill_culopt_flags(char_u *val, win_T *wp)
{
    char_u	*p;
    char_u	culopt_flags_new = 0;

    if (val == NULL)
	p = wp->w_p_culopt;
    else
	p = val;
    while (*p != NUL)
    {
	// Note: Keep this in sync with p_culopt_values.
	if (STRNCMP(p, "line", 4) == 0)
	{
	    p += 4;
	    culopt_flags_new |= CULOPT_LINE;
	}
	else if (STRNCMP(p, "both", 4) == 0)
	{
	    p += 4;
	    culopt_flags_new |= CULOPT_LINE | CULOPT_NBR;
	}
	else if (STRNCMP(p, "number", 6) == 0)
	{
	    p += 6;
	    culopt_flags_new |= CULOPT_NBR;
	}
	else if (STRNCMP(p, "screenline", 10) == 0)
	{
	    p += 10;
	    culopt_flags_new |= CULOPT_SCRLINE;
	}

	if (*p != ',' && *p != NUL)
	    return FAIL;
	if (*p == ',')
	    ++p;
    }

    // Can't have both "line" and "screenline".
    if ((culopt_flags_new & CULOPT_LINE) && (culopt_flags_new & CULOPT_SCRLINE))
	return FAIL;
    wp->w_p_culopt_flags = culopt_flags_new;

    return OK;
}
#endif

/*
 * Get the value of 'magic' adjusted for Vim9 script.
 */
    int
magic_isset(void)
{
    switch (magic_overruled)
    {
	case OPTION_MAGIC_ON:      return TRUE;
	case OPTION_MAGIC_OFF:     return FALSE;
	case OPTION_MAGIC_NOT_SET: break;
    }
#ifdef FEAT_EVAL
    if (in_vim9script())
	return TRUE;
#endif
    return p_magic;
}

/*
 * Set the callback function value for an option that accepts a function name,
 * lambda, et al. (e.g. 'operatorfunc', 'tagfunc', etc.)
 * Returns OK if the option is successfully set to a function, otherwise
 * returns FAIL.
 */
    int
option_set_callback_func(char_u *optval UNUSED, callback_T *optcb UNUSED)
{
#ifdef FEAT_EVAL
    typval_T	*tv;
    callback_T	cb;

    if (optval == NULL || *optval == NUL)
    {
	free_callback(optcb);
	return OK;
    }

    if (*optval == '{' || (in_vim9script() && *optval == '(')
	    || (STRNCMP(optval, "function(", 9) == 0)
	    || (STRNCMP(optval, "funcref(", 8) == 0))
	// Lambda expression or a funcref
	tv = eval_expr(optval, NULL);
    else
	// treat everything else as a function name string
	tv = alloc_string_tv(vim_strsave(optval));
    if (tv == NULL)
	return FAIL;

    cb = get_callback(tv);
    if (cb.cb_name == NULL || *cb.cb_name == NUL)
    {
	free_tv(tv);
	return FAIL;
    }

    free_callback(optcb);
    set_callback(optcb, &cb);
    if (cb.cb_free_name)
	vim_free(cb.cb_name);
    free_tv(tv);

    // when using Vim9 style "import.funcname" it needs to be expanded to
    // "import#funcname".
    expand_autload_callback(optcb);

    return OK;
#else
    return FAIL;
#endif
}

#if defined(FEAT_EVAL) || defined(PROTO)
    static void
didset_options_sctx(int opt_flags, char **buf)
{
	for (int i = 0; ; ++i)
	{
	    if (buf[i] == NULL)
		break;

	    int idx = findoption((char_u *)buf[i]);
	    if (idx >= 0)
		set_option_sctx_idx(idx, opt_flags, current_sctx);
	}
}
#endif