view src/textformat.c @ 33764:f2445075dbeb v9.0.2103

patch 9.0.2103: recursive callback may cause issues on some archs Commit: https://github.com/vim/vim/commit/2076463e383901cef44685aaf4b63e4306444f9e Author: Christian Brabandt <cb@256bit.org> Date: Sun Nov 12 16:59:29 2023 +0100 patch 9.0.2103: recursive callback may cause issues on some archs Problem: recursive callback may cause issues on some archs Solution: Decrease the limit drastically to 20 Recursive callback limit causes problems on some architectures Since commit 47510f3d6598a1218958c03ed11337a43b73f48d we have a test that causes a recursive popup callback function to be executed. However it seems the current limit of 'maxfuncdepth' option value is still too recursive for some 32bit architectures (e.g. 32bit ARM). So instead of allowing a default limit of 100 (default value for 'maxfuncdepth'), let's reduce this limit to 20. I don't think there is a use case where one would need such a high recursive callback limit and a limit of 20 seems reasonable (although it is currently hard-coded). closes: #13495 closes: #13502 Signed-off-by: Christian Brabandt <cb@256bit.org>
author Christian Brabandt <cb@256bit.org>
date Sun, 12 Nov 2023 17:15:03 +0100
parents 0839c759c9d1
children a522c6c0127b
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.
 */

/*
 * textformat.c: text formatting functions
 */

#include "vim.h"

static int	did_add_space = FALSE;	// auto_format() added an extra space
					// under the cursor

#define WHITECHAR(cc) (VIM_ISWHITE(cc) && (!enc_utf8 || !utf_iscomposing(utf_ptr2char(ml_get_cursor() + 1))))

/*
 * Return TRUE if format option 'x' is in effect.
 * Take care of no formatting when 'paste' is set.
 */
    int
has_format_option(int x)
{
    if (p_paste)
	return FALSE;
    return (vim_strchr(curbuf->b_p_fo, x) != NULL);
}

/*
 * Format text at the current insert position.
 *
 * If the INSCHAR_COM_LIST flag is present, then the value of second_indent
 * will be the comment leader length sent to open_line().
 */
    void
internal_format(
    int		textwidth,
    int		second_indent,
    int		flags,
    int		format_only,
    int		c) // character to be inserted (can be NUL)
{
    int		cc;
    int		skip_pos;
    int		save_char = NUL;
    int		haveto_redraw = FALSE;
    int		fo_ins_blank = has_format_option(FO_INS_BLANK);
    int		fo_multibyte = has_format_option(FO_MBYTE_BREAK);
    int		fo_rigor_tw  = has_format_option(FO_RIGOROUS_TW);
    int		fo_white_par = has_format_option(FO_WHITE_PAR);
    int		first_line = TRUE;
    colnr_T	leader_len;
    int		no_leader = FALSE;
    int		do_comments = (flags & INSCHAR_DO_COM);
#ifdef FEAT_LINEBREAK
    int		has_lbr = curwin->w_p_lbr;

    // make sure win_lbr_chartabsize() counts correctly
    curwin->w_p_lbr = FALSE;
#endif

    // When 'ai' is off we don't want a space under the cursor to be
    // deleted.  Replace it with an 'x' temporarily.
    if (!curbuf->b_p_ai && !(State & VREPLACE_FLAG))
    {
	cc = gchar_cursor();
	if (VIM_ISWHITE(cc))
	{
	    save_char = cc;
	    pchar_cursor('x');
	}
    }

    // Repeat breaking lines, until the current line is not too long.
    while (!got_int)
    {
	int	startcol;		// Cursor column at entry
	int	wantcol;		// column at textwidth border
	int	foundcol;		// column for start of spaces
	int	end_foundcol = 0;	// column for start of word
	colnr_T	len;
	colnr_T	virtcol;
	int	orig_col = 0;
	char_u	*saved_text = NULL;
	colnr_T	col;
	colnr_T	end_col;
	int	wcc;			// counter for whitespace chars
	int	did_do_comment = FALSE;

	virtcol = get_nolist_virtcol()
				   + char2cells(c != NUL ? c : gchar_cursor());
	if (virtcol <= (colnr_T)textwidth)
	    break;

	if (no_leader)
	    do_comments = FALSE;
	else if (!(flags & INSCHAR_FORMAT)
				       && has_format_option(FO_WRAP_COMS))
	    do_comments = TRUE;

	// Don't break until after the comment leader
	if (do_comments)
	{
	    char_u *line = ml_get_curline();

	    leader_len = get_leader_len(line, NULL, FALSE, TRUE);
	    if (leader_len == 0 && curbuf->b_p_cin)
	    {
		int		comment_start;

		// Check for a line comment after code.
		comment_start = check_linecomment(line);
		if (comment_start != MAXCOL)
		{
		    leader_len = get_leader_len(
				      line + comment_start, NULL, FALSE, TRUE);
		    if (leader_len != 0)
			leader_len += comment_start;
		}
	    }
	}
	else
	    leader_len = 0;

	// If the line doesn't start with a comment leader, then don't
	// start one in a following broken line.  Avoids that a %word
	// moved to the start of the next line causes all following lines
	// to start with %.
	if (leader_len == 0)
	    no_leader = TRUE;
	if (!(flags & INSCHAR_FORMAT)
		&& leader_len == 0
		&& !has_format_option(FO_WRAP))

	    break;
	if ((startcol = curwin->w_cursor.col) == 0)
	    break;

	// find column of textwidth border
	coladvance((colnr_T)textwidth);
	wantcol = curwin->w_cursor.col;

	curwin->w_cursor.col = startcol;
	foundcol = 0;
	skip_pos = 0;

	// Find position to break at.
	// Stop at first entered white when 'formatoptions' has 'v'
	while ((!fo_ins_blank && !has_format_option(FO_INS_VI))
		    || (flags & INSCHAR_FORMAT)
		    || curwin->w_cursor.lnum != Insstart.lnum
		    || curwin->w_cursor.col >= Insstart.col)
	{
	    if (curwin->w_cursor.col == startcol && c != NUL)
		cc = c;
	    else
		cc = gchar_cursor();
	    if (WHITECHAR(cc))
	    {
		// remember position of blank just before text
		end_col = curwin->w_cursor.col;

		// find start of sequence of blanks
		wcc = 0;
		while (curwin->w_cursor.col > 0 && WHITECHAR(cc))
		{
		    dec_cursor();
		    cc = gchar_cursor();

		    // Increment count of how many whitespace chars in this
		    // group; we only need to know if it's more than one.
		    if (wcc < 2)
			wcc++;
		}
		if (curwin->w_cursor.col == 0 && WHITECHAR(cc))
		    break;		// only spaces in front of text

		// Don't break after a period when 'formatoptions' has 'p' and
		// there are less than two spaces.
		if (has_format_option(FO_PERIOD_ABBR) && cc == '.' && wcc < 2)
		    continue;

		// Don't break until after the comment leader
		if (curwin->w_cursor.col < leader_len)
		    break;
		if (has_format_option(FO_ONE_LETTER))
		{
		    // do not break after one-letter words
		    if (curwin->w_cursor.col == 0)
			break;	// one-letter word at begin
		    // do not break "#a b" when 'tw' is 2
		    if (curwin->w_cursor.col <= leader_len)
			break;
		    col = curwin->w_cursor.col;
		    dec_cursor();
		    cc = gchar_cursor();

		    if (WHITECHAR(cc))
			continue;	// one-letter, continue
		    curwin->w_cursor.col = col;
		}

		inc_cursor();

		end_foundcol = end_col + 1;
		foundcol = curwin->w_cursor.col;
		if (curwin->w_cursor.col <= (colnr_T)wantcol)
		    break;
	    }
	    else if ((cc >= 0x100 || !utf_allow_break_before(cc))
							       && fo_multibyte)
	    {
		int ncc;
		int allow_break;

		// Break after or before a multi-byte character.
		if (curwin->w_cursor.col != startcol)
		{
		    // Don't break until after the comment leader
		    if (curwin->w_cursor.col < leader_len)
			break;
		    col = curwin->w_cursor.col;
		    inc_cursor();
		    ncc = gchar_cursor();

		    allow_break =
			(enc_utf8 && utf_allow_break(cc, ncc))
			|| enc_dbcs;

		    // If we have already checked this position, skip!
		    if (curwin->w_cursor.col != skip_pos && allow_break)
		    {
			foundcol = curwin->w_cursor.col;
			end_foundcol = foundcol;
			if (curwin->w_cursor.col <= (colnr_T)wantcol)
			    break;
		    }
		    curwin->w_cursor.col = col;
		}

		if (curwin->w_cursor.col == 0)
		    break;

		ncc = cc;
		col = curwin->w_cursor.col;

		dec_cursor();
		cc = gchar_cursor();

		if (WHITECHAR(cc))
		    continue;		// break with space
		// Don't break until after the comment leader.
		if (curwin->w_cursor.col < leader_len)
		    break;

		curwin->w_cursor.col = col;
		skip_pos = curwin->w_cursor.col;

		allow_break =
		    (enc_utf8 && utf_allow_break(cc, ncc))
		    || enc_dbcs;

		// Must handle this to respect line break prohibition.
		if (allow_break)
		{
		    foundcol = curwin->w_cursor.col;
		    end_foundcol = foundcol;
		}
		if (curwin->w_cursor.col <= (colnr_T)wantcol)
		{
		    int ncc_allow_break =
			 (enc_utf8 && utf_allow_break_before(ncc)) || enc_dbcs;

		    if (allow_break)
			break;
		    if (!ncc_allow_break && !fo_rigor_tw)
		    {
			// Enable at most 1 punct hang outside of textwidth.
			if (curwin->w_cursor.col == startcol)
			{
			    // We are inserting a non-breakable char, postpone
			    // line break check to next insert.
			    end_foundcol = foundcol = 0;
			    break;
			}

			// Neither cc nor ncc is NUL if we are here, so
			// it's safe to inc_cursor.
			col = curwin->w_cursor.col;

			inc_cursor();
			cc  = ncc;
			ncc = gchar_cursor();
			// handle insert
			ncc = (ncc != NUL) ? ncc : c;

			allow_break =
				(enc_utf8 && utf_allow_break(cc, ncc))
				|| enc_dbcs;

			if (allow_break)
			{
			    // Break only when we are not at end of line.
			    end_foundcol = foundcol =
				      ncc == NUL? 0 : curwin->w_cursor.col;
			    break;
			}
			curwin->w_cursor.col = col;
		    }
		}
	    }
	    if (curwin->w_cursor.col == 0)
		break;
	    dec_cursor();
	}

	if (foundcol == 0)		// no spaces, cannot break line
	{
	    curwin->w_cursor.col = startcol;
	    break;
	}

	// Going to break the line, remove any "$" now.
	undisplay_dollar();

	// Offset between cursor position and line break is used by replace
	// stack functions.  MODE_VREPLACE does not use this, and backspaces
	// over the text instead.
	if (State & VREPLACE_FLAG)
	    orig_col = startcol;	// Will start backspacing from here
	else
	    replace_offset = startcol - end_foundcol;

	// adjust startcol for spaces that will be deleted and
	// characters that will remain on top line
	curwin->w_cursor.col = foundcol;
	while ((cc = gchar_cursor(), WHITECHAR(cc))
		    && (!fo_white_par || curwin->w_cursor.col < startcol))
	    inc_cursor();
	startcol -= curwin->w_cursor.col;
	if (startcol < 0)
	    startcol = 0;

	if (State & VREPLACE_FLAG)
	{
	    // In MODE_VREPLACE state, we will backspace over the text to be
	    // wrapped, so save a copy now to put on the next line.
	    saved_text = vim_strsave(ml_get_cursor());
	    curwin->w_cursor.col = orig_col;
	    if (saved_text == NULL)
		break;	// Can't do it, out of memory
	    saved_text[startcol] = NUL;

	    // Backspace over characters that will move to the next line
	    if (!fo_white_par)
		backspace_until_column(foundcol);
	}
	else
	{
	    // put cursor after pos. to break line
	    if (!fo_white_par)
		curwin->w_cursor.col = foundcol;
	}

	// Split the line just before the margin.
	// Only insert/delete lines, but don't really redraw the window.
	open_line(FORWARD, OPENLINE_DELSPACES + OPENLINE_MARKFIX
		+ (fo_white_par ? OPENLINE_KEEPTRAIL : 0)
		+ (do_comments ? OPENLINE_DO_COM : 0)
		+ OPENLINE_FORMAT
		+ ((flags & INSCHAR_COM_LIST) ? OPENLINE_COM_LIST : 0)
		, ((flags & INSCHAR_COM_LIST) ? second_indent : old_indent),
		&did_do_comment);
	if (!(flags & INSCHAR_COM_LIST))
	    old_indent = 0;

	// If a comment leader was inserted, may also do this on a following
	// line.
	if (did_do_comment)
	    no_leader = FALSE;

	replace_offset = 0;
	if (first_line)
	{
	    if (!(flags & INSCHAR_COM_LIST))
	    {
		// This section is for auto-wrap of numeric lists.  When not
		// in insert mode (i.e. format_lines()), the INSCHAR_COM_LIST
		// flag will be set and open_line() will handle it (as seen
		// above).  The code here (and in get_number_indent()) will
		// recognize comments if needed...
		if (second_indent < 0 && has_format_option(FO_Q_NUMBER))
		    second_indent =
				 get_number_indent(curwin->w_cursor.lnum - 1);
		if (second_indent >= 0)
		{
		    if (State & VREPLACE_FLAG)
			change_indent(INDENT_SET, second_indent,
							    FALSE, NUL, TRUE);
		    else
			if (leader_len > 0 && second_indent - leader_len > 0)
		    {
			int i;
			int padding = second_indent - leader_len;

			// We started at the first_line of a numbered list
			// that has a comment.  the open_line() function has
			// inserted the proper comment leader and positioned
			// the cursor at the end of the split line.  Now we
			// add the additional whitespace needed after the
			// comment leader for the numbered list.
			for (i = 0; i < padding; i++)
			    ins_str((char_u *)" ");
		    }
		    else
		    {
			(void)set_indent(second_indent, SIN_CHANGED);
		    }
		}
	    }
	    first_line = FALSE;
	}

	if (State & VREPLACE_FLAG)
	{
	    // In MODE_VREPLACE state we have backspaced over the text to be
	    // moved, now we re-insert it into the new line.
	    ins_bytes(saved_text);
	    vim_free(saved_text);
	}
	else
	{
	    // Check if cursor is not past the NUL off the line, cindent
	    // may have added or removed indent.
	    curwin->w_cursor.col += startcol;
	    len = (colnr_T)STRLEN(ml_get_curline());
	    if (curwin->w_cursor.col > len)
		curwin->w_cursor.col = len;
	}

	haveto_redraw = TRUE;
	set_can_cindent(TRUE);
	// moved the cursor, don't autoindent or cindent now
	did_ai = FALSE;
	did_si = FALSE;
	can_si = FALSE;
	can_si_back = FALSE;
	line_breakcheck();
    }

    if (save_char != NUL)		// put back space after cursor
	pchar_cursor(save_char);

#ifdef FEAT_LINEBREAK
    curwin->w_p_lbr = has_lbr;
#endif
    if (!format_only && haveto_redraw)
    {
	update_topline();
	redraw_curbuf_later(UPD_VALID);
    }
}

/*
 * Blank lines, and lines containing only the comment leader, are left
 * untouched by the formatting.  The function returns TRUE in this
 * case.  It also returns TRUE when a line starts with the end of a comment
 * ('e' in comment flags), so that this line is skipped, and not joined to the
 * previous line.  A new paragraph starts after a blank line, or when the
 * comment leader changes -- webb.
 */
    static int
fmt_check_par(
    linenr_T	lnum,
    int		*leader_len,
    char_u	**leader_flags,
    int		do_comments)
{
    char_u	*flags = NULL;	    // init for GCC
    char_u	*ptr;

    ptr = ml_get(lnum);
    if (do_comments)
	*leader_len = get_leader_len(ptr, leader_flags, FALSE, TRUE);
    else
	*leader_len = 0;

    if (*leader_len > 0)
    {
	// Search for 'e' flag in comment leader flags.
	flags = *leader_flags;
	while (*flags && *flags != ':' && *flags != COM_END)
	    ++flags;
    }

    return (*skipwhite(ptr + *leader_len) == NUL
	    || (*leader_len > 0 && *flags == COM_END)
	    || startPS(lnum, NUL, FALSE));
}

/*
 * Return TRUE if line "lnum" ends in a white character.
 */
    static int
ends_in_white(linenr_T lnum)
{
    char_u	*s = ml_get(lnum);
    size_t	l;

    if (*s == NUL)
	return FALSE;
    // Don't use STRLEN() inside VIM_ISWHITE(), SAS/C complains: "macro
    // invocation may call function multiple times".
    l = STRLEN(s) - 1;
    return VIM_ISWHITE(s[l]);
}

/*
 * Return TRUE if the two comment leaders given are the same.  "lnum" is
 * the first line.  White-space is ignored.  Note that the whole of
 * 'leader1' must match 'leader2_len' characters from 'leader2' -- webb
 */
    static int
same_leader(
    linenr_T lnum,
    int	    leader1_len,
    char_u  *leader1_flags,
    int	    leader2_len,
    char_u  *leader2_flags)
{
    int	    idx1 = 0, idx2 = 0;
    char_u  *p;
    char_u  *line1;
    char_u  *line2;

    if (leader1_len == 0)
	return (leader2_len == 0);

    // If first leader has 'f' flag, the lines can be joined only if the
    // second line does not have a leader.
    // If first leader has 'e' flag, the lines can never be joined.
    // If first leader has 's' flag, the lines can only be joined if there is
    // some text after it and the second line has the 'm' flag.
    if (leader1_flags != NULL)
    {
	for (p = leader1_flags; *p && *p != ':'; ++p)
	{
	    if (*p == COM_FIRST)
		return (leader2_len == 0);
	    if (*p == COM_END)
		return FALSE;
	    if (*p == COM_START)
	    {
		int line_len = (int)STRLEN(ml_get(lnum));
		if (line_len <= leader1_len)
		    return FALSE;
		if (leader2_flags == NULL || leader2_len == 0)
		    return FALSE;
		for (p = leader2_flags; *p && *p != ':'; ++p)
		    if (*p == COM_MIDDLE)
			return TRUE;
		return FALSE;
	    }
	}
    }

    // Get current line and next line, compare the leaders.
    // The first line has to be saved, only one line can be locked at a time.
    line1 = vim_strsave(ml_get(lnum));
    if (line1 != NULL)
    {
	for (idx1 = 0; VIM_ISWHITE(line1[idx1]); ++idx1)
	    ;
	line2 = ml_get(lnum + 1);
	for (idx2 = 0; idx2 < leader2_len; ++idx2)
	{
	    if (!VIM_ISWHITE(line2[idx2]))
	    {
		if (line1[idx1++] != line2[idx2])
		    break;
	    }
	    else
		while (VIM_ISWHITE(line1[idx1]))
		    ++idx1;
	}
	vim_free(line1);
    }
    return (idx2 == leader2_len && idx1 == leader1_len);
}

/*
 * Return TRUE when a paragraph starts in line "lnum".  Return FALSE when the
 * previous line is in the same paragraph.  Used for auto-formatting.
 */
    static int
paragraph_start(linenr_T lnum)
{
    char_u	*p;
    int		leader_len = 0;		// leader len of current line
    char_u	*leader_flags = NULL;	// flags for leader of current line
    int		next_leader_len;	// leader len of next line
    char_u	*next_leader_flags;	// flags for leader of next line
    int		do_comments;		// format comments

    if (lnum <= 1)
	return TRUE;		// start of the file

    p = ml_get(lnum - 1);
    if (*p == NUL)
	return TRUE;		// after empty line

    do_comments = has_format_option(FO_Q_COMS);
    if (fmt_check_par(lnum - 1, &leader_len, &leader_flags, do_comments))
	return TRUE;		// after non-paragraph line

    if (fmt_check_par(lnum, &next_leader_len, &next_leader_flags, do_comments))
	return TRUE;		// "lnum" is not a paragraph line

    if (has_format_option(FO_WHITE_PAR) && !ends_in_white(lnum - 1))
	return TRUE;		// missing trailing space in previous line.

    if (has_format_option(FO_Q_NUMBER) && (get_number_indent(lnum) > 0))
	return TRUE;		// numbered item starts in "lnum".

    if (!same_leader(lnum - 1, leader_len, leader_flags,
					  next_leader_len, next_leader_flags))
	return TRUE;		// change of comment leader.

    return FALSE;
}

/*
 * Called after inserting or deleting text: When 'formatoptions' includes the
 * 'a' flag format from the current line until the end of the paragraph.
 * Keep the cursor at the same position relative to the text.
 * The caller must have saved the cursor line for undo, following ones will be
 * saved here.
 */
    void
auto_format(
    int		trailblank,	// when TRUE also format with trailing blank
    int		prev_line)	// may start in previous line
{
    pos_T	pos;
    colnr_T	len;
    char_u	*old;
    char_u	*new, *pnew;
    int		wasatend;
    int		cc;

    if (!has_format_option(FO_AUTO))
	return;

    pos = curwin->w_cursor;
    old = ml_get_curline();

    // may remove added space
    check_auto_format(FALSE);

    // Don't format in Insert mode when the cursor is on a trailing blank, the
    // user might insert normal text next.  Also skip formatting when "1" is
    // in 'formatoptions' and there is a single character before the cursor.
    // Otherwise the line would be broken and when typing another non-white
    // next they are not joined back together.
    wasatend = (pos.col == (colnr_T)STRLEN(old));
    if (*old != NUL && !trailblank && wasatend)
    {
	dec_cursor();
	cc = gchar_cursor();
	if (!WHITECHAR(cc) && curwin->w_cursor.col > 0
					  && has_format_option(FO_ONE_LETTER))
	    dec_cursor();
	cc = gchar_cursor();
	if (WHITECHAR(cc))
	{
	    curwin->w_cursor = pos;
	    return;
	}
	curwin->w_cursor = pos;
    }

    // With the 'c' flag in 'formatoptions' and 't' missing: only format
    // comments.
    if (has_format_option(FO_WRAP_COMS) && !has_format_option(FO_WRAP)
				&& get_leader_len(old, NULL, FALSE, TRUE) == 0)
	return;

    // May start formatting in a previous line, so that after "x" a word is
    // moved to the previous line if it fits there now.  Only when this is not
    // the start of a paragraph.
    if (prev_line && !paragraph_start(curwin->w_cursor.lnum))
    {
	--curwin->w_cursor.lnum;
	if (u_save_cursor() == FAIL)
	    return;
    }

    // Do the formatting and restore the cursor position.  "saved_cursor" will
    // be adjusted for the text formatting.
    saved_cursor = pos;
    format_lines((linenr_T)-1, FALSE);
    curwin->w_cursor = saved_cursor;
    saved_cursor.lnum = 0;

    if (curwin->w_cursor.lnum > curbuf->b_ml.ml_line_count)
    {
	// "cannot happen"
	curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
	coladvance((colnr_T)MAXCOL);
    }
    else
	check_cursor_col();

    // Insert mode: If the cursor is now after the end of the line while it
    // previously wasn't, the line was broken.  Because of the rule above we
    // need to add a space when 'w' is in 'formatoptions' to keep a paragraph
    // formatted.
    if (!wasatend && has_format_option(FO_WHITE_PAR))
    {
	new = ml_get_curline();
	len = (colnr_T)STRLEN(new);
	if (curwin->w_cursor.col == len)
	{
	    pnew = vim_strnsave(new, len + 2);
	    pnew[len] = ' ';
	    pnew[len + 1] = NUL;
	    ml_replace(curwin->w_cursor.lnum, pnew, FALSE);
	    // remove the space later
	    did_add_space = TRUE;
	}
	else
	    // may remove added space
	    check_auto_format(FALSE);
    }

    check_cursor();
}

/*
 * When an extra space was added to continue a paragraph for auto-formatting,
 * delete it now.  The space must be under the cursor, just after the insert
 * position.
 */
    void
check_auto_format(
    int		end_insert)	    // TRUE when ending Insert mode
{
    int		c = ' ';
    int		cc;

    if (!did_add_space)
	return;

    cc = gchar_cursor();
    if (!WHITECHAR(cc))
	// Somehow the space was removed already.
	did_add_space = FALSE;
    else
    {
	if (!end_insert)
	{
	    inc_cursor();
	    c = gchar_cursor();
	    dec_cursor();
	}
	if (c != NUL)
	{
	    // The space is no longer at the end of the line, delete it.
	    del_char(FALSE);
	    did_add_space = FALSE;
	}
    }
}

/*
 * Find out textwidth to be used for formatting:
 *	if 'textwidth' option is set, use it
 *	else if 'wrapmargin' option is set, use curwin->w_width - 'wrapmargin'
 *	if invalid value, use 0.
 *	Set default to window width (maximum 79) for "gq" operator.
 */
    int
comp_textwidth(
    int		ff)	// force formatting (for "gq" command)
{
    int		textwidth;

    textwidth = curbuf->b_p_tw;
    if (textwidth == 0 && curbuf->b_p_wm)
    {
	// The width is the window width minus 'wrapmargin' minus all the
	// things that add to the margin.
	textwidth = curwin->w_width - curbuf->b_p_wm;
	if (cmdwin_type != 0)
	    textwidth -= 1;
#ifdef FEAT_FOLDING
	textwidth -= curwin->w_p_fdc;
#endif
#ifdef FEAT_SIGNS
	if (signcolumn_on(curwin))
	    textwidth -= 1;
#endif
	if (curwin->w_p_nu || curwin->w_p_rnu)
	    textwidth -= 8;
    }
    if (textwidth < 0)
	textwidth = 0;
    if (ff && textwidth == 0)
    {
	textwidth = curwin->w_width - 1;
	if (textwidth > 79)
	    textwidth = 79;
    }
    return textwidth;
}

/*
 * Implementation of the format operator 'gq'.
 */
    void
op_format(
    oparg_T	*oap,
    int		keep_cursor)		// keep cursor on same text char
{
    long	old_line_count = curbuf->b_ml.ml_line_count;

    // Place the cursor where the "gq" or "gw" command was given, so that "u"
    // can put it back there.
    curwin->w_cursor = oap->cursor_start;

    if (u_save((linenr_T)(oap->start.lnum - 1),
				       (linenr_T)(oap->end.lnum + 1)) == FAIL)
	return;
    curwin->w_cursor = oap->start;

    if (oap->is_VIsual)
	// When there is no change: need to remove the Visual selection
	redraw_curbuf_later(UPD_INVERTED);

    if ((cmdmod.cmod_flags & CMOD_LOCKMARKS) == 0)
	// Set '[ mark at the start of the formatted area
	curbuf->b_op_start = oap->start;

    // For "gw" remember the cursor position and put it back below (adjusted
    // for joined and split lines).
    if (keep_cursor)
	saved_cursor = oap->cursor_start;

    format_lines(oap->line_count, keep_cursor);

    // Leave the cursor at the first non-blank of the last formatted line.
    // If the cursor was moved one line back (e.g. with "Q}") go to the next
    // line, so "." will do the next lines.
    if (oap->end_adjusted && curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
	++curwin->w_cursor.lnum;
    beginline(BL_WHITE | BL_FIX);
    old_line_count = curbuf->b_ml.ml_line_count - old_line_count;
    msgmore(old_line_count);

    if ((cmdmod.cmod_flags & CMOD_LOCKMARKS) == 0)
	// put '] mark on the end of the formatted area
	curbuf->b_op_end = curwin->w_cursor;

    if (keep_cursor)
    {
	curwin->w_cursor = saved_cursor;
	saved_cursor.lnum = 0;

	// formatting may have made the cursor position invalid
	check_cursor();
    }

    if (oap->is_VIsual)
    {
	win_T	*wp;

	FOR_ALL_WINDOWS(wp)
	{
	    if (wp->w_old_cursor_lnum != 0)
	    {
		// When lines have been inserted or deleted, adjust the end of
		// the Visual area to be redrawn.
		if (wp->w_old_cursor_lnum > wp->w_old_visual_lnum)
		    wp->w_old_cursor_lnum += old_line_count;
		else
		    wp->w_old_visual_lnum += old_line_count;
	    }
	}
    }
}

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * Implementation of the format operator 'gq' for when using 'formatexpr'.
 */
    void
op_formatexpr(oparg_T *oap)
{
    if (oap->is_VIsual)
	// When there is no change: need to remove the Visual selection
	redraw_curbuf_later(UPD_INVERTED);

    if (fex_format(oap->start.lnum, oap->line_count, NUL) != 0)
	// As documented: when 'formatexpr' returns non-zero fall back to
	// internal formatting.
	op_format(oap, FALSE);
}

    int
fex_format(
    linenr_T	lnum,
    long	count,
    int		c)	// character to be inserted
{
    int		use_sandbox = was_set_insecurely((char_u *)"formatexpr",
								   OPT_LOCAL);
    int		r;
    char_u	*fex;
    sctx_T	save_sctx = current_sctx;

    // Set v:lnum to the first line number and v:count to the number of lines.
    // Set v:char to the character to be inserted (can be NUL).
    set_vim_var_nr(VV_LNUM, lnum);
    set_vim_var_nr(VV_COUNT, count);
    set_vim_var_char(c);

    // Make a copy, the option could be changed while calling it.
    fex = vim_strsave(curbuf->b_p_fex);
    if (fex == NULL)
	return 0;
    current_sctx = curbuf->b_p_script_ctx[BV_FEX];

    // Evaluate the function.
    if (use_sandbox)
	++sandbox;
    r = (int)eval_to_number(fex, TRUE);
    if (use_sandbox)
	--sandbox;

    set_vim_var_string(VV_CHAR, NULL, -1);
    vim_free(fex);
    current_sctx = save_sctx;

    return r;
}
#endif

/*
 * Format "line_count" lines, starting at the cursor position.
 * When "line_count" is negative, format until the end of the paragraph.
 * Lines after the cursor line are saved for undo, caller must have saved the
 * first line.
 */
    void
format_lines(
    linenr_T	line_count,
    int		avoid_fex)		// don't use 'formatexpr'
{
    int		max_len;
    int		is_not_par;		// current line not part of parag.
    int		next_is_not_par;	// next line not part of paragraph
    int		is_end_par;		// at end of paragraph
    int		prev_is_end_par = FALSE;// prev. line not part of parag.
    int		next_is_start_par = FALSE;
    int		leader_len = 0;		// leader len of current line
    int		next_leader_len;	// leader len of next line
    char_u	*leader_flags = NULL;	// flags for leader of current line
    char_u	*next_leader_flags = NULL; // flags for leader of next line
    int		do_comments;		// format comments
    int		do_comments_list = 0;	// format comments with 'n' or '2'
    int		advance = TRUE;
    int		second_indent = -1;	// indent for second line (comment
					// aware)
    int		do_second_indent;
    int		do_number_indent;
    int		do_trail_white;
    int		first_par_line = TRUE;
    int		smd_save;
    long	count;
    int		need_set_indent = TRUE;	// set indent of next paragraph
    linenr_T	first_line = curwin->w_cursor.lnum;
    int		force_format = FALSE;
    int		old_State = State;

    // length of a line to force formatting: 3 * 'tw'
    max_len = comp_textwidth(TRUE) * 3;

    // check for 'q', '2', 'n' and 'w' in 'formatoptions'
    do_comments = has_format_option(FO_Q_COMS);
    do_second_indent = has_format_option(FO_Q_SECOND);
    do_number_indent = has_format_option(FO_Q_NUMBER);
    do_trail_white = has_format_option(FO_WHITE_PAR);

    // Get info about the previous and current line.
    if (curwin->w_cursor.lnum > 1)
	is_not_par = fmt_check_par(curwin->w_cursor.lnum - 1
				, &leader_len, &leader_flags, do_comments);
    else
	is_not_par = TRUE;
    next_is_not_par = fmt_check_par(curwin->w_cursor.lnum
			  , &next_leader_len, &next_leader_flags, do_comments);
    is_end_par = (is_not_par || next_is_not_par);
    if (!is_end_par && do_trail_white)
	is_end_par = !ends_in_white(curwin->w_cursor.lnum - 1);

    curwin->w_cursor.lnum--;
    for (count = line_count; count != 0 && !got_int; --count)
    {
	// Advance to next paragraph.
	if (advance)
	{
	    curwin->w_cursor.lnum++;
	    prev_is_end_par = is_end_par;
	    is_not_par = next_is_not_par;
	    leader_len = next_leader_len;
	    leader_flags = next_leader_flags;
	}

	// The last line to be formatted.
	if (count == 1 || curwin->w_cursor.lnum == curbuf->b_ml.ml_line_count)
	{
	    next_is_not_par = TRUE;
	    next_leader_len = 0;
	    next_leader_flags = NULL;
	}
	else
	{
	    next_is_not_par = fmt_check_par(curwin->w_cursor.lnum + 1
			  , &next_leader_len, &next_leader_flags, do_comments);
	    if (do_number_indent)
		next_is_start_par =
			   (get_number_indent(curwin->w_cursor.lnum + 1) > 0);
	}
	advance = TRUE;
	is_end_par = (is_not_par || next_is_not_par || next_is_start_par);
	if (!is_end_par && do_trail_white)
	    is_end_par = !ends_in_white(curwin->w_cursor.lnum);

	// Skip lines that are not in a paragraph.
	if (is_not_par)
	{
	    if (line_count < 0)
		break;
	}
	else
	{
	    // For the first line of a paragraph, check indent of second line.
	    // Don't do this for comments and empty lines.
	    if (first_par_line
		    && (do_second_indent || do_number_indent)
		    && prev_is_end_par
		    && curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
	    {
		if (do_second_indent && !LINEEMPTY(curwin->w_cursor.lnum + 1))
		{
		    if (leader_len == 0 && next_leader_len == 0)
		    {
			// no comment found
			second_indent =
				   get_indent_lnum(curwin->w_cursor.lnum + 1);
		    }
		    else
		    {
			second_indent = next_leader_len;
			do_comments_list = 1;
		    }
		}
		else if (do_number_indent)
		{
		    if (leader_len == 0 && next_leader_len == 0)
		    {
			// no comment found
			second_indent =
				     get_number_indent(curwin->w_cursor.lnum);
		    }
		    else
		    {
			// get_number_indent() is now "comment aware"...
			second_indent =
				     get_number_indent(curwin->w_cursor.lnum);
			do_comments_list = 1;
		    }
		}
	    }

	    // When the comment leader changes, it's the end of the paragraph.
	    if (curwin->w_cursor.lnum >= curbuf->b_ml.ml_line_count
		    || !same_leader(curwin->w_cursor.lnum,
					leader_len, leader_flags,
					   next_leader_len, next_leader_flags))
	    {
		// Special case: If the next line starts with a line comment
		// and this line has a line comment after some text, the
		// paragraph doesn't really end.
		if (next_leader_flags == NULL
			|| STRNCMP(next_leader_flags, "://", 3) != 0
			|| check_linecomment(ml_get_curline()) == MAXCOL)
		is_end_par = TRUE;
	    }

	    // If we have got to the end of a paragraph, or the line is
	    // getting long, format it.
	    if (is_end_par || force_format)
	    {
		if (need_set_indent)
		{
		    int		indent = 0; // amount of indent needed

		    // Replace indent in first line of a paragraph with minimal
		    // number of tabs and spaces, according to current options.
		    // For the very first formatted line keep the current
		    // indent.
		    if (curwin->w_cursor.lnum == first_line)
			indent = get_indent();
		    else if (curbuf->b_p_lisp)
			indent = get_lisp_indent();
		    else
		    {
			if (cindent_on())
			{
			    indent =
# ifdef FEAT_EVAL
				 *curbuf->b_p_inde != NUL ? get_expr_indent() :
# endif
				 get_c_indent();
			}
			else
			    indent = get_indent();
		    }
		    (void)set_indent(indent, SIN_CHANGED);
		}

		// put cursor on last non-space
		State = MODE_NORMAL;	// don't go past end-of-line
		coladvance((colnr_T)MAXCOL);
		while (curwin->w_cursor.col && vim_isspace(gchar_cursor()))
		    dec_cursor();

		// do the formatting, without 'showmode'
		State = MODE_INSERT;	// for open_line()
		smd_save = p_smd;
		p_smd = FALSE;
		insertchar(NUL, INSCHAR_FORMAT
			+ (do_comments ? INSCHAR_DO_COM : 0)
			+ (do_comments && do_comments_list
						       ? INSCHAR_COM_LIST : 0)
			+ (avoid_fex ? INSCHAR_NO_FEX : 0), second_indent);
		State = old_State;
		p_smd = smd_save;
		second_indent = -1;
		// at end of par.: need to set indent of next par.
		need_set_indent = is_end_par;
		if (is_end_par)
		{
		    // When called with a negative line count, break at the
		    // end of the paragraph.
		    if (line_count < 0)
			break;
		    first_par_line = TRUE;
		}
		force_format = FALSE;
	    }

	    // When still in same paragraph, join the lines together.  But
	    // first delete the leader from the second line.
	    if (!is_end_par)
	    {
		advance = FALSE;
		curwin->w_cursor.lnum++;
		curwin->w_cursor.col = 0;
		if (line_count < 0 && u_save_cursor() == FAIL)
		    break;
		if (next_leader_len > 0)
		{
		    (void)del_bytes((long)next_leader_len, FALSE, FALSE);
		    mark_col_adjust(curwin->w_cursor.lnum, (colnr_T)0, 0L,
						    (long)-next_leader_len, 0);
		}
		else if (second_indent > 0)  // the "leader" for FO_Q_SECOND
		{
		    int indent = getwhitecols_curline();

		    if (indent > 0)
		    {
			(void)del_bytes(indent, FALSE, FALSE);
			mark_col_adjust(curwin->w_cursor.lnum,
					     (colnr_T)0, 0L, (long)-indent, 0);
		    }
		}
		curwin->w_cursor.lnum--;
		if (do_join(2, TRUE, FALSE, FALSE, FALSE) == FAIL)
		{
		    beep_flush();
		    break;
		}
		first_par_line = FALSE;
		// If the line is getting long, format it next time
		if (STRLEN(ml_get_curline()) > (size_t)max_len)
		    force_format = TRUE;
		else
		    force_format = FALSE;
	    }
	}
	line_breakcheck();
    }
}