view src/os_vms.c @ 34021:46ebf4ffad49 v9.0.2186

patch 9.0.2186: LTCG compile error ARM64 for write_chars Commit: https://github.com/vim/vim/commit/38bea30f53da8e4a8847407404597b255b20334e Author: Saleem Abdulrasool <compnerd@compnerd.org> Date: Wed Dec 27 18:57:12 2023 +0100 patch 9.0.2186: LTCG compile error ARM64 for write_chars Problem: LTCG compile error on Win/ARM64 for `write_chars()` Solution: Explicitly initialise the storage to use data rather than BSS (Saleem Abdulrasool) win32: add a workaround for a LTCG issue on Windows ARM64 It appears that the implicit initialisation which would push `g_coords` into BSS causes an aliasing issue with LTCG on ARM64. By explicitly initialising the value, we use usual data storage but prevent the aliasing. This allows the console version of VIM to run on Windows ARM64 again. fixes: #13453 closes: #13775 Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org> Signed-off-by: Christian Brabandt <cb@256bit.org>
author Christian Brabandt <cb@256bit.org>
date Wed, 27 Dec 2023 19:15:03 +0100
parents 50555279168b
children
line wrap: on
line source

/* vi:set ts=8 sts=4 sw=4 noet:
 *
 * VIM - Vi IMproved		by Bram Moolenaar
 * VMS port			by Henk Elbers
 * VMS deport			by Zoltan Arpadffy
 *
 * 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.
 */

#include	"vim.h"

// define _generic_64 for use in time functions
#if !defined(VAX) && !defined(PROTO)
#   include <gen64def.h>
#else
// based on Alpha's gen64def.h; the file is absent on VAX
typedef struct _generic_64 {
#   pragma __nomember_alignment
    __union  {				// You can treat me as...
	// long long is not available on VAXen
	// unsigned __int64 gen64$q_quadword; ...a single 64-bit value, or

	unsigned int gen64$l_longword [2]; // ...two 32-bit values, or
	unsigned short int gen64$w_word [4]; // ...four 16-bit values
    } gen64$r_quad_overlay;
} GENERIC_64;
#endif

typedef struct
{
    char	class;
    char	type;
    short	width;
    union
    {
	struct
	{
	    char	_basic[3];
	    char	length;
	}	y;
	int	basic;
    }	x;
    int		extended;
}	TT_MODE;

typedef struct
{
    short	buflen;
    short	itemcode;
    char	*bufadrs;
    int		*retlen;
}	ITEM;

typedef struct
{
    ITEM	equ;
    int		nul;
}	ITMLST1;

typedef struct
{
    ITEM	index;
    ITEM	string;
    int	nul;
}	ITMLST2;

static TT_MODE	orgmode;
static short	iochan;			// TTY I/O channel
static short	iosb[4];		// IO status block

static int vms_match_num = 0;
static int vms_match_free = 0;
static char_u **vms_fmatch = NULL;
static char *Fspec_Rms;		       // rms file spec, passed implicitly between routines



static TT_MODE	get_tty(void);
static void	set_tty(int row, int col);

#define EXPL_ALLOC_INC 64

#define EQN(S1,S2,LN) (strncmp(S1,S2,LN) == 0)
#define SKIP_FOLLOWING_SLASHES(Str) do { while (Str[1] == '/') ++Str; } while (0)


/*
 *	vul_desc	vult een descriptor met een string en de lengte
 *			hier van.
 */
    static void
vul_desc(DESC *des, char *str)
{
    des->dsc$b_dtype = DSC$K_DTYPE_T;
    des->dsc$b_class = DSC$K_CLASS_S;
    des->dsc$a_pointer = str;
    des->dsc$w_length = str ? strlen(str) : 0;
}

/*
 *	vul_item	vult een item met een aantal waarden
 */
    static void
vul_item(ITEM *itm, short len, short cod, char *adr, int *ret)
{
    itm->buflen   = len;
    itm->itemcode = cod;
    itm->bufadrs  = adr;
    itm->retlen   = ret;
}

    void
mch_settmode(tmode_T tmode)
{
    int	status;

    if ( tmode == TMODE_RAW )
	set_tty(0, 0);
    else
    {
	switch (orgmode.width)
	{
	    case 132:	OUT_STR_NF((char_u *)"\033[?3h\033>");	break;
	    case 80:	OUT_STR_NF((char_u *)"\033[?3l\033>");	break;
	    default:	break;
	}
	out_flush();
	status = sys$qiow(0, iochan, IO$_SETMODE, iosb, 0, 0,
					  &orgmode, sizeof(TT_MODE), 0,0,0,0);
	if (status!=SS$_NORMAL || (iosb[0]&0xFFFF)!=SS$_NORMAL)
	    return;
	(void)sys$dassgn(iochan);
	iochan = 0;
    }
}

    static void
set_tty(int row, int col)
{
    int		    status;
    TT_MODE	    newmode;		// New TTY mode bits
    static short    first_time = TRUE;

    if (first_time)
    {
	orgmode = get_tty();
	first_time = FALSE;
    }
    newmode = get_tty();
    if (col)
	newmode.width		 = col;
    if (row)
	newmode.x.y.length       = row;
    newmode.x.basic		|= (TT$M_NOECHO | TT$M_HOSTSYNC);
    newmode.x.basic		&= ~TT$M_TTSYNC;
    newmode.extended		|= TT2$M_PASTHRU;
    status = sys$qiow(0, iochan, IO$_SETMODE, iosb, 0, 0,
			  &newmode, sizeof(newmode), 0, 0, 0, 0);
    if (status!=SS$_NORMAL || (iosb[0]&0xFFFF)!=SS$_NORMAL)
	return;
}

    static TT_MODE
get_tty(void)
{

    static $DESCRIPTOR(odsc,"SYS$OUTPUT");   // output descriptor

    int		status;
    TT_MODE	tt_mode;

    if (!iochan)
	status = sys$assign(&odsc,&iochan,0,0);

    status = sys$qiow(0, iochan, IO$_SENSEMODE, iosb, 0, 0,
		      &tt_mode, sizeof(tt_mode), 0, 0, 0, 0);
    if (status != SS$_NORMAL || (iosb[0] & 0xFFFF) != SS$_NORMAL)
    {
	tt_mode.width		= 0;
	tt_mode.type		= 0;
	tt_mode.class		= 0;
	tt_mode.x.basic		= 0;
	tt_mode.x.y.length	= 0;
	tt_mode.extended	= 0;
    }
    return(tt_mode);
}

/*
 * Get the current window size in Rows and Columns.
 */
    int
mch_get_shellsize(void)
{
    TT_MODE	tmode;

    tmode = get_tty();			// get size from VMS
    Columns = tmode.width;
    Rows = tmode.x.y.length;
    return OK;
}

/*
 * Try to set the window size to Rows and new_Columns.
 */
    void
mch_set_shellsize(void)
{
    set_tty(Rows, Columns);
    switch (Columns)
    {
	case 132:	OUT_STR_NF((char_u *)"\033[?3h\033>");	break;
	case 80:	OUT_STR_NF((char_u *)"\033[?3l\033>");	break;
	default:	break;
    }
    out_flush();
    screen_start();
}

    char_u *
mch_getenv(char_u *lognam)
{
    DESC		d_file_dev, d_lognam  ;
    static char		buffer[LNM$C_NAMLENGTH+1];
    char_u		*cp = NULL;
    unsigned long	attrib;
    int			lengte = 0, dum = 0, idx = 0;
    ITMLST2		itmlst;
    char		*sbuf = NULL;

    vul_desc(&d_lognam, (char *)lognam);
    vul_desc(&d_file_dev, "LNM$FILE_DEV");
    attrib = LNM$M_CASE_BLIND;
    vul_item(&itmlst.index, sizeof(int), LNM$_INDEX, (char *)&idx, &dum);
    vul_item(&itmlst.string, LNM$C_NAMLENGTH, LNM$_STRING, buffer, &lengte);
    itmlst.nul	= 0;
    if (sys$trnlnm(&attrib, &d_file_dev, &d_lognam, NULL,&itmlst) == SS$_NORMAL)
    {
	buffer[lengte] = '\0';
	if (cp = alloc(lengte + 1))
	    strcpy((char *)cp, buffer);
	return(cp);
    }
    else if ((sbuf = getenv((char *)lognam)))
    {
	lengte = strlen(sbuf) + 1;
	cp = alloc(lengte);
	if (cp)
	    strcpy((char *)cp, sbuf);
	return cp;
    }
    else
	return(NULL);
}

/*
 *	mch_setenv	VMS version of setenv()
 */
    int
mch_setenv(char *var, char *value, int x)
{
    int		res, dum;
    long	attrib = 0L;
    char	acmode = PSL$C_SUPER;	// needs SYSNAM privilege
    DESC	tabnam, lognam;
    ITMLST1	itmlst;

    vul_desc(&tabnam, "LNM$JOB");
    vul_desc(&lognam, var);
    vul_item(&itmlst.equ, value ? strlen(value) : 0, value ? LNM$_STRING : 0,
	    value, &dum);
    itmlst.nul	= 0;
    res = sys$crelnm(&attrib, &tabnam, &lognam, &acmode, &itmlst);
    return((res == 1) ? 0 : -1);
}

    int
vms_sys(char *cmd, char *out, char *inp)
{
    DESC	cdsc, odsc, idsc;
    long	status;

    if (cmd)
	vul_desc(&cdsc, cmd);
    if (out)
	vul_desc(&odsc, out);
    if (inp)
	vul_desc(&idsc, inp);

    lib$spawn(cmd ? &cdsc : NULL,		// command string
	      inp ? &idsc : NULL,		// input file
	      out ? &odsc : NULL,		// output file
	      0, 0, 0, &status, 0, 0, 0, 0, 0, 0);
    return status;
}

/*
 * Convert string to lowercase - most often filename
 */
    char *
vms_tolower( char *name )
{
    int i,nlen = strlen(name);
    for (i = 0; i < nlen; i++)
	name[i] = TOLOWER_ASC(name[i]);
    return name;
}

/*
 * Convert VMS system() or lib$spawn() return code to Unix-like exit value.
 */
    int
vms_sys_status(int status)
{
    if (status != SS$_NORMAL && (status & STS$M_SUCCESS) == 0)
	return status;		// Command failed.
    return 0;
}

/*
 * vms_read()
 * function for low level char input
 *
 * Returns: input length
 */
    int
vms_read(char *inbuf, size_t nbytes)
{
    int		status, function, len;
    TT_MODE	tt_mode;
    ITEM	itmlst[2];     // terminates on everything
    static long trm_mask[8] = {-1, -1, -1, -1, -1, -1, -1, -1};

    // whatever happened earlier we need an iochan here
    if (!iochan)
	tt_mode = get_tty();

    // important: clean the inbuf
    memset(inbuf, 0, nbytes);

    // set up the itemlist for the first read
    vul_item(&itmlst[0], 0, TRM$_MODIFIERS,
	 (char *)( TRM$M_TM_NOECHO  | TRM$M_TM_NOEDIT	 |
		   TRM$M_TM_NOFILTR | TRM$M_TM_TRMNOECHO |
		   TRM$M_TM_NORECALL) , 0);
    vul_item(&itmlst[1], sizeof(trm_mask), TRM$_TERM, (char *)&trm_mask, 0);

    // wait forever for a char
    function = (IO$_READLBLK | IO$M_EXTEND);
    status = sys$qiow(0, iochan, function, &iosb, 0, 0,
			 inbuf, nbytes-1, 0, 0, &itmlst, sizeof(itmlst));
    len = strlen(inbuf); // how many chars we got?

    // read immediately the rest in the IO queue
    function = (IO$_READLBLK | IO$M_TIMED | IO$M_ESCAPE | IO$M_NOECHO | IO$M_NOFILTR);
    status = sys$qiow(0, iochan, function, &iosb, 0, 0,
			 inbuf+len, nbytes-1-len, 0, 0, 0, 0);

    len = strlen(inbuf); // return the total length

    return len;
}

/*
 * vms_wproc() is called for each matching filename by decc$to_vms().
 * We want to save each match for later retrieval.
 *
 * Returns:  1 - continue finding matches
 *	     0 - stop trying to find any further matches
 */
    static int
vms_wproc(char *name, int val)
{
    int i;
    static int vms_match_alloced = 0;

    if (val == DECC$K_FOREIGN ) // foreign non VMS files are not counting
	return 1;

    // accept all DECC$K_FILE and DECC$K_DIRECTORY
    if (vms_match_num == 0)
    {
	// first time through, setup some things
	if (NULL == vms_fmatch)
	{
	    vms_fmatch = ALLOC_MULT(char_u *, EXPL_ALLOC_INC);
	    if (!vms_fmatch)
		return 0;
	    vms_match_alloced = EXPL_ALLOC_INC;
	    vms_match_free = EXPL_ALLOC_INC;
	}
	else
	{
	    // re-use existing space
	    vms_match_free = vms_match_alloced;
	}
    }

    // make matches look uniform
    vms_remove_version(name);
    name=vms_tolower(name);

    // if name already exists, don't add it
    for (i = 0; i<vms_match_num; i++)
    {
	if (0 == STRCMP((char_u *)name,vms_fmatch[i]))
	    return 1;
    }
    if (--vms_match_free == 0)
    {
	char_u **old_vms_fmatch = vms_fmatch;

	// add more space to store matches
	vms_match_alloced += EXPL_ALLOC_INC;
	vms_fmatch = vim_realloc(old_vms_fmatch,
		sizeof(char **) * vms_match_alloced);
	if (!vms_fmatch)
	{
	    vim_free(old_vms_fmatch);
	    return 0;
	}
	vms_match_free = EXPL_ALLOC_INC;
    }
    vms_fmatch[vms_match_num] = vim_strsave((char_u *)name);

    ++vms_match_num;
    return 1;
}

/*
 *	mch_expand_wildcards	this code does wild-card pattern
 *				matching NOT using the shell
 *
 *	return OK for success, FAIL for error (you may lose some
 *	memory) and put an error message in *file.
 *
 *	num_pat	   number of input patterns
 *	pat	   array of pointers to input patterns
 *	num_file   pointer to number of matched file names
 *	file	   pointer to array of pointers to matched file names
 *
 */
    int
mch_expand_wildcards(int num_pat, char_u **pat, int *num_file, char_u ***file, int flags)
{
    int		i, cnt = 0;
    char_u	buf[MAXPATHL];
    char       *result;
    int		dir;
    int files_alloced, files_free;

    *num_file = 0;			// default: no files found
    files_alloced = EXPL_ALLOC_INC;
    files_free = EXPL_ALLOC_INC;
    *file = ALLOC_MULT(char_u *, files_alloced);
    if (*file == NULL)
    {
	*num_file = 0;
	return FAIL;
    }
    for (i = 0; i < num_pat; i++)
    {
	// expand environment var or home dir
	if (vim_strchr(pat[i],'$') || vim_strchr(pat[i],'~'))
	    expand_env(pat[i],buf,MAXPATHL);
	else
	    STRCPY(buf,pat[i]);

	vms_match_num = 0; // reset collection counter
	result = decc$translate_vms(vms_fixfilename(buf));
	if ( (int) result == 0 || (int) result == -1  )
	{
	    cnt = 0;
	}
	else
	{
	    cnt = decc$to_vms(result, vms_wproc, 1 /*allow wild*/ , (flags & EW_DIR ? 0:1 ) /*allow directory*/) ;
	}
	if (cnt > 0)
	    cnt = vms_match_num;

	if (cnt < 1)
	    continue;

	for (i = 0; i < cnt; i++)
	{
	    // files should exist if expanding interactively
	    if (!(flags & EW_NOTFOUND) && mch_getperm(vms_fmatch[i]) < 0)
		continue;

	    // do not include directories
	    dir = (mch_isdir(vms_fmatch[i]));
	    if (( dir && !(flags & EW_DIR)) || (!dir && !(flags & EW_FILE)))
		continue;

	    // Skip files that are not executable if we check for that.
	    if (!dir && (flags & EW_EXEC)
		 && !mch_can_exe(vms_fmatch[i], NULL, !(flags & EW_SHELLCMD)))
		continue;

	    // allocate memory for pointers
	    if (--files_free < 1)
	    {
		char_u **old_file = *file;

		files_alloced += EXPL_ALLOC_INC;
		*file = vim_realloc(old_file, sizeof(char_u **) * files_alloced);
		if (*file == NULL)
		{
		    vim_free(old_file);
		    *file = (char_u **)"";
		    *num_file = 0;
		    return(FAIL);
		}
		files_free = EXPL_ALLOC_INC;
	    }

	    (*file)[*num_file++] = vms_fmatch[i];
	}
    }
    return OK;
}

    int
mch_expandpath(garray_T *gap, char_u *path, int flags)
{
    int		i,cnt = 0;
    char       *result;

    vms_match_num = 0;
    // the result from the decc$translate_vms needs to be handled
    // otherwise it might create ACCVIO error in decc$to_vms
    result = decc$translate_vms(vms_fixfilename(path));
    if ( (int) result == 0 || (int) result == -1  )
    {
	cnt = 0;
    }
    else
    {
	cnt = decc$to_vms(result, vms_wproc, 1 /*allow_wild*/, (flags & EW_DIR ? 0:1 ) /*allow directory*/);
    }
    if (cnt > 0)
	cnt = vms_match_num;
    for (i = 0; i < cnt; i++)
    {
	if (mch_getperm(vms_fmatch[i]) >= 0) // add existing file
	    addfile(gap, vms_fmatch[i], flags);
    }
    return cnt;
}

/*
 * attempt to translate a mixed unix-vms file specification to pure vms
 */
    static void
vms_unix_mixed_filespec(char *in, char *out)
{
    char *lastcolon;
    char *end_of_dir;
    char ch;
    int len;
    char *out_str=out;

    // copy vms filename portion up to last colon
    // (node and/or disk)
    lastcolon = strrchr(in, ':');   // find last colon
    if (lastcolon != NULL)
    {
	len = lastcolon - in + 1;
	strncpy(out, in, len);
	out += len;
	in += len;
    }

    end_of_dir = NULL;	// default: no directory

    // start of directory portion
    ch = *in;
    if ((ch == '[') || (ch == '/') || (ch == '<')) // start of directory(s) ?
    {
	ch = '[';
	SKIP_FOLLOWING_SLASHES(in);
    }
    else if (EQN(in, "../", 3)) // Unix parent directory?
    {
	*out++ = '[';
	*out++ = '-';
	end_of_dir = out;
	ch = '.';
	in += 2;
	SKIP_FOLLOWING_SLASHES(in);
    }
    else
    {		    // not a special character
	while (EQN(in, "./", 2))	// Ignore Unix "current dir"
	{
	    in += 2;
	    SKIP_FOLLOWING_SLASHES(in);
    }
    if (strchr(in, '/') == NULL)  // any more Unix directories ?
    {
	strcpy(out, in);	// No - get rest of the spec
	return;
    }
    else
    {
	*out++ = '[';	    // Yes, denote a Vms subdirectory
	ch = '.';
	--in;
	}
    }

    // if we get here, there is a directory part of the filename

    // initialize output file spec
    *out++ = ch;
    ++in;

    while (*in != '\0')
    {
	ch = *in;
	if ((ch == ']') || (ch == '/') || (ch == '>') )	// end of (sub)directory ?
	{
	    end_of_dir = out;
	    ch = '.';
	    SKIP_FOLLOWING_SLASHES(in);
	    }
	else if (EQN(in, "../", 3))	// Unix parent directory?
	{
	    *out++ = '-';
	    end_of_dir = out;
	    ch = '.';
	    in += 2;
	    SKIP_FOLLOWING_SLASHES(in);
	    }
	else
	{
	    while (EQN(in, "./", 2))  // Ignore Unix "current dir"
	    {
		end_of_dir = out;
		in += 2;
		SKIP_FOLLOWING_SLASHES(in);
		ch = *in;
	    }
	}

    // Place next character into output file spec
	*out++ = ch;
	++in;
    }

    *out = '\0';    // Terminate output file spec

    if (end_of_dir != NULL) // Terminate directory portion
	*end_of_dir = ']';
}

/*
 * for decc$to_vms in vms_fixfilename
 */
    static int
vms_fspec_proc(char *fil, int val)
{
    strcpy(Fspec_Rms,fil);
    return(1);
}

/*
 * change unix and mixed filenames to VMS
 */
    void *
vms_fixfilename(void *instring)
{
    static char		*buf = NULL;
    static size_t	buflen = 0;
    size_t		len;

    // get a big-enough buffer
    len = strlen(instring) + 1;
    if (len > buflen)
    {
	buflen = len + 128;
	buf = vim_realloc(buf, buflen * sizeof(char));
    }

#ifdef DEBUG
     char		 *tmpbuf = NULL;
     tmpbuf = ALLOC_MULT(char, buflen);
     strcpy(tmpbuf, instring);
#endif

    Fspec_Rms = buf;				// for decc$to_vms

    if (strchr(instring,'/') == NULL)
	// It is already a VMS file spec
	strcpy(buf, instring);
    else if (strchr(instring,'"') == NULL)	// password in the path?
    {
	// Seems it is a regular file, let guess that it is pure Unix fspec
	if ( (strchr(instring,'[') == NULL) && (strchr(instring,'<') == NULL) &&
	     (strchr(instring,']') == NULL) && (strchr(instring,'>') == NULL) &&
	     (strchr(instring,':') == NULL) )
	{
	    // It must be a truly unix fspec
	    decc$to_vms(instring, vms_fspec_proc, 0, 0);
	}
	else
	{
	    // It is a mixed fspec
	    vms_unix_mixed_filespec(instring, buf);
	}
    }
    else
	// we have a password in the path
	// decc$ functions can not handle
	// this is our only hope to resolv
	vms_unix_mixed_filespec(instring, buf);

    return buf;
}

/*
 * Remove version number from file name
 * we need it in some special cases as:
 * creating swap file name and writing new file
 */
    void
vms_remove_version(void * fname)
{
    char_u	*cp;
    char_u	*fp;

    if ((cp = vim_strchr( fname, ';')) != NULL) // remove version
	*cp = '\0';
    else if ((cp = vim_strrchr( fname, '.')) != NULL )
    {
	if      ((fp = vim_strrchr( fname, ']')) != NULL )
	    {;}
	else if ((fp = vim_strrchr( fname, '>')) != NULL )
	    {;}
	else
	    fp = fname;

	while ( *fp != '\0' && fp < cp )
	    if ( *fp++ == '.' )
		*cp = '\0';
    }
    return ;
}

struct typeahead_st {
    unsigned short numchars;
    unsigned char  firstchar;
    unsigned char  reserved0;
    unsigned long  reserved1;
} typeahead;

/*
 * Wait "msec" msec until a character is available from file descriptor "fd".
 * "msec" == 0 will check for characters once.
 * "msec" == -1 will block until a character is available.
 */
    int
RealWaitForChar(
    int		fd UNUSED, // always read from iochan
    long	msec,
    int		*check_for_gpm UNUSED,
    int		*interrupted)
{
    int status;
    struct _generic_64 time_curr;
    struct _generic_64 time_diff;
    struct _generic_64 time_out;
    unsigned int convert_operation = LIB$K_DELTA_SECONDS_F;
    float sec =(float) msec/1000;

    // make sure the iochan is set
    if (!iochan)
	get_tty();

    if (sec > 0)
    {
	// time-out specified; convert it to absolute time
	// sec>0 requirement of lib$cvtf_to_internal_time()

	// get current time (number of 100ns ticks since the VMS Epoch)
	status = sys$gettim(&time_curr);
	if (status != SS$_NORMAL)
	    return 0; // error
	// construct the delta time
#if __G_FLOAT==0
# ifndef VAX
	// IEEE is default on IA64, but can be used on Alpha too - but not on VAX
	status = lib$cvts_to_internal_time(
		&convert_operation, &sec, &time_diff);
# endif
#else   // default on Alpha and VAX
	status = lib$cvtf_to_internal_time(
		&convert_operation, &sec, &time_diff);
#endif
	if (status != LIB$_NORMAL)
	    return 0; // error
	// add them up
	status = lib$add_times(
		&time_curr,
		&time_diff,
		&time_out);
	if (status != LIB$_NORMAL)
	    return 0; // error
    }

    while (TRUE)
    {
	// select()
	status = sys$qiow(0, iochan, IO$_SENSEMODE | IO$M_TYPEAHDCNT, iosb,
		0, 0, &typeahead, 8, 0, 0, 0, 0);
	if (status != SS$_NORMAL || (iosb[0] & 0xFFFF) != SS$_NORMAL)
	    return 0; // error

	if (typeahead.numchars)
	    return 1; // ready to read

	// there's nothing to read; what now?
	if (msec == 0)
	{
	    // immediate time-out; return impatiently
	    return 0;
	}
	else if (msec < 0)
	{
	    // no time-out; wait on indefinitely
	    return 1; // fakeout to force a wait in vms_read()
	}
	else
	{
	    // time-out needs to be checked
	    status = sys$gettim(&time_curr);
	    if (status != SS$_NORMAL)
		return 0; // error

	    status = lib$sub_times(
		    &time_out,
		    &time_curr,
		    &time_diff);
	    if (status != LIB$_NORMAL)
		return 0; // error, incl. time_diff < 0 (i.e. time-out)

	    // otherwise wait some more
	}
    }
}