/*
 *	filec.c
 *
 * Filename prompting and completion routines
 * Written by T.E.Dickey for vile (march 1993).
 *
 *
 * $Header: /usr/build/vile/vile/RCS/filec.c,v 1.121 2005/01/20 01:58:58 tom Exp $
 *
 */

#include "estruct.h"
#include "edef.h"

#undef USE_QSORT
#if SYS_OS2
# define USE_QSORT 0
# define INCL_DOSFILEMGR
# define INCL_ERRORS
# include <os2.h>
# define FoundDirectory(path) ((fb.attrFile & FILE_DIRECTORY) != 0)
#endif

#ifndef USE_QSORT
#define USE_QSORT 1
#endif

/* Systems that can have leafnames beginning with '.' (this doesn't include
 * VMS, which does allow this as unlikely as that may seem, because the logic
 * that masks dots simply won't work in conjunction with the other translations
 * to/from hybrid form).
 */
#if (SYS_UNIX || SYS_WINNT) && ! OPT_VMS_PATH
#define USE_DOTNAMES 1
#else
#define USE_DOTNAMES 0
#endif

#define isDotname(leaf) (!strcmp(leaf, ".") || !strcmp(leaf, ".."))

#if defined(MISSING_EXTERN_ENVIRON) || (defined(__DJGPP__) && __DJGPP__ >= 2)
extern char **environ;
#endif

#if CC_LCC_WIN32
#define environ _environ
#endif

#define	SLASH (EOS+1)		/* less than everything but EOS */

#if OPT_VMS_PATH
#define	KBD_FLAGS	KBD_NORMAL|KBD_UPPERC
#endif

#ifndef	KBD_FLAGS
#define	KBD_FLAGS	KBD_NORMAL
#endif

#ifndef FoundDirectory
# define FoundDirectory(path) is_directory(path)
#endif

static char **MyGlob;		/* expanded list */
static int in_glob;		/* index into MyGlob[] */
static int only_dir;		/* can only match real directories */

static void
free_expansion(void)
{
    MyGlob = glob_free(MyGlob);
    in_glob = -1;
}

#if COMPLETE_DIRS || COMPLETE_FILES

#include "dirstuff.h"

#if OPT_VMS_PATH
static void vms2hybrid(char *path);
#endif

/*--------------------------------------------------------------------------*/

/*
 * Test if the path has a trailing slash-delimiter (i.e., can be syntactically
 * distinguished from non-directory paths).
 */
static int
trailing_slash(const char *path)
{
    int len = strlen(path);
    if (len > 0) {
#if OPT_VMS_PATH
	if (is_vms_pathname(path, TRUE))
	    return TRUE;
#endif
	return (is_slashc(path[len - 1]));
    }
    return FALSE;
}

/*
 * Force a trailing slash on the end of the path, returns the length of the
 * resulting path.
 */
static size_t
force_slash(char *path)
{
    size_t len = strlen(path);

#if OPT_VMS_PATH
    if (!is_vms_pathname(path, -TRUE))	/* must be unix-style name */
#endif
	if (!trailing_slash(path)) {
	    path[len++] = SLASHC;
	    path[len] = EOS;
	}
    return len;
}

/*
 * Compare two paths lexically.
 */
static int
pathcmp(const LINE *lp, const char *text)
{
    const char *l, *t;
    int lc, tc;

    if (llength(lp) <= 0)	/* (This happens on the first insertion) */
	return -1;

    l = lp->l_text;
    t = text;
    for_ever {
	lc = *l++;
	tc = *t++;
#if OPT_CASELESS
	if (isUpper(lc))
	    lc = toLower(lc);
	if (isUpper(tc))
	    tc = toLower(tc);
#endif
	if (lc == tc) {
	    if (tc == EOS)
		return 0;
	} else {
	    if (is_slashc(lc)) {
		lc = (*l != EOS) ? SLASH : EOS;
	    }
	    if (is_slashc(tc)) {
		tc = (*t != EOS) ? SLASH : EOS;
	    }
	    return lc - tc;
	}
    }
}

/*
 * Insert a pathname at the given line-pointer.
 * Allocate up to three extra bytes for possible trailing slash, EOS, and
 * directory scan indicator.  The latter is only used when there is a trailing
 * slash.
 */
static LINE *
makeString(BUFFER *bp, LINE *lp, char *text, size_t len)
{
    LINE *np;
    int extra = (len != 0 && is_slashc(text[len - 1])) ? 2 : 3;

    beginDisplay();
    if ((np = lalloc((int) len + extra, bp)) == NULL) {
	lp = 0;
    } else {
#if !OPT_MSDOS_PATH
	/*
	 * If we are NOT processing MSDOS pathnames, we may have literal
	 * backslashes in the pathnames.  Escape those by doubling them.
	 */
	text = add_backslashes(text);
#endif
	(void) strcpy(np->l_text, text);
	np->l_text[len + extra - 1] = 0;	/* clear scan indicator */
	llength(np) -= extra;	/* hide the null and scan indicator */

	set_lforw(lback(lp), np);
	set_lback(np, lback(lp));
	set_lback(lp, np);
	set_lforw(np, lp);
	lp = np;
    }
    endofDisplay();
    return lp;
}

/*
 * Create a buffer to store null-terminated strings.
 *
 * The file (or directory) completion buffer is initialized at the beginning of
 * each command.  Wildcard expansion causes entries to be read for a given path
 * on demand.  Resetting the buffer in this fashion is a tradeoff between
 * efficiency (allows reuse of a pattern in NAMEC/TESTC operations) and speed
 * (directory scanning is slow).
 *
 * The tags buffer is initialized only once for a given tags-file.
 */
static BUFFER *
bs_init(const char *name)
{
    BUFFER *bp;

    if ((bp = bfind(name, BFINVS)) != 0) {
	b_clr_scratch(bp);	/* make it nonvolatile */
	(void) bclear(bp);
	bp->b_active = TRUE;
    }
    return bp;
}

/*
 * Look for or insert a pathname string into the given buffer.  Start looking
 * at the given line if non-null.  The pathname is expected to be in
 * canonical form.
 *
 * fname - pathname to find
 * len   - ...its length
 * bp    - buffer to search
 * lpp	 - in/out line pointer, for iteration 
 */
static int
bs_find(char *fname, size_t len, BUFFER *bp, LINE **lpp)
{
    LINE *lp;
    int doit = FALSE;
#if OPT_VMS_PATH
    char temp[NFILEN];
    if (!is_slashc(*fname))
	vms2hybrid(fname = strcpy(temp, fname));
#endif

    if (lpp == NULL || (lp = *lpp) == NULL)
	lp = buf_head(bp);
    lp = lforw(lp);

    for_ever {
	int r = pathcmp(lp, fname);

	if (r == 0) {
	    if (trailing_slash(fname)
		&& !trailing_slash(lp->l_text)) {
		/* reinsert so it is sorted properly! */
		lremove(bp, lp);
		return bs_find(fname, len, bp, lpp);
	    }
	    break;
	} else if (r > 0) {
	    doit = TRUE;
	    break;
	}

	lp = lforw(lp);
	if (lp == buf_head(bp)) {
	    doit = TRUE;
	    break;
	}
    }

    if (doit) {
	lp = makeString(bp, lp, fname, len);
	b_clr_counted(bp);
    }

    if (lpp)
	*lpp = lp;
    return TRUE;
}
#endif /* COMPLETE_DIRS || COMPLETE_FILES */

#if COMPLETE_DIRS || COMPLETE_FILES

static BUFFER *MyBuff;		/* the buffer containing pathnames */
static const char *MyName;	/* name of buffer for name-completion */

/*
 * Returns true if the string looks like an environment variable (i.e.,
 * a '$' followed by an optional name.
 */
static int
is_environ(const char *s)
{
    if (*s++ == '$') {
	while (*s != EOS) {
	    if (!isAlnum(*s) && (*s != '_'))
		return FALSE;
	    s++;
	}
	return TRUE;
    }
    return FALSE;
}

/*
 * Tests if the given path has been scanned during this prompt/reply operation
 *
 * If there is anything else in the list that we can do completion with, return
 * true.  This allows the case in which we scan a directory (for directory
 * completion and then look at the subdirectories.  It should not permit
 * directories which have already been scanned to be rescanned.
 */
static int
already_scanned(BUFFER *bp, char *path)
{
    LINE *lp;
    size_t len;
    char fname[NFILEN];
    LINE *slp;

    len = force_slash(strcpy(fname, path));

    for_each_line(lp, bp) {
#if OPT_CASELESS
	if (stricmp(fname, lp->l_text) == 0)
#else
	if (strcmp(fname, lp->l_text) == 0)
#endif
	{
	    if (lp->l_text[llength(lp) + 1])
		return TRUE;
	    else
		break;		/* name should not occur more than once */
	}
    }

    /* force the name in with a trailing slash */
    slp = buf_head(bp);
    (void) bs_find(fname, len, bp, &slp);

    /*
     * mark name as scanned (since that is what we're about to do after
     * returning)
     */
    lp = slp;
    lp->l_text[llength(lp) + 1] = 1;
    return FALSE;
}

#if USE_DOTNAMES
/*
 * Before canonicalizing a pathname, check for a leaf consisting of trailing
 * dots.  Convert this to another form so that it won't be combined with
 * other leaves.  We do this because we don't want to prevent the user from
 * doing filename completion with leaves that begin with dots.
 */
static void
mask_dots(char *path, size_t *dots)
{
    char *leaf = pathleaf(path);
    if (isDotname(leaf)) {
	*dots = strlen(leaf);
	memset(leaf, '?', *dots);
    } else
	*dots = 0;
}

/*
 * Restore the leaf to its original form.
 */
static void
add_dots(char *path, size_t dots)
{
    if (dots != 0) {
	memset(pathleaf(path), '.', dots);
    }
}

static void
strip_dots(char *path, size_t *dots)
{
    char *leaf = pathleaf(path);
    if (isDotname(leaf)) {
	*dots = strlen(leaf);
	*leaf = EOS;
    }
}
#define if_dots(path, dots) if (!strncmp(path, "..", dots))
#else
#define mask_dots(path, dots)	/* nothing */
#define add_dots(path, dots)	/* nothing */
#define strip_dots(path, dots)	/* nothing */
#define if_dots(path, dots)	/* nothing */
#endif /* USE_DOTNAMES */

#if OPT_VMS_PATH
/*
 * Convert a canonical VMS pathname to a hybrid form, in which the leaf (e.g.,
 * "name.type;ver") is left untouched, but the directory portion is in UNIX
 * form.  This alleviates a sticky problem with VMS's pathname delimiters by
 * making them all '/' characters.
 */
static void
vms2hybrid(char *path)
{
    char leaf[NFILEN];
    char head[NFILEN];
    char *s = strcpy(head, path);
    char *t;

    TRACE(("vms2hybrid '%s'\n", path));
    (void) strcpy(leaf, s = pathleaf(head));
    if ((t = is_vms_dirtype(leaf)) != 0)
	(void) strcpy(t, "/");
    *s = EOS;
    if (s == path)		/* a non-canonical name got here somehow */
	(void) strcpy(head, current_directory(FALSE));
    pathcat(path, mkupper(vms2unix_path(head, head)), leaf);
    TRACE((" -> '%s' (vms2hybrid)\n", path));
}

static void
hybrid2vms(char *path)
{
    char leaf[NFILEN];
    char head[NFILEN];
    char *s = strcpy(head, path);

    TRACE(("hybrid2vms '%s'\n", path));
    (void) strcpy(leaf, s = pathleaf(head));
    *s = EOS;
    if (s == head)		/* a non-canonical name got here somehow */
	(void) vms2unix_path(head, current_directory(FALSE));
    (void) pathcat(path, head, leaf);
    if (isDotname(leaf)) {
	force_slash(path);	/* ...so we'll interpret as directory */
	lengthen_path(path);	/* ...makes VMS-style absolute-path */
    } else {
	unix2vms_path(path, path);
    }
    TRACE((" -> '%s' hybrid2vms\n", path));
}

static void
hybrid2unix(char *path)
{
    char leaf[NFILEN];
    char head[NFILEN];
    char *s = strcpy(head, path);

    TRACE(("hybrid2unix '%s'\n", path));
    (void) strcpy(leaf, s = pathleaf(head));
    *s = EOS;
    if (s == path)		/* a non-canonical name got here somehow */
	(void) vms2unix_path(head, current_directory(FALSE));
    pathcat(path, head, leaf);

    /* The semicolon that indicates the version is a little tricky.  When
     * simulating via fakevms.c on UNIX, we've got to trim the version
     * marker at this point.  Otherwise, it'll be changed to a dollar sign
     * the next time the string is converted from UNIX to VMS form.  A
     * side-effect is that the name-completion echos (for UNIX only!) the
     * version, but doesn't store it in the buffer returned to the caller.
     */
    if ((s = strrchr(path, ';')) != 0) {
#if SYS_UNIX
	*s = EOS;		/* ...we're only simulating */
#else
	*s = '.';		/* this'll be interpreted as version-mark */
#endif
    }
    TRACE((" -> '%s' hybrid2unix\n", path));
}
#endif /* OPT_VMS_PATH */

#if USE_QSORT
/*
 * Compare two lines (containing paths) for quicksort by calling pathcmp().
 * If the paths compare equal force the one with the trailing slash to be
 * less than.  This'll make deleting the ones without slashes easier in
 * sortMyBuff().
 */
static int
qs_pathcmp(const void *lpp1, const void *lpp2)
{
    const LINE *lp1 = *(const LINE *const *) lpp1;
    int r = pathcmp(lp1, (*(const LINE *const *) lpp2)->l_text);

    if (r == 0) {
	if (llength(lp1) > 0 && is_slashc(lgetc(lp1, llength(lp1) - 1)))
	    return -1;
	else			/* Don't care if the other one has slash or not... */
	    return 1;		/* ...returning 1 for two equal elements won't do  */
	/* any harm. */
    } else
	return r;
}

static void
remove_duplicates(BUFFER *bp)
{
    LINE *plp = lforw(buf_head(bp));
    LINE *lp;

    while (plp != buf_head(bp)) {
	if ((lp = lforw(plp)) != buf_head(bp)) {
	    if (pathcmp(plp, lp->l_text) == 0) {
		lremove(bp, lp);
		lfree(lp, bp);
		continue;
	    }
	}
	plp = lforw(plp);
    }
}

static void
sortMyBuff(BUFFER *bp)
{
    L_NUM n;
    LINE **sortvec;
    LINE *lp, *plp;
    LINE **slp;

    b_clr_counted(bp);
    if ((n = vl_line_count(bp)) > 0) {
	beginDisplay();
	if ((sortvec = typecallocn(LINE *, (size_t) n)) != NULL) {
	    slp = sortvec;
	    for_each_line(lp, bp) {
		*slp++ = lp;
	    }
	    qsort((char *) sortvec, (size_t) n, sizeof(LINE *), qs_pathcmp);

	    plp = buf_head(bp);
	    slp = sortvec;
	    while (n-- > 0) {
		lp = *slp++;
		set_lforw(plp, lp);
		set_lback(lp, plp);
		plp = lp;
	    }
	    lp = buf_head(bp);
	    set_lforw(plp, lp);
	    set_lback(lp, plp);
	    remove_duplicates(bp);
	    b_clr_counted(bp);

	    free(sortvec);
	}
	endofDisplay();
    }
}
#endif /* USE_QSORT */

int
fill_directory_buffer(BUFFER *bp, char *path, int dots GCC_UNUSED)
{
    int count = 0;
    char *s;
#if SYS_OS2
    FILEFINDBUF3 fb;
    ULONG entries;
    HDIR hdir;
    APIRET rc;
    int case_preserving = is_case_preserving(path);
#else /* UNIX, VMS or MSDOS */
    char *leaf;
    DIR *dp;
    DIRENT *de;
#endif
    char temp[NFILEN];

    path = strcpy(temp, path);

    TRACE(("fill_directory_buffer '%s'\n", path));

#if SYS_OS2
    s = path + force_slash(path);
    (void) strcat(path, "*.*");

    hdir = HDIR_CREATE;
    entries = 1;
    rc = DosFindFirst(SL_TO_BSL(path), &hdir,
		      FILE_DIRECTORY | FILE_READONLY,
		      &fb, sizeof(fb), &entries, FIL_STANDARD);
    if (rc == NO_ERROR) {
	do {
	    (void) strcpy(s, fb.achName);
	    if (!case_preserving)
		(void) mklower(s);

	    if (isDotname(s))
		continue;

	    if (only_dir) {
		if (!FoundDirectory(path))
		    continue;
		(void) force_slash(path);
	    }
#if COMPLETE_DIRS
	    else {
		if (global_g_val(GMDDIRC) && FoundDirectory(path))
		    (void) force_slash(path);
	    }
#endif
	    TRACE(("> '%s'\n", path));
	    if_dots(s, dots) count++;
	    (void) bs_find(path, strlen(path), bp, (LINE **) 0);

	} while (entries = 1,
		 DosFindNext(hdir, &fb, sizeof(fb), &entries) == NO_ERROR
		 && entries == 1);

	DosFindClose(hdir);
    }
#else /* UNIX, VMS or MSDOS */
    /* For MS-DOS pathnames, force the use of '\' instead of '/' in the
     * open-directory operation to allow for runtime libraries that
     * don't allow using UNIX-style '/' pathnames.
     */
    if ((dp = opendir(SL_TO_BSL(path))) != 0) {
	s = path;
#if !OPT_VMS_PATH
	s += force_slash(path);
#endif

	leaf = s;
	while ((de = readdir(dp)) != 0) {
#if SYS_UNIX || SYS_VMS || SYS_WINNT
# if USE_D_NAMLEN
	    (void) strncpy(leaf, de->d_name, (size_t) (de->d_namlen));
	    leaf[de->d_namlen] = EOS;
# else
	    (void) strcpy(leaf, de->d_name);
# endif
#else
# if SYS_MSDOS
	    (void) mklower(strcpy(leaf, de->d_name));
# else
	    problem with ifdef;
# endif
#endif
#if OPT_VMS_PATH
	    vms_dir2path(path);
#else
# if SYS_UNIX || SYS_MSDOS || SYS_OS2 || SYS_WINNT
	    if (isDotname(leaf))
		continue;
# endif
#endif
	    if (only_dir) {
		if (!FoundDirectory(path))
		    continue;
		(void) force_slash(path);
	    }
#if COMPLETE_DIRS
	    else {
		if (global_g_val(GMDDIRC) && FoundDirectory(path))
		    (void) force_slash(path);
	    }
#endif
	    TRACE(("> '%s'\n", path));
	    if_dots(leaf, dots) count++;
#if USE_QSORT
#if OPT_VMS_PATH
	    if (temp != path)
		strcpy(temp, path);
	    vms2hybrid(s = temp);
#else
	    s = path;
#endif
	    (void) makeString(bp, buf_head(bp), s, strlen(s));
#else /* !USE_QSORT */
	    (void) bs_find(path, strlen(path), bp, (LINE **) 0);
#endif /* USE_QSORT/!USE_QSORT */
	}
	(void) closedir(dp);
#if USE_QSORT
	sortMyBuff(bp);
#endif
    }
#endif /* SYS_OS2/!SYS_OS2 */
    TRACE(("...fill_directory_buffer returns %d\n", count));
    return count;
}

/*
 * If the given path is not in the completion-buffer, expand it, and add the
 * expanded paths to the buffer.  Because the user may be trying to get an
 * intermediate directory-name, we must 'stat()' each name, so that we can
 * provide the trailing slash in the completion.  This is slow.
 */
static int
fillMyBuff(BUFFER *bp, char *name)
{
    size_t dots = 0;
    int count = 0;
    int trim_leaf = FALSE;
    char *s;
    char path[NFILEN + 2];
    char temp[NFILEN + 2];

    TRACE(("fillMyBuff '%s'\n", name));

	/**********************************************************************/
    if (is_environ(name)) {
	LINE *lp;
	int n;
	size_t len = strlen(name) - 1;

	/*
	 * If an environment variable happens to evaluate to a
	 * directory name, this chunk of logic returns a '1' to tell
	 * our caller that it's time to add a slash.
	 */
	for (n = 0; (s = environ[n]) != 0; n++) {
	    if (!strncmp(s, name + 1, len)
		&& s[len] == '=') {
		return already_scanned(bp, name) ? 1 : 0;
	    }
	}

	/*
	 * The presence of any environment variable in the list is
	 * sufficient indication that we've copied the environment.
	 */
	for_each_line(lp, bp) {
	    if (is_environ(lp->l_text))
		return 0;
	}

	/*
	 * Copy all of the environment-variable names, prefixed with
	 * the '$' that indicates what they are.
	 */
	for (n = 0; environ[n] != 0; n++) {
	    char *d = path;

	    s = environ[n];
	    *d++ = name[0];
	    while (((*d = *s++) != '=') && (*d != EOS)) {
		if ((size_t) (d++ - path) > sizeof(path) - 2)
		    break;
	    }
	    *d = EOS;
#if SYS_MSDOS || SYS_OS2
	    mklower(path);	/* glob.c will uppercase for getenv */
#endif
#if USE_QSORT
	    (void) makeString(bp, buf_head(bp), path, strlen(path));
#else /* !USE_QSORT */
	    (void) bs_find(path, strlen(path), bp, (LINE **) 0);
#endif /* USE_QSORT/!USE_QSORT */
	    TRACE(("> '%s'\n", path));
	}
#if USE_QSORT
	sortMyBuff(bp);
#endif
    } else {
	(void) strcpy(path, name);
#if OPT_MSDOS_PATH
	bsl_to_sl_inplace(path);
#endif
#if OPT_VMS_PATH
	hybrid2vms(path);	/* convert to canonical VMS name */
#else
	strip_dots(path, &dots);	/* ignore trailing /. or /.. */
#endif
	if (!is_environ(path) && !is_directory(path)) {
	    trim_leaf = TRUE;
	    *pathleaf(path) = EOS;
	    if (!is_directory(path))
		return 1;
	}
#if OPT_VMS_PATH
	(void) strcpy(temp, name);	/* will match the hybrid name */
	if (trim_leaf)
	    *pathleaf(temp) = EOS;
#else
	(void) strcpy(temp, path);
#endif

	if (already_scanned(bp, temp)) {
#if OPT_VMS_PATH
	    count = 1;
#else
#if USE_DOTNAMES
	    /*
	     * Handle the special cases where we're continuing a completion
	     * with ".." on the end of the path.  We have to distinguish
	     * the return value so that we can drive a second scan for the
	     * case where there's no dot-names found.
	     */
	    if (dots) {
		LINE *lp;
		size_t need, want;

		while (dots--)
		    strcat(path, ".");
		(void) lengthen_path(strcpy(temp, path));
		need = strlen(temp);
		want = strlen(path);
		for_each_line(lp, bp) {
		    size_t have = llength(lp);
		    if (have == need
			&& !memcmp(lp->l_text, temp, need))
			count = -1;
		    else if (have >= want
			     && !memcmp(lp->l_text, path, want)) {
			count = 1;
			break;
		    }
		}
	    }
#endif
#endif
	} else {
	    count = fill_directory_buffer(bp, path, dots);
	}
    }

    TRACE(("...fillMyBuff returns %d\n", count));
    return count;
}

/*
 * Make the list of names needed for name-completion
 */
static void
makeMyList(BUFFER *bp, char *name)
{
    size_t need;
    int n;
    LINE *lp;
    char *slashocc;
    int len = strlen(name);

    beginDisplay();
    if (is_slashc(name[len - 1]))
	len++;

    (void) bsizes(bp);
    need = bp->b_linecount + 2;
    if (bp->b_index_size < need) {
	bp->b_index_size = need * 2;
	if (bp->b_index_list == 0)
	    bp->b_index_list = typeallocn(char *, bp->b_index_size);
	else
	    bp->b_index_list = typereallocn(char *, bp->b_index_list, bp->b_index_size);
    }

    if (bp->b_index_list != 0) {
	n = 0;
	for_each_line(lp, bp) {
	    /* exclude listings of subdirectories below
	       current directory */
	    if (llength(lp) >= len
		&& ((slashocc = strchr(lp->l_text + len, SLASHC)) == NULL
		    || slashocc[1] == EOS))
		bp->b_index_list[n++] = lp->l_text;
	}
	bp->b_index_list[n] = 0;
    } else {
	bp->b_index_size = 0;
    }
    endofDisplay();
}

#if NO_LEAKS
static void
freeMyList(BUFFER *bp)
{
    if (valid_buffer(bp)) {
	beginDisplay();
	FreeAndNull(bp->b_index_list);
	bp->b_index_size = 0;
	endofDisplay();
    }
}

#else
#define	freeMyList(bp)		/* nothing */
#endif

static void
force_output(int c, char *buf, unsigned *pos)
{
    kbd_putc(c);
    term.flush();
    buf[*pos] = (char) c;
    *pos += 1;
    buf[*pos] = EOS;
}

/*
 * Initialize the file-completion module.  We'll only do either file- or
 * directory-completion during any given command, and they use different
 * buffers (and slightly different parsing).
 */
void
init_filec(const char *buffer_name)
{
    MyBuff = 0;
    MyName = buffer_name;
}

/*
 * Perform the name-completion/display.  Note that we must convert a copy of
 * the pathname to absolute form so that we can match against the strings that
 * are stored in the completion table.  However, the characters that might be
 * added are always applicable to the original buffer.
 *
 * We only do name-completion if asked; if we did it when the user typed a
 * return it would be too slow.
 */
int
path_completion(DONE_ARGS)
{
    int code = FALSE;
    int action = (c == NAMEC || c == TESTC);
    int ignore;
#if USE_DOTNAMES
    size_t dots = 0;
    int count;
#endif

    TRACE(("path_completion(%#x '%c' %d:\"%s\")\n",
	   flags, c, *pos, visible_buff(buf, (int) *pos, TRUE)));
    (void) flags;

    if (buf == 0)
	return FALSE;

    ignore = (*buf != EOS && isInternalName(buf));
#if OPT_VMS_PATH
    if (ignore && action) {	/* resolve scratch-name conflict */
	if (is_vms_pathname(buf, -TRUE))
	    ignore = FALSE;
    }
#endif
    if (ignore) {
	if (action) {		/* completion-chars have no meaning */
	    force_output(c, buf, pos);
	}
    } else if (action) {
	char *s;
	char path[NFILEN];
	unsigned oldlen;
	unsigned newlen;

	/* initialize only on demand */
	if (MyBuff == 0) {
	    if (MyName == 0
		|| (MyBuff = bs_init(MyName)) == 0)
		return FALSE;
	}

	/*
	 * Copy 'buf' into 'path', making it canonical-form.
	 */
#if OPT_VMS_PATH
	if (*strcpy(path, buf) == EOS) {
	    (void) strcpy(path, current_directory(FALSE));
	} else if (!is_environ(path)) {
	    char frac[NFILEN];

	    if (is_vms_pathname(path, -TRUE)) {
		s = vms_pathleaf(path);
		(void) strcpy(frac, s);
		*s = EOS;
	    } else {
		s = pathleaf(path);
		if (strcmp(s, ".")
		    && is_vms_pathname(s, -TRUE)) {
		    (void) strcpy(frac, s);
		    *s = EOS;
		} else {	/* e.g., path=".." */
		    *frac = EOS;
		}
	    }
	    if (*path == EOS)
		(void) strcpy(path, current_directory(FALSE));
	    else {
		if (!is_vms_pathname(path, -TRUE)) {
		    unix2vms_path(path, path);
		    if (*path == EOS)
			(void) strcpy(path, current_directory(FALSE));
		}
		(void) lengthen_path(path);
	    }
	    (void) strcat(path, frac);
	}
	if (is_vms_pathname(path, -TRUE)) {
	    int pad = is_vms_pathname(path, TRUE);

	    vms2hybrid(path);
	    /*
	     * FIXME: This compensates for the hack in canonpath
	     */
	    if (!strcmp(buf, "/")) {
		while ((size_t) *pos < strlen(path))
		    force_output(path[*pos], buf, pos);
	    } else if (pad && *buf != EOS && !trailing_slash(buf)) {
		force_output(SLASHC, buf, pos);
	    }
	}
#else
	if (is_environ(buf)) {
	    (void) strcpy(path, buf);
	} else {
# if SYS_UNIX || OPT_MSDOS_PATH
	    char **expand;

	    /*
	     * Expand _unique_ wildcards and environment variables.
	     * Like 'doglob()', but without the prompt.
	     */
	    expand = glob_string(strcpy(path, buf));
	    switch (glob_length(expand)) {
	    default:
		(void) glob_free(expand);
		kbd_alarm();
		return FALSE;
	    case 1:
		(void) strcpy(path, expand[0]);
		/*FALLTHRU */
	    case 0:
		(void) glob_free(expand);
		break;
	    }
	    mask_dots(path, &dots);
	    (void) lengthen_path(path);
	    add_dots(path, dots);
#  if OPT_MSDOS_PATH
	    /*
	     * Pick up slash (special case) when we've just expanded a
	     * device such as "c:" to "c:/".
	     */
	    if ((newlen = strlen(path)) == 3
		&& (oldlen = strlen(buf)) == 2
		&& is_slashc(path[newlen - 1])
		&& path[newlen - 2] == ':') {
		force_output(SLASHC, buf, pos);
	    }
#  endif
# endif
	}
#endif

	if ((s = is_appendname(buf)) == 0)
	    s = buf;
	if ((*s == EOS) || trailing_slash(s)) {
	    if (*path == EOS)
		(void) strcpy(path, ".");
	    (void) force_slash(path);
	}

	if ((s = is_appendname(path)) != NULL) {
	    char *d;
	    for (d = path; (*d++ = *s++) != EOS;) {
		/* EMPTY */ ;
	    }
	}
#if OPT_MSDOS_PATH
	/* if the user typed a back-slash, we need to
	 * convert it, since it's stored as '/' in the file
	 * completion buffer to avoid conflicts with the use of
	 * backslash for escaping special characters.
	 */
	bsl_to_sl_inplace(path);
#endif

	newlen =
	    oldlen = strlen(path);

#if USE_DOTNAMES
	/*
	 * If we're on a filesystem that allows names beginning with
	 * ".", try to handle the ambiguity between .name and ./ by
	 * preferring matches on the former.  If we get a zero return
	 * from the first scan, it means that we've only the latter
	 * case to consider.
	 */
	count = fillMyBuff(MyBuff, path);
	if (dots == 2) {
	    if (count == 0) {
		force_slash(path);
		lengthen_path(path);
		newlen =
		    oldlen = strlen(path);
		(void) fillMyBuff(MyBuff, path);
	    } else if (count < 0) {
		lengthen_path(path);
		newlen =
		    oldlen = strlen(path);
	    }
	} else if (dots == 1) {
	    if (count == 0) {
		lengthen_path(path);
		newlen =
		    oldlen = strlen(path);
	    }
	}
#else
	(void) fillMyBuff(MyBuff, path);
#endif
	makeMyList(MyBuff, path);

	/* FIXME: should also force-dot to the matched line, as in history.c */
	/* FIXME: how can I force buffer-update to show? */

#if OPT_CASELESS
	code = kbd_complete(KBD_CASELESS, c, path, &newlen,
			    (const char *) &MyBuff->b_index_list[0],
			    sizeof(MyBuff->b_index_list[0]));
#if 0				/* case insensitive reply correction doesn't work reliably yet */
	(void) strcpy(buf, path);
#else
	(void) strcat(buf, path + oldlen);
#endif
#else
	code = kbd_complete(0, c, path, &newlen,
			    (const char *) &MyBuff->b_index_list[0],
			    sizeof(MyBuff->b_index_list[0]));
	(void) strcat(buf, path + oldlen);
#endif
#if OPT_VMS_PATH
	if (*buf != EOS
	    && !is_vms_pathname(buf, -TRUE))
	    hybrid2unix(buf);
#endif
	*pos = strlen(buf);

	/* avoid accidentally picking up directory names for files */
	if ((code == TRUE)
	    && !only_dir
	    && !trailing_slash(path)
	    && is_directory(path)) {
	    force_output(SLASHC, buf, pos);
	    code = FALSE;
	}
    }
    TRACE((" -> '%s' path_completion\n", buf));
    return code;
}
#else /* no filename-completion */
#define	freeMyList(bp)		/* nothing */
#endif /* filename-completion */

/******************************************************************************/

#ifdef GMDWARNBLANKS
static int
has_non_graphics(char *path)
{
    int ch;

    while ((ch = *path++) != EOS) {
	if (isSpace(ch) || !isPrint(ch))
	    return TRUE;
    }
    return FALSE;
}

static int
strip_non_graphics(char *path)
{
    char *t = path;
    int ch;
    int rc = FALSE;

    while ((ch = *path++) != EOS) {
	if (!isSpace(ch) && isPrint(ch)) {
	    *t++ = (char) ch;
	    rc = TRUE;
	}
    }
    *t = 0;
    return rc;
}
#endif

/******************************************************************************/

/*
 * Prompt for a file name, allowing completion via tab and '?'
 * 
 * flag - +1 to read, -1 to write, 0 don't care
 */
int
mlreply_file(const char *prompt, TBUFF **buffer, UINT flag, char *result)
{
    int status;
    static TBUFF *last;
    char Reply[NFILEN];
    int (*complete) (DONE_ARGS) = no_completion;
    int had_fname = (valid_buffer(curbp)
		     && curbp->b_fname != 0
		     && curbp->b_fname[0] != EOS);
    int do_prompt = (clexec || isnamedcmd || (flag & FILEC_PROMPT));
    int ok_expand = (flag & FILEC_EXPAND);

    flag &= ~(FILEC_PROMPT | FILEC_EXPAND);

#if COMPLETE_FILES
    if (do_prompt && !clexec) {
	complete = shell_complete;
	init_filec(FILECOMPLETION_BufName);
    }
#endif

    /* use the current filename if none given */
    if (buffer == 0) {
	(void) tb_scopy(buffer = &last,
			had_fname && is_pathname(curbp->b_fname)
			? shorten_path(strcpy(Reply, curbp->b_fname),
				       FALSE)
			: "");
    }

    if (do_prompt) {
	char *t1 = tb_values(*buffer);
	char *t2 = is_appendname(t1);

	if (t1 != 0)
	    (void) strcpy(Reply, (t2 != 0) ? t2 : t1);
	else
	    *Reply = EOS;

	status = kbd_string(prompt, Reply, sizeof(Reply),
			    '\n', KBD_FLAGS | KBD_MAYBEC, complete);
	freeMyList(MyBuff);

	if (status == ABORT)
	    return status;
	if (status != TRUE) {
	    if ((flag == FILEC_REREAD)
		&& had_fname
		&& (!global_g_val(GMDWARNREREAD)
		    || ((status = mlyesno("Reread current buffer")) == TRUE)))
		(void) strcpy(Reply, curbp->b_fname);
	    else
		return status;
	} else if (kbd_is_pushed_back() && isShellOrPipe(Reply)) {
	    /*
	     * The first call on 'kbd_string()' split the text off
	     * the shell command.  This is needed for the logic of
	     * colon-commands, but is inappropriate for filename
	     * prompting.  Read the rest of the text into Reply.
	     */
	    status = kbd_string(prompt, Reply, sizeof(Reply),
				'\n', KBD_FLAGS | KBD_MAYBEC, complete);
	}
	/*
	 * Not everyone expects to be able to write files whose names
	 * have embedded (or leading/trailing) blanks.
	 */
#ifdef GMDWARNBLANKS
	if (status == TRUE
	    && global_g_val(GMDWARNBLANKS)
	    && has_non_graphics(Reply)) {
	    if ((status = mlyesno("Strip nonprinting chars?")) == TRUE)
		status = strip_non_graphics(Reply);
	}
	if (status != TRUE)
	    return status;
#endif
    } else if (!screen_to_bname(Reply)) {
	return FALSE;
    }
    if (flag >= FILEC_UNKNOWN && is_appendname(Reply) != 0) {
	mlforce("[file is not a legal input]");
	return FALSE;
    }

    free_expansion();
    if (ok_expand) {
	if ((MyGlob = glob_string(Reply)) == 0
	    || (status = glob_length(MyGlob)) == 0) {
	    mlforce("[No files found] %s", Reply);
	    return FALSE;
	}
	if (status > 1) {
	    char tmp[80];
	    (void) lsprintf(tmp, "Will create %d buffers. Okay", status);
	    status = mlyesno(tmp);
	    mlerase();
	    if (status != TRUE)
		return status;
	}
    } else if (doglob(Reply) != TRUE) {
	return FALSE;
    }

    (void) strcpy(result, Reply);
    if (flag <= FILEC_WRITE) {	/* we want to write a file */
	if (!isInternalName(Reply)
	    && !same_fname(Reply, curbp, TRUE)
	    && cfg_locate(Reply, FL_CDIR | FL_READABLE)) {
	    if (mlyesno("File exists, okay to overwrite") != TRUE) {
		mlwrite("File not written");
		return FALSE;
	    }
	}
    }

    (void) tb_scopy(buffer, Reply);
    return TRUE;
}

/******************************************************************************/

/*
 * Prompt for a directory name, allowing completion via tab and '?'
 */
int
mlreply_dir(const char *prompt, TBUFF **buffer, char *result)
{
    int status;
    static TBUFF *last;
    char Reply[NFILEN];
    int (*complete) (DONE_ARGS) = no_completion;

#if COMPLETE_DIRS
    if (isnamedcmd && !clexec) {
	complete = path_completion;
	init_filec(DIRCOMPLETION_BufName);
    }
#endif
    /* use the current directory if none given */
    if (buffer == 0) {
	(void) tb_scopy(buffer = &last,
			strcpy(Reply, current_directory(TRUE)));
    }

    if (clexec || isnamedcmd) {
	if (tb_values(*buffer) != 0)
	    (void) strcpy(Reply, tb_values(*buffer));
	else
	    *Reply = EOS;

	only_dir = TRUE;
	status = kbd_string(prompt, Reply, sizeof(Reply), '\n',
			    KBD_FLAGS | KBD_MAYBEC, complete);
	freeMyList(MyBuff);
	only_dir = FALSE;
	if (status != TRUE)
	    return status;

    } else if (!screen_to_bname(Reply)) {
	return FALSE;
    }

    (void) tb_scopy(buffer, strcpy(result, Reply));
    return TRUE;
}

/******************************************************************************/

/*
 * This is called after 'mlreply_file()' to iterate over the list of files
 * that are matched by a glob-expansion.
 */
char *
filec_expand(void)
{
    if (MyGlob != 0) {
	if (MyGlob[++in_glob] != 0)
	    return MyGlob[in_glob];
	free_expansion();
    }
    return 0;
}