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you keep saying LIST_END. I do not think it means what you think it
means.

If we hit an OOM condition, mg started to try and dump the older undo buffer
entries in order to be able to continue. OTOH, it was grabbing this entry with
LIST_END, which like all *_END() list macros evaluates to NULL.

Do what we actually want and switch that list to a TAILQ and use
TAILQ_LAST to grab the last entry.

Wrote this a loooooong time ago after a mail from Matthew Dempsky on
bugs@. ok kjell@, beck@ also looked at this months ago and thought it
was alright.

/*	$OpenBSD: buffer.c,v 1.74 2010/06/30 19:12:54 oga Exp $	*/

/* This file is in the public domain. */

/*
 *		Buffer handling.
 */

#include <libgen.h>
#include <stdarg.h>

#include "def.h"
#include "kbd.h"		/* needed for modes */

static struct buffer  *makelist(void);
static struct buffer *bnew(const char *);

/* Flag for global working dir */
extern int globalwd;

/* ARGSUSED */
int
togglereadonly(int f, int n)
{
	int s;

	if ((s = checkdirty(curbp)) != TRUE)
		return (s);
	if (!(curbp->b_flag & BFREADONLY))
		curbp->b_flag |= BFREADONLY;
	else {
		curbp->b_flag &= ~BFREADONLY;
		if (curbp->b_flag & BFCHG)
			ewprintf("Warning: Buffer was modified");
	}
	curwp->w_rflag |= WFMODE;

	return (TRUE);
}

/* Switch to the named buffer.
 * If no name supplied, switch to the default (alternate) buffer.
 */
int
usebufname(const char *bufp)
{
	struct buffer *bp;

	if (bufp == NULL)
		return (ABORT);
	if (bufp[0] == '\0' && curbp->b_altb != NULL)
		bp = curbp->b_altb;
	else if ((bp = bfind(bufp, TRUE)) == NULL)
		return (FALSE);

	/* and put it in current window */
	curbp = bp;
	return (showbuffer(bp, curwp, WFFRAME | WFFULL));
}

/*
 * Attach a buffer to a window. The values of dot and mark come
 * from the buffer if the use count is 0. Otherwise, they come
 * from some other window.  *scratch* is the default alternate
 * buffer.
 */
/* ARGSUSED */
int
usebuffer(int f, int n)
{
	char    bufn[NBUFN], *bufp;

	/* Get buffer to use from user */
	if ((curbp->b_altb == NULL) &&
	    ((curbp->b_altb = bfind("*scratch*", TRUE)) == NULL))
		bufp = eread("Switch to buffer: ", bufn, NBUFN, EFNEW | EFBUF);
	else
		bufp = eread("Switch to buffer: (default %s) ", bufn, NBUFN,
		    EFNUL | EFNEW | EFBUF, curbp->b_altb->b_bname);

	return (usebufname(bufp));
}

/*
 * pop to buffer asked for by the user.
 */
/* ARGSUSED */
int
poptobuffer(int f, int n)
{
	struct buffer *bp;
	struct mgwin  *wp;
	char    bufn[NBUFN], *bufp;

	/* Get buffer to use from user */
	if ((curbp->b_altb == NULL) &&
	    ((curbp->b_altb = bfind("*scratch*", TRUE)) == NULL))
		bufp = eread("Switch to buffer in other window: ", bufn, NBUFN,
		    EFNEW | EFBUF);
	else
		bufp = eread("Switch to buffer in other window: (default %s) ",
		    bufn, NBUFN, EFNUL | EFNEW | EFBUF, curbp->b_altb->b_bname);
	if (bufp == NULL)
		return (ABORT);
	if (bufp[0] == '\0' && curbp->b_altb != NULL)
		bp = curbp->b_altb;
	else if ((bp = bfind(bufn, TRUE)) == NULL)
		return (FALSE);
	if (bp == curbp)
		return (splitwind(f, n));
	/* and put it in a new, non-ephemeral window */
	if ((wp = popbuf(bp, WNONE)) == NULL)
		return (FALSE);
	curbp = bp;
	curwp = wp;
	return (TRUE);
}

/*
 * Dispose of a buffer, by name.
 * Ask for the name. Look it up (don't get too
 * upset if it isn't there at all!). Clear the buffer (ask
 * if the buffer has been changed). Then free the header
 * line and the buffer header. Bound to "C-X k".
 */
/* ARGSUSED */
int
killbuffer_cmd(int f, int n)
{
	struct buffer *bp;
	char    bufn[NBUFN], *bufp;

	if ((bufp = eread("Kill buffer: (default %s) ", bufn, NBUFN,
	    EFNUL | EFNEW | EFBUF, curbp->b_bname)) == NULL)
		return (ABORT);
	else if (bufp[0] == '\0')
		bp = curbp;
	else if ((bp = bfind(bufn, FALSE)) == NULL)
		return (FALSE);
	return (killbuffer(bp));
}

int
killbuffer(struct buffer *bp)
{
	struct buffer *bp1;
	struct buffer *bp2;
	struct mgwin  *wp;
	int s;
	struct undo_rec *rec, *next;

	/*
	 * Find some other buffer to display. Try the alternate buffer,
	 * then the first different buffer in the buffer list.  If there's
	 * only one buffer, create buffer *scratch* and make it the alternate
	 * buffer.  Return if *scratch* is only buffer...
	 */
	if ((bp1 = bp->b_altb) == NULL) {
		bp1 = (bp == bheadp) ? bp->b_bufp : bheadp;
		if (bp1 == NULL) {
			/* only one buffer. see if it's *scratch* */
			if (bp == bfind("*scratch*", FALSE))
				return (TRUE);
			/* create *scratch* for alternate buffer */
			if ((bp1 = bfind("*scratch*", TRUE)) == NULL)
				return (FALSE);
		}
	}
	if ((s = bclear(bp)) != TRUE)
		return (s);
	for (wp = wheadp; bp->b_nwnd > 0; wp = wp->w_wndp) {
		if (wp->w_bufp == bp) {
			bp2 = bp1->b_altb;	/* save alternate buffer */
			if (showbuffer(bp1, wp, WFMODE | WFFRAME | WFFULL))
				bp1->b_altb = bp2;
			else
				bp1 = bp2;
		}
	}
	if (bp == curbp)
		curbp = bp1;
	free(bp->b_headp);			/* Release header line.  */
	bp2 = NULL;				/* Find the header.	 */
	bp1 = bheadp;
	while (bp1 != bp) {
		if (bp1->b_altb == bp)
			bp1->b_altb = (bp->b_altb == bp1) ? NULL : bp->b_altb;
		bp2 = bp1;
		bp1 = bp1->b_bufp;
	}
	bp1 = bp1->b_bufp;			/* Next one in chain.	 */
	if (bp2 == NULL)			/* Unlink it.		 */
		bheadp = bp1;
	else
		bp2->b_bufp = bp1;
	while (bp1 != NULL) {			/* Finish with altb's	 */
		if (bp1->b_altb == bp)
			bp1->b_altb = (bp->b_altb == bp1) ? NULL : bp->b_altb;
		bp1 = bp1->b_bufp;
	}
	rec = TAILQ_FIRST(&bp->b_undo);

	while (rec != NULL) {
		next = TAILQ_NEXT(rec, next);
		free_undo_record(rec);
		rec = next;
	}

	free(bp->b_bname);			/* Release name block	 */
	free(bp);				/* Release buffer block */
	return (TRUE);
}

/*
 * Save some buffers - just call anycb with the arg flag.
 */
/* ARGSUSED */
int
savebuffers(int f, int n)
{
	if (anycb(f) == ABORT)
		return (ABORT);
	return (TRUE);
}

/*
 * Listing buffers.
 */
static int listbuf_ncol;

static int	listbuf_goto_buffer(int f, int n);
static int	listbuf_goto_buffer_one(int f, int n);
static int	listbuf_goto_buffer_helper(int f, int n, int only);

static PF listbuf_pf[] = {
	listbuf_goto_buffer
};
static PF listbuf_one[] = {
	listbuf_goto_buffer_one
};


static struct KEYMAPE (2 + IMAPEXT) listbufmap = {
	2,
	2 + IMAPEXT,
	rescan,
	{
		{
			CCHR('M'), CCHR('M'), listbuf_pf, NULL
		},
		{
			'1', '1', listbuf_one, NULL
		}
	}
};

/*
 * Display the buffer list. This is done
 * in two parts. The "makelist" routine figures out
 * the text, and puts it in a buffer. "popbuf"
 * then pops the data onto the screen. Bound to
 * "C-X C-B".
 */
/* ARGSUSED */
int
listbuffers(int f, int n)
{
	static int		 initialized = 0;
	struct buffer		*bp;
	struct mgwin		*wp;

	if (!initialized) {
		maps_add((KEYMAP *)&listbufmap, "listbufmap");
		initialized = 1;
	}

	if ((bp = makelist()) == NULL || (wp = popbuf(bp, WNONE)) == NULL)
		return (FALSE);
	wp->w_dotp = bp->b_dotp; /* fix up if window already on screen */
	wp->w_doto = bp->b_doto;
	bp->b_modes[0] = name_mode("fundamental");
	bp->b_modes[1] = name_mode("listbufmap");
	bp->b_nmodes = 1;

	return (TRUE);
}

/*
 * This routine rebuilds the text for the
 * list buffers command. Return pointer
 * to new list if everything works.
 * Return NULL if there is an error (if
 * there is no memory).
 */
static struct buffer *
makelist(void)
{
	int		w = ncol / 2;
	struct buffer	*bp, *blp;
	struct line	*lp;

	if ((blp = bfind("*Buffer List*", TRUE)) == NULL)
		return (NULL);
	if (bclear(blp) != TRUE)
		return (NULL);
	blp->b_flag &= ~BFCHG;		/* Blow away old.	 */
	blp->b_flag |= BFREADONLY;

	listbuf_ncol = ncol;		/* cache ncol for listbuf_goto_buffer */

	if (addlinef(blp, "%-*s%s", w, " MR Buffer", "Size   File") == FALSE ||
	    addlinef(blp, "%-*s%s", w, " -- ------", "----   ----") == FALSE)
		return (NULL);

	for (bp = bheadp; bp != NULL; bp = bp->b_bufp) {
		RSIZE nbytes;

		nbytes = 0;			/* Count bytes in buf.	 */
		if (bp != blp) {
			lp = bfirstlp(bp);
			while (lp != bp->b_headp) {
				nbytes += llength(lp) + 1;
				lp = lforw(lp);
			}
			if (nbytes)
				nbytes--;	/* no bonus newline	 */
		}

		if (addlinef(blp, "%c%c%c %-*.*s%c%-6d %-*s",
		    (bp == curbp) ? '.' : ' ',	/* current buffer ? */
		    ((bp->b_flag & BFCHG) != 0) ? '*' : ' ',	/* changed ? */
		    ((bp->b_flag & BFREADONLY) != 0) ? ' ' : '*',
		    w - 5,		/* four chars already written */
		    w - 5,		/* four chars already written */
		    bp->b_bname,	/* buffer name */
		    strlen(bp->b_bname) < w - 5 ? ' ' : '$', /* truncated? */
		    nbytes,		/* buffer size */
		    w - 7,		/* seven chars already written */
		    bp->b_fname) == FALSE)
			return (NULL);
	}
	blp->b_dotp = bfirstlp(blp);		/* put dot at beginning of
						 * buffer */
	blp->b_doto = 0;
	return (blp);				/* All done		 */
}

static int
listbuf_goto_buffer(int f, int n)
{
	return (listbuf_goto_buffer_helper(f, n, 0));
}

static int
listbuf_goto_buffer_one(int f, int n)
{
	return (listbuf_goto_buffer_helper(f, n, 1));
}

static int
listbuf_goto_buffer_helper(int f, int n, int only)
{
	struct buffer	*bp;
	struct mgwin	*wp;
	char		*line = NULL;
	int		 i, ret = FALSE;

	if (curwp->w_dotp->l_text[listbuf_ncol/2 - 1] == '$') {
		ewprintf("buffer name truncated");
		return (FALSE);
	}

	if ((line = malloc(listbuf_ncol/2)) == NULL)
		return (FALSE);

	memcpy(line, curwp->w_dotp->l_text + 4, listbuf_ncol/2 - 5);
	for (i = listbuf_ncol/2 - 6; i > 0; i--) {
		if (line[i] != ' ') {
			line[i + 1] = '\0';
			break;
		}
	}
	if (i == 0)
		goto cleanup;

	for (bp = bheadp; bp != NULL; bp = bp->b_bufp) {
		if (strcmp(bp->b_bname, line) == 0)
			break;
	}
	if (bp == NULL)
		goto cleanup;

	if ((wp = popbuf(bp, WNONE)) == NULL)
		goto cleanup;
	curbp = bp;
	curwp = wp;

	if (only)
		ret = (onlywind(f, n));
	else
		ret = TRUE;

cleanup:
	free(line);

	return (ret);
}

/*
 * The argument "fmt" points to a format string.  Append this line to the
 * buffer. Handcraft the EOL on the end.  Return TRUE if it worked and
 * FALSE if you ran out of room.
 */
int
addlinef(struct buffer *bp, char *fmt, ...)
{
	va_list		 ap;
	struct line	*lp;

	if ((lp = lalloc(0)) == NULL)
		return (FALSE);
	va_start(ap, fmt);
	if (vasprintf(&lp->l_text, fmt, ap) == -1) {
		lfree(lp);
		va_end(ap);
		return (FALSE);
	}
	lp->l_used = strlen(lp->l_text);
	va_end(ap);

	bp->b_headp->l_bp->l_fp = lp;		/* Hook onto the end	 */
	lp->l_bp = bp->b_headp->l_bp;
	bp->b_headp->l_bp = lp;
	lp->l_fp = bp->b_headp;
	bp->b_lines++;

	return (TRUE);
}

/*
 * Look through the list of buffers, giving the user a chance to save them.
 * Return TRUE if there are any changed buffers afterwards.  Buffers that don't
 * have an associated file don't count.  Return FALSE if there are no changed
 * buffers.  Return ABORT if an error occurs or if the user presses c-g.
 */
int
anycb(int f)
{
	struct buffer	*bp;
	int		 s = FALSE, save = FALSE, ret;
	char		 pbuf[NFILEN + 11];

	for (bp = bheadp; bp != NULL; bp = bp->b_bufp) {
		if (bp->b_fname != NULL && *(bp->b_fname) != '\0' &&
		    (bp->b_flag & BFCHG) != 0) {
			ret = snprintf(pbuf, sizeof(pbuf), "Save file %s",
			    bp->b_fname);
			if (ret < 0 || ret >= sizeof(pbuf)) {
				ewprintf("Error: filename too long!");
				return (ABORT);
			}
			if ((f == TRUE || (save = eyorn(pbuf)) == TRUE) &&
			    buffsave(bp) == TRUE) {
				bp->b_flag &= ~BFCHG;
				upmodes(bp);
			} else
				s = TRUE;
			if (save == ABORT)
				return (save);
			save = TRUE;
		}
	}
	if (save == FALSE /* && kbdmop == NULL */ )	/* experimental */
		ewprintf("(No files need saving)");
	return (s);
}

/*
 * Search for a buffer, by name.
 * If not found, and the "cflag" is TRUE,
 * create a new buffer. Return pointer to the found
 * (or new) buffer.
 */
struct buffer *
bfind(const char *bname, int cflag)
{
	struct buffer	*bp;

	bp = bheadp;
	while (bp != NULL) {
		if (strcmp(bname, bp->b_bname) == 0)
			return (bp);
		bp = bp->b_bufp;
	}
	if (cflag != TRUE)
		return (NULL);

	bp = bnew(bname);

	return (bp);
}

/*
 * Create a new buffer and put it in the list of
 * all buffers.
 */
static struct buffer *
bnew(const char *bname)
{
	struct buffer	*bp;
	struct line	*lp;
	int		 i;
	size_t		len;

	bp = calloc(1, sizeof(struct buffer));
	if (bp == NULL) {
		ewprintf("Can't get %d bytes", sizeof(struct buffer));
		return (NULL);
	}
	if ((lp = lalloc(0)) == NULL) {
		free(bp);
		return (NULL);
	}
	bp->b_altb = bp->b_bufp = NULL;
	bp->b_dotp = lp;
	bp->b_doto = 0;
	bp->b_markp = NULL;
	bp->b_marko = 0;
	bp->b_flag = defb_flag;
	/* if buffer name starts and ends with '*', we ignore changes */
	len = strlen(bname);
	if (len) {
		if (bname[0] == '*' && bname[len - 1] == '*')
			bp->b_flag |= BFIGNDIRTY;
	}
	bp->b_nwnd = 0;
	bp->b_headp = lp;
	bp->b_nmodes = defb_nmodes;
	TAILQ_INIT(&bp->b_undo);
	bp->b_undoptr = NULL;
	memset(&bp->b_undopos, 0, sizeof(bp->b_undopos));
	i = 0;
	do {
		bp->b_modes[i] = defb_modes[i];
	} while (i++ < defb_nmodes);
	bp->b_fname[0] = '\0';
	bp->b_cwd[0] = '\0';
	bzero(&bp->b_fi, sizeof(bp->b_fi));
	lp->l_fp = lp;
	lp->l_bp = lp;
	bp->b_bufp = bheadp;
	bheadp = bp;
	bp->b_dotline = bp->b_markline = 1;
	bp->b_lines = 1;
	if ((bp->b_bname = strdup(bname)) == NULL) {
		ewprintf("Can't get %d bytes", strlen(bname) + 1);
		return (NULL);
	}

	return (bp);
}

/*
 * This routine blows away all of the text
 * in a buffer. If the buffer is marked as changed
 * then we ask if it is ok to blow it away; this is
 * to save the user the grief of losing text. The
 * window chain is nearly always wrong if this gets
 * called; the caller must arrange for the updates
 * that are required. Return TRUE if everything
 * looks good.
 */
int
bclear(struct buffer *bp)
{
	struct line	*lp;
	int		 s;

	/* Has buffer changed, and do we care? */
	if (!(bp->b_flag & BFIGNDIRTY) && (bp->b_flag & BFCHG) != 0 &&
	    (s = eyesno("Buffer modified; kill anyway")) != TRUE)
		return (s);
	bp->b_flag &= ~BFCHG;	/* Not changed		 */
	while ((lp = lforw(bp->b_headp)) != bp->b_headp)
		lfree(lp);
	bp->b_dotp = bp->b_headp;	/* Fix dot */
	bp->b_doto = 0;
	bp->b_markp = NULL;	/* Invalidate "mark"	 */
	bp->b_marko = 0;
	bp->b_dotline = bp->b_markline = 1;
	bp->b_lines = 1;

	return (TRUE);
}

/*
 * Display the given buffer in the given window. Flags indicated
 * action on redisplay. Update modified flag so insert loop can check it.
 */
int
showbuffer(struct buffer *bp, struct mgwin *wp, int flags)
{
	struct buffer	*obp;
	struct mgwin	*owp;

	/* Ensure file has not been modified elsewhere */
	if (fchecktime(bp) != TRUE)
		bp->b_flag |= BFDIRTY;

	if (wp->w_bufp == bp) {	/* Easy case! */
		wp->w_rflag |= flags;
		wp->w_dotp = bp->b_dotp;
		wp->w_doto = bp->b_doto;
		return (TRUE);
	}
	/* First, detach the old buffer from the window */
	if ((bp->b_altb = obp = wp->w_bufp) != NULL) {
		if (--obp->b_nwnd == 0) {
			obp->b_dotp = wp->w_dotp;
			obp->b_doto = wp->w_doto;
			obp->b_markp = wp->w_markp;
			obp->b_marko = wp->w_marko;
			obp->b_dotline = wp->w_dotline;
			obp->b_markline = wp->w_markline;
		}
	}
	/* Now, attach the new buffer to the window */
	wp->w_bufp = bp;

	if (bp->b_nwnd++ == 0) {	/* First use.		 */
		wp->w_dotp = bp->b_dotp;
		wp->w_doto = bp->b_doto;
		wp->w_markp = bp->b_markp;
		wp->w_marko = bp->b_marko;
		wp->w_dotline = bp->b_dotline;
		wp->w_markline = bp->b_markline;
	} else
		/* already on screen, steal values from other window */
		for (owp = wheadp; owp != NULL; owp = wp->w_wndp)
			if (wp->w_bufp == bp && owp != wp) {
				wp->w_dotp = owp->w_dotp;
				wp->w_doto = owp->w_doto;
				wp->w_markp = owp->w_markp;
				wp->w_marko = owp->w_marko;
				wp->w_dotline = owp->w_dotline;
				wp->w_markline = owp->w_markline;
				break;
			}
	wp->w_rflag |= WFMODE | flags;
	return (TRUE);
}

/*
 * Augment a buffer name with a number, if necessary
 *
 * If more than one file of the same basename() is open,
 * the additional buffers are named "file<2>", "file<3>", and
 * so forth.  This function adjusts a buffer name to
 * include the number, if necessary.
 */
int
augbname(char *bn, const char *fn, size_t bs)
{
	int	 count;
	size_t	 remain, len;

	len = strlcpy(bn, basename(fn), bs);
	if (len >= bs)
		return (FALSE);

	remain = bs - len;
	for (count = 2; bfind(bn, FALSE) != NULL; count++)
		snprintf(bn + len, remain, "<%d>", count);

	return (TRUE);
}

/*
 * Pop the buffer we got passed onto the screen.
 * Returns a status.
 */
struct mgwin *
popbuf(struct buffer *bp, int flags)
{
	struct mgwin	*wp;

	if (bp->b_nwnd == 0) {	/* Not on screen yet.	 */
		/* 
		 * Pick a window for a pop-up.
		 * If only one window, split the screen.
		 * Flag the new window as ephemeral
		 */
		if (wheadp->w_wndp == NULL &&
		    splitwind(FFOTHARG, flags) == FALSE)
 			return (NULL);

		/*
		 * Pick the uppermost window that isn't
		 * the current window. An LRU algorithm
		 * might be better. Return a pointer, or NULL on error. 
		 */
		wp = wheadp;

		while (wp != NULL && wp == curwp)
			wp = wp->w_wndp;
	} else
		for (wp = wheadp; wp != NULL; wp = wp->w_wndp)
			if (wp->w_bufp == bp) {
				wp->w_rflag |= WFFULL | WFFRAME;
				return (wp);
			}
	if (showbuffer(bp, wp, WFFULL) != TRUE)
		return (NULL);
	return (wp);
}

/*
 * Insert another buffer at dot.  Very useful.
 */
/* ARGSUSED */
int
bufferinsert(int f, int n)
{
	struct buffer *bp;
	struct line   *clp;
	int	clo, nline;
	char	bufn[NBUFN], *bufp;

	/* Get buffer to use from user */
	if (curbp->b_altb != NULL)
		bufp = eread("Insert buffer: (default %s) ", bufn, NBUFN,
		    EFNUL | EFNEW | EFBUF, curbp->b_altb->b_bname);
	else
		bufp = eread("Insert buffer: ", bufn, NBUFN, EFNEW | EFBUF);
	if (bufp == NULL)
		return (ABORT);
	if (bufp[0] == '\0' && curbp->b_altb != NULL)
		bp = curbp->b_altb;
	else if ((bp = bfind(bufn, FALSE)) == NULL)
		return (FALSE);

	if (bp == curbp) {
		ewprintf("Cannot insert buffer into self");
		return (FALSE);
	}
	/* insert the buffer */
	nline = 0;
	clp = bfirstlp(bp);
	for (;;) {
		for (clo = 0; clo < llength(clp); clo++)
			if (linsert(1, lgetc(clp, clo)) == FALSE)
				return (FALSE);
		if ((clp = lforw(clp)) == bp->b_headp)
			break;
		if (newline(FFRAND, 1) == FALSE)	/* fake newline */
			return (FALSE);
		nline++;
	}
	if (nline == 1)
		ewprintf("[Inserted 1 line]");
	else
		ewprintf("[Inserted %d lines]", nline);

	clp = curwp->w_linep;		/* cosmetic adjustment	*/
	if (curwp->w_dotp == clp) {	/* for offscreen insert */
		while (nline-- && lback(clp) != curbp->b_headp)
			clp = lback(clp);
		curwp->w_linep = clp;	/* adjust framing.	*/
		curwp->w_rflag |= WFFULL;
	}
	return (TRUE);
}

/*
 * Turn off the dirty bit on this buffer.
 */
/* ARGSUSED */
int
notmodified(int f, int n)
{
	struct mgwin *wp;

	curbp->b_flag &= ~BFCHG;
	wp = wheadp;		/* Update mode lines.	 */
	while (wp != NULL) {
		if (wp->w_bufp == curbp)
			wp->w_rflag |= WFMODE;
		wp = wp->w_wndp;
	}
	ewprintf("Modification-flag cleared");
	return (TRUE);
}

#ifndef NO_HELP
/*
 * Popbuf and set all windows to top of buffer.	 Currently only used by
 * help functions.
 */
int
popbuftop(struct buffer *bp, int flags)
{
	struct mgwin *wp;

	bp->b_dotp = bfirstlp(bp);
	bp->b_doto = 0;
	if (bp->b_nwnd != 0) {
		for (wp = wheadp; wp != NULL; wp = wp->w_wndp)
			if (wp->w_bufp == bp) {
				wp->w_dotp = bp->b_dotp;
				wp->w_doto = 0;
				wp->w_rflag |= WFFULL;
			}
	}
	return (popbuf(bp, flags) != NULL);
}
#endif

/*
 * Return the working directory for the current buffer, terminated
 * with a '/'. First, try to extract it from the current buffer's
 * filename. If that fails, use global cwd.
 */
int
getbufcwd(char *path, size_t plen)
{
	char cwd[NFILEN];

	if (plen == 0)
		return (FALSE);

	if (globalwd == FALSE && curbp->b_cwd[0] != '\0') {
		(void)strlcpy(path, curbp->b_cwd, plen);
	} else {
		if (getcwdir(cwd, sizeof(cwd)) == FALSE)
			goto error;
		(void)strlcpy(path, cwd, plen);
	}
	return (TRUE);
error:
	path[0] = '\0';
	return (FALSE);
}

/*
 * Ensures a buffer has not been modified elsewhere; e.g. on disk.
 * Prompt the user if it has.
 * Returns TRUE if it has NOT (i.e. buffer is ok to edit).
 * FALSE or ABORT otherwise
 */
int
checkdirty(struct buffer *bp)
{
	int s;
	
	if ((bp->b_flag & (BFDIRTY | BFIGNDIRTY)) == BFDIRTY) {
		if ((s = eyorn("File changed on disk; really edit the buffer"))
		    != TRUE)
			return (s);
		bp->b_flag &= ~BFDIRTY;
		bp->b_flag |= BFIGNDIRTY;
	}

	return (TRUE);
}