Re: zsh 4.3.4 crashes in prompt-related code under Mac OS X

[Peter Stephenson <pws@csr.com>]

Vincent Lefevre wrote:
> If I understand correctly, the crash occurs here in preprompt():
> 
>         /* The PROMPT_SP heuristic will move the prompt down to a new line
>          * if there was any dangling output on the line (assuming the termina
> l
>          * has automatic margins, but we try even if hasam isn't set). */
>         char *str;
>         int percents = opts[PROMPTPERCENT];
>         opts[PROMPTPERCENT] = 1;
>         str = promptexpand("%B%S%#%s%b", 0, NULL, NULL);
>         opts[PROMPTPERCENT] = percents;
>         fprintf(shout, "%s%*s\r", str, (int)columns - 1 - !hasxn, "");
>         free(str);
>         ^^^^

Thanks for looking...

The obvious cause is some allocation error in promptexpand().  However,
I can't see any sign of it.  We allocate 256 bytes initially, which is
bound to be enough for the string being expanded there.  (I see one
thing that worried me a bit that I've fixed but I don't think that can
possibly be related.)

The only other possibility I can see locally is that (columns - 1 -
!hasxn) is returning a negative width that's having a bad effect, but
it should simply change the effect of the alignment.

Or maybe "shout" has got into some unusable state.  I suppose it's not
unreasonable to test it's not NULL, although it's rather paranoid.

Otherwise it's presumably a knock-on effect from some other part of the
code.

Index: Src/prompt.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/prompt.c,v
retrieving revision 1.42
diff -u -r1.42 prompt.c
--- Src/prompt.c	21 Sep 2006 16:36:53 -0000	1.42
+++ Src/prompt.c	22 Oct 2007 10:09:40 -0000
@@ -181,10 +181,10 @@
     bp1 = NULL;
     truncwidth = 0;
     putpromptchar(1, '\0');
-    addbufspc(1);
+    addbufspc(2);
     if(dontcount)
 	*bp++ = Outpar;
-    *bp = 0;
+    *bp = '\0';
     if (!ns) {
 	/* If zero, Inpar, Outpar and Nularg should be removed. */
 	for (bp = buf; *bp; ) {
Index: Src/utils.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/utils.c,v
retrieving revision 1.167
diff -u -r1.167 utils.c
--- Src/utils.c	5 Sep 2007 16:16:17 -0000	1.167
+++ Src/utils.c	22 Oct 2007 10:09:41 -0000
@@ -1160,7 +1160,7 @@
     int period = getiparam("PERIOD");
     int mailcheck = getiparam("MAILCHECK");
 
-    if (isset(PROMPTSP) && isset(PROMPTCR) && !use_exit_printed) {
+    if (isset(PROMPTSP) && isset(PROMPTCR) && !use_exit_printed && shout) {
 	/* The PROMPT_SP heuristic will move the prompt down to a new line
 	 * if there was any dangling output on the line (assuming the terminal
 	 * has automatic margins, but we try even if hasam isn't set).
@@ -1284,7 +1284,7 @@
 		checkmailpath(arr);
 		popheap();
 	    }
-	} else {
+	} else if (shout) {
 	    if (st.st_size && st.st_atime <= st.st_mtime &&
 		st.st_mtime > lastmailcheck) {
 		if (!u) {
@@ -2302,7 +2302,7 @@
 	if (ask) {
 	    if (noquery(0)) {
 		x = 'n';
-	    } else {
+	    } else if (shout) {
 		char *pptbuf;
 		pptbuf = promptexpand(sprompt, 0, best, guess);
 		zputs(pptbuf, shout);


-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070