Re: Bug#245974: zsh: export LC_ALL=da_DK causes segfault

[Peter Stephenson <pws@csr.com>]

Clint Adams wrote:
> > This is a better patch, although it's not ideal, owing to the interface
> > of strftime which doesn't signal success or failure properly.
> 
> glibc suggests this method
> 
>           buf[0] = '\1';
>           len = strftime (buf, bufsize, format, tp);
>           if (len == 0 && buf[0] != '\0')
>             {
>               /* Something went wrong in the strftime call.  */
>               ...
>             }
> 
> If it's portable, it would seem a better hack.

I agree, although I don't know if it's portable... the following allows
ztrftime to return -1 for an error.  If the fix isn't portable, it means
we won't handle long strings properly.  I've still limited the size of
the loop in the prompt, since I'm paranoid.  I think making the size
of the buffer depend on the length of the format should also improve
matters there.

Index: Src/prompt.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/prompt.c,v
retrieving revision 1.16
diff -u -r1.16 prompt.c
--- Src/prompt.c	4 May 2004 04:17:29 -0000	1.16
+++ Src/prompt.c	4 May 2004 15:25:22 -0000
@@ -526,11 +526,16 @@
 		    }
 		    timet = time(NULL);
 		    tm = localtime(&timet);
-		    for(t0=80; ; t0*=2) {
+		    /*
+		     * Hack because strftime won't say how
+		     * much space it actually needs.  Try to add it
+		     * a few times until it works.  Some formats don't
+		     * actually have a length, so we could go on for
+		     * ever.
+		     */
+		    for(j = 0, t0 = strlen(tmfmt)*8; j < 3; j++, t0*=2) {
 			addbufspc(t0);
-			if (ztrftime(bp, t0, tmfmt, tm) ||
-			    !strcmp("%P", tmfmt) ||
-			    !strcmp("%p", tmfmt))
+			if (ztrftime(bp, t0, tmfmt, tm) >= 0)
 			    break;
 		    }
 		    bp += strlen(bp);
Index: Src/utils.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/utils.c,v
retrieving revision 1.59
diff -u -r1.59 utils.c
--- Src/utils.c	4 May 2004 04:17:29 -0000	1.59
+++ Src/utils.c	4 May 2004 15:25:31 -0000
@@ -1719,6 +1719,11 @@
  * Like the system function, this returns the number of characters
  * copied, not including the terminating NUL.  This may be zero
  * if the string didn't fit.
+ *
+ * As an extension, try to detect an error in strftime --- typically
+ * not enough memory --- and return -1.  Not guaranteed to be portable,
+ * since the strftime() interface doesn't make any guarantees about
+ * the state of the buffer if it returns zero.
  */
 
 /**/
@@ -1831,9 +1836,14 @@
 		 */
 		*buf = '\0';
 		tmp[1] = fmt[-1];
-		if (!strftime(buf, bufsize + 2, tmp, tm) &&
-		    tmp[1]!='p' && tmp[1]!='P')
+		if (!strftime(buf, bufsize + 2, tmp, tm))
+		{
+		    if (*buf) {
+			buf[0] = '\0';
+			return -1;
+		    }
 		    return 0;
+		}
 		decr = strlen(buf);
 		buf += decr;
 		bufsize -= decr - 2;
Index: Src/Modules/datetime.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Modules/datetime.c,v
retrieving revision 1.7
diff -u -r1.7 datetime.c
--- Src/Modules/datetime.c	22 Jan 2004 17:51:06 -0000	1.7
+++ Src/Modules/datetime.c	4 May 2004 15:25:31 -0000
@@ -61,7 +61,7 @@
     buffer = zalloc(bufsize);
 
     for (x=0; x < 4; x++) {
-        if (ztrftime(buffer, bufsize, argv[0], t))
+        if (ztrftime(buffer, bufsize, argv[0], t) >= 0)
 	    break;
 	buffer = zrealloc(buffer, bufsize *= 2);
     }

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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