Re: latest from CVS segfaults when FD ulimit is set too low

[Peter Stephenson <p.w.stephenson@ntlworld.com>]

On Fri, 18 Sep 2009 11:48:13 +0200
Jim Meyering <jim@meyering.net> wrote:
>   $ printf '_src_etc_profile_d() { f=; }\n_src_etc_profile_d\n' > k
>   $ Src/zsh -f -c '( . ./k; ulimit -n 7 && exec 0</dev/null )'
>   zsh:1: cannot duplicate fd 0: invalid argument
>   zsh: segmentation fault  Src/zsh -f ...

This fixes the segmentation fault:  it was intermittent because we were
accessing uninitialised memory, so this is a fully paid up bug
regardless of file descriptor limitations.

I haven't looked further: this sort of stuff is certainly not well
tested and there could well be more nasties.  If you can provide any
further code to exercise it, splendid.

Index: Src/exec.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/exec.c,v
retrieving revision 1.170
diff -u -r1.170 exec.c
--- Src/exec.c	12 Jul 2009 15:10:07 -0000	1.170
+++ Src/exec.c	21 Sep 2009 20:41:49 -0000
@@ -1980,6 +1980,7 @@
 		     */
 		    if (fdN < 0 && errno != EBADF) {
 			zerr("cannot duplicate fd %d: %e", fd1, errno);
+			mfds[fd1] = NULL;
 			closemnodes(mfds);
 			return;
 		    }
Index: Src/utils.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/utils.c,v
retrieving revision 1.229
diff -u -r1.229 utils.c
--- Src/utils.c	9 Jul 2009 20:20:53 -0000	1.229
+++ Src/utils.c	21 Sep 2009 20:41:49 -0000
@@ -1631,7 +1631,8 @@
 #else
 	int fe = movefd(dup(fd));
 #endif
-	zclose(fd);
+	if (fe != -1)
+	    zclose(fd);
 	fd = fe;
     }
     if(fd != -1) {

-- 
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/