Re: Using 'command -v' in a shellscript results in a coredump

[Bart Schaefer <schaefer@brasslantern.com>]

On Thu, 19 Aug 2004, Michael Prokop wrote:

> #!/bin/sh
> command -v blub > /dev/null 2>&1
> 
> Running it results in 'zsh: segmentation fault (core dumped)'.

The following prevents the core dump without producing any errors from
"make test", but I suspect there's something deeper that should be fixed
instead.

The crash happens whenever 'command -v' or 'command -V' is used with the 
POSIXBUILTINS option set.

The problem is that the code in execcmd() near line 1848 assigns 'hn' to
point at the special 'commandbn' struct, but then 1952 is reached and
tries (again) to find the builtin named "command" which fails.  Nothing
picks up the error after that and a null 'hn' is eventually dereferenced
by execbuiltin().

Index: Src/exec.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/exec.c,v
retrieving revision 1.69
diff -u -r1.69 exec.c
--- Src/exec.c	29 Jul 2004 15:09:51 -0000	1.69
+++ Src/exec.c	19 Aug 2004 07:03:43 -0000
@@ -1949,7 +1949,7 @@
 		is_shfunc = 1;
 		break;
 	    }
-	    if (!(hn = builtintab->getnode(builtintab, cmdarg))) {
+	    if (!hn && !(hn = builtintab->getnode(builtintab, cmdarg))) {
 		if (cflags & BINF_BUILTIN) {
 		    zwarn("no such builtin: %s", cmdarg, 0);
 		    lastval = 1;