Zsh - possible bug report

Zsh - possible bug report

[Simon Guilliams]

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Hello,

I have found a behavior of zsh I cannot explain. I don't know if it is a
bug and I hope this is not a duplicate.

$ cat print-argv0.c
> #include <stdio.h>
> int main(int ac, char **av)
> {
> if (ac > 0)
> fputs(av[0], stdout);
> }
> $ cc print-argv0.c
> $ zsh -f -c "exec -a '' ./a.out | hexdump -vC"
> 00000000  9b 9b                                             |..|
> 00000002
> $ zsh -f -c "exec -a \"\" ./a.out | hexdump -vC"
> 00000000  9c 9c                                             |..|
> 00000002


Zsh makes argv[0] hold two bytes, 0x9b9b or 0x9c9c depending on quotes or
double-quotes.
Bash does make argv[0] an empty string.

$ bash -c "exec -a '' ./a.out | hexdump -vC"
> $ bash -c "exec -a \"\" ./a.out | hexdump -vC"
> $


Why does this happen? Is this expected behavior?

Thank you

Re: Zsh - possible bug report

[Peter Stephenson]

On Sun, 10 Sep 2017 15:00:28 +0200
Simon Guilliams <simon.guilliams@gmail.com> wrote:
> Hello,
> 
> I have found a behavior of zsh I cannot explain. I don't know if it is a
> bug and I hope this is not a duplicate.
> 
> $ cat print-argv0.c
> > #include <stdio.h>
> > int main(int ac, char **av)
> > {
> > if (ac > 0)
> > fputs(av[0], stdout);
> > }
> > $ cc print-argv0.c
> > $ zsh -f -c "exec -a '' ./a.out | hexdump -vC"
> > 00000000  9b 9b                                             |..|
> > 00000002
> > $ zsh -f -c "exec -a \"\" ./a.out | hexdump -vC"
> > 00000000  9c 9c                                             |..|
> > 00000002

Bug.

Thanks for the clear demonstration.

pws

diff --git a/Src/exec.c b/Src/exec.c
index 76a6bb1..e2432fd 100644
--- a/Src/exec.c
+++ b/Src/exec.c
@@ -3007,6 +3007,9 @@ execcmd_exec(Estate state, Execcmd_params eparams,
 		}
 		if (exec_argv0) {
 		    char *str, *s;
+		    exec_argv0 = dupstring(exec_argv0);
+		    remnulargs(exec_argv0);
+		    untokenize(exec_argv0);
 		    size_t sz = strlen(exec_argv0);
 		    str = s = zalloc(5 + 1 + sz + 1);
 		    strcpy(s, "ARGV0=");
diff --git a/Test/A01grammar.ztst b/Test/A01grammar.ztst
index 0302c96..5e7d6ac 100644
--- a/Test/A01grammar.ztst
+++ b/Test/A01grammar.ztst
@@ -103,6 +103,12 @@
 0:`exec' with -a option, no space
 >/bin/SPLOOSH
 
+  (exec -a foo* $ZTST_testdir/../Src/zsh -fc 'print -r -- ${(V)0}')
+  (exec -a "" $ZTST_testdir/../Src/zsh -fc 'print -r -- ${(V)0}')
+0:rationalisation of arguments to exec -a
+>foo*
+>
+
   (
     opts=(-a /bin/WHOOOSH)
     exec $opts /bin/sh -c 'echo $0'