[bug] shift: shell exits with status 0 on bad math expression

[bug] shift: shell exits with status 0 on bad math expression

[Martijn Dekker]

When an argument is given to 'shift' that constitutes a bad math 
expression, the (sub)shell prints an error and exits, but the exit 
status is zero (= success) under most conditions.

$ zsh -c 'shift @/@'; echo $?
zsh:1: bad math expression: illegal character: @
0
$ zsh -c 'builtin shift @/@'; echo $?
zsh:1: bad math expression: illegal character: @
0
$ zsh -c 'emulate sh; shift @/@'; echo $?
zsh:1: bad math expression: illegal character: @
1
$ zsh -c 'emulate sh; command shift @/@'; echo $?
zsh:1: bad math expression: illegal character: @
0

The exit status should be non-zero in all cases.

The behaviour is the same from current git down to zsh 5.0.7, the 
earliest version I tested.

- M.

Re: [bug] shift: shell exits with status 0 on bad math expression

[Peter Stephenson]

On Wed, 20 Jun 2018 09:45:36 +0100
Martijn Dekker <martijn@inlv.org> wrote:
> When an argument is given to 'shift' that constitutes a bad math 
> expression, the (sub)shell prints an error and exits, but the exit 
> status is zero (= success) under most conditions.

diff --git a/Src/builtin.c b/Src/builtin.c
index 1cba97d..93fa911 100644
--- a/Src/builtin.c
+++ b/Src/builtin.c
@@ -5318,8 +5318,13 @@ bin_shift(char *name, char **argv, Options ops, UNUSED(int func))
 
     /* optional argument can be either numeric or an array */
     queue_signals();
-    if (*argv && !getaparam(*argv))
+    if (*argv && !getaparam(*argv)) {
         num = mathevali(*argv++);
+	if (errflag) {
+	    unqueue_signals();
+	    return 1;
+	}
+    }
 
     if (num < 0) {
 	unqueue_signals();