hush: fix a bug in FEATURE_SH_STANDALONE=y config. Closes 9186

Run this in a "sh SCRIPT":

sha256sum /dev/null
echo END

sha256sum is a NOEXEC applet. It runs in a forked child. Then child exit()s.
By this time, entire script is read, and buffered in a FILE object
from fopen("SCRIPT"). But fgetc() did not consume entire input.
exit() lseeks back by -9 bytes, from <eof> to 'e' in 'echo'.
(this may be libc-specific).
This change of fd position *is shared with the parent*!

Now parent can read more, and it thinks there is another "echo END".
End result: two "echo END"s are run.

Fix this by _exit()ing instead.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index c341817e2..f760af2cb 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -877,7 +877,9 @@ void FAST_FUNC run_applet_no_and_exit(int applet_no, char **argv)
         }
         if (ENABLE_FEATURE_SUID)
                 check_suid(applet_no);
-        exit(applet_main[applet_no](argc, argv));
+        xfunc_error_retval = applet_main[applet_no](argc, argv);
+        /* Note: applet_main() may also not return (die on a xfunc or such) */
+        xfunc_die();
 }
 # endif /* NUM_APPLETS > 0 */