Merge tag 'zsh-5.5.1-test-2' into debian

Test release: 5.5.1-test-2.

1 files changed, 24 insertions, 7 deletions

diff --git a/Src/options.c b/Src/options.c
index 590652ea9..600b649e4 100644
--- a/Src/options.c
+++ b/Src/options.c
@@ -769,15 +769,32 @@ dosetopt(int optno, int value, int force, char *new_opts)
     } else if(optno == PRIVILEGED && !value) {
 	/* unsetting PRIVILEGED causes the shell to make itself unprivileged */
 #ifdef HAVE_SETUID
-	setuid(getuid());
-	setgid(getgid());
-        if (setuid(getuid())) {
-            zwarn("failed to change user ID: %e", errno);
-            return -1;
-	} else if (setgid(getgid())) {
+	int ignore_err;
+	errno = 0;
+	/*
+	 * Set the GID first as if we set the UID to non-privileged it
+	 * might be impossible to restore the GID.
+	 *
+	 * Some OSes (possibly no longer around) have been known to
+	 * fail silently the first time, so we attempt the change twice.
+	 * If it fails we are guaranteed to pick this up the second
+	 * time, so ignore the first time.
+	 *
+	 * Some versions of gcc make it hard to ignore the results the
+	 * first time, hence the following.  (These are probably not
+	 * systems that require the doubled calls.)
+	 */
+	ignore_err = setgid(getgid());
+	(void)ignore_err;
+	ignore_err = setuid(getuid());
+	(void)ignore_err;
+	if (setgid(getgid())) {
             zwarn("failed to change group ID: %e", errno);
             return -1;
-        }
+        } else if (setuid(getuid())) {
+            zwarn("failed to change user ID: %e", errno);
+            return -1;
+	}
 #else
         zwarn("setuid not available");
         return -1;