daemon: ensure that base-path is an existing directory

Any request to the daemon would fail if base-path (if specified) is not
a directory. We now check for this condition early.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

daemon.c

@@ -1184,6 +1184,14 @@ int main(int argc, char **argv)
 	if (strict_paths && (!ok_paths || !*ok_paths))
 		die("option --strict-paths requires a whitelist");
 
+	if (base_path) {
+		struct stat st;
+
+		if (stat(base_path, &st) || !S_ISDIR(st.st_mode))
+			die("base-path '%s' does not exist or "
+			    "is not a directory", base_path);
+	}
+
 	if (inetd_mode) {
 		struct sockaddr_storage ss;
 		struct sockaddr *peer = (struct sockaddr *)&ss;