From: Keith Packard <keithp@keithp.com>
Date: Sat, 19 Nov 2016 07:37:44 +0000 (-0800)
Subject: altos/lisp: Move stack recursion check after null check
X-Git-Tag: 1.7~125
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=329f76d5e2732ab1c1b10223842d7816275c7e8b;hp=1999b2c915bd5b7df70cffa7777e411d3032d2d5

altos/lisp: Move stack recursion check after null check

Don't crash when printing null stack this way.

Signed-off-by: Keith Packard <keithp@keithp.com>
---

diff --git a/src/lisp/ao_lisp_stack.c b/src/lisp/ao_lisp_stack.c
index ef07b88a..53adf432 100644
--- a/src/lisp/ao_lisp_stack.c
+++ b/src/lisp/ao_lisp_stack.c
@@ -160,11 +160,11 @@ ao_lisp_stack_print(ao_poly poly)
 {
 	struct ao_lisp_stack *s = ao_lisp_poly_stack(poly);
 
-	if (s->type & AO_LISP_STACK_PRINT) {
-		printf("[recurse...]");
-		return;
-	}
 	while (s) {
+		if (s->type & AO_LISP_STACK_PRINT) {
+			printf("[recurse...]");
+			return;
+		}
 		s->type |= AO_LISP_STACK_PRINT;
 		printf("\t[\n");
 		printf("\t\texpr:   "); ao_lisp_poly_print(s->list); printf("\n");