From: NeilBrown <neilb@suse.de>
Date: Sat, 10 May 2014 23:43:41 +0000 (+1000)
Subject: parsergen: Don't look beyond the bottom of stack...
X-Git-Tag: workingparser~45
X-Git-Url: https://ocean-lang.org/code/?p=ocean;a=commitdiff_plain;h=3daaa7843ec07f357d93d6dfd9524273a165419c

parsergen: Don't look beyond the bottom of stack...

If the stack is empty, looking beyond for whether newlines are
permitted is dangerous.

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/csrc/parsergen.mdc b/csrc/parsergen.mdc
index 37dcf7e..2cfcb45 100644
--- a/csrc/parsergen.mdc
+++ b/csrc/parsergen.mdc
@@ -2530,7 +2530,7 @@ at the start of a production.
 				// will fail).
 			}
 			if (p.next.sym == TK_newline) {
-				if (! p.stack[p.tos-1].newline_permitted) {
+				if (!p.tos || ! p.stack[p.tos-1].newline_permitted) {
 					free(tk);
 					tk = NULL;
 					continue;