commit 33cdf63251a23d71906cb482bce4ca02ce6d94c0
from: Erik Quanstrom <quanstro@quanstro.net>
via: Russ Cox <rsc@swtch.com>
date: Sun Oct 21 16:08:49 2012 UTC

libmemdraw: fix int size bug

R=rsc, quanstro
CC=plan9port.codebot
http://codereview.appspot.com/6657043

commit - c5bfba483f4002c539cbeb4087827524dba8d0f8
commit + 33cdf63251a23d71906cb482bce4ca02ce6d94c0
blob - b6ad61a73511c09d9c969629c292374b752e28bf
blob + fa23b5e03cd8a5db59d03610494d0c20423e2d35
--- src/libmemdraw/alloc.c
+++ src/libmemdraw/alloc.c
@@ -141,7 +141,8 @@ byteaddr(Memimage *i, Point p)
 {
 	uchar *a;
 
-	a = i->data->bdata+i->zero+sizeof(u32int)*p.y*i->width;
+	/* careful to sign-extend negative p.y for 64-bits */
+	a = i->data->bdata+i->zero+(int)(sizeof(u32int)*p.y*i->width);
 
 	if(i->depth < 8){
 		/*