From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sat, 26 Oct 2024 18:00:39 +0000 (+0100)
Subject: Stop dopalt() reading off the end of the character bitmap
X-Git-Tag: bedstead-3.246~100
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~bjharris/git?a=commitdiff_plain;h=b2bda72f7213448deb5ef22375d0b8da1cb549d1;p=bedstead.git

Stop dopalt() reading off the end of the character bitmap

Spotted by GCC -Warray-bounds.
---

diff --git a/bedstead.c b/bedstead.c
index db7caed..089cc0f 100644
--- a/bedstead.c
+++ b/bedstead.c
@@ -2618,7 +2618,7 @@ static struct glyph const *glyphs_by_name[NGLYPHS];
 static void dolookups(struct glyph const *);
 
 static bool
-getpix(char const data[YSIZE], int x, int y, unsigned flags)
+getpix(char const data[YSIZE - 1], int x, int y, unsigned flags)
 {
 
 	/*
@@ -3093,7 +3093,7 @@ dopalt(struct glyph const *g)
 	 * one pixel, and a right side-bearing of zero.  Space
 	 * characters get an advance width of three pixels.
 	 */
-	for (i = 0; i < YSIZE; i++)
+	for (i = 0; i < YSIZE - 1; i++)
 		cols |= g->data[i] & ((1 << XSIZE) - 1);
 	if (cols == 0)
 		dh = 3 - XSIZE;