From 80b32af794b659cb15745cfb2a19fce0829c42c7 Mon Sep 17 00:00:00 2001
From: noname <noname@inventati.org>
Date: Wed, 23 Apr 2014 02:08:13 +0400
Subject: Simplify tdeletechar and tinsertblank and fix memory corruption.

Current CSI parsing code uses strtol to parse arguments and allows them
to be negative. Negative argument is not properly handled in tdeletechar
and tinsertblank and results in memory corruption in memmove.

Reproduce with printf '\e[-500@'

Patch also removes special handling for corner case and simplifies
the code.

Removed
	term.dirty[term.c.y] = 1
because tclearregion sets dirty flag.
---
 st.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

(limited to 'st.c')

diff --git a/st.c b/st.c
index 60243a7..263abaa 100644
--- a/st.c
+++ b/st.c
@@ -1586,37 +1586,31 @@ tclearregion(int x1, int y1, int x2, int y2) {
 
 void
 tdeletechar(int n) {
-	int src = term.c.x + n;
-	int dst = term.c.x;
-	int size = term.col - src;
+	int dst, src, size;
 
-	term.dirty[term.c.y] = 1;
+	LIMIT(n, 0, term.col - term.c.x);
 
-	if(src >= term.col) {
-		tclearregion(term.c.x, term.c.y, term.col-1, term.c.y);
-		return;
-	}
+	dst = term.c.x;
+	src = term.c.x + n;
+	size = term.col - src;
 
 	memmove(&term.line[term.c.y][dst], &term.line[term.c.y][src],
-			size * sizeof(Glyph));
+	        size * sizeof(Glyph));
 	tclearregion(term.col-n, term.c.y, term.col-1, term.c.y);
 }
 
 void
 tinsertblank(int n) {
-	int src = term.c.x;
-	int dst = src + n;
-	int size = term.col - dst;
+	int dst, src, size;
 
-	term.dirty[term.c.y] = 1;
+	LIMIT(n, 0, term.col - term.c.x);
 
-	if(dst >= term.col) {
-		tclearregion(term.c.x, term.c.y, term.col-1, term.c.y);
-		return;
-	}
+	dst = term.c.x + n;
+	src = term.c.x;
+	size = term.col - dst;
 
 	memmove(&term.line[term.c.y][dst], &term.line[term.c.y][src],
-			size * sizeof(Glyph));
+	        size * sizeof(Glyph));
 	tclearregion(src, term.c.y, dst - 1, term.c.y);
 }
 
-- 
cgit v1.2.3-13-gbd6f