[PATCH] Fix count-delta overcounting

The count-delta routine sometimes overcounted the copied source
material which resulted in unsigned int wraparound.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

count-delta.c

@@ -88,5 +88,8 @@ unsigned long count_delta(void *delta_buf, unsigned long delta_size)
 	/* delete size is what was _not_ copied from source.
 	 * edit size is that and literal additions.
 	 */
+	if (src_size + added_literal < copied_from_source)
+		/* we ended up overcounting and underflowed */
+		return 0;
 	return (src_size - copied_from_source) + added_literal;
 }