[PATCH] Fix count-delta overcounting

Junio C Hamano · Linus Torvalds · commit 8b7d510fb182 · 2005-05-29T12:01:06.000-07:00
The count-delta routine sometimes overcounted the copied source
material which resulted in unsigned int wraparound.

Signed-off-by: Junio C Hamano &lt;junkio@cox.net&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
diff --git a/count-delta.c b/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;
 }

Original file line number	Diff line number	Diff line change
`@@ -88,5 +88,8 @@ unsigned long count_delta(void *delta_buf, unsigned long delta_size)`
`88`	`88`	`/* delete size is what was _not_ copied from source.`
`89`	`89`	`* edit size is that and literal additions.`
`90`	`90`	`*/`
	`91`	`+ if (src_size + added_literal < copied_from_source)`
	`92`	`+ /* we ended up overcounting and underflowed */`
	`93`	`+ return 0;`
`91`	`94`	`return (src_size - copied_from_source) + added_literal;`
`92`	`95`	`}`