[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>

diff --git a/count-delta.c b/count-delta.c
index 3bcc205..e10c832 100644 (file)
--- 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.
         */
        /* 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;
 }
        return (src_size - copied_from_source) + added_literal;
 }