From 19716b21a4255ecc7148b54ab2c78039c59f25bf Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Sun, 8 Oct 2017 14:29:37 -0400 Subject: cleanup: fix possible overflow errors in binary search A common mistake when writing binary search is to allow possible integer overflow by using the simple average: mid = (min + max) / 2; Instead, use the overflow-safe version: mid = min + (max - min) / 2; This translation is safe since the operation occurs inside a loop conditioned on "min < max". The included changes were found using the following git grep: git grep '/ *2;' '*.c' Making this cleanup will prevent future review friction when a new binary search is contructed based on existing code. Signed-off-by: Derrick Stolee Reviewed-by: Jeff King Signed-off-by: Junio C Hamano --- packfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'packfile.c') diff --git a/packfile.c b/packfile.c index eab7542487..4a5fe7ab18 100644 --- a/packfile.c +++ b/packfile.c @@ -1743,7 +1743,7 @@ off_t find_pack_entry_one(const unsigned char *sha1, sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects); while (lo < hi) { - unsigned mi = (lo + hi) / 2; + unsigned mi = lo + (hi - lo) / 2; int cmp = hashcmp(index + mi * stride, sha1); if (debug_lookup) -- cgit v1.2.3