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 <dstolee@microsoft.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/xdiff/xpatience.c b/xdiff/xpatience.c
index a613efc703..9f91702de7 100644
--- a/xdiff/xpatience.c
+++ b/xdiff/xpatience.c
@@ -166,7 +166,7 @@ static int binary_search(struct entry **sequence, int longest,
 	int left = -1, right = longest;
 
 	while (left + 1 < right) {
-		int middle = (left + right) / 2;
+		int middle = left + (right - left) / 2;
 		/* by construction, no two entries can be equal */
 		if (sequence[middle]->line2 > entry->line2)
 			right = middle;