[PATCH] sha1_name: make wraparound of the index into ring-buffer explicit

[René Scharfe]

Overflow is defined for unsigned integers, but not for signed ones.
Wrap around explicitly for the new ring-buffer in find_unique_abbrev()
as we did in bb84735c for the ones in sha1_to_hex() and get_pathname(),
thus avoiding signed overflows and getting rid of the magic number 3.

Signed-off-by: Rene Scharfe <l....@web.de>
---
 sha1_name.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sha1_name.c b/sha1_name.c
index 06409a3..73a915f 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -510,7 +510,8 @@ const char *find_unique_abbrev(const unsigned char *sha1, 
int len)
 {
        static int bufno;
        static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
-       char *hex = hexbuffer[3 & ++bufno];
+       char *hex = hexbuffer[bufno];
+       bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
        find_unique_abbrev_r(hex, sha1, len);
        return hex;
 }
-- 
2.10.2