From: René Scharfe Date: Sun, 23 Oct 2016 17:57:30 +0000 (+0200) Subject: hex: make wraparound of the index into ring-buffer explicit X-Git-Tag: v2.10.3~18^2 X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/bb84735c hex: make wraparound of the index into ring-buffer explicit Overflow is defined for unsigned integers, but not for signed ones. We could make the ring-buffer index in sha1_to_hex() and get_pathname() unsigned to be on the safe side to resolve this, but let's make it explicit that we are wrapping around at whatever the number of elements the ring-buffer has. The compiler is smart enough to turn modulus into bitmask for these codepaths that use ring-buffers of a size that is a power of 2. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano --- diff --git a/hex.c b/hex.c index ab2610e498..845b01a874 100644 --- a/hex.c +++ b/hex.c @@ -78,7 +78,8 @@ char *sha1_to_hex(const unsigned char *sha1) { static int bufno; static char hexbuffer[4][GIT_SHA1_HEXSZ + 1]; - return sha1_to_hex_r(hexbuffer[3 & ++bufno], sha1); + bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer); + return sha1_to_hex_r(hexbuffer[bufno], sha1); } char *oid_to_hex(const struct object_id *oid) diff --git a/path.c b/path.c index fe3c4d96c6..9bfaeda207 100644 --- a/path.c +++ b/path.c @@ -24,7 +24,8 @@ static struct strbuf *get_pathname(void) STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }; static int index; - struct strbuf *sb = &pathname_array[3 & ++index]; + struct strbuf *sb = &pathname_array[index]; + index = (index + 1) % ARRAY_SIZE(pathname_array); strbuf_reset(sb); return sb; }