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

rscharfe · gitster · commit 3e98919a188e · 2016-11-01T10:56:39.000-07:00
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 bb84735 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.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/sha1_name.c b/sha1_name.c
@@ -474,7 +474,8 @@ 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;
 }

Original file line number	Diff line number	Diff line change
`@@ -474,7 +474,8 @@ const char find_unique_abbrev(const unsigned char sha1, int len)`
`474`	`474`	`{`
`475`	`475`	`static int bufno;`
`476`	`476`	`static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];`
`477`		`- char *hex = hexbuffer[3 & ++bufno];`
	`477`	`+ char *hex = hexbuffer[bufno];`
	`478`	`+ bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);`
`478`	`479`	`find_unique_abbrev_r(hex, sha1, len);`
`479`	`480`	`return hex;`
`480`	`481`	`}`