path: use size_t for dir_prefix length

The strlen() function returns a size_t. Storing this in a standard
signed int is a bad practice that invites overflow vulnerabilities if
paths get absurdly long.

Switch the variable to size_t. This is safe to do because 'len' is
strictly used as an argument to strncmp() (which expects size_t) and
as a positive array index, involving no signed arithmetic that could
rely on negative values.

Signed-off-by: K Jayatheerth <jayatheerthkulkarni2005@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

path.c

@@ -58,7 +58,7 @@ static void strbuf_cleanup_path(struct strbuf *sb)
 
 static int dir_prefix(const char *buf, const char *dir)
 {
-	int len = strlen(dir);
+	size_t len = strlen(dir);
 	return !strncmp(buf, dir, len) &&
 		(is_dir_sep(buf[len]) || buf[len] == '\0');
 }