From 4184cbd635140e83c5f0d57c377eec93a9b6eedf Mon Sep 17 00:00:00 2001 From: Andrei Rybak Date: Tue, 8 Jun 2021 22:48:41 +0200 Subject: [PATCH] mailinfo: use starts_with() when checking scissors Existing checks for scissors characters using memcmp(3) never read past the end of the line, because all substrings we are interested in are two characters long, and the outer loop guarantees we have at least one character. So at most we will look at the NUL. However, this is too subtle and may lead to bugs in code which copies this behavior without realizing substring length requirement. So use starts_with() instead, which will stop at NUL regardless of the length of the prefix. Remove extra pair of parentheses while we are here. Helped-by: Jeff King Signed-off-by: Andrei Rybak Acked-by: Jeff King Signed-off-by: Junio C Hamano --- mailinfo.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mailinfo.c b/mailinfo.c index 5681d9130d..6f3bb5a22e 100644 --- a/mailinfo.c +++ b/mailinfo.c @@ -705,8 +705,8 @@ static int is_scissors_line(const char *line) perforation++; continue; } - if ((!memcmp(c, ">8", 2) || !memcmp(c, "8<", 2) || - !memcmp(c, ">%", 2) || !memcmp(c, "%<", 2))) { + if (starts_with(c, ">8") || starts_with(c, "8<") || + starts_with(c, ">%") || starts_with(c, "%<")) { in_perforation = 1; perforation += 2; scissors += 2;