Subject: [RFC PATCH v2 03/12] dir: fix off-by-one error in match_pathspec_item

From: Elijah Newren <[email-masked]>
Date: Thu, 5 Sep 2019 08:47:26 -0700

For a pathspec like 'foo/bar' comparing against a path named "foo/",
namelen will be 4, and match[namelen] will be 'b'.  The correct location
of the directory separator is namelen-1.

The reason the code worked anyway was that the following code immediately
checked whether the first matchlen characters matched (which they do) and
then bailed and return MATCHED_RECURSIVELY anyway since wildmatch doesn't
have the ability to check if "name" can be matched as a directory (or
prefix) against the pathspec.

Signed-off-by: Elijah Newren <[email-masked]>
---
 dir.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dir.c b/dir.c
index a9168bed96..bf1a74799e 100644
--- a/dir.c
+++ b/dir.c
@@ -356,8 +356,9 @@ static int match_pathspec_item(const struct index_state *istate,
 	/* Perform checks to see if "name" is a super set of the pathspec */
 	if (flags & DO_MATCH_SUBMODULE) {
 		/* name is a literal prefix of the pathspec */
+		int offset = name[namelen-1] == '/' ? 1 : 0;
 		if ((namelen < matchlen) &&
-		    (match[namelen] == '/') &&
+		    (match[namelen-offset] == '/') &&
 		    !ps_strncmp(item, match, name, namelen))
 			return MATCHED_RECURSIVELY;
 
-- 
2.22.1.11.g45a39ee867