[PATCH 3/3] match_basename: use strncmp instead of strcmp

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

strncmp provides length information, compared to strcmp, which could
be taken advantage by the implementation. Even better, we could check
if the lengths are equal before calling strncmp, eliminating a bit of
strncmp calls.

        before      after
user    0m0.519s    0m0.489s
user    0m0.521s    0m0.504s
user    0m0.523s    0m0.507s
user    0m0.532s    0m0.510s
user    0m0.534s    0m0.513s
user    0m0.536s    0m0.514s
user    0m0.537s    0m0.522s
user    0m0.545s    0m0.523s
user    0m0.546s    0m0.527s
user    0m0.548s    0m0.529s

While at there, fix an inconsistency about pattern/patternlen in how
attr handles EXC_FLAG_MUSTBEDIR. When parse_exclude_pattern detects
this flag, it sets patternlen _not_ to include the trailing slash and
expects the caller to trim it. add_exclude does, parse_attr_line does
not.

In attr.c, the pattern could be "foo/" while patternlen tells us it
only has 3 chars. Some functions do not care about patternlen and will
see the pattern as "foo/" while others may see it as "foo". This patch
makes patternlen 4 in this case. (Although for a piece of mind,
perhaps we should trim it to "foo" like exclude, and never pass a
pathname like "abc/" to match_{base,path}name)

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 attr.c | 2 ++
 dir.c  | 8 +++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/attr.c b/attr.c
index e2f9377..1818ba5 100644
--- a/attr.c
+++ b/attr.c
@@ -255,6 +255,8 @@ static struct match_attr *parse_attr_line(const char *line, const char *src,
 				      &res->u.pat.patternlen,
 				      &res->u.pat.flags,
 				      &res->u.pat.nowildcardlen);
+		if (res->u.pat.flags & EXC_FLAG_MUSTBEDIR)
+			res->u.pat.patternlen++;
 		if (res->u.pat.flags & EXC_FLAG_NEGATIVE) {
 			warning(_("Negative patterns are ignored in git attributes\n"
 				  "Use '\\!' for literal leading exclamation."));
diff --git a/dir.c b/dir.c
index f58320d..2a91d14 100644
--- a/dir.c
+++ b/dir.c
@@ -610,12 +610,14 @@ int match_basename(const char *basename, int basenamelen,
 		   int flags)
 {
 	if (prefix == patternlen) {
-		if (!strcmp_icase(pattern, basename))
+		if (patternlen == basenamelen &&
+		    !strncmp_icase(pattern, basename, patternlen))
 			return 1;
 	} else if (flags & EXC_FLAG_ENDSWITH) {
 		if (patternlen - 1 <= basenamelen &&
-		    !strcmp_icase(pattern + 1,
-				  basename + basenamelen - patternlen + 1))
+		    !strncmp_icase(pattern + 1,
+				   basename + basenamelen - patternlen + 1,
+				   patternlen - 1))
 			return 1;
 	} else {
 		if (fnmatch_icase(pattern, basename, 0) == 0)
-- 
1.8.1.2.536.gf441e6d