[PATCH v2 3/6] match_basename: use strncmp instead of strcmp

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

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

        before      after
user    0m0.548s    0m0.516s
user    0m0.549s    0m0.523s
user    0m0.554s    0m0.532s
user    0m0.557s    0m0.533s
user    0m0.558s    0m0.535s
user    0m0.559s    0m0.542s
user    0m0.562s    0m0.546s
user    0m0.564s    0m0.551s
user    0m0.566s    0m0.556s
user    0m0.569s    0m0.561s

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 9960a37..46b24db 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