[PATCH v3 04/13] 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.

treat_leading_path:   0.000  0.000
read_directory:       3.558  3.578
+treat_one_path:      2.305  2.323
++is_excluded:        2.098  2.117
+++prep_exclude:      0.223  0.224
+++matching:          1.529  1.544
++dir_exist:          0.035  0.035
++index_name_exists:  0.291  0.290
lazy_init_name_hash:  0.257  0.258
+simplify_away:       0.086  0.087
+dir_add_name:        0.445  0.445

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 a69c8ac..a2ab200 100644
--- a/dir.c
+++ b/dir.c
@@ -636,12 +636,14 @@ 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