Before calling strncmp(), see if we can get away with checking only the
first character of the passed path components instead.
Signed-off-by: Dan McGee <dpmcgee@xxxxxxxxx>
---
tree-walk.c | 26 ++++++++++++++++++--------
1 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/tree-walk.c b/tree-walk.c
index 41383b0..083b951 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -488,9 +488,10 @@ static int match_entry(const struct name_entry *entry, int pathlen,
const char *match, int matchlen,
int *never_interesting)
{
- int m = -1; /* signals that we haven't called strncmp() */
+ int m = -1; /* signals that we haven't compared strings */
if (*never_interesting) {
+ const int maxlen = (matchlen < pathlen) ? matchlen : pathlen;
/*
* We have not seen any match that sorts later
* than the current path.
@@ -500,10 +501,13 @@ static int match_entry(const struct name_entry *entry, int pathlen,
* Does match sort strictly earlier than path
* with their common parts?
*/
- m = strncmp(match, entry->path,
- (matchlen < pathlen) ? matchlen : pathlen);
- if (m < 0)
- return 0;
+ if (maxlen && match[0] > entry->path[0]) {
+ /* no good for the shortcut here, match must be <= */
+ } else {
+ m = strncmp(match, entry->path, maxlen);
+ if(m < 0)
+ return 0;
+ }
/*
* If we come here even once, that means there is at
@@ -531,12 +535,17 @@ static int match_entry(const struct name_entry *entry, int pathlen,
return 0;
}
- if (m == -1)
+ if (m == -1) {
/*
- * we cheated and did not do strncmp(), so we do
+ * we cheated and did compare strings, so we do
* that here.
*/
- m = strncmp(match, entry->path, pathlen);
+ if (pathlen && match[0] == entry->path[0])
+ /* invariant: matchlen == pathlen */
+ m = strncmp(match, entry->path, pathlen);
+ else
+ m = 1;
+ }
/*
* If common part matched earlier then it is a hit,
@@ -552,6 +561,7 @@ static int match_entry(const struct name_entry *entry, int pathlen,
static int match_dir_prefix(const char *base,
const char *match, int matchlen)
{
+ /* invariant: baselen >= matchlen */
if (strncmp(base, match, matchlen))
return 0;
--
1.7.4.2
--
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