Re: [PATCH] exclude: fix a bug in prefix comparison optimization

Nguyễn Thái Ngọc Duy [off-list ref] writes:

When "namelen" becomes zero at this stage, we have matched the fixed
part, but whether it actually matches the pattern still depends on the
pattern in "exclude". As demonstrated in t3001, path "three/a.3"
exists and it matches the "three/a.3" part in pattern "three/a.3[abc]",
but that does not mean a true match.

Don't be too optimistic and let fnmatch() do the job.

Yeah, the existing code is correct _only_ if the pattern part can
match an empty string (e.g. "three/a.3*") and this is a correct fix.

With your "teach attr.c match the same optimization as dir.c"
series, you would need something like this

diff --git i/attr.c w/attr.c
index 6d39406..528e935 100644
--- i/attr.c
+++ w/attr.c

@@ -710,7 +710,7 @@ static int path_matches(const char *pathname, int pathlen,
 	 * if the non-wildcard part is longer than the remaining
 	 * pathname, surely it cannot match.
 	 */
-	if (!namelen || prefix > namelen)
+	if (prefix > namelen)
 		return 0;
 	if (baselen != 0)
 		baselen++;

Comparing the corresponding code in dir.c, there is no "compare the
literal prefix part with strcmp() before doing the fnmatch()"
optimization.  Intended?

(warning: I haven't had my caffeine yet)