path: Fix bug in Match with non-greedy stars

path.Match() errors out when testing "*x" against "xxx"
because it matches the star non-greedily. Ensure that
the last chunk consumes the rest of the name.

R=r, rsc
CC=golang-dev
https://golang.org/cl/223050

src/pkg/path/match.go

@@ -41,7 +41,10 @@ Pattern:
 		}
 		// Look for match at current position.
 		t, ok, err := matchChunk(chunk, name)
-		if ok {
+		// if we're the last chunk, make sure we've exhausted the name
+		// otherwise we'll give a false result even if we could still match
+		// using the star
+		if ok && (len(t) == 0 || len(pattern) > 0) {
 			name = t
 			continue
 		}
@@ -54,6 +57,10 @@ Pattern:
 			for i := 0; i < len(name) && name[i] != '/'; i++ {
 				t, ok, err := matchChunk(chunk, name[i+1:])
 				if ok {
+					// if we're the last chunk, make sure we exhausted the name
+					if len(pattern) == 0 && len(t) > 0 {
+						continue
+					}
 					name = t
 					continue Pattern
 				}

src/pkg/path/match_test.go

@@ -64,6 +64,7 @@ var matchTests = []MatchTest{
 	MatchTest{"[-x]", "a", false, ErrBadPattern},
 	MatchTest{"\\", "a", false, ErrBadPattern},
 	MatchTest{"[a-b-c]", "a", false, ErrBadPattern},
+	MatchTest{"*x", "xxx", true, nil},
 }
 
 func TestMatch(t *testing.T) {