More gitignore-like implementation of negative ignore rules

Signed-off-by: Evan Anderson <evan@stacklok.com>

internal/ignore/doc.go

@@ -63,6 +63,6 @@ Notable differences from .gitignore:
   - The globbing library is Go's 'filepath.Match', not fnmatch(3)
   - Trailing spaces are always ignored (there is no supported escape sequence)
   - The evaluation of escape sequences has not been tested for compatibility
-  - There is no support for '\!' as a special leading sequence.
+  - There is no support for '\\!' as a special leading sequence for files that begin with `!`
 */
 package ignore // import "helm.sh/helm/v3/internal/ignore"

internal/ignore/rules.go

@@ -102,30 +102,22 @@ func (r *Rules) Ignore(path string, fi os.FileInfo) bool {
 	}
 	for _, p := range r.patterns {
 		if p.match == nil {
-			log.Printf("ignore: no matcher supplied for %q", p.raw)
 			return false
 		}
 
-		// For negative rules, we need to capture and return non-matches,
-		// and continue for matches.
-		if p.negate {
-			if p.mustDir && !fi.IsDir() {
-				return true
-			}
-			if !p.match(path, fi) {
-				return true
-			}
-			continue
-		}
-
 		// If the rule is looking for directories, and this is not a directory,
 		// skip it.
 		if p.mustDir && !fi.IsDir() {
 			continue
 		}
+
+		// For negative rules, we need to capture and return non-matches,
+		// and continue for matches.
 		if p.match(path, fi) {
-			return true
+			// if negate, then return false to "should I ignore"
+			return !p.negate
 		}
+
 	}
 	return false
 }

internal/ignore/rules_test.go

@@ -113,10 +113,12 @@ func TestIgnore(t *testing.T) {
 		{`helm.txt/`, "helm.txt", false},
 
 		// Negation tests
-		{`!helm.txt`, "helm.txt", false},
-		{`!helm.txt`, "tiller.txt", true},
-		{`!*.txt`, "cargo", true},
-		{`!cargo/`, "mast/", true},
+		{"!helm.txt\n*", "helm.txt", false},
+		{"!helm.txt", "tiller.txt", false}, // Don't ignore files that match zero patterns
+		{"!helm.txt\n*", "tiller.txt", true},
+		{"!*.txt\n*", "cargo", true},
+		{"!cargo/\n*", "cargo", false},
+		{"!cargo/\n*", "cargo/a.txt", true},
 
 		// Absolute path tests
 		{`/a.txt`, "a.txt", true},