fs: clean up helper functions

internal/archiver/archiver.go

@@ -446,7 +446,7 @@ func (arch *Archiver) save(ctx context.Context, snPath, target string, previous
 	}
 
 	switch {
-	case fs.IsRegularFile(fi):
+	case fi.Mode().IsRegular():
 		debug.Log("  %v regular file", target)
 
 		// check if the file has not changed before performing a fopen operation (more expensive, specially
@@ -505,7 +505,7 @@ func (arch *Archiver) save(ctx context.Context, snPath, target string, previous
 		}
 
 		// make sure it's still a file
-		if !fs.IsRegularFile(fi) {
+		if !fi.Mode().IsRegular() {
 			err = errors.Errorf("file %v changed type, refusing to archive", fi.Name())
 			_ = file.Close()
 			err = arch.error(abstarget, err)

internal/archiver/testing.go

@@ -169,7 +169,7 @@ func TestEnsureFiles(t testing.TB, target string, dir TestDir) {
 			}
 			return nil
 		case TestFile:
-			if !fs.IsRegularFile(fi) {
+			if !fi.Mode().IsRegular() {
 				t.Errorf("is not a regular file: %v", path)
 				return nil
 			}
@@ -208,7 +208,7 @@ func TestEnsureFiles(t testing.TB, target string, dir TestDir) {
 	})
 
 	// then, traverse the directory again, looking for additional files
-	err := fs.Walk(target, func(path string, fi os.FileInfo, err error) error {
+	err := filepath.Walk(target, func(path string, fi os.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}

internal/archiver/testing_test.go

@@ -122,7 +122,7 @@ func TestTestCreateFiles(t *testing.T) {
 
 				switch node := item.(type) {
 				case TestFile:
-					if !fs.IsRegularFile(fi) {
+					if !fi.Mode().IsRegular() {
 						t.Errorf("is not regular file: %v", name)
 						continue
 					}