Ignore global header entries when creating an FS (#19)

Closes #18

fs.go

@@ -53,6 +53,9 @@ func New(r io.Reader) (fs.FS, error) {
 		if err != nil {
 			return nil, err
 		}
+		if h.Typeflag == tar.TypeXGlobalHeader {
+			continue
+		}
 
 		name := path.Clean(h.Name)
 		if name == "." {

fs_test.go

@@ -413,3 +413,19 @@ func TestSparse(t *testing.T) {
 		assert.Equal([]byte("file2"), file2Actual, "fs.ReadFile(tfs, \"file2\")")
 	}
 }
+
+func TestIgnoreGlobalHeader(t *testing.T) {
+	require := require.New(t)
+
+	// This file was created by initializing a git repository,
+	// committing a few files, and running: `git archive HEAD`
+	f, err := os.Open("test-with-global-header.tar")
+	require.NoError(err)
+	defer f.Close()
+
+	tfs, err := New(f)
+	require.NoError(err)
+
+	err = fstest.TestFS(tfs, "bar", "dir1", "dir1/file11")
+	require.NoError(err)
+}