compare: implement proper testing with tar

While the full testing is broken due to bugs in the tar DH generator, we
ignore known bugs in the tar generator to at least allow us to test some
of the other semantics of Compare.

Signed-off-by: Aleksa Sarai <asarai@suse.de>

compare_test.go

@@ -1,10 +1,14 @@
 package mtree
 
 import (
+	"archive/tar"
+	"bytes"
+	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 )
 
 // simple walk of current directory, and imediately check it.
@@ -335,4 +339,115 @@ func TestCompareKeys(t *testing.T) {
 	}
 }
 
-// TODO: Add test for Compare(...) between a tar and a regular dh (to make sure that tar_time is handled correctly).
+func TestTarCompare(t *testing.T) {
+	dir, err := ioutil.TempDir("", "test-compare-tar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	// Create a bunch of objects.
+	tmpfile := filepath.Join(dir, "tmpfile")
+	if err := ioutil.WriteFile(tmpfile, []byte("some content"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	tmpdir := filepath.Join(dir, "testdir")
+	if err := os.Mkdir(tmpdir, 0755); err != nil {
+		t.Fatal(err)
+	}
+
+	tmpsubfile := filepath.Join(tmpdir, "anotherfile")
+	if err := ioutil.WriteFile(tmpsubfile, []byte("aaa"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	// Create a tar-like archive.
+	compareFiles := []fakeFile{
+		{"./", "", 0700, tar.TypeDir, 100, 0, nil},
+		{"tmpfile", "some content", 0644, tar.TypeReg, 100, 0, nil},
+		{"testdir/", "", 0755, tar.TypeDir, 100, 0, nil},
+		{"testdir/anotherfile", "aaa", 0644, tar.TypeReg, 100, 0, nil},
+	}
+
+	for _, file := range compareFiles {
+		path := filepath.Join(dir, file.Name)
+
+		// Change the time to something known with nanosec != 0.
+		chtime := time.Unix(file.Sec, 987654321)
+		if err := os.Chtimes(path, chtime, chtime); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	// Walk the current state.
+	old, err := Walk(dir, nil, append(DefaultKeywords, "sha1"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ts, err := makeTarStream(compareFiles)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	str := NewTarStreamer(bytes.NewBuffer(ts), append(DefaultTarKeywords, "sha1"))
+	if _, err = io.Copy(ioutil.Discard, str); err != nil && err != io.EOF {
+		t.Fatal(err)
+	}
+	if err = str.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	new, err := str.Hierarchy()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Compare.
+	diffs, err := Compare(old, new, append(DefaultTarKeywords, "sha1"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// 0 objects
+	if len(diffs) != 0 {
+		actualFailure := false
+		for i, delta := range diffs {
+			// XXX: Tar generation is slightly broken, so we need to ignore some bugs.
+			if delta.Path() == "." && delta.Type() == Modified {
+				// FIXME: This is a known bug.
+				t.Logf("'.' is different in the tar -- this is a bug in the tar generation")
+
+				// The tar generation bug means that '.' is missing a bunch of keys.
+				allMissing := true
+				for _, keyDelta := range delta.Diff() {
+					if keyDelta.Type() != Missing {
+						allMissing = false
+					}
+				}
+				if !allMissing {
+					t.Errorf("'.' has changed in a way not consistent with known bugs")
+				}
+
+				continue
+			}
+
+			// XXX: Another bug.
+			keys := delta.Diff()
+			if len(keys) == 1 && keys[0].Name() == "size" && keys[0].Type() == Missing {
+				// FIXME: Also a known bug with tar generation dropping size=.
+				t.Logf("'%s' is missing a size= keyword -- a bug in tar generation", delta.Path())
+
+				continue
+			}
+
+			actualFailure = true
+			t.Logf("FAILURE: diff[%d] = %#v", i, delta)
+		}
+
+		if actualFailure {
+			t.Errorf("expected the diff length to be 0, got %d", len(diffs))
+		}
+	}
+}

tar_test.go

@@ -6,7 +6,9 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"syscall"
 	"testing"
+	"time"
 )
 
 func ExampleStreamer() {
@@ -346,29 +348,39 @@ func TestHardlinks(t *testing.T) {
 	}
 }
 
-// minimal tar archive stream that mimics what is in ./testdata/test.tar
-func makeTarStream() ([]byte, error) {
+type fakeFile struct {
+	Name, Body string
+	Mode       int64
+	Type       byte
+	Sec, Nsec  int64
+	Xattrs     map[string]string
+}
+
+// minimal tar archive that mimics what is in ./testdata/test.tar
+var minimalFiles = []fakeFile{
+	{"x/", "", 0755, '5', 0, 0, nil},
+	{"x/files", "howdy\n", 0644, '0', 0, 0, nil},
+}
+
+func makeTarStream(ff []fakeFile) ([]byte, error) {
 	buf := new(bytes.Buffer)
 
 	// Create a new tar archive.
 	tw := tar.NewWriter(buf)
 
 	// Add some files to the archive.
-	var files = []struct {
-		Name, Body string
-		Mode       int64
-		Type       byte
-		Xattrs     map[string]string
-	}{
-		{"x/", "", 0755, '5', nil},
-		{"x/files", "howdy\n", 0644, '0', nil},
-	}
-	for _, file := range files {
+	for _, file := range ff {
 		hdr := &tar.Header{
-			Name:   file.Name,
-			Mode:   file.Mode,
-			Size:   int64(len(file.Body)),
-			Xattrs: file.Xattrs,
+			Name:       file.Name,
+			Uid:        syscall.Getuid(),
+			Gid:        syscall.Getgid(),
+			Mode:       file.Mode,
+			Typeflag:   file.Type,
+			Size:       int64(len(file.Body)),
+			ModTime:    time.Unix(file.Sec, file.Nsec),
+			AccessTime: time.Unix(file.Sec, file.Nsec),
+			ChangeTime: time.Unix(file.Sec, file.Nsec),
+			Xattrs:     file.Xattrs,
 		}
 		if err := tw.WriteHeader(hdr); err != nil {
 			return nil, err