Merge pull request #8 from microsoft/determinism

changes for deterministic outputs

Author: KenGordon

ext4/internal/compactext4/compact.go

@@ -538,6 +538,7 @@ func (w *Writer) lookup(name string, mustExist bool) (*inode, *inode, string, er
 // with the same permissions as that of it's parent directory. It is expected that the a
 // call to make these parent directories will be made at a later point with the correct
 // permissions, at that time the permissions of these directories will be updated.
+// We treat Atime, Mtime, Ctime, and Crtime in the same way.
 func (w *Writer) MakeParents(name string) error {
 	if err := w.finishInode(); err != nil {
 		return err
@@ -556,10 +557,10 @@ func (w *Writer) MakeParents(name string) error {
 		if _, ok := root.Children[dirname]; !ok {
 			f := &File{
 				Mode:     root.Mode,
-				Atime:    time.Now(),
-				Mtime:    time.Now(),
-				Ctime:    time.Now(),
-				Crtime:   time.Now(),
+				Atime:    fsTimeToTime(root.Atime),
+				Mtime:    fsTimeToTime(root.Mtime),
+				Ctime:    fsTimeToTime(root.Ctime),
+				Crtime:   fsTimeToTime(root.Crtime),
 				Size:     0,
 				Uid:      root.Uid,
 				Gid:      root.Gid,
@@ -1347,4 +1348,4 @@ func (w *Writer) Close() error {
 	}
 	w.seekBlock(diskSize)
 	return w.err
-}
+}

ext4/tar2ext4/tar2ext4_test.go

@@ -1,6 +1,9 @@
 package tar2ext4
 
 import (
+	"crypto/sha256"
+	"fmt"
+	"io"
 	"path/filepath"
 	"testing"
 
@@ -162,3 +165,76 @@ func Test_TarHardlinkToSymlink(t *testing.T) {
 		t.Fatalf("failed to convert tar to layer vhd: %s", err)
 	}
 }
+
+func calcExt4Sha256(t *testing.T, layerTar *os.File) string {
+	t.Helper()
+	if _, err := layerTar.Seek(0, 0); err != nil {
+		t.Fatalf("failed to seek file: %s", err)
+	}
+
+	opts := []Option{ConvertWhiteout}
+
+	tmpExt4Path := filepath.Join(os.TempDir(), "test.ext4")
+	layerVhd, err := os.Create(tmpExt4Path)
+	if err != nil {
+		t.Fatalf("failed to create output VHD: %s", err)
+	}
+	defer os.Remove(tmpExt4Path)
+
+	if err := Convert(layerTar, layerVhd, opts...); err != nil {
+		t.Fatalf("failed to convert tar to layer vhd: %s", err)
+	}
+
+	if _, err := layerVhd.Seek(0, 0); err != nil {
+		t.Fatalf("failed to seek file: %s", err)
+	}
+
+	hasher := sha256.New()
+	if _, err = io.Copy(hasher, layerVhd); err != nil {
+		t.Fatalf("filed to initialize hasher: %s", err)
+	}
+
+	hash := hasher.Sum(nil)
+	return fmt.Sprintf("%x", hash)
+}
+
+// Test_MissingParentDirExpansion tests that we are correctly able to expand a layer tar file
+// even if its file does not include the parent directory in its file name.
+func Test_MissingParentDirExpansion(t *testing.T) {
+	tmpTarFilePath := filepath.Join(os.TempDir(), "test-layer.tar")
+	layerTar, err := os.Create(tmpTarFilePath)
+	if err != nil {
+		t.Fatalf("failed to create output file: %s", err)
+	}
+	defer os.Remove(tmpTarFilePath)
+
+	tw := tar.NewWriter(layerTar)
+	var file = struct {
+		path, body string
+	}{"foo/bar.txt", "inside bar.txt"}
+	hdr := &tar.Header{
+		Name:       file.path,
+		Mode:       0777,
+		Size:       int64(len(file.body)),
+		ModTime:    time.Now(),
+		AccessTime: time.Now(),
+		ChangeTime: time.Now(),
+	}
+	if err := tw.WriteHeader(hdr); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := tw.Write([]byte(file.body)); err != nil {
+		t.Fatal(err)
+	}
+	if err := tw.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Now import the tar file and check the conversion to ext4 is deterministic.
+	hash1 := calcExt4Sha256(t, layerTar)
+	hash2 := calcExt4Sha256(t, layerTar)
+
+	if hash1 != hash2 {
+		t.Fatalf("hash doesn't match")
+	}
+}