Merge pull request #2259 from aeijdenberg/setfixedtimestampforarchiveentries

feat: add Timestamp to TarOptions

pkg/archive/archive.go

@@ -16,6 +16,7 @@ import (
 	"strings"
 	"sync"
 	"syscall"
+	"time"
 
 	"github.com/containers/storage/pkg/fileutils"
 	"github.com/containers/storage/pkg/idtools"
@@ -67,6 +68,8 @@ type (
 		CopyPass bool
 		// ForceMask, if set, indicates the permission mask used for created files.
 		ForceMask *os.FileMode
+		// Timestamp, if set, will be set in each header as create/mod/access time
+		Timestamp *time.Time
 	}
 )
 
@@ -494,15 +497,19 @@ type tarWriter struct {
 	// from the traditional behavior/format to get features like subsecond
 	// precision in timestamps.
 	CopyPass bool
+
+	// Timestamp, if set, will be set in each header as create/mod/access time
+	Timestamp *time.Time
 }
 
-func newTarWriter(idMapping *idtools.IDMappings, writer io.Writer, chownOpts *idtools.IDPair) *tarWriter {
+func newTarWriter(idMapping *idtools.IDMappings, writer io.Writer, chownOpts *idtools.IDPair, timestamp *time.Time) *tarWriter {
 	return &tarWriter{
 		SeenFiles:  make(map[uint64]string),
 		TarWriter:  tar.NewWriter(writer),
 		Buffer:     pools.BufioWriter32KPool.Get(nil),
 		IDMappings: idMapping,
 		ChownOpts:  chownOpts,
+		Timestamp:  timestamp,
 	}
 }
 
@@ -600,6 +607,13 @@ func (ta *tarWriter) addFile(path, name string) error {
 		hdr.Gname = ""
 	}
 
+	// if override timestamp set, replace all times with this
+	if ta.Timestamp != nil {
+		hdr.ModTime = *ta.Timestamp
+		hdr.AccessTime = *ta.Timestamp
+		hdr.ChangeTime = *ta.Timestamp
+	}
+
 	maybeTruncateHeaderModTime(hdr)
 
 	if ta.WhiteoutConverter != nil {
@@ -866,6 +880,7 @@ func TarWithOptions(srcPath string, options *TarOptions) (io.ReadCloser, error)
 			idtools.NewIDMappingsFromMaps(options.UIDMaps, options.GIDMaps),
 			compressWriter,
 			options.ChownOpts,
+			options.Timestamp,
 		)
 		ta.WhiteoutConverter = GetWhiteoutConverter(options.WhiteoutFormat, options.WhiteoutData)
 		ta.CopyPass = options.CopyPass

pkg/archive/archive_test.go

@@ -12,6 +12,7 @@ import (
 	"runtime"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/containers/storage/pkg/idtools"
 	"github.com/stretchr/testify/assert"
@@ -1222,3 +1223,46 @@ func readFileFromArchive(t *testing.T, archive io.ReadCloser, name string, expec
 	assert.NoError(t, err)
 	return string(content)
 }
+
+func TestTimestamp(t *testing.T) {
+	// write single file into dir that we'll tar
+	td := t.TempDir()
+	tf := filepath.Join(td, "foo")
+
+	require.NoError(t, os.WriteFile(tf, []byte("bar"), 0o644))
+
+	// helper function to tar that dir and return byte slice
+	tarToByteSlice := func(options *TarOptions) []byte {
+		rc, err := TarWithOptions(td, options)
+		assert.NoError(t, err)
+		defer rc.Close()
+
+		rv, err := io.ReadAll(rc)
+		assert.NoError(t, err)
+		return rv
+	}
+
+	// default options
+	defaultOptions := &TarOptions{}
+
+	// override timestamp option
+	epochOptions := &TarOptions{Timestamp: &time.Time{}}
+
+	// get tar bytes slices now
+	origTarDefaultOptions := tarToByteSlice(defaultOptions)
+	origTarEpochOptions := tarToByteSlice(epochOptions)
+
+	// set the mod time of the file to an hour later
+	oneHourLater := time.Now().Add(time.Hour)
+	require.NoError(t, os.Chtimes(tf, oneHourLater, oneHourLater))
+
+	// then tar again
+	laterTarDefaultOptions := tarToByteSlice(defaultOptions)
+	laterTarEpochOptions := tarToByteSlice(epochOptions)
+
+	// we expect the ones without a fixed timestamp to be different
+	assert.NotEqual(t, origTarDefaultOptions, laterTarDefaultOptions)
+
+	// we expect the ones with a fixed timestamp to be the same
+	assert.Equal(t, origTarEpochOptions, laterTarEpochOptions)
+}

pkg/archive/changes.go

@@ -452,7 +452,7 @@ func ChangesSize(newDir string, changes []Change) int64 {
 func ExportChanges(dir string, changes []Change, uidMaps, gidMaps []idtools.IDMap) (io.ReadCloser, error) {
 	reader, writer := io.Pipe()
 	go func() {
-		ta := newTarWriter(idtools.NewIDMappingsFromMaps(uidMaps, gidMaps), writer, nil)
+		ta := newTarWriter(idtools.NewIDMappingsFromMaps(uidMaps, gidMaps), writer, nil, nil)
 
 		// this buffer is needed for the duration of this piped stream
 		defer pools.BufioWriter32KPool.Put(ta.Buffer)