Migrate Sirupsen to sirupsen.

vendor/github.com/docker/docker/builder/remotecontext/filehash.go

@@ -0,0 +1,45 @@
+package remotecontext
+
+import (
+	"archive/tar"
+	"crypto/sha256"
+	"hash"
+	"os"
+
+	"github.com/docker/docker/pkg/archive"
+	"github.com/docker/docker/pkg/tarsum"
+)
+
+// NewFileHash returns new hash that is used for the builder cache keys
+func NewFileHash(path, name string, fi os.FileInfo) (hash.Hash, error) {
+	var link string
+	if fi.Mode()&os.ModeSymlink != 0 {
+		var err error
+		link, err = os.Readlink(path)
+		if err != nil {
+			return nil, err
+		}
+	}
+	hdr, err := archive.FileInfoHeader(name, fi, link)
+	if err != nil {
+		return nil, err
+	}
+	if err := archive.ReadSecurityXattrToTarHeader(path, hdr); err != nil {
+		return nil, err
+	}
+	tsh := &tarsumHash{hdr: hdr, Hash: sha256.New()}
+	tsh.Reset() // initialize header
+	return tsh, nil
+}
+
+type tarsumHash struct {
+	hash.Hash
+	hdr *tar.Header
+}
+
+// Reset resets the Hash to its initial state.
+func (tsh *tarsumHash) Reset() {
+	// comply with hash.Hash and reset to the state hash had before any writes
+	tsh.Hash.Reset()
+	tarsum.WriteV1Header(tsh.hdr, tsh.Hash)
+}