Fix tarsum for go 1.10

Remove invalid flush commands, flush should only occur when file
has been completely written. This is already handle, remove these calls.
Ensure data gets written after EOF in correct order and before close.
Remove gname and uname from sum for hash compatibility.
Update tarsum tests for gname/uname removal.
Return valid length after eof.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/tarsum/tarsum.go

@@ -160,6 +160,11 @@ func (sth simpleTHash) Hash() hash.Hash { return sth.h() }
 
 func (ts *tarSum) encodeHeader(h *tar.Header) error {
 	for _, elem := range ts.headerSelector.selectHeaders(h) {
+		// Ignore these headers to be compatible with versions
+		// before go 1.10
+		if elem[0] == "gname" || elem[0] == "uname" {
+			elem[1] = ""
+		}
 		if _, err := ts.h.Write([]byte(elem[0] + elem[1])); err != nil {
 			return err
 		}
@@ -219,6 +224,10 @@ func (ts *tarSum) Read(buf []byte) (int, error) {
 				ts.first = false
 			}
 
+			if _, err := ts.tarW.Write(buf2[:n]); err != nil {
+				return 0, err
+			}
+
 			currentHeader, err := ts.tarR.Next()
 			if err != nil {
 				if err == io.EOF {
@@ -232,10 +241,11 @@ func (ts *tarSum) Read(buf []byte) (int, error) {
 						return 0, err
 					}
 					ts.finished = true
-					return n, nil
+					return ts.bufWriter.Read(buf)
 				}
-				return n, err
+				return 0, err
 			}
+
 			ts.currentFile = path.Join(".", path.Join("/", currentHeader.Name))
 			if err := ts.encodeHeader(currentHeader); err != nil {
 				return 0, err
@@ -243,10 +253,7 @@ func (ts *tarSum) Read(buf []byte) (int, error) {
 			if err := ts.tarW.WriteHeader(currentHeader); err != nil {
 				return 0, err
 			}
-			if _, err := ts.tarW.Write(buf2[:n]); err != nil {
-				return 0, err
-			}
-			ts.tarW.Flush()
+
 			if _, err := io.Copy(ts.writer, ts.bufTar); err != nil {
 				return 0, err
 			}
@@ -254,7 +261,7 @@ func (ts *tarSum) Read(buf []byte) (int, error) {
 
 			return ts.bufWriter.Read(buf)
 		}
-		return n, err
+		return 0, err
 	}
 
 	// Filling the hash buffer
@@ -266,7 +273,6 @@ func (ts *tarSum) Read(buf []byte) (int, error) {
 	if _, err = ts.tarW.Write(buf2[:n]); err != nil {
 		return 0, err
 	}
-	ts.tarW.Flush()
 
 	// Filling the output writer
 	if _, err = io.Copy(ts.writer, ts.bufTar); err != nil {

pkg/tarsum/tarsum_test.go

@@ -69,19 +69,19 @@ var testLayers = []testLayer{
 	{
 		// this tar has two files with the same path
 		filename: "testdata/collision/collision-0.tar",
-		tarsum:   "tarsum+sha256:08653904a68d3ab5c59e65ef58c49c1581caa3c34744f8d354b3f575ea04424a"},
+		tarsum:   "tarsum+sha256:7cabb5e9128bb4a93ff867b9464d7c66a644ae51ea2e90e6ef313f3bef93f077"},
 	{
 		// this tar has the same two files (with the same path), but reversed order. ensuring is has different hash than above
 		filename: "testdata/collision/collision-1.tar",
-		tarsum:   "tarsum+sha256:b51c13fbefe158b5ce420d2b930eef54c5cd55c50a2ee4abdddea8fa9f081e0d"},
+		tarsum:   "tarsum+sha256:805fd393cfd58900b10c5636cf9bab48b2406d9b66523122f2352620c85dc7f9"},
 	{
 		// this tar has newer of collider-0.tar, ensuring is has different hash
 		filename: "testdata/collision/collision-2.tar",
-		tarsum:   "tarsum+sha256:381547080919bb82691e995508ae20ed33ce0f6948d41cafbeb70ce20c73ee8e"},
+		tarsum:   "tarsum+sha256:85d2b8389f077659d78aca898f9e632ed9161f553f144aef100648eac540147b"},
 	{
 		// this tar has newer of collider-1.tar, ensuring is has different hash
 		filename: "testdata/collision/collision-3.tar",
-		tarsum:   "tarsum+sha256:f886e431c08143164a676805205979cd8fa535dfcef714db5515650eea5a7c0f"},
+		tarsum:   "tarsum+sha256:cbe4dee79fe979d69c16c2bccd032e3205716a562f4a3c1ca1cbeed7b256eb19"},
 	{
 		options: &sizedOptions{1, 1024 * 1024, false, false}, // a 1mb file (in memory)
 		tarsum:  "tarsum+md5:0d7529ec7a8360155b48134b8e599f53",
@@ -436,7 +436,7 @@ func TestIteration(t *testing.T) {
 			[]byte(""),
 		},
 		{
-			"tarsum.dev+sha256:b38166c059e11fb77bef30bf16fba7584446e80fcc156ff46d47e36c5305d8ef",
+			"tarsum.dev+sha256:862964db95e0fa7e42836ae4caab3576ab1df8d275720a45bdd01a5a3730cc63",
 			VersionDev,
 			&tar.Header{
 				Name:     "another.txt",
@@ -452,7 +452,7 @@ func TestIteration(t *testing.T) {
 			[]byte("test"),
 		},
 		{
-			"tarsum.dev+sha256:4cc2e71ac5d31833ab2be9b4f7842a14ce595ec96a37af4ed08f87bc374228cd",
+			"tarsum.dev+sha256:4b1ba03544b49d96a32bacc77f8113220bd2f6a77e7e6d1e7b33cd87117d88e7",
 			VersionDev,
 			&tar.Header{
 				Name:     "xattrs.txt",
@@ -470,7 +470,7 @@ func TestIteration(t *testing.T) {
 			[]byte("test"),
 		},
 		{
-			"tarsum.dev+sha256:65f4284fa32c0d4112dd93c3637697805866415b570587e4fd266af241503760",
+			"tarsum.dev+sha256:410b602c898bd4e82e800050f89848fc2cf20fd52aa59c1ce29df76b878b84a6",
 			VersionDev,
 			&tar.Header{
 				Name:     "xattrs.txt",
@@ -488,7 +488,7 @@ func TestIteration(t *testing.T) {
 			[]byte("test"),
 		},
 		{
-			"tarsum+sha256:c12bb6f1303a9ddbf4576c52da74973c00d14c109bcfa76b708d5da1154a07fa",
+			"tarsum+sha256:b1f97eab73abd7593c245e51070f9fbdb1824c6b00a0b7a3d7f0015cd05e9e86",
 			Version0,
 			&tar.Header{
 				Name:     "xattrs.txt",