archive/tar: update to fix writing of PAX headers

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)

hack/vendor.sh

@@ -55,7 +55,7 @@ clone hg code.google.com/p/gosqlite 74691fb6f837
 
 # get Go tip's archive/tar, for xattr support and improved performance
 # TODO after Go 1.4 drops, bump our minimum supported version and drop this vendored dep
-clone hg code.google.com/p/go 17404efd6b02
+clone hg code.google.com/p/go 1b17b3426e3c
 mv src/code.google.com/p/go/src/pkg/archive/tar tmp-tar
 rm -rf src/code.google.com/p/go
 mkdir -p src/code.google.com/p/go/src/pkg/archive

vendor/src/code.google.com/p/go/src/pkg/archive/tar/writer.go

@@ -39,7 +39,8 @@ type Writer struct {
 	closed     bool
 	usedBinary bool            // whether the binary numeric field extension was used
 	preferPax  bool            // use pax header instead of binary numeric header
-	hdrBuff    [blockSize]byte // buffer to use in writeHeader
+	hdrBuff    [blockSize]byte // buffer to use in writeHeader when writing a regular header
+	paxHdrBuff [blockSize]byte // buffer to use in writeHeader when writing a pax header
 }
 
 // NewWriter creates a new Writer writing to w.
@@ -161,7 +162,17 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
 	// subsecond time resolution, but for now let's just capture
 	// too long fields or non ascii characters
 
-	header := tw.hdrBuff[:]
+	var header []byte
+
+	// We need to select which scratch buffer to use carefully,
+	// since this method is called recursively to write PAX headers.
+	// If allowPax is true, this is the non-recursive call, and we will use hdrBuff.
+	// If allowPax is false, we are being called by writePAXHeader, and hdrBuff is
+	// already being used by the non-recursive call, so we must use paxHdrBuff.
+	header = tw.hdrBuff[:]
+	if !allowPax {
+		header = tw.paxHdrBuff[:]
+	}
 	copy(header, zeroBlock)
 	s := slicer(header)
 

vendor/src/code.google.com/p/go/src/pkg/archive/tar/writer_test.go

@@ -454,3 +454,38 @@ func TestUSTARLongName(t *testing.T) {
 		t.Fatal("Couldn't recover long name")
 	}
 }
+
+func TestValidTypeflagWithPAXHeader(t *testing.T) {
+	var buffer bytes.Buffer
+	tw := NewWriter(&buffer)
+
+	fileName := strings.Repeat("ab", 100)
+
+	hdr := &Header{
+		Name:     fileName,
+		Size:     4,
+		Typeflag: 0,
+	}
+	if err := tw.WriteHeader(hdr); err != nil {
+		t.Fatalf("Failed to write header: %s", err)
+	}
+	if _, err := tw.Write([]byte("fooo")); err != nil {
+		t.Fatalf("Failed to write the file's data: %s", err)
+	}
+	tw.Close()
+
+	tr := NewReader(&buffer)
+
+	for {
+		header, err := tr.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			t.Fatalf("Failed to read header: %s", err)
+		}
+		if header.Typeflag != 0 {
+			t.Fatalf("Typeflag should've been 0, found %d", header.Typeflag)
+		}
+	}
+}