3 files changed, 59 insertions, 8 deletions

diff --git a/libgo/go/archive/tar/reader.go b/libgo/go/archive/tar/reader.go
index 920a9b08f90..a27559d0f04 100644
--- a/libgo/go/archive/tar/reader.go
+++ b/libgo/go/archive/tar/reader.go
@@ -29,10 +29,11 @@ const maxNanoSecondIntSize = 9
 // The Next method advances to the next file in the archive (including the first),
 // and then it can be treated as an io.Reader to access the file's data.
 type Reader struct {
-	r    io.Reader
-	err  error
-	pad  int64          // amount of padding (ignored) after current file entry
-	curr numBytesReader // reader for current file entry
+	r       io.Reader
+	err     error
+	pad     int64           // amount of padding (ignored) after current file entry
+	curr    numBytesReader  // reader for current file entry
+	hdrBuff [blockSize]byte // buffer to use in readHeader
 }
 
 // A numBytesReader is an io.Reader with a numBytes method, returning the number
@@ -426,7 +427,9 @@ func (tr *Reader) verifyChecksum(header []byte) bool {
 }
 
 func (tr *Reader) readHeader() *Header {
-	header := make([]byte, blockSize)
+	header := tr.hdrBuff[:]
+	copy(header, zeroBlock)
+
 	if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil {
 		return nil
 	}
diff --git a/libgo/go/archive/tar/writer.go b/libgo/go/archive/tar/writer.go
index 6eff6f6f84d..dafb2cabf37 100644
--- a/libgo/go/archive/tar/writer.go
+++ b/libgo/go/archive/tar/writer.go
@@ -37,8 +37,10 @@ type Writer struct {
 	nb         int64 // number of unwritten bytes for current file entry
 	pad        int64 // amount of padding to write after current file entry
 	closed     bool
-	usedBinary bool // whether the binary numeric field extension was used
-	preferPax  bool // use pax header instead of binary numeric header
+	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 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.
@@ -160,7 +162,18 @@ 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 := make([]byte, blockSize)
+	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)
 
 	// keep a reference to the filename to allow to overwrite it later if we detect that we can use ustar longnames instead of pax
diff --git a/libgo/go/archive/tar/writer_test.go b/libgo/go/archive/tar/writer_test.go
index 512fab1a6f1..5e42e322f9c 100644
--- a/libgo/go/archive/tar/writer_test.go
+++ b/libgo/go/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)
+		}
+	}
+}