Consume z.current prepared by Reader.Read in Reader.WriteTo (#50)

... to fix missing data when WriteTo is called after Read.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

gunzip.go

@@ -513,6 +513,19 @@ func (z *Reader) Read(p []byte) (n int, err error) {
 
 func (z *Reader) WriteTo(w io.Writer) (n int64, err error) {
 	total := int64(0)
+	avail := z.current[z.roff:]
+	if len(avail) != 0 {
+		n, err := w.Write(avail)
+		if n != len(avail) {
+			return total, io.ErrShortWrite
+		}
+		total += int64(n)
+		if err != nil {
+			return total, err
+		}
+		z.blockPool <- z.current
+		z.current = nil
+	}
 	for {
 		if z.err != nil {
 			return total, z.err