lib/readers: add GzipReader

lib/readers/gzip.go

@@ -0,0 +1,42 @@
+package readers
+
+import (
+	"compress/gzip"
+	"io"
+)
+
+// gzipReader wraps a *gzip.Reader so it closes the underlying stream
+// which the gzip library doesn't.
+type gzipReader struct {
+	*gzip.Reader
+	in io.ReadCloser
+}
+
+// NewGzipReader returns an io.ReadCloser which will read the stream
+// and close it when Close is called.
+//
+// Unfortunately gz.Reader does not close the underlying stream so we
+// can't use that directly.
+func NewGzipReader(in io.ReadCloser) (io.ReadCloser, error) {
+	zr, err := gzip.NewReader(in)
+	if err != nil {
+		return nil, err
+	}
+	return &gzipReader{
+		Reader: zr,
+		in:     in,
+	}, nil
+}
+
+// Close the underlying stream and the gzip reader
+func (gz *gzipReader) Close() error {
+	zrErr := gz.Reader.Close()
+	inErr := gz.in.Close()
+	if inErr != nil {
+		return inErr
+	}
+	if zrErr != nil {
+		return zrErr
+	}
+	return nil
+}

lib/readers/gzip_test.go

@@ -0,0 +1,47 @@
+package readers
+
+import (
+	"bytes"
+	"compress/gzip"
+	"io"
+	"testing"
+
+	"github.com/rclone/rclone/lib/random"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type checkClose struct {
+	io.Reader
+	closed bool
+}
+
+func (cc *checkClose) Close() error {
+	cc.closed = true
+	return nil
+}
+
+func TestGzipReader(t *testing.T) {
+	// Create some compressed data
+	data := random.String(1000)
+	var out bytes.Buffer
+	zw := gzip.NewWriter(&out)
+	_, err := io.Copy(zw, bytes.NewBufferString(data))
+	require.NoError(t, err)
+	require.NoError(t, zw.Close())
+	gzData := out.Bytes()
+
+	// Check we can decompress it
+	cc := &checkClose{Reader: bytes.NewBuffer(gzData)}
+	var decompressed bytes.Buffer
+	zr, err := NewGzipReader(cc)
+	require.NoError(t, err)
+	_, err = io.Copy(&decompressed, zr)
+	require.NoError(t, err)
+	assert.Equal(t, data, string(decompressed.Bytes()))
+
+	// Check the underlying close gets called
+	assert.False(t, cc.closed)
+	require.NoError(t, zr.Close())
+	assert.True(t, cc.closed)
+}