rbd: add GetMirrorUUID function

* Add GetMirrorUUID implementing rbd_mirror_uuid_get

This function is be used to get the mirroring uuid for the pool.
Basic tests included.

Signed-off-by: RAJAT SINGH <rajasing@redhat.com>

rbd/mirror.go

@@ -71,6 +71,34 @@ func (imm ImageMirrorMode) String() string {
 	}
 }
 
+//  GetMirrorUUID returns a string naming the mirroring uuid for the pool
+//  associated with the ioctx.
+//
+//  Implements:
+//  int rbd_mirror_uuid_get(rados_ioctx_t io_ctx,
+//	                       char *uuid, size_t *max_len);
+func GetMirrorUUID(ioctx *rados.IOContext) (string, error) {
+	var (
+		err   error
+		buf   []byte
+		cSize C.size_t
+	)
+	retry.WithSizes(1024, 1<<16, func(size int) retry.Hint {
+		cSize = C.size_t(size)
+		buf = make([]byte, cSize)
+		ret := C.rbd_mirror_uuid_get(
+			cephIoctx(ioctx),
+			(*C.char)(unsafe.Pointer(&buf[0])),
+			&cSize)
+		err = getErrorIfNegative(ret)
+		return retry.Size(int(cSize)).If(err == errRange)
+	})
+	if err != nil {
+		return "", err
+	}
+	return string(buf[:cSize]), nil
+}
+
 // SetMirrorMode is used to enable or disable pool level mirroring with either
 // an automatic or per-image behavior.
 //

rbd/mirror_test.go

@@ -17,6 +17,51 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestGetMirrorUUID(t *testing.T) {
+	conn := radosConnect(t)
+	poolName := GetUUID()
+	err := conn.MakePool(poolName)
+	require.NoError(t, err)
+	defer func() {
+		assert.NoError(t, conn.DeletePool(poolName))
+		conn.Shutdown()
+	}()
+
+	ioctx, err := conn.OpenIOContext(poolName)
+	assert.NoError(t, err)
+	defer func() {
+		ioctx.Destroy()
+	}()
+
+	// verify that mirroring is not enabled on this new pool
+	m, err := GetMirrorMode(ioctx)
+	assert.NoError(t, err)
+	assert.Equal(t, m, MirrorModeDisabled)
+
+	// enable per-image mirroring for this pool
+	err = SetMirrorMode(ioctx, MirrorModeImage)
+	require.NoError(t, err)
+
+	name1 := GetUUID()
+	options := NewRbdImageOptions()
+	assert.NoError(t,
+		options.SetUint64(ImageOptionOrder, uint64(testImageOrder)))
+	err = CreateImage(ioctx, name1, testImageSize, options)
+	require.NoError(t, err)
+	t.Run("getUUID", func(t *testing.T) {
+		img, err := OpenImage(ioctx, name1, NoSnapshot)
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, img.Close())
+		}()
+
+		err = img.MirrorEnable(ImageMirrorModeSnapshot)
+		assert.NoError(t, err)
+		miid, err := GetMirrorUUID(ioctx)
+		assert.NoError(t, err)
+		assert.NotEqual(t, miid, "")
+	})
+}
 func TestGetMirrorMode(t *testing.T) {
 	conn := radosConnect(t)
 	poolName := GetUUID()