rbd: add snapshot ID related functions

added wrappers for rbd_snap_get_name() and rbd_snap_get_id()

Signed-off-by: Mudit Agarwal <muagarwa@redhat.com>

rbd/snapshot_octopus.go

@@ -0,0 +1,66 @@
+// +build octopus
+
+package rbd
+
+// #cgo LDFLAGS: -lrbd
+// #include <stdlib.h>
+// #include <rbd/librbd.h>
+import "C"
+
+import (
+	"unsafe"
+
+	"github.com/ceph/go-ceph/internal/retry"
+)
+
+// GetSnapID returns the snapshot ID for the given snapshot name.
+//
+// Implements:
+//  int rbd_snap_get_id(rbd_image_t image, const char *snapname, uint64_t *snap_id)
+func (image *Image) GetSnapID(snapName string) (uint64, error) {
+	var snapID C.uint64_t
+	if err := image.validate(imageIsOpen); err != nil {
+		return uint64(snapID), err
+	}
+	if snapName == "" {
+		return uint64(snapID), ErrSnapshotNoName
+	}
+
+	cSnapName := C.CString(snapName)
+	defer C.free(unsafe.Pointer(cSnapName))
+
+	ret := C.rbd_snap_get_id(image.image, cSnapName, &snapID)
+	return uint64(snapID), getError(ret)
+}
+
+// GetSnapByID returns the snapshot name for the given snapshot ID.
+//
+// Implements:
+//  int rbd_snap_get_name(rbd_image_t image, uint64_t snap_id, char *snapname, size_t *name_len)
+func (image *Image) GetSnapByID(snapID uint64) (string, error) {
+	if err := image.validate(imageIsOpen); err != nil {
+		return "", err
+	}
+
+	var (
+		buf []byte
+		err error
+	)
+	// range from 1k to 64KiB
+	retry.WithSizes(1024, 1<<16, func(len int) retry.Hint {
+		cLen := C.size_t(len)
+		buf = make([]byte, cLen)
+		ret := C.rbd_snap_get_name(
+			image.image,
+			(C.uint64_t)(snapID),
+			(*C.char)(unsafe.Pointer(&buf[0])),
+			&cLen)
+		err = getError(ret)
+		return retry.Size(int(cLen)).If(err == errRange)
+	})
+
+	if err != nil {
+		return "", err
+	}
+	return C.GoString((*C.char)(unsafe.Pointer(&buf[0]))), nil
+}

rbd/snapshot_octopus_test.go

@@ -0,0 +1,113 @@
+// +build octopus
+
+package rbd
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSnapIDFunctions(t *testing.T) {
+	conn := radosConnect(t)
+	poolName := GetUUID()
+	err := conn.MakePool(poolName)
+	assert.NoError(t, err)
+	ioctx, err := conn.OpenIOContext(poolName)
+	assert.NoError(t, err)
+
+	defer func() {
+		ioctx.Destroy()
+		assert.NoError(t, conn.DeletePool(poolName))
+		conn.Shutdown()
+	}()
+
+	t.Run("happyPath", func(t *testing.T) {
+		imgName := "myImage"
+		img, err := Create(ioctx, imgName, testImageSize, testImageOrder, 1)
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, img.Remove())
+		}()
+
+		img, err = OpenImage(ioctx, imgName, NoSnapshot)
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, img.Close())
+		}()
+
+		snapName := "mySnap"
+		snapshot, err := img.CreateSnapshot(snapName)
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, snapshot.Remove())
+		}()
+
+		snapID, err := img.GetSnapID(snapshot.name)
+		assert.NoError(t, err)
+		snapNameByID, err := img.GetSnapByID(snapID)
+		assert.NoError(t, err)
+		assert.Equal(t, snapshot.name, snapNameByID)
+	})
+
+	t.Run("closedImage", func(t *testing.T) {
+		imgName := "myImage"
+		closedImg, err := Create(ioctx, imgName, testImageSize, testImageOrder, 1)
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, closedImg.Remove())
+		}()
+
+		img, err := OpenImage(ioctx, imgName, NoSnapshot)
+		assert.NoError(t, err)
+		snapName := "mySnap"
+		snapshot, err := img.CreateSnapshot(snapName)
+		assert.NoError(t, err)
+
+		snapID, err := img.GetSnapID(snapshot.name)
+		assert.NoError(t, err)
+
+		// close the image
+		assert.NoError(t, img.Close())
+
+		// try to get the ID again
+		_, err = img.GetSnapID(snapshot.name)
+		assert.Error(t, err)
+
+		_, err = img.GetSnapByID(snapID)
+		assert.Error(t, err)
+
+		// Open the image for snapshot removal
+		img, err = OpenImage(ioctx, imgName, NoSnapshot)
+		assert.NoError(t, err)
+		snapshot = img.GetSnapshot(snapName)
+		assert.NoError(t, snapshot.Remove())
+		assert.NoError(t, img.Close())
+	})
+
+	t.Run("invalidOptions", func(t *testing.T) {
+		imgName := "someImage"
+		img, err := Create(ioctx, imgName, testImageSize, testImageOrder, 1)
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, img.Remove())
+		}()
+
+		img, err = OpenImage(ioctx, imgName, NoSnapshot)
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, img.Close())
+		}()
+
+		_, err = img.GetSnapID("")
+		assert.Error(t, err)
+
+		_, err = img.GetSnapID("someSnap")
+		assert.Error(t, err)
+
+		var snapID uint64
+		snapID = 22
+		_, err = img.GetSnapByID(snapID)
+		assert.Error(t, err)
+	})
+}