rados: add wrapper for rados_ioctx_snap_rollback() function

Implemented RollbackSnapshot() and testcases for the same.

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

rados/snapshot.go

@@ -149,3 +149,22 @@ func (ioctx *IOContext) ListSnaps() ([]SnapID, error) {
 	}
 	return snapList[:ret], nil
 }
+
+// RollbackSnap rollbacks the object with key oID to the pool snapshot.
+// The contents of the object will be the same as when the snapshot was taken.
+//
+// Implements:
+//  int rados_ioctx_snap_rollback(rados_ioctx_t io, const char *oid, const char *snapname);
+func (ioctx *IOContext) RollbackSnap(oid, snapName string) error {
+	if err := ioctx.validate(); err != nil {
+		return err
+	}
+
+	coid := C.CString(oid)
+	defer C.free(unsafe.Pointer(coid))
+	cSnapName := C.CString(snapName)
+	defer C.free(unsafe.Pointer(cSnapName))
+
+	ret := C.rados_ioctx_snap_rollback(ioctx.ioctx, coid, cSnapName)
+	return getError(ret)
+}

rados/snapshot_test.go

@@ -187,3 +187,70 @@ func (suite *RadosTestSuite) TestListSnapshot() {
 		}
 	})
 }
+
+func (suite *RadosTestSuite) TestRollbackSnapshot() {
+	suite.SetupConnection()
+
+	suite.T().Run("InvalidArgs", func(t *testing.T) {
+		ioctx, err := suite.conn.OpenIOContext(suite.pool)
+		require.NoError(suite.T(), err)
+		oid := suite.GenObjectName()
+		defer suite.ioctx.Delete(oid)
+
+		err = ioctx.RollbackSnap(oid, "someName")
+		assert.Error(t, err)
+
+		err = ioctx.CreateSnap("")
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, ioctx.RemoveSnap(""))
+		}()
+		err = ioctx.RollbackSnap("someObj", "")
+		assert.NoError(t, err)
+	})
+
+	suite.T().Run("invalidIOContext", func(t *testing.T) {
+		ioctx := &IOContext{}
+		err := ioctx.RollbackSnap("someObj", "someName")
+		assert.Error(t, err)
+		assert.Equal(t, err, ErrInvalidIOContext)
+	})
+
+	suite.T().Run("WriteAndRollback", func(t *testing.T) {
+		ioctx, err := suite.conn.OpenIOContext(suite.pool)
+		require.NoError(suite.T(), err)
+		oid := suite.GenObjectName()
+		defer suite.ioctx.Delete(oid)
+
+		bytesIn := []byte("Harry Potter")
+		err = suite.ioctx.Write(oid, bytesIn, 0)
+		assert.NoError(t, err)
+		// Take snap.
+		err = ioctx.CreateSnap("mySnap")
+		assert.NoError(t, err)
+		defer func() {
+			assert.NoError(t, ioctx.RemoveSnap("mySnap"))
+		}()
+		// Overwrite.
+		bytesOver := []byte("Potter Harry")
+		err = suite.ioctx.Write(oid, bytesOver, 0)
+		assert.NoError(t, err)
+
+		// Before rollback.
+		bytesOut := make([]byte, len(bytesOver))
+		nOut, err := suite.ioctx.Read(oid, bytesOut, 0)
+		assert.NoError(t, err)
+		assert.Equal(t, nOut, len(bytesOver))
+		assert.Equal(t, bytesOver, bytesOut)
+
+		// Rollback.
+		err = ioctx.RollbackSnap(oid, "mySnap")
+		assert.NoError(t, err)
+
+		// After Rollback.
+		nOut, err = suite.ioctx.Read(oid, bytesOut, 0)
+		assert.NoError(t, err)
+		assert.Equal(t, nOut, len(bytesIn))
+		assert.Equal(t, bytesOut, bytesIn)
+	})
+}