fs_mgr/libsnapshot/android/snapshot/snapshot.proto

// Copyright (C) 2019 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto3";
package android.snapshot;

option optimize_for = LITE_RUNTIME;

// Next: 4
enum SnapshotState {
    // No snapshot is found.
    NONE = 0;

    // The snapshot has been created and possibly written to. Rollbacks are
    // possible by destroying the snapshot.
    CREATED = 1;

    // Changes are being merged. No rollbacks are possible beyond this point.
    MERGING = 2;

    // Changes have been merged, Future reboots may map the base device
    // directly.
    MERGE_COMPLETED = 3;
}

// Next: 9
message SnapshotStatus {
    // Name of the snapshot. This is usually the name of the snapshotted
    // logical partition; for example, "system_b".
    string name = 1;

    SnapshotState state = 2;

    // Size of the full (base) device.
    uint64 device_size = 3;

    // Size of the snapshot. This is the sum of lengths of ranges in the base
    // device that needs to be snapshotted during the update.
    // This must be less than or equal to |device_size|.
    // This value is 0 if no snapshot is needed for this device because
    // no changes
    uint64 snapshot_size = 4;

    // Size of the "COW partition". A COW partition is a special logical
    // partition represented in the super partition metadata. This partition and
    // the "COW image" form the "COW device" that supports the snapshot device.
    //
    // When SnapshotManager creates a COW device, it first searches for unused
    // blocks in the super partition, and use those before creating the COW
    // image if the COW partition is not big enough.
    //
    // This value is 0 if no space in super is left for the COW partition.
    // |cow_partition_size + cow_file_size| must not be zero if |snapshot_size|
    // is non-zero.
    uint64 cow_partition_size = 5;

    // Size of the "COW file", or "COW image". A COW file / image is created
    // when the "COW partition" is not big enough to store changes to the
    // snapshot device.
    //
    // This value is 0 if |cow_partition_size| is big enough to hold all changes
    // to the snapshot device.
    uint64 cow_file_size = 6;

    // Sectors allocated for the COW device. Recording this value right after
    // the update and before the merge allows us to infer the progress of the
    // merge process.
    // This is non-zero when |state| == MERGING or MERGE_COMPLETED.
    uint64 sectors_allocated = 7;

    // Metadata sectors allocated for the COW device. Recording this value right
    // before the update and before the merge allows us to infer the progress of
    // the merge process.
    // This is non-zero when |state| == MERGING or MERGE_COMPLETED.
    uint64 metadata_sectors = 8;
}