Sketch out libsnapshot for update_engine integration.
This is a skeleton API so we can begin implementing both libsnapshot and
the relevant changes in update_engine.
Bug: 136678799
Test: builds
Change-Id: I5dc0fc1f401e94da2b5996cd69ab4076847282a4
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
new file mode 100644
index 0000000..3a08049
--- /dev/null
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -0,0 +1,36 @@
+//
+// Copyright (C) 2018 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.
+//
+
+cc_library {
+ name: "libsnapshot",
+ recovery_available: true,
+ defaults: ["fs_mgr_defaults"],
+ cppflags: [
+ "-D_FILE_OFFSET_BITS=64",
+ ],
+ srcs: [
+ "snapshot.cpp",
+ ],
+ shared_libs: [
+ "libbase",
+ "liblog",
+ ],
+ static_libs: [
+ "libdm",
+ "libext2_uuid",
+ ],
+ export_include_dirs: ["include"],
+}
diff --git a/fs_mgr/libsnapshot/OWNERS b/fs_mgr/libsnapshot/OWNERS
new file mode 100644
index 0000000..0cfa7e4
--- /dev/null
+++ b/fs_mgr/libsnapshot/OWNERS
@@ -0,0 +1,2 @@
+dvander@google.com
+elsk@google.com
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
new file mode 100644
index 0000000..5cfd7fa
--- /dev/null
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -0,0 +1,88 @@
+// 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.
+
+#pragma once
+
+#include <stdint.h>
+
+#include <chrono>
+#include <memory>
+#include <string>
+
+namespace android {
+namespace snapshot {
+
+enum class UpdateStatus {
+ // No update or merge is in progress.
+ None,
+
+ // An update is pending, but has not been successfully booted yet.
+ Unverified,
+
+ // The kernel is merging in the background.
+ Merging,
+
+ // Merging is complete, and needs to be acknowledged.
+ MergeCompleted
+};
+
+class SnapshotManager final {
+ public:
+ // Return a new SnapshotManager instance, or null on error.
+ static std::unique_ptr<SnapshotManager> New();
+
+ // Create a new snapshot device with the given name, base device, and COW device
+ // size. The new device path will be returned in |dev_path|. If timeout_ms is
+ // greater than zero, this function will wait the given amount of time for
+ // |dev_path| to become available, and fail otherwise. If timeout_ms is 0, then
+ // no wait will occur and |dev_path| may not yet exist on return.
+ bool CreateSnapshot(const std::string& name, const std::string& base_device, uint64_t cow_size,
+ std::string* dev_path, const std::chrono::milliseconds& timeout_ms);
+
+ // Map a snapshot device that was previously created with CreateSnapshot.
+ // If a merge was previously initiated, the device-mapper table will have a
+ // snapshot-merge target instead of a snapshot target. The timeout parameter
+ // is the same as in CreateSnapshotDevice.
+ bool MapSnapshotDevice(const std::string& name, const std::string& base_device,
+ const std::chrono::milliseconds& timeout_ms, std::string* dev_path);
+
+ // Unmap a snapshot device previously mapped with MapSnapshotDevice().
+ bool UnmapSnapshotDevice(const std::string& name);
+
+ // Remove the backing copy-on-write image for the named snapshot. If the
+ // device is still mapped, this will attempt an Unmap, and fail if the
+ // unmap fails.
+ bool DeleteSnapshot(const std::string& name);
+
+ // Initiate a merge on all snapshot devices. This should only be used after an
+ // update has been marked successful after booting.
+ bool InitiateMerge();
+
+ // Wait for the current merge to finish, then perform cleanup when it
+ // completes. It is necessary to call this after InitiateMerge(), or when
+ // a merge is detected for the first time after boot.
+ bool WaitForMerge();
+
+ // Find the status of the current update, if any.
+ //
+ // |progress| depends on the returned status:
+ // None: 0
+ // Unverified: 0
+ // Merging: Value in the range [0, 100)
+ // MergeCompleted: 100
+ UpdateStatus GetUpdateStatus(double* progress);
+};
+
+} // namespace snapshot
+} // namespace android
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
new file mode 100644
index 0000000..3e80239
--- /dev/null
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -0,0 +1,72 @@
+// 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.
+
+#include <libsnapshot/snapshot.h>
+
+namespace android {
+namespace snapshot {
+
+std::unique_ptr<SnapshotManager> SnapshotManager::New() {
+ return std::make_unique<SnapshotManager>();
+}
+
+bool SnapshotManager::CreateSnapshot(const std::string& name, const std::string& base_device,
+ uint64_t cow_size, std::string* dev_path,
+ const std::chrono::milliseconds& timeout_ms) {
+ // (1) Create COW device using libgsi_image.
+ // (2) Create snapshot device using libdm + DmTargetSnapshot.
+ // (3) Record partition in /metadata/ota.
+ (void)name;
+ (void)base_device;
+ (void)cow_size;
+ (void)dev_path;
+ (void)timeout_ms;
+ return false;
+}
+
+bool SnapshotManager::MapSnapshotDevice(const std::string& name, const std::string& base_device,
+ const std::chrono::milliseconds& timeout_ms,
+ std::string* dev_path) {
+ (void)name;
+ (void)base_device;
+ (void)dev_path;
+ (void)timeout_ms;
+ return false;
+}
+
+bool SnapshotManager::UnmapSnapshotDevice(const std::string& name) {
+ (void)name;
+ return false;
+}
+
+bool SnapshotManager::DeleteSnapshot(const std::string& name) {
+ (void)name;
+ return false;
+}
+
+bool SnapshotManager::InitiateMerge() {
+ return false;
+}
+
+bool SnapshotManager::WaitForMerge() {
+ return false;
+}
+
+UpdateStatus SnapshotManager::GetUpdateStatus(double* progress) {
+ *progress = 0.0f;
+ return UpdateStatus::None;
+}
+
+} // namespace snapshot
+} // namespace android