From 07ad1b3566ae58655a9bf3a126afd458c0a9e3a7 Mon Sep 17 00:00:00 2001
From: David Anderson <dvander@google.com>
Date: Mon, 26 Oct 2020 22:41:13 -0700
Subject: [PATCH] libsnapshot: Add a skeleton API for mapping and unmapping all
 snapshots.

Bug: 168554689
Test: builds
Change-Id: I0da50275cc4d0a85bd6b176b5c1286659d51a25c
---
 fs_mgr/libsnapshot/include/libsnapshot/mock_snapshot.h |  2 ++
 fs_mgr/libsnapshot/include/libsnapshot/snapshot.h      | 10 ++++++++++
 fs_mgr/libsnapshot/include/libsnapshot/snapshot_stub.h |  2 ++
 fs_mgr/libsnapshot/snapshot.cpp                        | 10 ++++++++++
 fs_mgr/libsnapshot/snapshot_stub.cpp                   | 10 ++++++++++
 5 files changed, 34 insertions(+)

diff --git a/fs_mgr/libsnapshot/include/libsnapshot/mock_snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/mock_snapshot.h
index 6dee3d43d..92e79107a 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/mock_snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/mock_snapshot.h
@@ -47,6 +47,8 @@ class MockSnapshotManager : public ISnapshotManager {
     MOCK_METHOD(bool, CreateLogicalAndSnapshotPartitions,
                 (const std::string& super_device, const std::chrono::milliseconds& timeout_ms),
                 (override));
+    MOCK_METHOD(bool, MapAllSnapshots, (const std::chrono::milliseconds& timeout_ms), (override));
+    MOCK_METHOD(bool, UnmapAllSnapshots, (), (override));
     MOCK_METHOD(bool, HandleImminentDataWipe, (const std::function<void()>& callback), (override));
     MOCK_METHOD(bool, FinishMergeInRecovery, (), (override));
     MOCK_METHOD(CreateResult, RecoveryCreateSnapshotDevices, (), (override));
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index 5b50ca97b..0764bc767 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -206,6 +206,14 @@ class ISnapshotManager {
     virtual bool CreateLogicalAndSnapshotPartitions(
             const std::string& super_device, const std::chrono::milliseconds& timeout_ms = {}) = 0;
 
+    // Map all snapshots. This is analogous to CreateLogicalAndSnapshotPartitions, except it maps
+    // the target slot rather than the current slot. It should only be used immediately after
+    // applying an update, before rebooting to the new slot.
+    virtual bool MapAllSnapshots(const std::chrono::milliseconds& timeout_ms = {}) = 0;
+
+    // Unmap all snapshots. This should be called to undo MapAllSnapshots().
+    virtual bool UnmapAllSnapshots() = 0;
+
     // This method should be called preceding any wipe or flash of metadata or
     // userdata. It is only valid in recovery or fastbootd, and it ensures that
     // a merge has been completed.
@@ -321,6 +329,8 @@ class SnapshotManager final : public ISnapshotManager {
     bool Dump(std::ostream& os) override;
     std::unique_ptr<AutoDevice> EnsureMetadataMounted() override;
     ISnapshotMergeStats* GetSnapshotMergeStatsInstance() override;
+    bool MapAllSnapshots(const std::chrono::milliseconds& timeout_ms = {}) override;
+    bool UnmapAllSnapshots() override;
 
   private:
     FRIEND_TEST(SnapshotTest, CleanFirstStageMount);
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot_stub.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot_stub.h
index ed790a0f9..cba356005 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot_stub.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot_stub.h
@@ -52,6 +52,8 @@ class SnapshotManagerStub : public ISnapshotManager {
     bool Dump(std::ostream& os) override;
     std::unique_ptr<AutoDevice> EnsureMetadataMounted() override;
     ISnapshotMergeStats* GetSnapshotMergeStatsInstance() override;
+    bool MapAllSnapshots(const std::chrono::milliseconds& timeout_ms) override;
+    bool UnmapAllSnapshots() override;
 };
 
 }  // namespace android::snapshot
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 6574457db..e42e66874 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -1861,6 +1861,16 @@ bool SnapshotManager::UnmapCowDevices(LockedFile* lock, const std::string& name)
     return true;
 }
 
+bool SnapshotManager::MapAllSnapshots(const std::chrono::milliseconds&) {
+    LOG(ERROR) << "Not yet implemented.";
+    return false;
+}
+
+bool SnapshotManager::UnmapAllSnapshots() {
+    LOG(ERROR) << "Not yet implemented.";
+    return false;
+}
+
 auto SnapshotManager::OpenFile(const std::string& file, int lock_flags)
         -> std::unique_ptr<LockedFile> {
     unique_fd fd(open(file.c_str(), O_RDONLY | O_CLOEXEC | O_NOFOLLOW));
diff --git a/fs_mgr/libsnapshot/snapshot_stub.cpp b/fs_mgr/libsnapshot/snapshot_stub.cpp
index 5be3c10c8..26b9129b8 100644
--- a/fs_mgr/libsnapshot/snapshot_stub.cpp
+++ b/fs_mgr/libsnapshot/snapshot_stub.cpp
@@ -136,4 +136,14 @@ std::unique_ptr<ISnapshotWriter> SnapshotManagerStub::OpenSnapshotWriter(
     return nullptr;
 }
 
+bool SnapshotManagerStub::MapAllSnapshots(const std::chrono::milliseconds&) {
+    LOG(ERROR) << __FUNCTION__ << " should never be called.";
+    return false;
+}
+
+bool SnapshotManagerStub::UnmapAllSnapshots() {
+    LOG(ERROR) << __FUNCTION__ << " should never be called.";
+    return false;
+}
+
 }  // namespace android::snapshot