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Commit a2b5d997 authored by David Anderson's avatar David Anderson
Browse files

libsnapshot: Add Initialize and InitializeAppend methods to ISnapshotWriter. 

This is so update engine can resume from the correct label.

Bug: 168554689
Test: vts_libsnapshot_test
Change-Id: Ib04e80e8219f954f105d5a85f86efa7bb9097579
parent 0544f91a

fs_mgr/libsnapshot/include/libsnapshot/snapshot.h

+3 −0
Original line number Diff line number Diff line
@@ -185,6 +185,9 @@ class ISnapshotManager { 
    // must be suffixed. If a source partition exists, it must be specified as well. The source

    // partition will only be used if raw bytes are needed. The source partition should be an

    // absolute path to the device, not a partition name.

    //

    // After calling OpenSnapshotWriter, the caller must invoke Initialize or InitializeForAppend

    // before invoking write operations.

    virtual std::unique_ptr<ISnapshotWriter> OpenSnapshotWriter(

            const android::fs_mgr::CreateLogicalPartitionParams& params,

            const std::optional<std::string>& source_device) = 0;

fs_mgr/libsnapshot/include/libsnapshot/snapshot_writer.h

+14 −0
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ 


#pragma once



#include <optional>



#include <android-base/unique_fd.h>



#include <libsnapshot/cow_writer.h>
@@ -37,6 +39,13 @@ class ISnapshotWriter : public ICowWriter { 
    // device is only opened on the first operation that requires it.

    void SetSourceDevice(const std::string& source_device);



    // Open the writer in write mode (no append).

    virtual bool Initialize() = 0;



    // Open the writer in append mode, optionally with the last label to resume

    // from. See CowWriter::InitializeAppend.

    virtual bool InitializeAppend(std::optional<uint64_t> label = {}) = 0;



    virtual std::unique_ptr<FileDescriptor> OpenReader() = 0;



  protected:
@@ -56,6 +65,8 @@ class CompressedSnapshotWriter : public ISnapshotWriter { 
    // Sets the COW device; this is required.

    bool SetCowDevice(android::base::unique_fd&& cow_device);



    bool Initialize() override;

    bool InitializeAppend(std::optional<uint64_t> label = {}) override;

    bool Finalize() override;

    uint64_t GetCowSize() override;

    std::unique_ptr<FileDescriptor> OpenReader() override;
@@ -80,6 +91,9 @@ class OnlineKernelSnapshotWriter : public ISnapshotWriter { 
    // Set the device used for all writes.

    void SetSnapshotDevice(android::base::unique_fd&& snapshot_fd, uint64_t cow_size);



    bool Initialize() override { return true; }

    bool InitializeAppend(std::optional<uint64_t>) override { return true; }



    bool Finalize() override;

    uint64_t GetCowSize() override { return cow_size_; }

    std::unique_ptr<FileDescriptor> OpenReader() override;

fs_mgr/libsnapshot/snapshot_reader_test.cpp

+1 −0
Original line number Diff line number Diff line
@@ -157,6 +157,7 @@ TEST_F(OfflineSnapshotTest, CompressedSnapshot) { 
    auto writer = std::make_unique<CompressedSnapshotWriter>(options);

    writer->SetSourceDevice(base_->path);

    ASSERT_TRUE(writer->SetCowDevice(std::move(cow_fd)));

    ASSERT_TRUE(writer->Initialize());

    ASSERT_NO_FATAL_FAILURE(WriteCow(writer.get()));

    ASSERT_NO_FATAL_FAILURE(TestReads(writer.get()));

}

fs_mgr/libsnapshot/snapshot_test.cpp

+3 −0
Original line number Diff line number Diff line
@@ -907,6 +907,9 @@ class SnapshotUpdateTest : public SnapshotTest { 
        if (!result) {

            return AssertionFailure() << "Cannot open snapshot for writing: " << name;

        }

        if (!result->Initialize()) {

            return AssertionFailure() << "Cannot initialize snapshot for writing: " << name;

        }



        if (writer) {

            *writer = std::move(result);

fs_mgr/libsnapshot/snapshot_writer.cpp

+13 −2
Original line number Diff line number Diff line
@@ -56,9 +56,9 @@ CompressedSnapshotWriter::CompressedSnapshotWriter(const CowOptions& options) 
bool CompressedSnapshotWriter::SetCowDevice(android::base::unique_fd&& cow_device) {

    cow_device_ = std::move(cow_device);

    cow_ = std::make_unique<CowWriter>(options_);



    return cow_->Initialize(cow_device_);

    return true;

}



bool CompressedSnapshotWriter::Finalize() {

    return cow_->Finalize();

}
@@ -112,6 +112,17 @@ bool CompressedSnapshotWriter::EmitLabel(uint64_t label) { 
    return cow_->AddLabel(label);

}



bool CompressedSnapshotWriter::Initialize() {

    return cow_->Initialize(cow_device_, CowWriter::OpenMode::WRITE);

}



bool CompressedSnapshotWriter::InitializeAppend(std::optional<uint64_t> label) {

    if (label) {

        return cow_->InitializeAppend(cow_device_, *label);

    }

    return cow_->Initialize(cow_device_, CowWriter::OpenMode::APPEND);

}



OnlineKernelSnapshotWriter::OnlineKernelSnapshotWriter(const CowOptions& options)

    : ISnapshotWriter(options) {}