Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ee4075d8 authored by David Anderson's avatar David Anderson
Browse files

liblp: Add ReadImageFromBlob. 

This change enables reading metadata images from memory, for situations
where using file descriptors is not practical (such as fastbootd flash).

Bug: 78793464
Test: liblp_test gtest
Change-Id: I9ad08b0ddd4cbb96e87583237a90785e0f4befa4
parent 1eb3ea37

fs_mgr/liblp/images.cpp

+17 −0
Original line number Diff line number Diff line
@@ -41,6 +41,23 @@ std::unique_ptr<LpMetadata> ReadFromImageFile(int fd) { 
    return ParseMetadata(geometry, fd);

}



std::unique_ptr<LpMetadata> ReadFromImageBlob(const void* data, size_t bytes) {

    if (bytes < LP_METADATA_GEOMETRY_SIZE) {

        LERROR << __PRETTY_FUNCTION__ << ": " << bytes << " is smaller than geometry header";

        return nullptr;

    }



    LpMetadataGeometry geometry;

    if (!ParseGeometry(data, &geometry)) {

        return nullptr;

    }



    const uint8_t* metadata_buffer =

            reinterpret_cast<const uint8_t*>(data) + LP_METADATA_GEOMETRY_SIZE;

    size_t metadata_buffer_size = bytes - LP_METADATA_GEOMETRY_SIZE;

    return ParseMetadata(geometry, metadata_buffer, metadata_buffer_size);

}



std::unique_ptr<LpMetadata> ReadFromImageFile(const char* file) {

    android::base::unique_fd fd(open(file, O_RDONLY));

    if (fd < 0) {

fs_mgr/liblp/include/liblp/liblp.h

+1 −0
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ bool WriteToSparseFile(const char* file, const LpMetadata& metadata, uint32_t bl 
                       const std::map<std::string, std::string>& images);

bool WriteToImageFile(const char* file, const LpMetadata& metadata);

std::unique_ptr<LpMetadata> ReadFromImageFile(const char* file);

std::unique_ptr<LpMetadata> ReadFromImageBlob(const void* data, size_t bytes);



// Helper to extract safe C++ strings from partition info.

std::string GetPartitionName(const LpMetadataPartition& partition);

fs_mgr/liblp/io_test.cpp

+21 −0
Original line number Diff line number Diff line
@@ -394,6 +394,27 @@ TEST(liblp, ImageFiles) { 
    ASSERT_NE(imported, nullptr);

}



// Test that we can read images from buffers.

TEST(liblp, ImageFilesInMemory) {

    unique_ptr<MetadataBuilder> builder = CreateDefaultBuilder();

    ASSERT_NE(builder, nullptr);

    ASSERT_TRUE(AddDefaultPartitions(builder.get()));

    unique_ptr<LpMetadata> exported = builder->Export();



    unique_fd fd(syscall(__NR_memfd_create, "image_file", 0));

    ASSERT_GE(fd, 0);

    ASSERT_TRUE(WriteToImageFile(fd, *exported.get()));



    int64_t offset = SeekFile64(fd, 0, SEEK_CUR);

    ASSERT_GE(offset, 0);

    ASSERT_EQ(SeekFile64(fd, 0, SEEK_SET), 0);



    size_t bytes = static_cast<size_t>(offset);

    std::unique_ptr<char[]> buffer = std::make_unique<char[]>(bytes);

    ASSERT_TRUE(android::base::ReadFully(fd, buffer.get(), bytes));

    ASSERT_NE(ReadFromImageBlob(buffer.get(), bytes), nullptr);

}



class BadWriter {

  public:

    // When requested, write garbage instead of the requested bytes, then

fs_mgr/liblp/reader.cpp

+27 −3
Original line number Diff line number Diff line
@@ -48,9 +48,27 @@ class FileReader final : public Reader { 
    int fd_;

};



// Parse an LpMetadataGeometry from a buffer. The buffer must be at least

// LP_METADATA_GEOMETRY_SIZE bytes in size.

static bool ParseGeometry(const void* buffer, LpMetadataGeometry* geometry) {

class MemoryReader final : public Reader {

  public:

    MemoryReader(const void* buffer, size_t size)

        : buffer_(reinterpret_cast<const uint8_t*>(buffer)), size_(size), pos_(0) {}

    bool ReadFully(void* out, size_t length) override {

        if (size_ - pos_ < length) {

            errno = EINVAL;

            return false;

        }

        memcpy(out, buffer_ + pos_, length);

        pos_ += length;

        return true;

    }



  private:

    const uint8_t* buffer_;

    size_t size_;

    size_t pos_;

};



bool ParseGeometry(const void* buffer, LpMetadataGeometry* geometry) {

    static_assert(sizeof(*geometry) <= LP_METADATA_GEOMETRY_SIZE);

    memcpy(geometry, buffer, sizeof(*geometry));
@@ -254,6 +272,12 @@ static std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geome 
    return metadata;

}



std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, const void* buffer,

                                          size_t size) {

    MemoryReader reader(buffer, size);

    return ParseMetadata(geometry, &reader);

}



std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, int fd) {

    FileReader reader(fd);

    return ParseMetadata(geometry, &reader);

fs_mgr/liblp/reader.h

+7 −2
Original line number Diff line number Diff line
@@ -26,11 +26,16 @@ 
namespace android {

namespace fs_mgr {



std::unique_ptr<LpMetadata> ReadMetadata(int fd, uint32_t slot_number);

// Parse an LpMetadataGeometry from a buffer. The buffer must be at least

// LP_METADATA_GEOMETRY_SIZE bytes in size.

bool ParseGeometry(const void* buffer, LpMetadataGeometry* geometry);



// Helper functions for manually reading geometry and metadata.

bool ReadLogicalPartitionGeometry(int fd, LpMetadataGeometry* geometry);

std::unique_ptr<LpMetadata> ReadMetadata(int fd, uint32_t slot_number);

std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, int fd);

std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, const void* buffer,

                                          size_t size);

bool ReadLogicalPartitionGeometry(int fd, LpMetadataGeometry* geometry);



// These functions assume a valid geometry and slot number.

std::unique_ptr<LpMetadata> ReadPrimaryMetadata(int fd, const LpMetadataGeometry& geometry,