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Commit 1eb3ea37 authored by David Anderson's avatar David Anderson
Browse files

liblp: Refactor ParseMetadata to read from non-descriptors. 

This is in preparation for "fastboot flash super", where we want to
verify the validity of a super image before writing it. To do so, we
need to parse the image from the download buffer, and it is useful to do
this from memory rather than a file descriptor.

Bug: 78793464
Test: liblp_test gtest
Change-Id: I7fb1ef4fdf2e8f1d93aea38f75626157fcb4bfc1
parent f1222908

fs_mgr/liblp/reader.cpp

+27 −3
Original line number Diff line number Diff line
@@ -30,6 +30,24 @@ 
namespace android {

namespace fs_mgr {



// Helper class for reading descriptors and memory buffers in the same manner.

class Reader {

  public:

    virtual ~Reader(){};

    virtual bool ReadFully(void* buffer, size_t length) = 0;

};



class FileReader final : public Reader {

  public:

    explicit FileReader(int fd) : fd_(fd) {}

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

        return android::base::ReadFully(fd_, buffer, length);

    }



  private:

    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) {
@@ -171,10 +189,11 @@ static bool ValidateMetadataHeader(const LpMetadataHeader& header) { 


// Parse and validate all metadata at the current position in the given file

// descriptor.

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

static std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry,

                                                 Reader* reader) {

    // First read and validate the header.

    std::unique_ptr<LpMetadata> metadata = std::make_unique<LpMetadata>();

    if (!android::base::ReadFully(fd, &metadata->header, sizeof(metadata->header))) {

    if (!reader->ReadFully(&metadata->header, sizeof(metadata->header))) {

        PERROR << __PRETTY_FUNCTION__ << "read " << sizeof(metadata->header) << "bytes failed";

        return nullptr;

    }
@@ -192,7 +211,7 @@ std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, in 
        LERROR << "Out of memory reading logical partition tables.";

        return nullptr;

    }

    if (!android::base::ReadFully(fd, buffer.get(), header.tables_size)) {

    if (!reader->ReadFully(buffer.get(), header.tables_size)) {

        PERROR << __PRETTY_FUNCTION__ << "read " << header.tables_size << "bytes failed";

        return nullptr;

    }
@@ -235,6 +254,11 @@ std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, in 
    return metadata;

}



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

    FileReader reader(fd);

    return ParseMetadata(geometry, &reader);

}



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

                                                uint32_t slot_number) {

    int64_t offset = GetPrimaryMetadataOffset(geometry, slot_number);