lz4.cpp

QByteArray Firefox::parseJsonlz4RecoveryFilePath(const QString &recoveryFilePath)
{
    const char mozlz4_magic[] = {109, 111, 122, 76, 122, 52, 48, 0};  /* "mozLz40\0" */
    const int decomp_size = 4;  /* 4 bytes size come after the header */
    const size_t magic_size = sizeof mozlz4_magic;
    char *encryptedData = nullptr;
    char *decryptedData = nullptr;

    int readSize = 0;
    size_t outputBufferSize = 0;

    QFile f(recoveryFilePath);
    f.open(QIODevice::ReadOnly);
    QByteArray encryptedByteData = f.readAll();
    f.close();
    if (!encryptedByteData.isEmpty()) {
        encryptedData = encryptedByteData.data();
        readSize = encryptedByteData.size();
    } else {
        qDebug() << "[FirefoxUtils::parseJsonlz4RecoveryFilePath] Empty file";
        return QByteArray();
    }

    if (readSize < magic_size + decomp_size || memcmp(mozlz4_magic, encryptedData, magic_size) != 0) {
        qDebug() << "[FirefoxUtils::parseJsonlz4RecoveryFilePath] Unsupported file format: " + recoveryFilePath;
        return QByteArray();
    }

    size_t i = 0;
    for (i = magic_size; i < magic_size + decomp_size; i++) {
        outputBufferSize += (unsigned char) encryptedData[i] << (8 * (i - magic_size));
    }

    if (!(decryptedData = (char *) malloc(outputBufferSize))) {
        qDebug() << "[FirefoxUtils::parseJsonlz4RecoveryFilePath] Failed to allocate a buffer for an output.";
        return QByteArray();
    }

    int decryptedDataSize = LZ4_decompress_safe(encryptedData + i, decryptedData, (int) (readSize - i), (int) outputBufferSize);
    if (decryptedDataSize < 0) {
        qDebug() << "[FirefoxUtils::parseJsonlz4RecoveryFilePath] Failed to decompress a file: " + recoveryFilePath;
        free(decryptedData);
        return QByteArray();
    }
    QByteArray qDecryptedData = QByteArray(decryptedData);
    free(decryptedData);

    int indexOfLastProperChar = qDecryptedData.lastIndexOf(QLatin1String("}"));
    QByteArray cutData = qDecryptedData.left(indexOfLastProperChar + 1);

    //    qDebug() << "[FirefoxUtils::parseJsonlz4RecoveryFilePath] Successfully decompressed a file: " + recoveryFilePath;
    //    // Debug: write to a D:/fx.json file
    //    QString filename = "/home/karol/Documents/fx.json";
    //    QFile file(filename);
    //    if (file.open(QIODevice::ReadWrite)) {
    //        QTextStream stream(&file);
    //        stream << cutData;
    //    }
    return cutData;
}

sample.pro

HEADERS += \
    $$PWD/lz4/lib/lz4.h

SOURCES += \
    $$PWD/lz4/lib/lz4.c