Method ParseMagicToken

code/AssetLib/Blender/BlenderLoader.cpp:1290–1339

}

BlenderImporter::StreamOrError BlenderImporter::ParseMagicToken(const std::string &pFile, IOSystem *pIOHandler) const {
    std::shared_ptr<IOStream> stream(pIOHandler->Open(pFile, "rb"));
    if (stream == nullptr) {
        return {{}, {}, "Could not open file for reading"};
    }

    char magic[8] = { 0 };
    stream->Read(magic, 7, 1);
    if (strcmp(magic, Token) == 0) {
        return {stream, {}, {}};
    }

    // Check for presence of the gzip header. If yes, assume it is a
    // compressed blend file and try uncompressing it, else fail. This is to
    // avoid uncompressing random files which our loader might end up with.
#ifdef ASSIMP_BUILD_NO_COMPRESSED_BLEND
    return {{}, {}, "BLENDER magic bytes are missing, is this file compressed (Assimp was built without decompression support)?"};
#else
    if (magic[0] != 0x1f || static_cast<uint8_t>(magic[1]) != 0x8b) {
        return {{}, {}, "BLENDER magic bytes are missing, couldn't find GZIP header either"};
    }

    LogDebug("Found no BLENDER magic word but a GZIP header, might be a compressed file");
    if (magic[2] != 8) {
        return {{}, {}, "Unsupported GZIP compression method"};
    }

    // http://www.gzip.org/zlib/rfc-gzip.html#header-trailer
    stream->Seek(0L, aiOrigin_SET);
    std::shared_ptr<StreamReaderLE> reader = std::shared_ptr<StreamReaderLE>(new StreamReaderLE(stream));

    size_t total = 0;
    Compression compression;
    auto uncompressed = std::make_shared<std::vector<char>>();
    if (compression.open(Compression::Format::Binary, Compression::FlushMode::NoFlush, 16 + Compression::MaxWBits)) {
        total = compression.decompress((unsigned char *)reader->GetPtr(), reader->GetRemainingSize(), *uncompressed);
        compression.close();
    }

    // replace the input stream with a memory stream
    stream = std::make_shared<MemoryIOStream>(reinterpret_cast<uint8_t *>(uncompressed->data()), total);

    // .. and retry
    stream->Read(magic, 7, 1);
    if (strcmp(magic, Token) == 0) {
        return {stream, uncompressed, {}};
    }
    return {{}, {}, "Found no BLENDER magic word in decompressed GZIP file"};
#endif
}

#endif // ASSIMP_BUILD_NO_BLEND_IMPORTER