assimp.assimp/code/Common/Compression.cpp

/*
Open Asset Import Library (assimp)
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  following disclaimer.

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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/

#include "Compression.h"
#include <assimp/ai_assert.h>
#include <assimp/Exceptional.h>

#ifdef ASSIMP_BUILD_NO_OWN_ZLIB
#include <zlib.h>
#else
#include "../contrib/zlib/zlib.h"
#endif

namespace Assimp {

struct Compression::impl {
    bool mOpen;
    z_stream mZSstream;

    impl() :
            mOpen(false) {}
};

Compression::Compression() :
        mImpl(new impl) {
    // empty
}

Compression::~Compression() {
    ai_assert(mImpl != nullptr);

    delete mImpl;
}

bool Compression::open(Format format) {
    ai_assert(mImpl != nullptr);

    if (mImpl->mOpen) {
        return false;
    }

    // build a zlib stream
    mImpl->mZSstream.opaque = Z_NULL;
    mImpl->mZSstream.zalloc = Z_NULL;
    mImpl->mZSstream.zfree = Z_NULL;
    if (format == Format::Binary) {
        mImpl->mZSstream.data_type = Z_BINARY;
    } else {
        mImpl->mZSstream.data_type = Z_ASCII;
    }

    // raw decompression without a zlib or gzip header
    inflateInit2(&mImpl->mZSstream, -MAX_WBITS);
    mImpl->mOpen = true;

    return mImpl->mOpen;
}

constexpr size_t MYBLOCK = 32786;

size_t Compression::decompress(const void *data, size_t in, std::vector<char> &uncompressed) {
    ai_assert(mImpl != nullptr);

    mImpl->mZSstream.next_in = (Bytef*)(data);
    mImpl->mZSstream.avail_in = (uInt)in;

    Bytef block[MYBLOCK] = {};
    int ret = 0;
    size_t total = 0l;
    do {
        mImpl->mZSstream.avail_out = MYBLOCK;
        mImpl->mZSstream.next_out = block;
        
        ret = inflate(&mImpl->mZSstream, Z_NO_FLUSH);

        if (ret != Z_STREAM_END && ret != Z_OK) {
            throw DeadlyImportError("Compression", "Failure decompressing this file using gzip.");

        }
        const size_t have = MYBLOCK - mImpl->mZSstream.avail_out;
        total += have;
        uncompressed.resize(total);
        ::memcpy(uncompressed.data() + total - have, block, have);
    } while (ret != Z_STREAM_END);

    return total;
}

size_t Compression::decompressBlock(const void *data, size_t in, char *out, size_t availableOut) {

    // push data to the stream
    mImpl->mZSstream.next_in = (Bytef *)data;
    mImpl->mZSstream.avail_in = (uInt)in;
    mImpl->mZSstream.next_out = (Bytef *)out;
    mImpl->mZSstream.avail_out = (uInt)availableOut;

    // and decompress the data ....
    int ret = ::inflate(&mImpl->mZSstream, Z_SYNC_FLUSH);
    if (ret != Z_OK && ret != Z_STREAM_END)
        throw DeadlyImportError("X: Failed to decompress MSZIP-compressed data");

    ::inflateReset(&mImpl->mZSstream);
    ::inflateSetDictionary(&mImpl->mZSstream, (const Bytef *)out, (uInt)availableOut - mImpl->mZSstream.avail_out);



    ::inflateReset(&mImpl->mZSstream);
    ::inflateSetDictionary(&mImpl->mZSstream, (const Bytef *)out, (uInt)availableOut - mImpl->mZSstream.avail_out);

    return availableOut - (size_t)mImpl->mZSstream.avail_out;
}

bool Compression::isOpen() const {
    ai_assert(mImpl != nullptr);

    return mImpl->mOpen;
}

bool Compression::close() {
    ai_assert(mImpl != nullptr);

    if (!mImpl->mOpen) {
        return false;
    }

    inflateEnd(&mImpl->mZSstream);
    mImpl->mOpen = false;

    return true;
}

} // namespace Assimp