assimp.assimp/code/Common/Compression.cpp

/*
Open Asset Import Library (assimp)
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  copyright notice, this list of conditions and the
  following disclaimer.

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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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*/

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

namespace Assimp {

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

    impl() :
            mOpen(false),
            mZSstream(),
            mFlushMode(Compression::FlushMode::NoFlush) {
        // empty
    }
};

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

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

    if (mImpl->mOpen) {
        close();
    }

    delete mImpl;
}

bool Compression::open(Format format, FlushMode flush, int windowBits) {
    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;
    mImpl->mFlushMode = flush;
    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
    if (windowBits == 0) {
        inflateInit(&mImpl->mZSstream);
    } else {
        inflateInit2(&mImpl->mZSstream, windowBits);
    }
    mImpl->mOpen = true;

    return mImpl->mOpen;
}

static int getFlushMode(Compression::FlushMode flush) {
    int z_flush = 0;
    switch (flush) {
        case Compression::FlushMode::NoFlush:
            z_flush = Z_NO_FLUSH;
            break;
        case Compression::FlushMode::Block:
            z_flush = Z_BLOCK;
            break;
        case Compression::FlushMode::Tree:
            z_flush = Z_TREES;
            break;
        case Compression::FlushMode::SyncFlush:
            z_flush = Z_SYNC_FLUSH;
            break;
        case Compression::FlushMode::Finish:
            z_flush = Z_FINISH;
            break;
        default:
            ai_assert(false);
            break;
    }

    return z_flush;
}

static constexpr size_t MYBLOCK = 32786;

size_t Compression::decompress(const void *data, size_t in, std::vector<char> &uncompressed) {
    ai_assert(mImpl != nullptr);
    if (data == nullptr || in == 0) {
        return 0l;
    }

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

    int ret = 0;
    size_t total = 0l;
    const int flushMode = getFlushMode(mImpl->mFlushMode);
    if (flushMode == Z_FINISH) {
        mImpl->mZSstream.avail_out = static_cast<uInt>(uncompressed.size());
        mImpl->mZSstream.next_out = reinterpret_cast<Bytef *>(&*uncompressed.begin());
        ret = inflate(&mImpl->mZSstream, Z_FINISH);

        if (ret != Z_STREAM_END && ret != Z_OK) {
            throw DeadlyImportError("Compression", "Failure decompressing this file using gzip.");
        }
        total = mImpl->mZSstream.avail_out;
    } else {
        do {
            Bytef block[MYBLOCK] = {};
            mImpl->mZSstream.avail_out = MYBLOCK;
            mImpl->mZSstream.next_out = block;

            ret = inflate(&mImpl->mZSstream, flushMode);

            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) {
    ai_assert(mImpl != nullptr);
    if (data == nullptr || in == 0 || out == nullptr || availableOut == 0) {
        return 0l;
    }

    // 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);

    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