assimp/code/Common/Compression.cpp

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
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* Neither the name of the assimp team, nor the names of its
  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the assimp team.

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
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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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