deflate.cpp

Go to the documentation of this file.

/* xoreos - A reimplementation of BioWare's Aurora engine
 *
 * xoreos is the legal property of its developers, whose names
 * can be found in the AUTHORS file distributed with this source
 * distribution.
 *
 * xoreos is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 3
 * of the License, or (at your option) any later version.
 *
 * xoreos is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with xoreos. If not, see <http://www.gnu.org/licenses/>.
 */

#include <zlib.h>

#include <boost/scope_exit.hpp>

#include "src/common/deflate.h"
#include "src/common/error.h"
#include "src/common/scopedptr.h"
#include "src/common/ptrvector.h"
#include "src/common/memreadstream.h"

namespace Common {

static void setZStreamInput(z_stream &strm, size_t size, const byte *data) {
    /* Set the input data for the zlib data stream.
     *
     * This ugly const cast is necessary because the zlib API wants a non-const
     * next_in pointer by default. Unless we define ZLIB_CONST, but that only
     * appeared in zlib 1.2.5.3. Not really worth bumping our required zlib
     * version for, IMHO. */

    strm.avail_in = size;
    strm.next_in  = const_cast<byte *>(data);
}

static void initZStream(z_stream &strm, int windowBits, size_t size, const byte *data) {
    /* Initialize the zlib data stream for decompression with our input data. */

    strm.zalloc   = Z_NULL;
    strm.zfree    = Z_NULL;
    strm.opaque   = Z_NULL;

    setZStreamInput(strm, size, data);

    int zResult = inflateInit2(&strm, windowBits);
    if (zResult != Z_OK)
        throw Exception("Could not initialize zlib inflate: %s (%d)", zError(zResult), zResult);
}

byte *decompressDeflate(const byte *data, size_t inputSize,
                        size_t outputSize, int windowBits) {

    ScopedArray<byte> decompressedData(new byte[outputSize]);

    z_stream strm;
    BOOST_SCOPE_EXIT( (&strm) ) {
            inflateEnd(&strm);
    } BOOST_SCOPE_EXIT_END

    initZStream(strm, windowBits, inputSize, data);

    // Set the output data pointer and size
    strm.avail_out = outputSize;
    strm.next_out  = decompressedData.get();

    // Decompress. Z_FINISH, because we want to decompress the whole thing in one go.
    int zResult = inflate(&strm, Z_FINISH);

    // Was the end of the input stream correctly reached?
    if ((zResult != Z_STREAM_END) || (strm.avail_out != 0)) {
        if (zResult == Z_OK)
            throw Exception("Failed to inflate: premature end of output buffer");

        if (strm.avail_out != 0)
            throw Exception("Failed to inflate: output buffer not completely filled");

        throw Exception("Failed to inflate: %s (%d)", zError(zResult), zResult);
    }

    return decompressedData.release();
}

byte *decompressDeflateWithoutOutputSize(const byte *data, size_t inputSize, size_t &outputSize,
                                         int windowBits, unsigned int frameSize) {
    z_stream strm;
    BOOST_SCOPE_EXIT( (&strm) ) {
            inflateEnd(&strm);
    } BOOST_SCOPE_EXIT_END

    initZStream(strm, windowBits, inputSize, data);

    Common::PtrVector<byte, Common::DeallocatorArray> buffers;

    int zResult = 0;
    do {
        buffers.push_back(new byte[frameSize]);

        // Set the output data pointer and size
        strm.avail_out = frameSize;
        strm.next_out = buffers.back();

        // Decompress. Z_SYNC_FLUSH, because we want to decompress partwise.
        zResult = inflate(&strm, Z_SYNC_FLUSH);
        if (zResult != Z_STREAM_END && zResult != Z_OK)
            throw Exception("Failed to inflate: %s (%d)", zError(zResult), zResult);

    } while (zResult != Z_STREAM_END);

    ScopedArray<byte> decompressedData(new byte[strm.total_out]);
    for (size_t i = 0, size = strm.total_out; i < buffers.size(); ++i, size -= frameSize)
        std::memcpy(decompressedData.get() + i * frameSize, buffers[i], MIN<size_t>(size, frameSize));

    outputSize = strm.total_out;
    return decompressedData.release();
}

SeekableReadStream *decompressDeflate(ReadStream &input, size_t inputSize,
                                      size_t outputSize, int windowBits) {

    ScopedArray<byte> compressedData(new byte[inputSize]);
    if (input.read(compressedData.get(), inputSize) != inputSize)
        throw Exception(kReadError);

    const byte *decompressedData = decompressDeflate(compressedData.get(), inputSize, outputSize, windowBits);

    return new MemoryReadStream(decompressedData, outputSize, true);
}

SeekableReadStream *decompressDeflateWithoutOutputSize(ReadStream &input, size_t inputSize,
                                                       int windowBits, unsigned int frameSize) {
    ScopedArray<byte> compressedData(new byte[inputSize]);
    if (input.read(compressedData.get(), inputSize) != inputSize)
        throw Exception(kReadError);

    size_t size = 0;
    byte *decompressedData = decompressDeflateWithoutOutputSize(compressedData.get(), inputSize, size, windowBits, frameSize);

    return new MemoryReadStream(decompressedData, size, true);
}

size_t decompressDeflateChunk(SeekableReadStream &input, int windowBits,
                              byte *output, size_t outputSize, unsigned int frameSize) {

    z_stream strm;
    BOOST_SCOPE_EXIT( (&strm) ) {
            inflateEnd(&strm);
    } BOOST_SCOPE_EXIT_END

    initZStream(strm, windowBits, 0, 0);

    strm.avail_out = outputSize;
    strm.next_out  = output;

    ScopedArray<byte> inputData(new byte[frameSize]);

    /* As long as the zlib stream has not ended, the chunk end was not reached.
     * Read a frame from the input buffer and decompress. */

    int zResult = 0;
    do {
        if (strm.avail_in == 0) {
            const size_t inputSize = MIN<size_t>(input.size() - input.pos(), frameSize);
            if (inputSize == 0)
                throw Exception("Failed to inflate: input buffer empty, stream not ended");

            if (input.read(inputData.get(), inputSize) != inputSize)
                throw Exception(kReadError);

            setZStreamInput(strm, inputSize, inputData.get());
        }

        // Decompress. Z_SYNC_FLUSH, because we want to decompress partwise.
        zResult = inflate(&strm, Z_SYNC_FLUSH);
        if (zResult != Z_STREAM_END && zResult != Z_OK)
            throw Exception("Failed to inflate: %s (%d)", zError(zResult), zResult);

    } while (zResult != Z_STREAM_END);

    /* Since we don't know where the chunk ends beforehand, we probably have
     * read past the chunk. Now that we know where the zlib stream ends, we
     * know where the chunk ended, so we can seek back to that place. */
    input.seek(- static_cast<ptrdiff_t>(strm.avail_in), SeekableReadStream::kOriginCurrent);

    return strm.total_out;
}

} // End of namespace Common