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strigi/src/streams

bz2inputstream.cpp

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/* This file is part of Strigi Desktop Search
 *
 * Copyright (C) 2006 Jos van den Oever <jos@vandenoever.info>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */
#include "bz2inputstream.h"
#include <bzlib.h>
#include <stdlib.h>
#include <cstring>

using namespace Strigi;

class BZ2InputStream::Private {
public:
    BZ2InputStream* const p;
    InputStream *input;
    bz_stream* bzstream;
    bool allocatedBz;

    Private(BZ2InputStream* p, InputStream* i);
    ~Private();
    void dealloc();
    void readFromStream();
    bool checkMagic();
};
bool
BZ2InputStream::checkHeader(const char* data, int32_t datasize) {
    static const char magic[] = {0x42, 0x5a};
    static const char compressed_magic[] = {0x31, 0x41, 0x59, 0x26, 0x53, 0x59};
    if (datasize < 10) return false;
    return (std::memcmp(data, magic, 2) == 0
            && (data[2] == 0x68 || data[2] == 0x30)
            && std::memcmp(data + 4, compressed_magic, 6) == 0);
}
BZ2InputStream::BZ2InputStream(InputStream* input) :p(new Private(this, input)){
}
BZ2InputStream::Private::Private(BZ2InputStream* bis, InputStream* i)
        :p(bis), input(i) {
    // initialize values that signal state
    this->input = input;

    // check first bytes of stream before allocating buffer
    if (!checkMagic()) {
        p->m_error = "Magic bytes for bz2 are wrong.";
        p->m_status = Error;
        allocatedBz = false;
        return;
    }

    bzstream = (bz_stream*)malloc(sizeof(bz_stream));
    bzstream->bzalloc = NULL;
    bzstream->bzfree = NULL;
    bzstream->opaque = NULL;
    bzstream->avail_in = 0;
    bzstream->next_in = NULL;
    int r;
    r = BZ2_bzDecompressInit(bzstream, 1, 0);
    if (r != BZ_OK) {
        p->m_error = "Error initializing BZ2InputStream.";
        fprintf(stderr, "Error initializing BZ2InputStream.\n");
        dealloc();
        p->m_status = Error;
        return;
    }
    allocatedBz = true;
    // signal that we need to read into the buffer
    bzstream->avail_out = 1;

    // set the minimum size for the output buffer
    p->setMinBufSize(262144);
}
BZ2InputStream::~BZ2InputStream() {
    delete p;
}
BZ2InputStream::Private::~Private() {
    dealloc();
}
void
BZ2InputStream::Private::dealloc() {
    if (allocatedBz) {
        BZ2_bzDecompressEnd(bzstream);
        free(bzstream);
        bzstream = 0;
    }
}
bool
BZ2InputStream::Private::checkMagic() {
    const char* begin;
    int32_t nread;

    int64_t pos = input->position();
    nread = input->read(begin, 10, 0);
    input->reset(pos);
    if (nread < 10) {
        return false;
    }

    return checkHeader(begin, 10);
}
void
BZ2InputStream::Private::readFromStream() {
    // read data from the input stream
    const char* inStart;
    int32_t nread;
    nread = input->read(inStart, 1, 0);
    if (nread <= -1) {
        p->m_status = Error;
        p->m_error = input->error();
    } else if (nread < 1) {
        p->m_status = Error;
        p->m_error = "unexpected end of stream";
    } else {
        bzstream->next_in = (char*)inStart;
        bzstream->avail_in = nread;
    }
}
int32_t
BZ2InputStream::fillBuffer(char* start, int32_t space) {
    bz_stream* bzstream = p->bzstream;
    if (bzstream == 0) return -1;
    // make sure there is data to decompress
    if (bzstream->avail_out != 0) {
        p->readFromStream();
        if (m_status != Ok) {
            // no data was read
            return -1;
        }
    }
    // make sure we can write into the buffer
    bzstream->avail_out = space;
    bzstream->next_out = start;
    // decompress
    int r = BZ2_bzDecompress(bzstream);
    // inform the buffer of the number of bytes that was read
    int32_t nwritten = space - bzstream->avail_out;
    switch (r) {
    case BZ_PARAM_ERROR:
        m_error = "BZ_PARAM_ERROR";
        m_status = Error;
        return -1;
    case BZ_DATA_ERROR:
        m_error = "BZ_DATA_ERROR";
        m_status = Error;
        return -1;
    case BZ_DATA_ERROR_MAGIC:
        m_error = "BZ_DATA_ERROR_MAGIC";
        m_status = Error;
        return -1;
    case BZ_MEM_ERROR:
        m_error = "BZ_MEM_ERROR";
        m_status = Error;
        return -1;
    case BZ_STREAM_END:
        if (bzstream->avail_in) {
            p->input->reset(p->input->position()-bzstream->avail_in);
        }
        // we are finished decompressing,
        // (but this stream is not yet finished)
        p->dealloc();
    }
    return nwritten;
}

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