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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 <strigi/gzipinputstream.h>
#include <strigi/strigiconfig.h>
#include <zlib.h>
#include <stdlib.h>
using namespace Strigi;
class GZipInputStream::Private {
public:
GZipInputStream* const p;
InputStream* input;
z_stream_s zstream;
bool started;
Private(GZipInputStream* gi, InputStream* input, ZipFormat format);
~Private();
void dealloc();
void readFromStream();
void decompressFromStream();
bool checkMagic();
};
GZipInputStream::GZipInputStream(InputStream* input, ZipFormat format)
:p(new Private(this, input, format)) {
}
bool
GZipInputStream::checkHeader(const char* data, int32_t datasize) {
return datasize>2 && (unsigned char)data[0]==0x1f && (unsigned char)data[1]==0x8b;
}
GZipInputStream::Private::Private(GZipInputStream* gi,
InputStream* i, ZipFormat format) :p(gi), input(i), started(false) {
// initialize values that signal state
p->m_status = Ok;
// check first bytes of stream before allocating buffer
if (format == GZIPFORMAT && !checkMagic()) {
p->m_error = "Magic bytes for gz are wrong.";
p->m_status = Error;
return;
}
// initialize the z_stream
zstream.zalloc = Z_NULL;
zstream.zfree = Z_NULL;
zstream.opaque = Z_NULL;
zstream.avail_in = 0;
zstream.next_in = Z_NULL;
// initialize for reading gzip streams
// for reading libz streams, you need inflateInit(zstream)
int r;
switch(format) {
case ZLIBFORMAT:
r = inflateInit(&zstream);
break;
case GZIPFORMAT:
r = inflateInit2(&zstream, 15+16);
break;
case ZIPFORMAT:
default:
r = inflateInit2(&zstream, -MAX_WBITS);
break;
}
started = true;
if (r != Z_OK) {
p->m_error = "Error initializing GZipInputStream.";
dealloc();
p->m_status = Error;
return;
}
// signal that we need to read into the buffer
zstream.avail_out = 1;
// initialize the buffer
p->setMinBufSize(262144);
}
GZipInputStream::~GZipInputStream() {
delete p;
}
GZipInputStream::Private::~Private() {
dealloc();
}
void
GZipInputStream::Private::dealloc() {
if (started) {
inflateEnd(&zstream);
started = false;
}
memset( &zstream, 0, sizeof( z_stream_s ) );
input = NULL;
}
bool
GZipInputStream::Private::checkMagic() {
const unsigned char* buf;
const char* begin;
int32_t nread;
int64_t pos = input->position();
nread = input->read(begin, 2, 2);
input->reset(pos);
if (nread != 2) {
return false;
}
buf = (const unsigned char*)begin;
return buf[0] == 0x1f && buf[1] == 0x8b;
}
void
GZipInputStream::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.assign("unexpected end of stream");
} else {
zstream.next_in = (Bytef*)inStart;
zstream.avail_in = nread;
}
}
int32_t
GZipInputStream::fillBuffer(char* start, int32_t space) {
if (p->input == NULL) return -1;
z_stream_s& zstream = p->zstream;
// make sure there is data to decompress
if (zstream.avail_out) {
p->readFromStream();
if (m_status == Error) {
// no data was read
return -1;
}
}
// make sure we can write into the buffer
zstream.avail_out = space;
zstream.next_out = (Bytef*)start;
// decompress
int r = inflate(&zstream, Z_SYNC_FLUSH);
// inform the buffer of the number of bytes that was read
int32_t nwritten = space - zstream.avail_out;
switch (r) {
case Z_NEED_DICT:
m_error.assign("Z_NEED_DICT while inflating stream.");
m_status = Error;
break;
case Z_DATA_ERROR:
m_error.assign("Z_DATA_ERROR while inflating stream.");
m_status = Error;
break;
case Z_MEM_ERROR:
m_error.assign("Z_MEM_ERROR while inflating stream.");
m_status = Error;
break;
case Z_STREAM_END:
if (zstream.avail_in) {
p->input->reset(p->input->position()-zstream.avail_in);
}
// we are finished decompressing,
// (but this stream is not yet finished)
p->dealloc();
}
return nwritten;
}
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