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/** @file
* @brief class wrapper around zlib
*/
/* Copyright (C) 2007,2009,2012,2013,2014,2016,2019 Olly Betts
* Copyright (C) 2009 Richard Boulton
* Copyright (C) 2012 Dan Colish
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <config.h>
#include "compression_stream.h"
#include "omassert.h"
#include "str.h"
#include "stringutils.h"
#include "xapian/error.h"
using namespace std;
CompressionStream::~CompressionStream() {
if (deflate_zstream) {
// Errors which we care about have already been handled, so just ignore
// any which get returned here.
(void) deflateEnd(deflate_zstream);
delete deflate_zstream;
}
if (inflate_zstream) {
// Errors which we care about have already been handled, so just ignore
// any which get returned here.
(void) inflateEnd(inflate_zstream);
delete inflate_zstream;
}
delete [] out;
}
const char*
CompressionStream::compress(const char* buf, size_t* p_size) {
lazy_alloc_deflate_zstream();
size_t size = *p_size;
if (!out || out_len < size) {
out_len = size;
delete [] out;
out = NULL;
out = new char[size];
}
deflate_zstream->avail_in = static_cast<uInt>(size);
deflate_zstream->next_in =
reinterpret_cast<Bytef*>(const_cast<char*>(buf));
deflate_zstream->next_out = reinterpret_cast<Bytef*>(out);
// Specify the output buffer size as being the size of the input so zlib
// will give up once it discovers it can't compress (while it might seem
// we could pass a buffer one byte smaller, in fact that doesn't actually
// work and results in us rejecting cases that compress saving one byte).
deflate_zstream->avail_out = static_cast<uInt>(size);
int zerr = deflate(deflate_zstream, Z_FINISH);
if (zerr != Z_STREAM_END) {
// Deflate failed - presumably the data wasn't compressible.
return NULL;
}
if (deflate_zstream->total_out >= size) {
// It didn't get smaller.
return NULL;
}
*p_size = deflate_zstream->total_out;
return out;
}
bool
CompressionStream::decompress_chunk(const char* p, int len, string& buf)
{
Bytef blk[8192];
inflate_zstream->next_in =
reinterpret_cast<Bytef*>(const_cast<char*>(p));
inflate_zstream->avail_in = static_cast<uInt>(len);
while (true) {
inflate_zstream->next_out = blk;
inflate_zstream->avail_out = static_cast<uInt>(sizeof(blk));
int err = inflate(inflate_zstream, Z_SYNC_FLUSH);
if (err != Z_OK && err != Z_STREAM_END) {
if (err == Z_MEM_ERROR) throw std::bad_alloc();
string msg = "inflate failed";
if (inflate_zstream->msg) {
msg += " (";
msg += inflate_zstream->msg;
msg += ')';
}
throw Xapian::DatabaseError(msg);
}
buf.append(reinterpret_cast<const char*>(blk),
inflate_zstream->next_out - blk);
if (err == Z_STREAM_END) return true;
if (inflate_zstream->avail_in == 0) return false;
}
}
void
CompressionStream::lazy_alloc_deflate_zstream() {
if (usual(deflate_zstream)) {
if (usual(deflateReset(deflate_zstream) == Z_OK)) return;
// Try to recover by deleting the stream and starting from scratch.
delete deflate_zstream;
}
deflate_zstream = new z_stream;
deflate_zstream->zalloc = reinterpret_cast<alloc_func>(0);
deflate_zstream->zfree = reinterpret_cast<free_func>(0);
deflate_zstream->opaque = static_cast<voidpf>(0);
// -15 means raw deflate with 32K LZ77 window (largest)
// memLevel 9 is the highest (8 is default)
int err = deflateInit2(deflate_zstream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
-15, 9, compress_strategy);
if (rare(err != Z_OK)) {
if (err == Z_MEM_ERROR) {
delete deflate_zstream;
deflate_zstream = 0;
throw std::bad_alloc();
}
string msg = "deflateInit2 failed (";
if (deflate_zstream->msg) {
msg += deflate_zstream->msg;
} else {
msg += str(err);
}
msg += ')';
delete deflate_zstream;
deflate_zstream = 0;
throw Xapian::DatabaseError(msg);
}
}
void
CompressionStream::lazy_alloc_inflate_zstream() {
if (usual(inflate_zstream)) {
if (usual(inflateReset(inflate_zstream) == Z_OK)) return;
// Try to recover by deleting the stream and starting from scratch.
delete inflate_zstream;
}
inflate_zstream = new z_stream;
inflate_zstream->zalloc = reinterpret_cast<alloc_func>(0);
inflate_zstream->zfree = reinterpret_cast<free_func>(0);
inflate_zstream->next_in = Z_NULL;
inflate_zstream->avail_in = 0;
int err = inflateInit2(inflate_zstream, -15);
if (rare(err != Z_OK)) {
if (err == Z_MEM_ERROR) {
delete inflate_zstream;
inflate_zstream = 0;
throw std::bad_alloc();
}
string msg = "inflateInit2 failed (";
if (inflate_zstream->msg) {
msg += inflate_zstream->msg;
} else {
msg += str(err);
}
msg += ')';
delete inflate_zstream;
inflate_zstream = 0;
throw Xapian::DatabaseError(msg);
}
}
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