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lziprecover/decoder.cc

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/* Lziprecover - Data recovery tool for lzipped files
Copyright (C) 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz.
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#define _FILE_OFFSET_BITS 64
#include <algorithm>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <stdint.h>
#include <unistd.h>
#include "lzip.h"
#include "decoder.h"
const CRC32 crc32;
void Pretty_print::operator()( const char * const msg, FILE * const f ) const
{
if( verbosity_ >= 0 )
{
if( first_post )
{
first_post = false;
std::fprintf( f, " %s: ", name_.c_str() );
for( unsigned i = 0; i < longest_name - name_.size(); ++i )
std::fprintf( f, " " );
if( !msg ) std::fflush( f );
}
if( msg ) std::fprintf( f, "%s.\n", msg );
}
}
// Returns the number of bytes really read.
// If (returned value < size) and (errno == 0), means EOF was reached.
//
int readblock( const int fd, uint8_t * const buf, const int size )
{
int rest = size;
errno = 0;
while( rest > 0 )
{
const int n = read( fd, buf + size - rest, rest );
if( n > 0 ) rest -= n;
else if( n == 0 ) break; // EOF
else if( errno != EINTR && errno != EAGAIN ) break;
errno = 0;
}
return size - rest;
}
// Returns the number of bytes really written.
// If (returned value < size), it is always an error.
//
int writeblock( const int fd, const uint8_t * const buf, const int size )
{
int rest = size;
errno = 0;
while( rest > 0 )
{
const int n = write( fd, buf + size - rest, rest );
if( n > 0 ) rest -= n;
else if( n < 0 && errno != EINTR && errno != EAGAIN ) break;
errno = 0;
}
return size - rest;
}
bool Range_decoder::read_block()
{
if( !at_stream_end )
{
stream_pos = readblock( infd, buffer, buffer_size );
if( stream_pos != buffer_size && errno ) throw Error( "Read error" );
at_stream_end = ( stream_pos < buffer_size );
partial_member_pos += pos;
pos = 0;
}
return pos < stream_pos;
}
void LZ_decoder::flush_data()
{
const int size = pos - stream_pos;
if( size > 0 )
{
crc32.update( crc_, buffer + stream_pos, size );
if( outfd >= 0 )
{
const unsigned long long sp = stream_position();
const long long i = positive_diff( outskip, sp );
const long long s =
std::min( positive_diff( outend, sp ), (unsigned long long)size ) - i;
if( s > 0 && writeblock( outfd, buffer + stream_pos + i, s ) != s )
throw Error( "Write error" );
}
if( pos >= buffer_size ) { partial_data_pos += pos; pos = 0; }
stream_pos = pos;
}
}
bool LZ_decoder::verify_trailer( const Pretty_print & pp ) const
{
File_trailer trailer;
const int trailer_size = File_trailer::size;
const unsigned long long member_size =
rdec.member_position() + trailer_size;
bool error = false;
int size = rdec.read_data( trailer.data, trailer_size );
if( size < trailer_size )
{
error = true;
if( pp.verbosity() >= 0 )
{
pp();
std::fprintf( stderr, "Trailer truncated at trailer position %d;"
" some checks may fail.\n", size );
}
while( size < trailer_size ) trailer.data[size++] = 0;
}
if( !rdec.code_is_zero() )
{
error = true;
pp( "Range decoder final code is not zero" );
}
if( trailer.data_crc() != crc() )
{
error = true;
if( pp.verbosity() >= 0 )
{
pp();
std::fprintf( stderr, "CRC mismatch; trailer says %08X, data CRC is %08X.\n",
trailer.data_crc(), crc() );
}
}
if( trailer.data_size() != data_position() )
{
error = true;
if( pp.verbosity() >= 0 )
{
pp();
std::fprintf( stderr, "Data size mismatch; trailer says %llu, data size is %llu (0x%llX).\n",
trailer.data_size(), data_position(), data_position() );
}
}
if( trailer.member_size() != member_size )
{
error = true;
if( pp.verbosity() >= 0 )
{
pp();
std::fprintf( stderr, "Member size mismatch; trailer says %llu, member size is %llu (0x%llX).\n",
trailer.member_size(), member_size, member_size );
}
}
if( !error && pp.verbosity() >= 2 && data_position() > 0 && member_size > 0 )
std::fprintf( stderr, "%6.3f:1, %6.3f bits/byte, %5.2f%% saved. ",
(double)data_position() / member_size,
( 8.0 * member_size ) / data_position(),
100.0 * ( 1.0 - ( (double)member_size / data_position() ) ) );
if( !error && pp.verbosity() >= 4 )
std::fprintf( stderr, "data CRC %08X, data size %9llu, member size %8llu. ",
trailer.data_crc(), trailer.data_size(), trailer.member_size() );
return !error;
}
// Return value: 0 = OK, 1 = decoder error, 2 = unexpected EOF,
// 3 = trailer error, 4 = unknown marker found.
int LZ_decoder::decode_member( const Pretty_print & pp )
{
Bit_model bm_literal[1<<literal_context_bits][0x300];
Bit_model bm_match[State::states][pos_states];
Bit_model bm_rep[State::states];
Bit_model bm_rep0[State::states];
Bit_model bm_rep1[State::states];
Bit_model bm_rep2[State::states];
Bit_model bm_len[State::states][pos_states];
Bit_model bm_dis_slot[max_dis_states][1<<dis_slot_bits];
Bit_model bm_dis[modeled_distances-end_dis_model];
Bit_model bm_align[dis_align_size];
Len_model match_len_model;
Len_model rep_len_model;
unsigned rep0 = 0; // rep[0-3] latest four distances
unsigned rep1 = 0; // used for efficient coding of
unsigned rep2 = 0; // repeated distances
unsigned rep3 = 0;
State state;
rdec.load();
while( !rdec.finished() )
{
const int pos_state = data_position() & pos_state_mask;
if( rdec.decode_bit( bm_match[state()][pos_state] ) == 0 ) // 1st bit
{
const uint8_t prev_byte = get_prev_byte();
if( state.is_char() )
put_byte( rdec.decode_tree( bm_literal[get_lit_state(prev_byte)], 8 ) );
else
put_byte( rdec.decode_matched( bm_literal[get_lit_state(prev_byte)],
get_byte( rep0 ) ) );
state.set_char();
}
else
{
int len;
if( rdec.decode_bit( bm_rep[state()] ) == 1 ) // 2nd bit
{
if( rdec.decode_bit( bm_rep0[state()] ) == 0 ) // 3rd bit
{
if( rdec.decode_bit( bm_len[state()][pos_state] ) == 0 ) // 4th bit
{ state.set_short_rep(); put_byte( get_byte( rep0 ) ); continue; }
}
else
{
unsigned distance;
if( rdec.decode_bit( bm_rep1[state()] ) == 0 ) // 4th bit
distance = rep1;
else
{
if( rdec.decode_bit( bm_rep2[state()] ) == 0 ) // 5th bit
distance = rep2;
else
{ distance = rep3; rep3 = rep2; }
rep2 = rep1;
}
rep1 = rep0;
rep0 = distance;
}
len = min_match_len + rdec.decode_len( rep_len_model, pos_state );
state.set_rep();
}
else
{
const unsigned rep0_saved = rep0;
len = min_match_len + rdec.decode_len( match_len_model, pos_state );
const int dis_slot = rdec.decode_tree6( bm_dis_slot[get_dis_state(len)] );
if( dis_slot < start_dis_model ) rep0 = dis_slot;
else
{
const int direct_bits = ( dis_slot >> 1 ) - 1;
rep0 = ( 2 | ( dis_slot & 1 ) ) << direct_bits;
if( dis_slot < end_dis_model )
rep0 += rdec.decode_tree_reversed( bm_dis + rep0 - dis_slot - 1,
direct_bits );
else
{
rep0 += rdec.decode( direct_bits - dis_align_bits ) << dis_align_bits;
rep0 += rdec.decode_tree_reversed4( bm_align );
if( rep0 == 0xFFFFFFFFU ) // Marker found
{
rep0 = rep0_saved;
rdec.normalize();
flush_data();
if( len == min_match_len ) // End Of Stream marker
{
if( verify_trailer( pp ) ) return 0; else return 3;
}
if( len == min_match_len + 1 ) // Sync Flush marker
{
rdec.load(); continue;
}
if( pp.verbosity() >= 0 )
{
pp();
std::fprintf( stderr, "Unsupported marker code '%d'.\n", len );
}
return 4;
}
}
}
rep3 = rep2; rep2 = rep1; rep1 = rep0_saved;
state.set_match();
if( rep0 >= (unsigned)dictionary_size ||
( rep0 >= (unsigned)pos && !partial_data_pos ) )
{ flush_data(); return 1; }
}
copy_block( rep0, len );
}
}
flush_data();
return 2;
}