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lzip/decoder.cc

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/* Lzip - LZMA lossless data compressor
Copyright (C) 2008-2024 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 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, 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"
/* Return the number of bytes really read.
If (value returned < size) and (errno == 0), means EOF was reached.
*/
int readblock( const int fd, uint8_t * const buf, const int size )
{
int sz = 0;
errno = 0;
while( sz < size )
{
const int n = read( fd, buf + sz, size - sz );
if( n > 0 ) sz += n;
else if( n == 0 ) break; // EOF
else if( errno != EINTR ) break;
errno = 0;
}
return sz;
}
/* Return the number of bytes really written.
If (value returned < size), it is always an error.
*/
int writeblock( const int fd, const uint8_t * const buf, const int size )
{
int sz = 0;
errno = 0;
while( sz < size )
{
const int n = write( fd, buf + sz, size - sz );
if( n > 0 ) sz += n;
else if( n < 0 && errno != EINTR ) break;
errno = 0;
}
return sz;
}
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;
show_dprogress();
}
return pos < stream_pos;
}
void LZ_decoder::flush_data()
{
if( pos > stream_pos )
{
const int size = pos - stream_pos;
crc32.update_buf( crc_, buffer + stream_pos, size );
if( outfd >= 0 && writeblock( outfd, buffer + stream_pos, size ) != size )
throw Error( "Write error" );
if( pos >= dictionary_size )
{ partial_data_pos += pos; pos = 0; pos_wrapped = true; }
stream_pos = pos;
}
}
int LZ_decoder::check_trailer( const Pretty_print & pp,
const bool ignore_empty ) const
{
Lzip_trailer trailer;
int size = rdec.read_data( trailer.data, trailer.size );
bool error = false;
if( size < trailer.size )
{
error = true;
if( 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;
}
const unsigned td_crc = trailer.data_crc();
if( td_crc != crc() )
{
error = true;
if( verbosity >= 0 )
{ pp();
std::fprintf( stderr, "CRC mismatch; stored %08X, computed %08X\n",
td_crc, crc() ); }
}
const unsigned long long data_size = data_position();
const unsigned long long td_size = trailer.data_size();
if( td_size != data_size )
{
error = true;
if( verbosity >= 0 )
{ pp();
std::fprintf( stderr, "Data size mismatch; stored %llu (0x%llX), computed %llu (0x%llX)\n",
td_size, td_size, data_size, data_size ); }
}
const unsigned long long member_size = rdec.member_position();
const unsigned long long tm_size = trailer.member_size();
if( tm_size != member_size )
{
error = true;
if( verbosity >= 0 )
{ pp();
std::fprintf( stderr, "Member size mismatch; stored %llu (0x%llX), computed %llu (0x%llX)\n",
tm_size, tm_size, member_size, member_size ); }
}
if( error ) return 3;
if( !ignore_empty && data_size == 0 ) return 5;
if( verbosity >= 2 )
{
if( verbosity >= 4 ) show_header( dictionary_size );
if( data_size == 0 || member_size == 0 )
std::fputs( "no data compressed. ", stderr );
else
std::fprintf( stderr, "%6.3f:1, %5.2f%% ratio, %5.2f%% saved. ",
(double)data_size / member_size,
( 100.0 * member_size ) / data_size,
100.0 - ( ( 100.0 * member_size ) / data_size ) );
if( verbosity >= 4 ) std::fprintf( stderr, "CRC %08X, ", td_crc );
if( verbosity >= 3 )
std::fprintf( stderr, "%9llu out, %8llu in. ", data_size, member_size );
}
return 0;
}
/* Return value: 0 = OK, 1 = decoder error, 2 = unexpected EOF,
3 = trailer error, 4 = unknown marker found,
5 = empty member found, 6 = marked member found. */
int LZ_decoder::decode_member( const Cl_options & cl_opts,
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[len_states][1<<dis_slot_bits];
Bit_model bm_dis[modeled_distances-end_dis_model+1];
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;
if( !rdec.load( cl_opts.ignore_marking ) ) return 6;
while( !rdec.finished() )
{
const int pos_state = data_position() & pos_state_mask;
if( rdec.decode_bit( bm_match[state()][pos_state] ) == 0 ) // 1st bit
{
// literal byte
Bit_model * const bm = bm_literal[get_lit_state(peek_prev())];
if( state.is_char_set_char() )
put_byte( rdec.decode_tree8( bm ) );
else
put_byte( rdec.decode_matched( bm, peek( rep0 ) ) );
continue;
}
// match or repeated match
int len;
if( rdec.decode_bit( bm_rep[state()] ) != 0 ) // 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( peek( 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;
}
state.set_rep();
len = rdec.decode_len( rep_len_model, pos_state );
}
else // match
{
len = rdec.decode_len( match_len_model, pos_state );
unsigned distance = rdec.decode_tree6( bm_dis_slot[get_len_state(len)] );
if( distance >= start_dis_model )
{
const unsigned dis_slot = distance;
const int direct_bits = ( dis_slot >> 1 ) - 1;
distance = ( 2 | ( dis_slot & 1 ) ) << direct_bits;
if( dis_slot < end_dis_model )
distance += rdec.decode_tree_reversed(
bm_dis + ( distance - dis_slot ), direct_bits );
else
{
distance +=
rdec.decode( direct_bits - dis_align_bits ) << dis_align_bits;
distance += rdec.decode_tree_reversed4( bm_align );
if( distance == 0xFFFFFFFFU ) // marker found
{
rdec.normalize();
flush_data();
if( len == min_match_len ) // End Of Stream marker
return check_trailer( pp, cl_opts.ignore_empty );
if( len == min_match_len + 1 ) // Sync Flush marker
{ rdec.load(); continue; }
if( verbosity >= 0 )
{
pp();
std::fprintf( stderr, "Unsupported marker code '%d'\n", len );
}
return 4;
}
}
}
rep3 = rep2; rep2 = rep1; rep1 = rep0; rep0 = distance;
state.set_match();
if( rep0 >= dictionary_size || ( rep0 >= pos && !pos_wrapped ) )
{ flush_data(); return 1; }
}
copy_block( rep0, len );
}
flush_data();
return 2;
}
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