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Diffstat (limited to 'decoder.cc')
| -rw-r--r-- | decoder.cc | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/decoder.cc b/decoder.cc new file mode 100644 index 0000000..345d02b --- /dev/null +++ b/decoder.cc @@ -0,0 +1,300 @@ +/* Lziprecover - Data recovery tool for the lzip format + Copyright (C) 2009-2022 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" + + +const CRC32 crc32; + + +/* Return the number of bytes really read. + If (value returned < size) and (errno == 0), means EOF was reached. +*/ +long long readblock( const int fd, uint8_t * const buf, const long long size ) + { + long long sz = 0; + errno = 0; + while( sz < size ) + { + const int n = read( fd, buf + sz, std::min( 1LL << 20, 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. +*/ +long long writeblock( const int fd, const uint8_t * const buf, + const long long size ) + { + long long sz = 0; + errno = 0; + while( sz < size ) + { + const int n = write( fd, buf + sz, std::min( 1LL << 20, 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 ) + { + 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 >= dictionary_size ) + { partial_data_pos += pos; pos = 0; pos_wrapped = true; } + stream_pos = pos; + } + } + + +bool LZ_decoder::verify_trailer( const Pretty_print & pp ) const + { + Lzip_trailer trailer; + int size = rdec.read_data( trailer.data, Lzip_trailer::size ); + const unsigned long long data_size = data_position(); + const unsigned long long member_size = rdec.member_position(); + bool error = false; + + if( size < Lzip_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 < Lzip_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 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 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 false; + 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 ); + } + if( rdec.get_code() != 0 && verbosity >= 1 ) + { // corruption in the last 4 bytes of the EOS marker + pp(); + std::fprintf( stderr, "Range decoder final code is %08X\n", rdec.get_code() ); + } + return true; + } + + +/* 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[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; + + 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 + { + // 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 + { + if( verify_trailer( pp ) ) return 0; else return 3; + } + 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; + } |