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Diffstat (limited to 'decoder.cc')
| -rw-r--r-- | decoder.cc | 310 |
1 files changed, 310 insertions, 0 deletions
diff --git a/decoder.cc b/decoder.cc new file mode 100644 index 0000000..b9fc3d8 --- /dev/null +++ b/decoder.cc @@ -0,0 +1,310 @@ +/* Lziprecover - Data recovery tool for lzipped files + Copyright (C) 2009, 2010, 2011 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 ) const throw() + { + if( verbosity_ >= 0 ) + { + if( first_post ) + { + first_post = false; + std::fprintf( stderr, " %s: ", name_.c_str() ); + for( unsigned int i = 0; i < longest_name - name_.size(); ++i ) + std::fprintf( stderr, " " ); + if( !msg ) std::fflush( stderr ); + } + if( msg ) std::fprintf( stderr, "%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 ) throw() + { + int rest = size; + errno = 0; + while( rest > 0 ) + { + errno = 0; + const int n = read( fd, buf + size - rest, rest ); + if( n > 0 ) rest -= n; + else if( n == 0 ) break; + else if( errno != EINTR && errno != EAGAIN ) break; + } + return ( rest > 0 ) ? size - rest : size; + } + + +// 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 ) throw() + { + int rest = size; + errno = 0; + while( rest > 0 ) + { + errno = 0; + const int n = write( fd, buf + size - rest, rest ); + if( n > 0 ) rest -= n; + else if( errno && errno != EINTR && errno != EAGAIN ) break; + } + return ( rest > 0 ) ? size - rest : size; + } + + +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 && + writeblock( outfd, buffer + stream_pos, size ) != size ) + 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( member_version ); + const long long member_size = range_decoder.member_position() + trailer_size; + bool error = false; + + for( int i = 0; i < trailer_size && !error; ++i ) + { + if( !range_decoder.finished() ) + trailer.data[i] = range_decoder.get_byte(); + else + { + error = true; + if( pp.verbosity() >= 0 ) + { + pp(); + std::fprintf( stderr, "Trailer truncated at trailer position %d;" + " some checks may fail.\n", i ); + } + for( ; i < trailer_size; ++i ) trailer.data[i] = 0; + } + } + if( member_version == 0 ) trailer.member_size( member_size ); + if( !range_decoder.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", + (unsigned int)trailer.data_crc(), (unsigned int)crc() ); + } + } + if( trailer.data_size() != data_position() ) + { + error = true; + if( pp.verbosity() >= 0 ) + { + pp(); + std::fprintf( stderr, "Data size mismatch; trailer says %lld, data size is %lld (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 %lld, member size is %lld (0x%llX).\n", + trailer.member_size(), member_size, member_size ); + } + } + if( !error && pp.verbosity() >= 3 && 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 %9lld, member size %8lld. ", + (unsigned int)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_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+1]; + Bit_model bm_align[dis_align_size]; + + unsigned int rep0 = 0; // rep[0-3] latest four distances + unsigned int rep1 = 0; // used for efficient coding of + unsigned int rep2 = 0; // repeated distances + unsigned int rep3 = 0; + + Len_decoder len_decoder; + Len_decoder rep_match_len_decoder; + Literal_decoder literal_decoder; + State state; + range_decoder.load(); + + while( true ) + { + if( range_decoder.finished() ) { flush_data(); return 2; } + const int pos_state = data_position() & pos_state_mask; + if( range_decoder.decode_bit( bm_match[state()][pos_state] ) == 0 ) + { + const uint8_t prev_byte = get_prev_byte(); + if( state.is_char() ) + put_byte( literal_decoder.decode( range_decoder, prev_byte ) ); + else + put_byte( literal_decoder.decode_matched( range_decoder, prev_byte, + get_byte( rep0 ) ) ); + state.set_char(); + } + else + { + int len; + if( range_decoder.decode_bit( bm_rep[state()] ) == 1 ) + { + len = 0; + if( range_decoder.decode_bit( bm_rep0[state()] ) == 1 ) + { + unsigned int distance; + if( range_decoder.decode_bit( bm_rep1[state()] ) == 0 ) + distance = rep1; + else + { + if( range_decoder.decode_bit( bm_rep2[state()] ) == 0 ) + distance = rep2; + else { distance = rep3; rep3 = rep2; } + rep2 = rep1; + } + rep1 = rep0; + rep0 = distance; + } + else + { + if( range_decoder.decode_bit( bm_len[state()][pos_state] ) == 0 ) + { state.set_short_rep(); len = 1; } + } + if( len == 0 ) + { + state.set_rep(); + len = min_match_len + rep_match_len_decoder.decode( range_decoder, pos_state ); + } + } + else + { + const unsigned int rep0_saved = rep0; + len = min_match_len + len_decoder.decode( range_decoder, pos_state ); + const int dis_slot = range_decoder.decode_tree( bm_dis_slot[get_dis_state(len)], dis_slot_bits ); + 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 += range_decoder.decode_tree_reversed( bm_dis + rep0 - dis_slot, direct_bits ); + else + { + rep0 += range_decoder.decode( direct_bits - dis_align_bits ) << dis_align_bits; + rep0 += range_decoder.decode_tree_reversed( bm_align, dis_align_bits ); + if( rep0 == 0xFFFFFFFFU ) // Marker found + { + rep0 = rep0_saved; + range_decoder.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 + { + range_decoder.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 int)dictionary_size || + ( rep0 >= (unsigned int)pos && !partial_data_pos ) ) + { flush_data(); return 1; } + } + copy_block( rep0, len ); + } + } + } |