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Diffstat (limited to 'decoder.cc')
| -rw-r--r-- | decoder.cc | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/decoder.cc b/decoder.cc new file mode 100644 index 0000000..341740b --- /dev/null +++ b/decoder.cc @@ -0,0 +1,218 @@ +/* Lzip - A data compressor based on the LZMA algorithm + Copyright (C) 2008, 2009 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 <cerrno> +#include <cstdio> +#include <cstdlib> +#include <cstring> +#include <string> +#include <vector> +#include <stdint.h> + +#include "lzip.h" +#include "decoder.h" + + +const CRC32 crc32; + + +bool Input_buffer::read_block() + { + if( at_stream_end ) return false; + stream_pos = readblock( ides_, (char *)buffer, buffer_size ); + if( stream_pos != buffer_size && errno ) throw Error( "read error" ); + pos = 0; + at_stream_end = ( stream_pos < buffer_size ); + return !finished(); + } + + +void LZ_decoder::flush_data() + { + if( !member_finished ) + { + if( odes_ >= 0 ) + { + const int wr = writeblock( odes_, (char *)buffer, pos ); + if( wr != pos ) throw Error( "write error" ); + } + if( pos >= buffer_size ) { partial_data_pos += pos; pos = 0; } + else member_finished = true; + } + } + + +bool LZ_decoder::verify_trailer( const Pretty_print & pp ) const + { + bool error = false; + File_trailer trailer; + const int trailer_size = trailer.size( format_version ); + for( int i = 0; i < trailer_size && !error; ++i ) + { + if( range_decoder.finished() ) + { + error = true; + if( verbosity >= 0 ) + { + pp(); + std::fprintf( stderr, "trailer truncated at trailer position %d;" + " some checks may fail.\n", i ); + } + } + ((uint8_t *)&trailer)[i] = range_decoder.read_byte(); + } + if( format_version == 0 ) trailer.member_size( member_position() ); + if( trailer.data_crc() != crc() ) + { + error = true; + if( 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( verbosity >= 0 ) + { + if( trailer.data_size() >= 0 ) + { pp(); + std::fprintf( stderr, "data size mismatch; trailer says %lld, data size is %lld.\n", + trailer.data_size(), data_position() ); } + else pp( "member trailer is corrupt" ); + } + } + if( trailer.member_size() != member_position() ) + { + error = true; + if( verbosity >= 0 ) + { + if( trailer.member_size() >= 0 ) + { pp(); + std::fprintf( stderr, "member size mismatch; trailer says %lld, member size is %lld.\n", + trailer.member_size(), member_position() ); } + else pp( "member trailer is corrupt" ); + } + } + if( !error && verbosity >= 3 ) + std::fprintf( stderr, "data crc %08X, data size %8lld, member size %8lld. ", + 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 ) + { + unsigned int rep0 = 0; + unsigned int rep1 = 0; + unsigned int rep2 = 0; + unsigned int rep3 = 0; + State state; + uint8_t prev_byte = 0; + + 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 ) + { + if( state.is_char() ) + prev_byte = literal_decoder.decode( range_decoder, prev_byte ); + else + prev_byte = literal_decoder.decode_matched( range_decoder, prev_byte, + get_byte( rep0 ) ); + put_byte( prev_byte ); + 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()] ) == 0 ) + { + if( range_decoder.decode_bit( bm_len[state()][pos_state] ) == 0 ) + { len = 1; state.set_short_rep(); } + } + else + { + 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; + } + if( len == 0 ) + { + len = min_match_len + rep_match_len_decoder.decode( range_decoder, pos_state ); + state.set_rep(); + } + } + else + { + rep3 = rep2; rep2 = rep1; rep1 = rep0; + len = min_match_len + len_decoder.decode( range_decoder, pos_state ); + state.set_match(); + 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 == 0xFFFFFFFF ) // Marker found + { + if( len == min_match_len ) // End Of Stream marker + { + flush_data(); + if( verify_trailer( pp ) ) return 0; else return 3; + } + if( verbosity >= 0 ) + { + pp(); + std::fprintf( stderr, "unsupported marker code `%d'.\n", len ); + } + flush_data(); + return 4; + } + } + } + } + if( !copy_block( rep0, len ) ) { flush_data(); return 1; } + prev_byte = get_byte( 0 ); + } + } + } |