diff options
Diffstat (limited to 'lzd.cc')
| -rw-r--r-- | lzd.cc | 46 |
1 files changed, 20 insertions, 26 deletions
@@ -1,5 +1,5 @@ -/* Lzd - Educational decompressor for lzip files - Copyright (C) 2013, 2014 Antonio Diaz Diaz. +/* Lzd - Educational decompressor for the lzip format + Copyright (C) 2013-2015 Antonio Diaz Diaz. This program is free software: you have unlimited permission to copy, distribute and modify it. @@ -241,7 +241,7 @@ class LZ_decoder void flush_data(); - uint8_t get_byte( const unsigned distance ) const + uint8_t peek( const unsigned distance ) const { unsigned i = pos - distance - 1; if( pos <= distance ) i += dictionary_size; @@ -255,7 +255,7 @@ class LZ_decoder } public: - LZ_decoder( const unsigned dict_size ) + explicit LZ_decoder( const unsigned dict_size ) : partial_data_pos( 0 ), dictionary_size( dict_size ), @@ -282,7 +282,7 @@ void LZ_decoder::flush_data() crc32.update_buf( crc_, buffer + stream_pos, size ); errno = 0; if( std::fwrite( buffer + stream_pos, 1, size, stdout ) != size ) - { std::fprintf( stderr, "Write error: %s.\n", std::strerror( errno ) ); + { std::fprintf( stderr, "Write error: %s\n", std::strerror( errno ) ); std::exit( 1 ); } if( pos >= dictionary_size ) { partial_data_pos += pos; pos = 0; } stream_pos = pos; @@ -315,16 +315,16 @@ bool LZ_decoder::decode_member() // Returns false if error 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_byte( 0 ); + const uint8_t prev_byte = peek( 0 ); const int literal_state = prev_byte >> ( 8 - literal_context_bits ); Bit_model * const bm = bm_literal[literal_state]; if( state.is_char() ) put_byte( rdec.decode_tree( bm, 8 ) ); else - put_byte( rdec.decode_matched( bm, get_byte( rep0 ) ) ); + put_byte( rdec.decode_matched( bm, peek( rep0 ) ) ); state.set_char(); } - else + else // match or repeated match { int len; if( rdec.decode_bit( bm_rep[state()] ) != 0 ) // 2nd bit @@ -348,12 +348,12 @@ bool LZ_decoder::decode_member() // Returns false if error else { if( rdec.decode_bit( bm_len[state()][pos_state] ) == 0 ) // 4th bit - { state.set_short_rep(); put_byte( get_byte( rep0 ) ); continue; } + { state.set_short_rep(); put_byte( peek( rep0 ) ); continue; } } state.set_rep(); len = min_match_len + rdec.decode_len( rep_len_model, pos_state ); } - else + else // match { rep3 = rep2; rep2 = rep1; rep1 = rep0; len = min_match_len + rdec.decode_len( match_len_model, pos_state ); @@ -372,7 +372,7 @@ bool LZ_decoder::decode_member() // Returns false if error { rep0 += rdec.decode( direct_bits - dis_align_bits ) << dis_align_bits; rep0 += rdec.decode_tree_reversed( bm_align, dis_align_bits ); - if( rep0 == 0xFFFFFFFFU ) // Marker found + if( rep0 == 0xFFFFFFFFU ) // marker found { flush_data(); return ( len == min_match_len ); // End Of Stream marker @@ -383,7 +383,7 @@ bool LZ_decoder::decode_member() // Returns false if error if( rep0 >= dictionary_size || rep0 >= data_position() ) { flush_data(); return false; } } - for( int i = 0; i < len; ++i ) put_byte( get_byte( rep0 ) ); + for( int i = 0; i < len; ++i ) put_byte( peek( rep0 ) ); } } flush_data(); @@ -395,14 +395,14 @@ int main( const int argc, const char * const argv[] ) { if( argc > 1 ) { - std::printf( "Lzd %s - Educational decompressor for lzip files.\n", + std::printf( "Lzd %s - Educational decompressor for the lzip format.\n", PROGVERSION ); std::printf( "Study the source to learn how a lzip decompressor works.\n" "See the lzip manual for an explanation of the code.\n" "It is not safe to use lzd for any real work.\n" "\nUsage: %s < file.lz > file\n", argv[0] ); std::printf( "Lzd decompresses from standard input to standard output.\n" - "\nCopyright (C) 2014 Antonio Diaz Diaz.\n" + "\nCopyright (C) 2015 Antonio Diaz Diaz.\n" "This is free software: you are free to change and redistribute it.\n" "There is NO WARRANTY, to the extent permitted by law.\n" "Report bugs to lzip-bug@nongnu.org\n" @@ -419,28 +419,22 @@ int main( const int argc, const char * const argv[] ) { File_header header; for( int i = 0; i < 6; ++i ) header[i] = std::getc( stdin ); - if( std::feof( stdin ) || std::memcmp( header, "LZIP", 4 ) != 0 ) + if( std::feof( stdin ) || std::memcmp( header, "LZIP\x01", 5 ) != 0 ) { if( first_member ) - { std::fprintf( stderr, "Bad magic number (file not in lzip format)\n" ); + { std::fputs( "Bad magic number (file not in lzip format).\n", stderr ); return 2; } break; } - if( header[4] != 1 ) - { - std::fprintf( stderr, "Version %d member format not supported.\n", - header[4] ); - return 2; - } unsigned dict_size = 1 << ( header[5] & 0x1F ); dict_size -= ( dict_size / 16 ) * ( ( header[5] >> 5 ) & 7 ); if( dict_size < min_dictionary_size || dict_size > max_dictionary_size ) - { std::fprintf( stderr, "Invalid dictionary size in member header\n" ); + { std::fputs( "Invalid dictionary size in member header.\n", stderr ); return 2; } LZ_decoder decoder( dict_size ); if( !decoder.decode_member() ) - { std::fprintf( stderr, "Data error\n" ); return 2; } + { std::fputs( "Data error\n", stderr ); return 2; } File_trailer trailer; for( int i = 0; i < 20; ++i ) trailer[i] = std::getc( stdin ); @@ -449,11 +443,11 @@ int main( const int argc, const char * const argv[] ) unsigned long long data_size = 0; for( int i = 11; i >= 4; --i ) { data_size <<= 8; data_size += trailer[i]; } if( crc != decoder.crc() || data_size != decoder.data_position() ) - { std::fprintf( stderr, "CRC error\n" ); return 2; } + { std::fputs( "CRC error\n", stderr ); return 2; } } if( std::fclose( stdout ) != 0 ) - { std::fprintf( stderr, "Can't close stdout: %s.\n", std::strerror( errno ) ); + { std::fprintf( stderr, "Can't close stdout: %s\n", std::strerror( errno ) ); return 1; } return 0; } |