Merging upstream version 0.3.
Signed-off-by: Daniel Baumann <daniel@debian.org>
This commit is contained in:
parent
4a29881d2b
commit
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GPG key ID:
FBB4F0E80A80222F
9 changed files with 193 additions and 186 deletions
459
lzd.cc
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459
lzd.cc
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/* Lzd - Educational decompressor for lzip files
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Copyright (C) 2013 Antonio Diaz Diaz.
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This program is free software: you have unlimited permission
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to copy, distribute and modify it.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/*
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Exit status: 0 for a normal exit, 1 for environmental problems
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(file not found, invalid flags, I/O errors, etc), 2 to indicate a
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corrupt or invalid input file.
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*/
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#include <algorithm>
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#include <cerrno>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <stdint.h>
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#include <unistd.h>
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#if defined(__MSVCRT__) || defined(__OS2__)
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#include <fcntl.h>
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#include <io.h>
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#endif
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class State
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{
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int st;
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public:
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enum { states = 12 };
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State() : st( 0 ) {}
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int operator()() const { return st; }
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bool is_char() const { return st < 7; }
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void set_char()
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{
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static const int next[states] = { 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 4, 5 };
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st = next[st];
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}
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void set_match() { st = ( st < 7 ) ? 7 : 10; }
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void set_rep() { st = ( st < 7 ) ? 8 : 11; }
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void set_short_rep() { st = ( st < 7 ) ? 9 : 11; }
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};
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enum {
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min_dictionary_size = 1 << 12,
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max_dictionary_size = 1 << 29,
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literal_context_bits = 3,
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pos_state_bits = 2,
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pos_states = 1 << pos_state_bits,
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pos_state_mask = pos_states - 1,
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dis_slot_bits = 6,
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start_dis_model = 4,
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end_dis_model = 14,
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modeled_distances = 1 << (end_dis_model / 2), // 128
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dis_align_bits = 4,
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dis_align_size = 1 << dis_align_bits,
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len_low_bits = 3,
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len_mid_bits = 3,
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len_high_bits = 8,
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len_low_symbols = 1 << len_low_bits,
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len_mid_symbols = 1 << len_mid_bits,
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len_high_symbols = 1 << len_high_bits,
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max_len_symbols = len_low_symbols + len_mid_symbols + len_high_symbols,
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min_match_len = 2, // must be 2
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max_dis_states = 4,
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bit_model_move_bits = 5,
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bit_model_total_bits = 11,
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bit_model_total = 1 << bit_model_total_bits };
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struct Bit_model
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{
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int probability;
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Bit_model() : probability( bit_model_total / 2 ) {}
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};
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struct Len_model
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{
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Bit_model choice1;
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Bit_model choice2;
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Bit_model bm_low[pos_states][len_low_symbols];
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Bit_model bm_mid[pos_states][len_mid_symbols];
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Bit_model bm_high[len_high_symbols];
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};
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class CRC32
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{
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uint32_t data[256]; // Table of CRCs of all 8-bit messages.
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public:
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CRC32()
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{
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for( unsigned n = 0; n < 256; ++n )
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{
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unsigned c = n;
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for( int k = 0; k < 8; ++k )
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{ if( c & 1 ) c = 0xEDB88320U ^ ( c >> 1 ); else c >>= 1; }
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data[n] = c;
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}
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}
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void update( uint32_t & crc, const uint8_t * const buffer, const int size ) const
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{
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for( int i = 0; i < size; ++i )
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crc = data[(crc^buffer[i])&0xFF] ^ ( crc >> 8 );
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}
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};
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const CRC32 crc32;
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typedef uint8_t File_header[6]; // 0-3 magic, 4 version, 5 coded_dict_size
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typedef uint8_t File_trailer[20];
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// 0-3 CRC32 of the uncompressed data
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// 4-11 size of the uncompressed data
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// 12-19 member size including header and trailer
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class Range_decoder
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{
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uint32_t code;
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uint32_t range;
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public:
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Range_decoder() : code( 0 ), range( 0xFFFFFFFFU )
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{
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for( int i = 0; i < 5; ++i ) code = (code << 8) | get_byte();
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}
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uint8_t get_byte() { return std::getc( stdin ); }
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int decode( const int num_bits )
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{
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int symbol = 0;
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for( int i = 0; i < num_bits; ++i )
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{
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range >>= 1;
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symbol <<= 1;
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if( code >= range ) { code -= range; symbol |= 1; }
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if( range <= 0x00FFFFFFU ) // normalize
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{ range <<= 8; code = (code << 8) | get_byte(); }
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}
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return symbol;
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}
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int decode_bit( Bit_model & bm )
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{
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int symbol;
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const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability;
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if( code < bound )
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{
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range = bound;
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bm.probability += (bit_model_total - bm.probability) >> bit_model_move_bits;
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symbol = 0;
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}
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else
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{
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range -= bound;
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code -= bound;
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bm.probability -= bm.probability >> bit_model_move_bits;
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symbol = 1;
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}
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if( range <= 0x00FFFFFFU ) // normalize
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{ range <<= 8; code = (code << 8) | get_byte(); }
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return symbol;
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}
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int decode_tree( Bit_model bm[], const int num_bits )
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{
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int symbol = 1;
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for( int i = 0; i < num_bits; ++i )
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symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
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return symbol - (1 << num_bits);
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}
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int decode_tree_reversed( Bit_model bm[], const int num_bits )
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{
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int symbol = decode_tree( bm, num_bits );
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int reversed_symbol = 0;
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for( int i = 0; i < num_bits; ++i )
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{
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reversed_symbol = ( reversed_symbol << 1 ) | ( symbol & 1 );
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symbol >>= 1;
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}
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return reversed_symbol;
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}
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int decode_matched( Bit_model bm[], const int match_byte )
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{
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Bit_model * const bm1 = bm + 0x100;
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int symbol = 1;
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for( int i = 7; i >= 0; --i )
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{
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const int match_bit = ( match_byte >> i ) & 1;
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const int bit = decode_bit( bm1[(match_bit<<8)+symbol] );
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symbol = ( symbol << 1 ) | bit;
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if( match_bit != bit )
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{
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while( symbol < 0x100 )
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symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
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break;
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}
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}
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return symbol - 0x100;
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}
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int decode_len( Len_model & lm, const int pos_state )
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{
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if( decode_bit( lm.choice1 ) == 0 )
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return decode_tree( lm.bm_low[pos_state], len_low_bits );
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if( decode_bit( lm.choice2 ) == 0 )
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return len_low_symbols +
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decode_tree( lm.bm_mid[pos_state], len_mid_bits );
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return len_low_symbols + len_mid_symbols +
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decode_tree( lm.bm_high, len_high_bits );
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}
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};
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class LZ_decoder
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{
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unsigned long long partial_data_pos;
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Range_decoder rdec;
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const unsigned dictionary_size;
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uint8_t * const buffer; // output buffer
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unsigned pos; // current pos in buffer
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unsigned stream_pos; // first byte not yet written to stdout
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uint32_t crc_;
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void flush_data();
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uint8_t get_byte( const unsigned distance ) const
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{
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unsigned i = pos - distance - 1;
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if( pos <= distance ) i += dictionary_size;
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return buffer[i];
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}
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void put_byte( const uint8_t b )
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{
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buffer[pos] = b;
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if( ++pos >= dictionary_size ) flush_data();
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}
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public:
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LZ_decoder( const unsigned dict_size )
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:
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partial_data_pos( 0 ),
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dictionary_size( dict_size ),
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buffer( new uint8_t[dictionary_size] ),
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pos( 0 ),
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stream_pos( 0 ),
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crc_( 0xFFFFFFFFU )
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{ buffer[dictionary_size-1] = 0; } // prev_byte of first_byte
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~LZ_decoder() { delete[] buffer; }
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unsigned crc() const { return crc_ ^ 0xFFFFFFFFU; }
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unsigned long long data_position() const { return partial_data_pos + pos; }
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bool decode_member();
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};
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void LZ_decoder::flush_data()
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{
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if( pos > stream_pos )
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{
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const unsigned size = pos - stream_pos;
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crc32.update( crc_, buffer + stream_pos, size );
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errno = 0;
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if( std::fwrite( buffer + stream_pos, 1, size, stdout ) != size )
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{ std::fprintf( stderr, "Write error: %s\n", std::strerror( errno ) );
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std::exit( 1 ); }
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if( pos >= dictionary_size ) { partial_data_pos += pos; pos = 0; }
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stream_pos = pos;
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}
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}
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bool LZ_decoder::decode_member() // Returns false if error
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{
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Bit_model bm_literal[1<<literal_context_bits][0x300];
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Bit_model bm_match[State::states][pos_states];
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Bit_model bm_rep[State::states];
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Bit_model bm_rep0[State::states];
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Bit_model bm_rep1[State::states];
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Bit_model bm_rep2[State::states];
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Bit_model bm_len[State::states][pos_states];
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Bit_model bm_dis_slot[max_dis_states][1<<dis_slot_bits];
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Bit_model bm_dis[modeled_distances-end_dis_model];
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Bit_model bm_align[dis_align_size];
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Len_model match_len_model;
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Len_model rep_len_model;
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unsigned rep0 = 0; // rep[0-3] latest four distances
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unsigned rep1 = 0; // used for efficient coding of
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unsigned rep2 = 0; // repeated distances
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unsigned rep3 = 0;
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State state;
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while( !std::feof( stdin ) && !std::ferror( stdin ) )
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{
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const int pos_state = data_position() & pos_state_mask;
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if( rdec.decode_bit( bm_match[state()][pos_state] ) == 0 ) // 1st bit
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{
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const uint8_t prev_byte = get_byte( 0 );
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const int literal_state = prev_byte >> ( 8 - literal_context_bits );
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Bit_model * const bm = bm_literal[literal_state];
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if( state.is_char() )
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put_byte( rdec.decode_tree( bm, 8 ) );
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else
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put_byte( rdec.decode_matched( bm, get_byte( rep0 ) ) );
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state.set_char();
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}
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else
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{
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int len;
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if( rdec.decode_bit( bm_rep[state()] ) == 1 ) // 2nd bit
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{
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if( rdec.decode_bit( bm_rep0[state()] ) == 0 ) // 3rd bit
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{
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if( rdec.decode_bit( bm_len[state()][pos_state] ) == 0 ) // 4th bit
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{ state.set_short_rep(); put_byte( get_byte( rep0 ) ); continue; }
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}
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else
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{
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unsigned distance;
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if( rdec.decode_bit( bm_rep1[state()] ) == 0 ) // 4th bit
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distance = rep1;
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else
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{
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if( rdec.decode_bit( bm_rep2[state()] ) == 0 ) // 5th bit
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distance = rep2;
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else
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{ distance = rep3; rep3 = rep2; }
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rep2 = rep1;
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}
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rep1 = rep0;
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rep0 = distance;
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}
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len = min_match_len + rdec.decode_len( rep_len_model, pos_state );
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state.set_rep();
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}
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else
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{
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rep3 = rep2; rep2 = rep1; rep1 = rep0;
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len = min_match_len + rdec.decode_len( match_len_model, pos_state );
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const int dis_state = std::min( len - min_match_len, max_dis_states - 1 );
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const int dis_slot =
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rdec.decode_tree( bm_dis_slot[dis_state], dis_slot_bits );
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if( dis_slot < start_dis_model ) rep0 = dis_slot;
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else
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{
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const int direct_bits = ( dis_slot >> 1 ) - 1;
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rep0 = ( 2 | ( dis_slot & 1 ) ) << direct_bits;
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if( dis_slot < end_dis_model )
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rep0 += rdec.decode_tree_reversed( bm_dis + rep0 - dis_slot - 1,
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direct_bits );
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else
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{
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rep0 += rdec.decode( direct_bits - dis_align_bits ) << dis_align_bits;
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rep0 += rdec.decode_tree_reversed( bm_align, dis_align_bits );
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if( rep0 == 0xFFFFFFFFU ) // Marker found
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{
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flush_data();
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return ( len == min_match_len ); // End Of Stream marker
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}
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}
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}
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state.set_match();
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if( rep0 >= dictionary_size || ( rep0 >= pos && !partial_data_pos ) )
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return false;
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}
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for( int i = 0; i < len; ++i )
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put_byte( get_byte( rep0 ) );
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}
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}
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return false;
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}
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int main( const int argc, const char * const argv[] )
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{
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if( argc > 1 )
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{
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std::printf( "Lzd %s - Educational decompressor for lzip files.\n",
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PROGVERSION );
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std::printf( "Study the source to learn how a lzip decompressor works.\n"
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"See the lzip manual for an explanation of the code.\n"
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"It is not safe to use lzd for any real work.\n"
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"\nUsage: %s < file.lz > file\n", argv[0] );
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std::printf( "Lzd decompresses from standard input to standard output.\n"
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"\nCopyright (C) 2013 Antonio Diaz Diaz.\n"
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"This is free software: you are free to change and redistribute it.\n"
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"There is NO WARRANTY, to the extent permitted by law.\n"
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"Report bugs to lzip-bug@nongnu.org\n"
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"Lzip home page: http://www.nongnu.org/lzip/lzip.html\n" );
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return 0;
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}
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#if defined(__MSVCRT__) || defined(__OS2__)
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setmode( STDIN_FILENO, O_BINARY );
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setmode( STDOUT_FILENO, O_BINARY );
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#endif
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for( bool first_member = true; ; first_member = false )
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{
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File_header header;
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for( int i = 0; i < 6; ++i )
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header[i] = std::getc( stdin );
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if( std::feof( stdin ) || std::memcmp( header, "LZIP", 4 ) != 0 )
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{
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if( first_member )
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{ std::fprintf( stderr, "Bad magic number (file not in lzip format)\n" );
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return 2; }
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break;
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}
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if( header[4] != 1 )
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{
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std::fprintf( stderr, "Version %d member format not supported.\n",
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header[4] );
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return 2;
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}
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unsigned dict_size = 1 << ( header[5] & 0x1F );
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dict_size -= ( dict_size / 16 ) * ( ( header[5] >> 5 ) & 7 );
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if( dict_size < min_dictionary_size || dict_size > max_dictionary_size )
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{ std::fprintf( stderr, "Invalid dictionary size in member header\n" );
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return 2; }
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LZ_decoder decoder( dict_size );
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if( !decoder.decode_member() )
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{ std::fprintf( stderr, "Data error\n" ); return 2; }
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File_trailer trailer;
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for( int i = 0; i < 20; ++i ) trailer[i] = std::getc( stdin );
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unsigned crc = 0;
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for( int i = 3; i >= 0; --i ) { crc <<= 8; crc += trailer[i]; }
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unsigned long long data_size = 0;
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for( int i = 11; i >= 4; --i ) { data_size <<= 8; data_size += trailer[i]; }
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if( crc != decoder.crc() || data_size != decoder.data_position() )
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{ std::fprintf( stderr, "CRC error\n" ); return 2; }
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}
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if( std::fclose( stdout ) != 0 )
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{ std::fprintf( stderr, "Can't close stdout: %s\n", std::strerror( errno ) );
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return 1; }
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return 0;
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}
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