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/* Lziprecover - Data recovery tool for the lzip format
Copyright (C) 2009-2021 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/>.
*/
class Range_mtester
{
const uint8_t * const buffer; // input buffer
const long long buffer_size;
long long pos; // current pos in buffer
uint32_t code;
uint32_t range;
bool at_stream_end;
public:
Range_mtester( const uint8_t * const buf, const long long buf_size )
:
buffer( buf ),
buffer_size( buf_size ),
pos( Lzip_header::size ),
code( 0 ),
range( 0xFFFFFFFFU ),
at_stream_end( false )
{}
bool finished() { return pos >= buffer_size; }
unsigned long long member_position() const { return pos; }
uint8_t get_byte()
{
// 0xFF avoids decoder error if member is truncated at EOS marker
if( finished() ) return 0xFF;
return buffer[pos++];
}
const Lzip_trailer * get_trailer()
{
if( buffer_size - pos < Lzip_trailer::size ) return 0;
const Lzip_trailer * const p = (const Lzip_trailer *)( buffer + pos );
pos += Lzip_trailer::size;
return p;
}
void load()
{
code = 0;
for( int i = 0; i < 5; ++i ) code = ( code << 8 ) | get_byte();
range = 0xFFFFFFFFU;
code &= range; // make sure that first byte is discarded
}
void normalize()
{
if( range <= 0x00FFFFFFU )
{ range <<= 8; code = ( code << 8 ) | get_byte(); }
}
unsigned decode( const int num_bits )
{
unsigned symbol = 0;
for( int i = num_bits; i > 0; --i )
{
normalize();
range >>= 1;
// symbol <<= 1;
// if( code >= range ) { code -= range; symbol |= 1; }
const bool bit = ( code >= range );
symbol <<= 1; symbol += bit;
code -= range & ( 0U - bit );
}
return symbol;
}
unsigned decode_bit( Bit_model & bm )
{
normalize();
const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability;
if( code < bound )
{
range = bound;
bm.probability +=
( bit_model_total - bm.probability ) >> bit_model_move_bits;
return 0;
}
else
{
range -= bound;
code -= bound;
bm.probability -= bm.probability >> bit_model_move_bits;
return 1;
}
}
unsigned decode_tree3( Bit_model bm[] )
{
unsigned symbol = 2 | decode_bit( bm[1] );
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
return symbol & 7;
}
unsigned decode_tree6( Bit_model bm[] )
{
unsigned symbol = 2 | decode_bit( bm[1] );
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
return symbol & 0x3F;
}
unsigned decode_tree8( Bit_model bm[] )
{
unsigned symbol = 1;
for( int i = 0; i < 8; ++i )
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
return symbol & 0xFF;
}
unsigned decode_tree_reversed( Bit_model bm[], const int num_bits )
{
unsigned model = 1;
unsigned symbol = 0;
for( int i = 0; i < num_bits; ++i )
{
const unsigned bit = decode_bit( bm[model] );
model <<= 1; model += bit;
symbol |= ( bit << i );
}
return symbol;
}
unsigned decode_tree_reversed4( Bit_model bm[] )
{
unsigned symbol = decode_bit( bm[1] );
symbol += decode_bit( bm[2+symbol] ) << 1;
symbol += decode_bit( bm[4+symbol] ) << 2;
symbol += decode_bit( bm[8+symbol] ) << 3;
return symbol;
}
unsigned decode_matched( Bit_model bm[], unsigned match_byte )
{
Bit_model * const bm1 = bm + 0x100;
unsigned symbol = 1;
while( symbol < 0x100 )
{
const unsigned match_bit = ( match_byte <<= 1 ) & 0x100;
const bool bit = decode_bit( bm1[symbol+match_bit] );
symbol <<= 1; symbol |= bit;
if( match_bit >> 8 != bit )
{
while( symbol < 0x100 )
symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
break;
}
}
return symbol & 0xFF;
}
unsigned decode_len( Len_model & lm, const int pos_state )
{
if( decode_bit( lm.choice1 ) == 0 )
return decode_tree3( lm.bm_low[pos_state] );
if( decode_bit( lm.choice2 ) == 0 )
return len_low_symbols + decode_tree3( lm.bm_mid[pos_state] );
return len_low_symbols + len_mid_symbols + decode_tree8( lm.bm_high );
}
};
class MD5SUM; // forward declaration
class LZ_mtester
{
unsigned long long partial_data_pos;
Range_mtester rdec;
const unsigned dictionary_size;
uint8_t * buffer; // output buffer
unsigned pos; // current pos in buffer
unsigned stream_pos; // first byte not yet written to file
uint32_t crc_;
const int outfd; // output file descriptor
unsigned rep0; // rep[0-3] latest four distances
unsigned rep1; // used for efficient coding of
unsigned rep2; // repeated distances
unsigned rep3;
State state;
MD5SUM * const md5sum;
unsigned long long total_packets_; // total number of packets in member
unsigned long long max_rep0_pos; // file position of maximum distance
unsigned max_rep0; // maximum distance found
std::vector< unsigned long long > max_packet_posv_; // file pos of large packets
unsigned max_packet_size_; // maximum packet size found
unsigned max_marker_size_; // maximum marker size found
bool pos_wrapped;
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;
void print_block( const int len );
void flush_data();
bool verify_trailer( FILE * const f = 0, unsigned long long byte_pos = 0 );
uint8_t peek_prev() const
{ return buffer[((pos > 0) ? pos : dictionary_size)-1]; }
uint8_t peek( const unsigned distance ) const
{
const unsigned i = ( ( pos > distance ) ? 0 : dictionary_size ) +
pos - distance - 1;
return buffer[i];
}
void put_byte( const uint8_t b )
{
buffer[pos] = b;
if( ++pos >= dictionary_size ) flush_data();
}
void copy_block( const unsigned distance, unsigned len )
{
unsigned lpos = pos, i = lpos - distance - 1;
bool fast, fast2;
if( lpos > distance )
{
fast = ( len < dictionary_size - lpos );
fast2 = ( fast && len <= lpos - i );
}
else
{
i += dictionary_size;
fast = ( len < dictionary_size - i ); // (i == pos) may happen
fast2 = ( fast && len <= i - lpos );
}
if( fast ) // no wrap
{
pos += len;
if( fast2 ) // no wrap, no overlap
std::memcpy( buffer + lpos, buffer + i, len );
else
for( ; len > 0; --len ) buffer[lpos++] = buffer[i++];
}
else for( ; len > 0; --len )
{
buffer[pos] = buffer[i];
if( ++pos >= dictionary_size ) flush_data();
if( ++i >= dictionary_size ) i = 0;
}
}
void set_max_packet( const unsigned new_size, const unsigned long long pos )
{
if( max_packet_size_ > new_size || new_size == 0 ) return;
if( max_packet_size_ < new_size ) // new max size
{ max_packet_size_ = new_size; max_packet_posv_.clear(); }
max_packet_posv_.push_back( pos - new_size ); // pos of first byte
}
void set_max_marker( const unsigned new_size )
{ if( max_marker_size_ < new_size ) max_marker_size_ = new_size; }
public:
LZ_mtester( const uint8_t * const ibuf, const long long ibuf_size,
const unsigned dict_size, const int ofd = -1,
MD5SUM * const md5sum_ = 0 )
:
partial_data_pos( 0 ),
rdec( ibuf, ibuf_size ),
dictionary_size( dict_size ),
buffer( new uint8_t[dictionary_size] ),
pos( 0 ),
stream_pos( 0 ),
crc_( 0xFFFFFFFFU ),
outfd( ofd ),
rep0( 0 ),
rep1( 0 ),
rep2( 0 ),
rep3( 0 ),
md5sum( md5sum_ ),
total_packets_( -1ULL ), // don't count EOS marker
max_rep0_pos( 0 ),
max_rep0( 0 ),
max_packet_size_( 0 ),
max_marker_size_( 0 ),
pos_wrapped( false )
// prev_byte of first byte; also for peek( 0 ) on corrupt file
{ buffer[dictionary_size-1] = 0; }
~LZ_mtester() { delete[] buffer; }
unsigned crc() const { return crc_ ^ 0xFFFFFFFFU; }
unsigned long long data_position() const { return partial_data_pos + pos; }
bool finished() { return rdec.finished(); }
unsigned long long member_position() const { return rdec.member_position(); }
unsigned long long total_packets() const { return total_packets_; }
unsigned long long max_distance_pos() const { return max_rep0_pos; }
unsigned max_distance() const { return max_rep0 + 1; }
const std::vector< unsigned long long > & max_packet_posv() const
{ return max_packet_posv_; }
unsigned max_packet_size() const { return max_packet_size_; }
unsigned max_marker_size() const { return max_marker_size_; }
const uint8_t * get_buffers( const uint8_t ** prev_bufferp,
int * sizep, int * prev_sizep ) const
{ *sizep = ( pos_wrapped && pos == 0 ) ? dictionary_size : pos;
*prev_sizep = ( pos_wrapped && pos > 0 ) ? dictionary_size - pos : 0;
*prev_bufferp = buffer + pos; return buffer; }
void duplicate_buffer();
// these two functions set max_rep0
int test_member( const unsigned long long mpos_limit = LLONG_MAX,
const unsigned long long dpos_limit = LLONG_MAX,
FILE * const f = 0, const unsigned long long byte_pos = 0 );
/* this function also sets max_rep0_pos, total_packets_, max_packet_size_,
max_packet_posv_, and max_marker_size_ */
int debug_decode_member( const long long dpos, const long long mpos,
const bool show_packets );
};
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