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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/>.
*/
#define _FILE_OFFSET_BITS 64
#include <algorithm>
#include <cerrno>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <stdint.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include "lzip.h"
#include "lzip_index.h"
/* Show how well the frequency of sequences of N repeated bytes in LZMA data
matches the value expected for random data. ( 1 / 2^( 8 * N ) )
Print cumulative data for all files followed by the name of the first
file with the longest sequence.
*/
int print_nrep_stats( const std::vector< std::string > & filenames,
const int repeated_byte, const bool ignore_errors,
const bool ignore_trailing, const bool loose_trailing )
{
std::vector< unsigned long > len_vector;
unsigned long long best_pos = 0, lzma_size = 0;
int best_name = -1, retval = 0;
const bool count_all = ( repeated_byte < 0 || repeated_byte >= 256 );
bool stdin_used = false;
for( unsigned i = 0; i < filenames.size(); ++i )
{
const bool from_stdin = ( filenames[i] == "-" );
if( from_stdin ) { if( stdin_used ) continue; else stdin_used = true; }
const char * const input_filename =
from_stdin ? "(stdin)" : filenames[i].c_str();
struct stat in_stats; // not used
const int infd = from_stdin ? STDIN_FILENO :
open_instream( input_filename, &in_stats, false, true );
if( infd < 0 ) { set_retval( retval, 1 ); continue; }
const Lzip_index lzip_index( infd, ignore_trailing, loose_trailing,
ignore_errors, ignore_errors );
if( lzip_index.retval() != 0 )
{
show_file_error( input_filename, lzip_index.error().c_str() );
set_retval( retval, lzip_index.retval() );
close( infd );
continue;
}
const unsigned long long cdata_size = lzip_index.cdata_size();
const uint8_t * const buffer =
(const uint8_t *)mmap( 0, cdata_size, PROT_READ, MAP_PRIVATE, infd, 0 );
close( infd );
if( buffer == MAP_FAILED )
{ show_file_error( input_filename, "Can't mmap", errno );
set_retval( retval, 1 ); continue; }
for( long j = 0; j < lzip_index.members(); ++j )
{
const Block & mb = lzip_index.mblock( j );
long long pos = mb.pos() + 7; // skip header (+1 byte) and
const long long end = mb.end() - 20; // trailer of each member
lzma_size += end - pos;
while( pos < end )
{
const uint8_t byte = buffer[pos++];
if( buffer[pos] == byte )
{
unsigned len = 2;
++pos;
while( pos < end && buffer[pos] == byte ) { ++pos; ++len; }
if( !count_all && repeated_byte != (int)byte ) continue;
if( len >= len_vector.size() ) { len_vector.resize( len + 1 );
best_name = i; best_pos = pos - len; }
++len_vector[len];
}
}
}
munmap( (void *)buffer, cdata_size );
}
if( count_all )
std::fputs( "\nShowing repeated sequences of any byte value.\n", stdout );
else
std::printf( "\nShowing repeated sequences of the byte value 0x%02X\n",
repeated_byte );
std::printf( "Total size of LZMA data: %llu bytes (%sBytes)\n",
lzma_size, format_num( lzma_size, 999 ) );
for( unsigned len = 2; len < len_vector.size(); ++len )
if( len_vector[len] > 0 )
std::printf( "len %u found %lu times, 1 every %llu bytes "
"(expected 1 every %sB)\n",
len, len_vector[len], lzma_size / len_vector[len],
format_num( 1ULL << ( 8 * ( len - count_all ) ), -1ULL, -1 ) );
if( best_name >= 0 )
std::printf( "Longest sequence found at position %llu of '%s'\n",
best_pos, filenames[best_name].c_str() );
return retval;
}
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