path: root/byte_repair.cc

/* Lziprecover - Data recovery tool for the lzip format
   Copyright (C) 2009-2024 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 <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <stdint.h>
#include <unistd.h>
#include <sys/stat.h>

#include "lzip.h"
#include "mtester.h"
#include "lzip_index.h"


namespace {

bool pending_newline = false;

void print_pending_newline( const char terminator )
  { if( pending_newline && terminator != '\n' ) std::fputc( '\n', stdout );
    pending_newline = false; }


bool gross_damage( const uint8_t * const mbuffer, const long msize )
  {
  enum { maxlen = 7 };		// max number of consecutive identical bytes
  long i = Lzip_header::size;
  const long end = msize - Lzip_trailer::size - maxlen;
  while( i < end )
    {
    const uint8_t byte = mbuffer[i];
    int len = 0;			// does not count the first byte
    while( mbuffer[++i] == byte ) if( ++len >= maxlen ) return true;
    }
  return false;
  }


// Return value: 0 = errors remain, 6 = repaired pos
int repair_nonzero( uint8_t * const mbuffer, const long msize )
  {
  mbuffer[6] = 0;
  const Lzip_header & header = *(Lzip_header *)mbuffer;
  const unsigned dictionary_size = header.dictionary_size();
  if( !isvalid_ds( dictionary_size ) ) return 0;
  LZ_mtester mtester( mbuffer, msize, dictionary_size );
  if( mtester.test_member() == 0 ) return 6;
  return 0;
  }


// Return value: 0 = no change, 5 = repaired pos
int repair_dictionary_size( uint8_t * const mbuffer, const long msize )
  {
  Lzip_header & header = *(Lzip_header *)mbuffer;
  unsigned dictionary_size = header.dictionary_size();
  const Lzip_trailer & trailer =
    *(const Lzip_trailer *)( mbuffer + msize - trailer.size );
  const unsigned long long data_size = trailer.data_size();
  const bool valid_ds = isvalid_ds( dictionary_size );
  if( valid_ds && dictionary_size >= data_size ) return 0;	// can't be bad

  const unsigned long long dict_size_9 = 1 << 25;	// dict size of opt -9
  if( !valid_ds || dictionary_size < dict_size_9 )
    {
    dictionary_size = std::min( data_size, dict_size_9 );
    if( dictionary_size < min_dictionary_size )
      dictionary_size = min_dictionary_size;
    LZ_mtester mtester( mbuffer, msize, dictionary_size );
    const int result = mtester.test_member();
    if( result == 0 )
      { header.dictionary_size( dictionary_size ); return 5; }	// fix DS
    if( result != 1 || mtester.max_distance() <= dictionary_size ||
        mtester.max_distance() > max_dictionary_size ) return 0;
    }
  if( data_size > dict_size_9 )
    {
    dictionary_size =
      std::min( data_size, (unsigned long long)max_dictionary_size );
    LZ_mtester mtester( mbuffer, msize, dictionary_size );
    if( mtester.test_member() == 0 )
      { header.dictionary_size( dictionary_size ); return 5; }	// fix DS
    }
  return 0;
  }


const LZ_mtester * prepare_master( const uint8_t * const buffer,
                                   const long buffer_size,
                                   const unsigned long pos_limit,
                                   const unsigned dictionary_size )
  {
  LZ_mtester * const master =
    new LZ_mtester( buffer, buffer_size, dictionary_size );
  if( master->test_member( pos_limit ) == -1 ) return master;
  delete master;
  return 0;
  }


bool test_member_rest( const LZ_mtester & master, uint8_t * const buffer2,
                       long * const failure_posp = 0 )
  {
  LZ_mtester mtester( master );		// tester with external buffer
  mtester.duplicate_buffer( buffer2 );
  if( mtester.test_member() == 0 && mtester.finished() ) return true;
  if( failure_posp ) *failure_posp = mtester.member_position();
  return false;
  }


// Return value: -1 = master failed, 0 = begin reached, > 0 = repaired pos
long repair_member( uint8_t * const mbuffer, const long long mpos,
                    const long msize, const long begin, const long end,
                    const unsigned dictionary_size, const char terminator )
  {
  uint8_t * const buffer2 = new uint8_t[dictionary_size];
  for( long pos = end; pos >= begin && pos > end - 50000; )
    {
    const long min_pos = std::max( begin, pos - 100 );
    const unsigned long pos_limit = std::max( min_pos - 16, 0L );
    const LZ_mtester * master =
      prepare_master( mbuffer, msize, pos_limit, dictionary_size );
    if( !master ) { delete[] buffer2; return -1; }
    for( ; pos >= min_pos; --pos )
      {
      if( verbosity >= 2 )
        {
        std::printf( "  Trying position %llu %c", mpos + pos, terminator );
        std::fflush( stdout ); pending_newline = true;
        }
      for( int j = 0; j < 255; ++j )
        {
        ++mbuffer[pos];
        if( test_member_rest( *master, buffer2 ) )
          { delete master; delete[] buffer2; return pos; }
        }
      ++mbuffer[pos];
      }
    delete master;
    }
  delete[] buffer2;
  return 0;
  }

} // end namespace


bool safe_seek( const int fd, const long long pos,
                const std::string & filename )
  {
  if( lseek( fd, pos, SEEK_SET ) == pos ) return true;
  show_file_error( filename.c_str(), "Seek error", errno );
  return false;
  }


long seek_write( const int fd, const uint8_t * const buf, const long size,
                 const long long pos )
  {
  if( lseek( fd, pos, SEEK_SET ) == pos )
    return writeblock( fd, buf, size );
  return 0;
  }


uint8_t * read_member( const int infd, const long long mpos,
                       const long long msize, const std::string & filename )
  {
  if( msize <= 0 || msize > LONG_MAX )
    { show_file_error( filename.c_str(),
        "Input file contains member larger than LONG_MAX." ); return 0; }
  if( !safe_seek( infd, mpos, filename ) ) return 0;
  uint8_t * const buffer = new uint8_t[msize];

  if( readblock( infd, buffer, msize ) != msize )
    { show_file_error( filename.c_str(), read_error_msg, errno );
      delete[] buffer; return 0; }
  return buffer;
  }


int byte_repair( const std::string & input_filename,
                 const std::string & default_output_filename,
                 const Cl_options & cl_opts,
                 const char terminator, const bool force )
  {
  const char * const filename = input_filename.c_str();
  struct stat in_stats;
  const int infd = open_instream( filename, &in_stats, false, true );
  if( infd < 0 ) return 1;

  const Lzip_index lzip_index( infd, cl_opts, true );
  if( lzip_index.retval() != 0 )
    { show_file_error( filename, lzip_index.error().c_str() );
      return lzip_index.retval(); }

  const bool to_file = default_output_filename.size();
  output_filename =
    to_file ? default_output_filename : insert_fixed( input_filename );
  if( !force && output_file_exists() ) return 1;
  outfd = -1;
  for( long i = 0; i < lzip_index.members(); ++i )
    {
    const long long mpos = lzip_index.mblock( i ).pos();
    const long long msize = lzip_index.mblock( i ).size();
    if( !safe_seek( infd, mpos, filename ) ) cleanup_and_fail( 1 );
    long long failure_pos = 0;
    bool nonzero = false;
    const int ret = test_member_from_file( infd, msize, &failure_pos, &nonzero );
    if( ret == 0 && !nonzero ) continue;
    if( ret != 0 && failure_pos < Lzip_header::size )		// End Of File
      { show_error( "Can't repair error in input file." );
        cleanup_and_fail( 2 ); }
    if( failure_pos >= msize - 8 ) failure_pos = msize - 8 - 1;

    if( verbosity >= 2 )		// damaged member found
      {
      std::printf( "Repairing member %ld of %ld  (failure pos = %llu)\n",
                   i + 1, lzip_index.members(), mpos + failure_pos );
      std::fflush( stdout );
      }
    uint8_t * const mbuffer = read_member( infd, mpos, msize, input_filename );
    if( !mbuffer ) cleanup_and_fail( 1 );
    const Lzip_header & header = *(const Lzip_header *)mbuffer;
    const unsigned dictionary_size = header.dictionary_size();
    long pos = 0;
    if( !nonzero && mbuffer[6] != 0 ) nonzero = true;		// bad DS
    if( !gross_damage( mbuffer, msize ) )
      {
      if( nonzero ) pos = repair_nonzero( mbuffer, msize );
      if( pos == 0 )
        pos = repair_dictionary_size( mbuffer, msize );
      if( pos == 0 )
        pos = repair_member( mbuffer, mpos, msize, header.size + 1,
                             header.size + 6, dictionary_size, terminator );
      if( pos == 0 )
        pos = repair_member( mbuffer, mpos, msize, header.size + 7,
                             failure_pos, dictionary_size, terminator );
      print_pending_newline( terminator );
      }
    if( pos < 0 )
      { show_error( "Can't prepare master." ); cleanup_and_fail( 1 ); }
    if( pos > 0 )
      {
      if( outfd < 0 )		// first damaged member repaired
        {
        if( !safe_seek( infd, 0, filename ) ) return 1;
        set_signal_handler();
        if( !open_outstream( true, true, false, true, to_file ) ) return 1;
        if( !copy_file( infd, outfd, input_filename, output_filename ) )
          cleanup_and_fail( 1 );		// copy whole file
        }
      if( ( nonzero && pos != 6 &&
            seek_write( outfd, mbuffer + 6, 1, mpos + 6 ) != 1 ) ||
          seek_write( outfd, mbuffer + pos, 1, mpos + pos ) != 1 )
        { show_file_error( printable_name( output_filename, false ),
            write_error_msg, errno ); cleanup_and_fail( 1 ); }
      }
    delete[] mbuffer;
    if( pos == 0 )
      {
      show_error( "Can't repair input file. Error is probably larger than 1 byte." );
      cleanup_and_fail( 2 );
      }
    }

  if( outfd < 0 )
    {
    if( verbosity >= 1 )
      std::fputs( "Input file has no errors. Recovery is not needed.\n", stdout );
    return 0;
    }
  if( !close_outstream( &in_stats ) ) return 1;
  if( verbosity >= 1 )
    std::printf( "Repaired copy of '%s' written to '%s'\n",
                 filename, output_filename.c_str() );
  return 0;
  }


int debug_delay( const std::string & input_filename,
                 const Cl_options & cl_opts, Block range,
                 const char terminator )
  {
  const char * const filename = input_filename.c_str();
  struct stat in_stats;				// not used
  const int infd = open_instream( filename, &in_stats, false, true );
  if( infd < 0 ) return 1;

  const Lzip_index lzip_index( infd, cl_opts );
  if( lzip_index.retval() != 0 )
    { show_file_error( filename, lzip_index.error().c_str() );
      return lzip_index.retval(); }

  if( range.end() > lzip_index.cdata_size() )
    range.size( std::max( 0LL, lzip_index.cdata_size() - range.pos() ) );
  if( range.size() <= 0 )
    { show_file_error( filename, "Nothing to do; range is empty." ); return 0; }

  for( long i = 0; i < lzip_index.members(); ++i )
    {
    const Block & mb = lzip_index.mblock( i );
    if( !range.overlaps( mb ) ) continue;
    const long long mpos = lzip_index.mblock( i ).pos();
    const long long msize = lzip_index.mblock( i ).size();
    const unsigned dictionary_size = lzip_index.dictionary_size( i );
    if( verbosity >= 2 )
      {
      std::printf( "Finding max delay in member %ld of %ld  (mpos = %llu, msize = %llu)\n",
                   i + 1, lzip_index.members(), mpos, msize );
      std::fflush( stdout );
      }
    uint8_t * const mbuffer = read_member( infd, mpos, msize, input_filename );
    if( !mbuffer ) return 1;
    uint8_t * const buffer2 = new uint8_t[dictionary_size];
    long pos = std::max( range.pos() - mpos, Lzip_header::size + 1LL );
    const long end = std::min( range.end() - mpos, msize );
    long max_delay = 0;
    while( pos < end )
      {
      const unsigned long pos_limit = std::max( pos - 16, 0L );
      const LZ_mtester * master =
        prepare_master( mbuffer, msize, pos_limit, dictionary_size );
      if( !master ) { show_error( "Can't prepare master." );
                      delete[] buffer2; delete[] mbuffer; return 1; }
      const long partial_end = std::min( pos + 100, end );
      for( ; pos < partial_end; ++pos )
        {
        if( verbosity >= 2 )
          {
          std::printf( "  Delays at position %llu %c", mpos + pos, terminator );
          std::fflush( stdout ); pending_newline = true;
          }
        int value = -1;
        for( int j = 0; j < 256; ++j )
          {
          ++mbuffer[pos];
          if( j == 255 ) break;
          long failure_pos = 0;
          if( test_member_rest( *master, buffer2, &failure_pos ) ) continue;
          const long delay = failure_pos - pos;
          if( delay > max_delay ) { max_delay = delay; value = mbuffer[pos]; }
          }
        if( value >= 0 && verbosity >= 2 )
          {
          std::printf( "  New max delay %lu at position %llu (0x%02X)\n",
                       max_delay, mpos + pos, value );
          std::fflush( stdout ); pending_newline = false;
          }
        if( pos + max_delay >= msize ) { pos = end; break; }
        }
      delete master;
      }
    delete[] buffer2;
    delete[] mbuffer;
    print_pending_newline( terminator );
    }

  if( verbosity >= 1 ) std::fputs( "Done.\n", stdout );
  return 0;
  }


int debug_byte_repair( const std::string & input_filename,
                       const Cl_options & cl_opts, const Bad_byte & bad_byte,
                       const char terminator )
  {
  const char * const filename = input_filename.c_str();
  struct stat in_stats;				// not used
  const int infd = open_instream( filename, &in_stats, false, true );
  if( infd < 0 ) return 1;

  const Lzip_index lzip_index( infd, cl_opts );
  if( lzip_index.retval() != 0 )
    { show_file_error( filename, lzip_index.error().c_str() );
      return lzip_index.retval(); }

  long idx = 0;
  for( ; idx < lzip_index.members(); ++idx )
    if( lzip_index.mblock( idx ).includes( bad_byte.pos ) ) break;
  if( idx >= lzip_index.members() )
    { show_file_error( filename, "Nothing to do; byte is beyond EOF." );
      return 0; }

  const long long mpos = lzip_index.mblock( idx ).pos();
  const long long msize = lzip_index.mblock( idx ).size();
  {
  long long failure_pos = 0;
  if( !safe_seek( infd, mpos, input_filename ) ) return 1;
  if( test_member_from_file( infd, msize, &failure_pos ) != 0 )
    {
    if( verbosity >= 0 )
      std::fprintf( stderr, "Member %ld of %ld already damaged  (failure pos = %llu)\n",
                    idx + 1, lzip_index.members(), mpos + failure_pos );
    return 2;
    }
  }
  uint8_t * const mbuffer = read_member( infd, mpos, msize, input_filename );
  if( !mbuffer ) return 1;
  const Lzip_header & header = *(const Lzip_header *)mbuffer;
  const unsigned dictionary_size = header.dictionary_size();
  const long long bad_pos = bad_byte.pos - mpos;
  const uint8_t good_value = mbuffer[bad_pos];
  const uint8_t bad_value = bad_byte( good_value );
  mbuffer[bad_pos] = bad_value;
  long failure_pos = 0;
  if( bad_pos != 5 || isvalid_ds( header.dictionary_size() ) )
    {
    LZ_mtester mtester( mbuffer, msize, header.dictionary_size() );
    if( mtester.test_member() == 0 && mtester.finished() )
      {
      if( verbosity >= 1 )
        std::fputs( "Member decompressed with no errors.\n", stdout );
      delete[] mbuffer;
      return 0;
      }
    failure_pos = mtester.member_position();
    }
  if( verbosity >= 2 )
    {
    std::printf( "Test repairing member %ld of %ld  (mpos = %llu, msize = %llu)\n"
                 "  (damage pos = %llu (0x%02X->0x%02X), failure pos = %llu, delay = %lld )\n",
                 idx + 1, lzip_index.members(), mpos, msize,
                 bad_byte.pos, good_value, bad_value, mpos + failure_pos,
                 mpos + failure_pos - bad_byte.pos );
    std::fflush( stdout );
    }
  if( failure_pos >= msize ) failure_pos = msize - 1;
  long pos = repair_dictionary_size( mbuffer, msize );
  if( pos == 0 )
    if( mbuffer[6] != 0 ) pos = repair_nonzero( mbuffer, msize );
  if( pos == 0 )
    pos = repair_member( mbuffer, mpos, msize, header.size + 1,
                         header.size + 6, dictionary_size, terminator );
  if( pos == 0 )
    pos = repair_member( mbuffer, mpos, msize, header.size + 7,
                         failure_pos, dictionary_size, terminator );
  print_pending_newline( terminator );
  delete[] mbuffer;
  if( pos < 0 ) { show_error( "Can't prepare master." ); return 1; }
  if( pos == 0 ) internal_error( "can't repair input file." );
  if( verbosity >= 1 ) std::fputs( "Member repaired successfully.\n", stdout );
  return 0;
  }


/* If show_packets is true, print to stdout descriptions of the decoded LZMA
   packets. Print also some global values; total number of packets in
   member, max distance (rep0) and its file position, max LZMA packet size
   in each member and the file position of these packets.
   (Packet sizes are a fractionary number of bytes. The packet and marker
   sizes shown by option -X are the number of extra bytes required to decode
   the packet, not counting the data present in the range decoder before and
   after the decoding.
   if bad_byte.pos >= cdata_size, bad_byte is ignored.
*/
int debug_decompress( const std::string & input_filename,
                      const Cl_options & cl_opts, const Bad_byte & bad_byte,
                      const bool show_packets )
  {
  const char * const filename = input_filename.c_str();
  struct stat in_stats;
  const int infd = open_instream( filename, &in_stats, false, true );
  if( infd < 0 ) return 1;

  const Lzip_index lzip_index( infd, cl_opts );
  if( lzip_index.retval() != 0 )
    { show_file_error( filename, lzip_index.error().c_str() );
      return lzip_index.retval(); }

  outfd = show_packets ? -1 : STDOUT_FILENO;
  int retval = 0;
  for( long i = 0; i < lzip_index.members(); ++i )
    {
    const long long dpos = lzip_index.dblock( i ).pos();
    const long long mpos = lzip_index.mblock( i ).pos();
    const long long msize = lzip_index.mblock( i ).size();
    const unsigned dictionary_size = lzip_index.dictionary_size( i );
    if( verbosity >= 1 && show_packets )
      std::printf( "Decoding LZMA packets in member %ld of %ld  (mpos = %llu, msize = %llu)\n"
                   "  mpos   dpos\n",
                   i + 1, lzip_index.members(), mpos, msize );
    if( !isvalid_ds( dictionary_size ) )
      { show_error( bad_dict_msg ); retval = 2; break; }
    uint8_t * const mbuffer = read_member( infd, mpos, msize, input_filename );
    if( !mbuffer ) { retval = 1; break; }
    if( bad_byte.pos >= 0 && lzip_index.mblock( i ).includes( bad_byte.pos ) )
      {
      const uint8_t good_value = mbuffer[bad_byte.pos-mpos];
      const uint8_t bad_value = bad_byte( good_value );
      mbuffer[bad_byte.pos-mpos] = bad_value;
      if( verbosity >= 1 && show_packets )
        std::printf( "Byte at pos %llu changed from 0x%02X to 0x%02X\n",
                     bad_byte.pos, good_value, bad_value );
      }
    LZ_mtester mtester( mbuffer, msize, dictionary_size, outfd );
    const int result = mtester.debug_decode_member( dpos, mpos, show_packets );
    delete[] mbuffer;
    if( show_packets )
      {
      const std::vector< unsigned long long > & mppv = mtester.max_packet_posv();
      const unsigned mpackets = mppv.size();
      std::printf( "Total packets in member   = %llu\n"
                   "Max distance in any match = %u at file position %llu\n"
                   "Max marker size found = %u\n"
                   "Max packet size found = %u (%u packets)%s",
                    mtester.total_packets(), mtester.max_distance(),
                    mtester.max_distance_pos(), mtester.max_marker_size(),
                    mtester.max_packet_size(), mpackets,
                    mpackets ? " at file positions" : "" );
      for( unsigned i = 0; i < mpackets; ++i )
        std::printf( " %llu", mppv[i] );
      std::fputc( '\n', stdout );
      }
    if( result != 0 )
      {
      if( verbosity >= 0 && result <= 2 && show_packets )
        std::printf( "%s at pos %llu\n", ( result == 2 ) ?
                     "File ends unexpectedly" : "Decoder error",
                     mpos + mtester.member_position() );
      retval = 2;
      if( result != 3 || !mtester.finished() || mtester.data_position() !=
          (unsigned long long)lzip_index.dblock( i ).size() ) break;
      }
    if( i + 1 < lzip_index.members() && show_packets )
      std::fputc( '\n', stdout );
    }

  if( !close_outstream( &in_stats ) && retval == 0 ) retval = 1;
  if( verbosity >= 1 && show_packets && retval == 0 )
    std::fputs( "Done.\n", stdout );
  return retval;
  }