/*  Lziprecover - Data recovery tool for the lzip format
    Copyright (C) 2009-2018 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/>.
*/

#include <algorithm>
#include <cerrno>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <stdint.h>
#include <unistd.h>

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


namespace {

/* Returns the address of a malloc'd buffer containing the file data and
   the file size in '*size'. The buffer is at least 20 bytes larger.
   In case of error, returns 0 and does not modify '*size'.
*/
uint8_t * read_file( const int infd, long * const size, const Pretty_print & pp )
  {
  long buffer_size = 1 << 20;
  uint8_t * buffer = (uint8_t *)std::malloc( buffer_size );
  if( !buffer ) throw std::bad_alloc();

  long file_size = readblock( infd, buffer, buffer_size - 20 );
  while( file_size >= buffer_size - 20 && !errno )
    {
    if( buffer_size >= LONG_MAX )
      { pp( "file is too large" ); std::free( buffer ); return 0; }
    buffer_size = ( buffer_size <= LONG_MAX / 2 ) ? 2 * buffer_size : LONG_MAX;
    uint8_t * const tmp = (uint8_t *)std::realloc( buffer, buffer_size );
    if( !tmp ) { std::free( buffer ); throw std::bad_alloc(); }
    buffer = tmp;
    file_size +=
      readblock( infd, buffer + file_size, buffer_size - 20 - file_size );
    }
  if( errno )
    {
    show_error( "Error reading file", errno );
    std::free( buffer ); return 0;
    }
  close( infd );
  *size = file_size;
  return buffer;
  }


bool validate_ds( unsigned * const dictionary_size )
  {
  if( *dictionary_size < min_dictionary_size )
    { *dictionary_size = min_dictionary_size; return false; }
  if( *dictionary_size > max_dictionary_size )
    { *dictionary_size = max_dictionary_size; return false; }
  return true;
  }

} // end namespace


int alone_to_lz( const int infd, const Pretty_print & pp )
  {
  enum { lzma_header_size = 13, offset = lzma_header_size - File_header::size };

  try {
    long file_size = 0;
    uint8_t * const buffer = read_file( infd, &file_size, pp );
    if( !buffer ) return 1;
    if( verbosity >= 1 ) pp();

    if( file_size < lzma_header_size )
      { pp( "file is too short" ); std::free( buffer ); return 2; }
    if( buffer[0] != 93 )			// (45 * 2) + (9 * 0) + 3
      {
      File_header & header = *(File_header *)buffer;
      const unsigned dictionary_size = header.dictionary_size();
      if( header.verify_magic() && header.verify_version() &&
          isvalid_ds( dictionary_size ) )
        pp( "file is already in lzip format" );
      else
        pp( "file has non-default LZMA properties" );
      std::free( buffer ); return 2;
      }
    for( int i = 5; i < 13; ++i ) if( buffer[i] != 0xFF )
      { pp( "file is non-streamed" ); std::free( buffer ); return 2; }

    unsigned dictionary_size = 0;
    for( int i = 4; i > 0; --i )
      { dictionary_size <<= 8; dictionary_size += buffer[i]; }
    const unsigned orig_dictionary_size = dictionary_size;
    validate_ds( &dictionary_size );
    File_header & header = *(File_header *)( buffer + offset );
    header.set_magic();
    header.dictionary_size( dictionary_size );
    for( int i = 0; i < File_trailer::size; ++i ) buffer[file_size++] = 0;
    {
    LZ_mtester mtester( buffer + offset, file_size - offset, dictionary_size );
    const int result = mtester.test_member();
    if( result == 1 && orig_dictionary_size > max_dictionary_size )
      { pp( "dictionary size is too large" ); std::free( buffer ); return 2; }
    if( result != 3 || !mtester.finished() )
      { pp( "file is corrupt" ); std::free( buffer ); return 2; }
    if( mtester.max_distance() < dictionary_size &&
        dictionary_size > min_dictionary_size )
      {
      dictionary_size =
        std::max( mtester.max_distance(), (unsigned)min_dictionary_size );
      header.dictionary_size( dictionary_size );
      }
    File_trailer & trailer =
      *(File_trailer *)( buffer + file_size - File_trailer::size );
    trailer.data_crc( mtester.crc() );
    trailer.data_size( mtester.data_position() );
    trailer.member_size( mtester.member_position() );
    }
    LZ_mtester mtester( buffer + offset, file_size - offset, dictionary_size );
    if( mtester.test_member() != 0 || !mtester.finished() )
      { pp( "conversion failed" ); std::free( buffer ); return 2; }
    if( writeblock( outfd, buffer + offset, file_size - offset ) != file_size - offset )
      {
      show_error( "Error writing output file", errno );
      std::free( buffer ); return 1;
      }
    std::free( buffer );
    }
  catch( std::bad_alloc ) { pp( "Not enough memory." ); return 1; }
  catch( Error e ) { pp(); show_error( e.msg, errno ); return 1; }
  if( verbosity >= 1 ) std::fputs( "done\n", stderr );
  return 0;
  }
