/*  Lziprecover - Data recovery tool for the lzip format
    Copyright (C) 2009-2017 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/>.
*/
/*
    Exit status: 0 for a normal exit, 1 for environmental problems
    (file not found, invalid flags, I/O errors, etc), 2 to indicate a
    corrupt or invalid input file, 3 for an internal consistency error
    (eg, bug) which caused lziprecover to panic.
*/

#define _FILE_OFFSET_BITS 64

#include <algorithm>
#include <cctype>
#include <cerrno>
#include <climits>
#include <csignal>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>
#include <utime.h>
#include <sys/stat.h>
#if defined(__MSVCRT__)
#include <io.h>
#define fchmod(x,y) 0
#define fchown(x,y,z) 0
#define SIGHUP SIGTERM
#define S_ISSOCK(x) 0
#define S_IRGRP 0
#define S_IWGRP 0
#define S_IROTH 0
#define S_IWOTH 0
#endif
#if defined(__OS2__)
#include <io.h>
#endif

#include "arg_parser.h"
#include "lzip.h"
#include "decoder.h"
#include "block.h"

#ifndef O_BINARY
#define O_BINARY 0
#endif

#if CHAR_BIT != 8
#error "Environments where CHAR_BIT != 8 are not supported."
#endif

std::string output_filename;		// global vars for output file
int outfd = -1;

namespace {

const char * const Program_name = "Lziprecover";
const char * const program_name = "lziprecover";
const char * const program_year = "2017";
const char * invocation_name = 0;

const struct { const char * from; const char * to; } known_extensions[] = {
  { ".lz",  ""     },
  { ".tlz", ".tar" },
  { 0,      0      } };

enum Mode { m_none, m_alone_to_lz, m_debug_decompress, m_debug_delay,
            m_debug_repair, m_decompress, m_list, m_merge, m_range_dec,
            m_repair, m_show_packets, m_split, m_test };

int verbosity = 0;
bool delete_output_on_interrupt = false;


void show_help()
  {
  std::printf( "%s - Data recovery tool and decompressor for the lzip format.\n", Program_name );
  std::printf( "\nLziprecover can repair perfectly most files with small errors (up to one\n"
               "single-byte error per member), without the need of any extra redundance\n"
               "at all. Losing an entire archive just because of a corrupt byte near the\n"
               "beginning is a thing of the past.\n"
               "\nLziprecover can also produce a correct file by merging the good parts of\n"
               "two or more damaged copies, extract data from damaged files, decompress\n"
               "files and test integrity of files.\n"
               "\nLziprecover provides random access to the data in multimember files; it\n"
               "only decompresses the members containing the desired data.\n"
               "\nLziprecover is not a replacement for regular backups, but a last line of\n"
               "defense for the case where the backups are also damaged.\n"
               "\nUsage: %s [options] [files]\n", invocation_name );
  std::printf( "\nOptions:\n"
               "  -h, --help                      display this help and exit\n"
               "  -V, --version                   output version information and exit\n"
               "  -a, --trailing-error            exit with error status if trailing data\n"
               "  -A, --alone-to-lz               convert lzma-alone files to lzip format\n"
               "  -c, --stdout                    write to standard output, keep input files\n"
               "  -d, --decompress                decompress\n"
               "  -D, --range-decompress=<range>  decompress a range of bytes (N-M) to stdout\n"
               "  -f, --force                     overwrite existing output files\n"
               "  -i, --ignore-errors             make '--range-decompress' ignore data errors\n"
               "  -k, --keep                      keep (don't delete) input files\n"
               "  -l, --list                      print (un)compressed file sizes\n"
               "  -m, --merge                     correct errors in file using several copies\n"
               "  -o, --output=<file>             place the output into <file>\n"
               "  -q, --quiet                     suppress all messages\n"
               "  -R, --repair                    try to repair a small error in file\n"
               "  -s, --split                     split multimember file in single-member files\n"
               "  -t, --test                      test compressed file integrity\n"
               "  -v, --verbose                   be verbose (a 2nd -v gives more)\n" );
  if( verbosity >= 1 )
    {
    std::printf( "  -W, --debug-decompress=<pos>,<val>  set pos to val and decompress to stdout\n"
                 "  -X, --show-packets[=<pos>,<val>]  show in stdout the decoded LZMA packets\n"
                 "  -Y, --debug-delay=<range>         find max error detection delay in <range>\n"
                 "  -Z, --debug-repair=<pos>,<val>    test repair one-byte error at <pos>\n" );
    }
  std::printf( "If no file names are given, or if a file is '-', lziprecover decompresses\n"
               "from standard input to standard output.\n"
               "Numbers may be followed by a multiplier: k = kB = 10^3 = 1000,\n"
               "Ki = KiB = 2^10 = 1024, M = 10^6, Mi = 2^20, G = 10^9, Gi = 2^30, etc...\n"
               "\nExit status: 0 for a normal exit, 1 for environmental problems (file\n"
               "not found, invalid flags, I/O errors, etc), 2 to indicate a corrupt or\n"
               "invalid input file, 3 for an internal consistency error (eg, bug) which\n"
               "caused lziprecover to panic.\n"
               "\nReport bugs to lzip-bug@nongnu.org\n"
               "Lziprecover home page: http://www.nongnu.org/lzip/lziprecover.html\n" );
  }


void show_version()
  {
  std::printf( "%s %s\n", program_name, PROGVERSION );
  std::printf( "Copyright (C) %s Antonio Diaz Diaz.\n", program_year );
  std::printf( "License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>\n"
               "This is free software: you are free to change and redistribute it.\n"
               "There is NO WARRANTY, to the extent permitted by law.\n" );
  }

} // end namespace

const char * bad_version( const unsigned version )
  {
  static char buf[80];
  snprintf( buf, sizeof buf, "Version %u member format not supported.",
            version );
  return buf;
  }


const char * format_ds( const unsigned dictionary_size )
  {
  enum { bufsize = 16, factor = 1024 };
  static char buf[bufsize];
  const char * const prefix[8] =
    { "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi", "Yi" };
  const char * p = "";
  const char * np = "  ";
  unsigned num = dictionary_size;
  bool exact = ( num % factor == 0 );

  for( int i = 0; i < 8 && ( num > 9999 || ( exact && num >= factor ) ); ++i )
    { num /= factor; if( num % factor != 0 ) exact = false;
      p = prefix[i]; np = ""; }
  snprintf( buf, bufsize, "%s%4u %sB", np, num, p );
  return buf;
  }


void show_header( const unsigned dictionary_size, const int vlevel )
  {
  if( verbosity >= vlevel )
    std::fprintf( stderr, "dictionary %s.  ", format_ds( dictionary_size ) );
  }

namespace {

long long getnum( const char * const ptr, const long long llimit = -LLONG_MAX,
                  const long long ulimit = LLONG_MAX,
                  const char ** const tailp = 0 )
  {
  char * tail;
  errno = 0;
  long long result = strtoll( ptr, &tail, 0 );
  if( tail == ptr )
    {
    show_error( "Bad or missing numerical argument.", 0, true );
    std::exit( 1 );
    }

  if( !errno && tail[0] )
    {
    char * const p = tail++;
    int factor;
    bool bsuf;					// 'B' suffix is present
    if( tail[0] == 'i' ) { ++tail; factor = 1024; } else factor = 1000;
    if( tail[0] == 'B' ) { ++tail; bsuf = true; } else bsuf = false;
    int exponent = -1;				// -1 = bad multiplier
    switch( *p )
      {
      case 'Y': exponent = 8; break;
      case 'Z': exponent = 7; break;
      case 'E': exponent = 6; break;
      case 'P': exponent = 5; break;
      case 'T': exponent = 4; break;
      case 'G': exponent = 3; break;
      case 'M': exponent = 2; break;
      case 'K': if( factor == 1024 ) exponent = 1; break;
      case 'k': if( factor == 1000 ) exponent = 1; break;
      case 'B': if( factor == 1000 && !bsuf ) exponent = 0; break;
      default : if( tailp ) { tail = p; exponent = 0; } break;
      }
    if( exponent < 0 )
      {
      show_error( "Bad multiplier in numerical argument.", 0, true );
      std::exit( 1 );
      }
    for( int i = 0; i < exponent; ++i )
      {
      if( LLONG_MAX / factor >= std::labs( result ) ) result *= factor;
      else { errno = ERANGE; break; }
      }
    }
  if( !errno && ( result < llimit || result > ulimit ) ) errno = ERANGE;
  if( errno )
    {
    show_error( "Numerical argument out of limits." );
    std::exit( 1 );
    }
  if( tailp ) *tailp = tail;
  return result;
  }


// Recognized formats: <begin> <begin>-<end> <begin>,<size> ,<size>
//
void parse_range( const char * const ptr, Block & range )
  {
  const char * tail = ptr;
  long long value =
    ( ptr[0] == ',' ) ? 0 : getnum( ptr, 0, INT64_MAX - 1, &tail );
  if( tail[0] == 0 || tail[0] == ',' || tail[0] == '-' )
    {
    range.pos( value );
    if( tail[0] == 0 ) { range.size( INT64_MAX - value ); return; }
    const bool issize = ( tail[0] == ',' );
    value = getnum( tail + 1, 1, INT64_MAX );		// size
    if( issize || value > range.pos() )
      {
      if( !issize ) value -= range.pos();
      if( INT64_MAX - range.pos() >= value ) { range.size( value ); return; }
      }
    }
  show_error( "Bad decompression range.", 0, true );
  std::exit( 1 );
  }


// Recognized formats: <pos>,<value> <pos>,+<value> <pos>,f<value>
//
void parse_pos_value( const char * const ptr, Bad_byte & bad_byte )
  {
  const char * tail;
  bad_byte.pos = getnum( ptr, 0, INT64_MAX, &tail );
  if( tail[0] != ',' )
    {
    show_error( "Bad separator between <pos> and <val>.", 0, true );
    std::exit( 1 );
    }
  if( tail[1] == '+' ) { ++tail; bad_byte.mode = Bad_byte::delta; }
  else if( tail[1] == 'f' ) { ++tail; bad_byte.mode = Bad_byte::flip; }
  else bad_byte.mode = Bad_byte::literal;
  bad_byte.value = getnum( tail + 1, 0, 255 );
  }


void one_file( const int files )
  {
  if( files != 1 )
    {
    show_error( "You must specify exactly 1 file.", 0, true );
    std::exit( 1 );
    }
  }


void set_mode( Mode & program_mode, const Mode new_mode )
  {
  if( program_mode != m_none && program_mode != new_mode )
    {
    show_error( "Only one operation can be specified.", 0, true );
    std::exit( 1 );
    }
  program_mode = new_mode;
  }


int extension_index( const std::string & name )
  {
  for( int eindex = 0; known_extensions[eindex].from; ++eindex )
    {
    const std::string ext( known_extensions[eindex].from );
    if( name.size() > ext.size() &&
        name.compare( name.size() - ext.size(), ext.size(), ext ) == 0 )
      return eindex;
    }
  return -1;
  }

} // end namespace

int open_instream( const char * const name, struct stat * const in_statsp,
                   const bool no_ofile, const bool reg_only )
  {
  int infd = open( name, O_RDONLY | O_BINARY );
  if( infd < 0 )
    show_file_error( name, "Can't open input file", errno );
  else
    {
    const int i = fstat( infd, in_statsp );
    const mode_t mode = in_statsp->st_mode;
    const bool can_read = ( i == 0 && !reg_only &&
                            ( S_ISBLK( mode ) || S_ISCHR( mode ) ||
                              S_ISFIFO( mode ) || S_ISSOCK( mode ) ) );
    if( i != 0 || ( !S_ISREG( mode ) && ( !can_read || !no_ofile ) ) )
      {
      if( verbosity >= 0 )
        std::fprintf( stderr, "%s: Input file '%s' is not a regular file%s.\n",
                      program_name, name,
                      ( can_read && !no_ofile ) ?
                      ",\n             and '--stdout' was not specified" : "" );
      close( infd );
      infd = -1;
      }
    }
  return infd;
  }

namespace {

void set_a_outname( const std::string & name )
  {
  output_filename = name;
  if( name.size() > 5 && name.compare( name.size() - 5, 5, ".lzma" ) == 0 )
    output_filename.erase( name.size() - 2 );
  else if( name.size() > 4 && name.compare( name.size() - 4, 4, ".tlz" ) == 0 )
    output_filename.insert( name.size() - 2, "ar." );
  else if( name.size() <= 3 || name.compare( name.size() - 3, 3, ".lz" ) != 0 )
    output_filename += known_extensions[0].from;
  }


void set_d_outname( const std::string & name, const int eindex )
  {
  if( eindex >= 0 )
    {
    const std::string from( known_extensions[eindex].from );
    if( name.size() > from.size() )
      {
      output_filename.assign( name, 0, name.size() - from.size() );
      output_filename += known_extensions[eindex].to;
      return;
      }
    }
  output_filename = name; output_filename += ".out";
  if( verbosity >= 1 )
    std::fprintf( stderr, "%s: Can't guess original name for '%s' -- using '%s'\n",
                  program_name, name.c_str(), output_filename.c_str() );
  }

} // end namespace

bool open_outstream( const bool force, const bool from_stdin,
                     const bool rw, const bool skipping )
  {
  const mode_t usr_rw = S_IRUSR | S_IWUSR;
  const mode_t all_rw = usr_rw | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
  const mode_t outfd_mode = from_stdin ? all_rw : usr_rw;
  int flags = O_CREAT | ( rw ? O_RDWR : O_WRONLY ) | O_BINARY;
  if( force ) flags |= O_TRUNC; else flags |= O_EXCL;

  outfd = open( output_filename.c_str(), flags, outfd_mode );
  if( outfd >= 0 ) delete_output_on_interrupt = true;
  else if( verbosity >= 0 )
    {
    if( errno == EEXIST )
      std::fprintf( stderr, "%s: Output file '%s' already exists%s.\n",
                    program_name, output_filename.c_str(), skipping ?
                    ", skipping" : ". Use '--force' to overwrite it" );
    else
      std::fprintf( stderr, "%s: Can't create output file '%s': %s\n",
                    program_name, output_filename.c_str(), std::strerror( errno ) );
    }
  return ( outfd >= 0 );
  }


bool file_exists( const std::string & filename )
  {
  struct stat st;
  if( stat( filename.c_str(), &st ) == 0 )
    {
    if( verbosity >= 0 )
      std::fprintf( stderr, "%s: Output file '%s' already exists."
                            " Use '--force' to overwrite it.\n",
                    program_name, filename.c_str() );
    return true;
    }
  return false;
  }


bool check_tty( const char * const input_filename, const int infd,
                const Mode program_mode )
  {
  if( program_mode == m_alone_to_lz && isatty( outfd ) )
    {
    show_error( "I won't write compressed data to a terminal.", 0, true );
    return false;
    }
  if( isatty( infd ) )			// all modes read compressed data
    {
    show_file_error( input_filename,
                     "I won't read compressed data from a terminal." );
    return false;
    }
  return true;
  }


void cleanup_and_fail( const int retval )
  {
  if( delete_output_on_interrupt )
    {
    delete_output_on_interrupt = false;
    if( verbosity >= 0 )
      std::fprintf( stderr, "%s: Deleting output file '%s', if it exists.\n",
                    program_name, output_filename.c_str() );
    if( outfd >= 0 ) { close( outfd ); outfd = -1; }
    if( std::remove( output_filename.c_str() ) != 0 && errno != ENOENT )
      show_error( "WARNING: deletion of output file (apparently) failed." );
    }
  std::exit( retval );
  }

namespace {

     // Set permissions, owner and times.
void close_and_set_permissions( const struct stat * const in_statsp )
  {
  bool warning = false;
  if( in_statsp )
    {
    const mode_t mode = in_statsp->st_mode;
    // fchown will in many cases return with EPERM, which can be safely ignored.
    if( fchown( outfd, in_statsp->st_uid, in_statsp->st_gid ) == 0 )
      { if( fchmod( outfd, mode ) != 0 ) warning = true; }
    else
      if( errno != EPERM ||
          fchmod( outfd, mode & ~( S_ISUID | S_ISGID | S_ISVTX ) ) != 0 )
        warning = true;
    }
  if( close( outfd ) != 0 )
    {
    show_error( "Error closing output file", errno );
    cleanup_and_fail( 1 );
    }
  outfd = -1;
  delete_output_on_interrupt = false;
  if( in_statsp )
    {
    struct utimbuf t;
    t.actime = in_statsp->st_atime;
    t.modtime = in_statsp->st_mtime;
    if( utime( output_filename.c_str(), &t ) != 0 ) warning = true;
    }
  if( warning && verbosity >= 1 )
    show_error( "Can't change output file attributes." );
  }


unsigned char xdigit( const unsigned value )
  {
  if( value <= 9 ) return '0' + value;
  if( value <= 15 ) return 'A' + value - 10;
  return 0;
  }


bool show_trailing_data( const uint8_t * const data, const int size,
                         const Pretty_print & pp, const bool all,
                         const bool ignore_trailing )
  {
  if( verbosity >= 4 || !ignore_trailing )
    {
    std::string msg;
    if( !all ) msg = "first bytes of ";
    msg += "trailing data = ";
    for( int i = 0; i < size; ++i )
      {
      msg += xdigit( data[i] >> 4 );
      msg += xdigit( data[i] & 0x0F );
      msg += ' ';
      }
    msg += '\'';
    for( int i = 0; i < size; ++i )
      { if( std::isprint( data[i] ) ) msg += data[i]; else msg += '.'; }
    msg += '\'';
    pp( msg.c_str() );
    if( !ignore_trailing ) show_file_error( pp.name(), trailing_msg );
    }
  return ignore_trailing;
  }


int decompress( const int infd, const Pretty_print & pp,
                const bool ignore_trailing, const bool testing )
  {
  int retval = 0;

  try {
    unsigned long long partial_file_pos = 0;
    Range_decoder rdec( infd );
    for( bool first_member = true; ; first_member = false )
      {
      File_header header;
      rdec.reset_member_position();
      const int size = rdec.read_data( header.data, File_header::size );
      if( rdec.finished() )			// End Of File
        {
        if( first_member || header.verify_prefix( size ) )
          { pp( "File ends unexpectedly at member header." ); retval = 2; }
        else if( size > 0 && !show_trailing_data( header.data, size, pp,
                                                  true, ignore_trailing ) )
          retval = 2;
        break;
        }
      if( !header.verify_magic() )
        {
        if( first_member )
          { show_file_error( pp.name(), bad_magic_msg ); retval = 2; }
        else if( !show_trailing_data( header.data, size, pp, false, ignore_trailing ) )
          retval = 2;
        break;
        }
      if( !header.verify_version() )
        { pp( bad_version( header.version() ) ); retval = 2; break; }
      const unsigned dictionary_size = header.dictionary_size();
      if( !isvalid_ds( dictionary_size ) )
        { pp( bad_dict_msg ); retval = 2; break; }

      if( verbosity >= 2 || ( verbosity == 1 && first_member ) )
        { pp(); show_header( dictionary_size ); }

      LZ_decoder decoder( rdec, dictionary_size, outfd );
      const int result = decoder.decode_member( pp );
      partial_file_pos += rdec.member_position();
      if( result != 0 )
        {
        if( verbosity >= 0 && result <= 2 )
          {
          pp();
          std::fprintf( stderr, "%s at pos %llu\n", ( result == 2 ) ?
                        "File ends unexpectedly" : "Decoder error",
                        partial_file_pos );
          }
        retval = 2; break;
        }
      if( verbosity >= 2 )
        { std::fputs( testing ? "ok\n" : "done\n", stderr ); pp.reset(); }
      }
    }
  catch( std::bad_alloc ) { pp( "Not enough memory." ); retval = 1; }
  catch( Error e ) { pp(); show_error( e.msg, errno ); retval = 1; }
  if( verbosity == 1 && retval == 0 )
    std::fputs( testing ? "ok\n" : "done\n", stderr );
  return retval;
  }


extern "C" void signal_handler( int )
  {
  show_error( "Control-C or similar caught, quitting." );
  cleanup_and_fail( 1 );
  }


void set_signals()
  {
  std::signal( SIGHUP, signal_handler );
  std::signal( SIGINT, signal_handler );
  std::signal( SIGTERM, signal_handler );
  }

} // end namespace


int close_outstream( const struct stat * const in_statsp )
  {
  if( delete_output_on_interrupt )
    close_and_set_permissions( in_statsp );
  if( outfd >= 0 && close( outfd ) != 0 )
    { show_error( "Can't close stdout", errno ); return 1; }
  outfd = -1;
  return 0;
  }


std::string insert_fixed( std::string name )
  {
  if( name.size() > 7 && name.compare( name.size() - 7, 7, ".tar.lz" ) == 0 )
    name.insert( name.size() - 7, "_fixed" );
  else if( name.size() > 3 && name.compare( name.size() - 3, 3, ".lz" ) == 0 )
    name.insert( name.size() - 3, "_fixed" );
  else if( name.size() > 4 && name.compare( name.size() - 4, 4, ".tlz" ) == 0 )
    name.insert( name.size() - 4, "_fixed" );
  else name += "_fixed.lz";
  return name;
  }


void show_error( const char * const msg, const int errcode, const bool help )
  {
  if( verbosity < 0 ) return;
  if( msg && msg[0] )
    {
    std::fprintf( stderr, "%s: %s", program_name, msg );
    if( errcode > 0 ) std::fprintf( stderr, ": %s", std::strerror( errcode ) );
    std::fputc( '\n', stderr );
    }
  if( help )
    std::fprintf( stderr, "Try '%s --help' for more information.\n",
                  invocation_name );
  }


void show_file_error( const char * const filename, const char * const msg,
                      const int errcode )
  {
  if( verbosity < 0 ) return;
  std::fprintf( stderr, "%s: %s: %s", program_name, filename, msg );
  if( errcode > 0 ) std::fprintf( stderr, ": %s", std::strerror( errcode ) );
  std::fputc( '\n', stderr );
  }


void internal_error( const char * const msg )
  {
  if( verbosity >= 0 )
    std::fprintf( stderr, "%s: internal error: %s\n", program_name, msg );
  std::exit( 3 );
  }


void show_error2( const char * const msg1, const char * const name,
                  const char * const msg2 )
  {
  if( verbosity >= 0 )
    std::fprintf( stderr, "%s: %s '%s' %s\n", program_name, msg1, name, msg2 );
  }


void show_error4( const char * const msg1, const char * const name1,
                  const char * const name2, const char * const msg2 )
  {
  if( verbosity >= 0 )
    std::fprintf( stderr, "%s: %s '%s' and '%s' %s\n",
                  program_name, msg1, name1, name2, msg2 );
  }


int main( const int argc, const char * const argv[] )
  {
  Block range( 0, 0 );
  Bad_byte bad_byte;
  std::string default_output_filename;
  std::vector< std::string > filenames;
  int infd = -1;
  Mode program_mode = m_none;
  bool force = false;
  bool ignore_errors = false;
  bool ignore_trailing = true;
  bool keep_input_files = false;
  bool to_stdout = false;
  invocation_name = argv[0];

  const Arg_parser::Option options[] =
    {
    { 'a', "trailing-error",   Arg_parser::no  },
    { 'A', "alone-to-lz",      Arg_parser::no  },
    { 'c', "stdout",           Arg_parser::no  },
    { 'd', "decompress",       Arg_parser::no  },
    { 'D', "range-decompress", Arg_parser::yes },
    { 'f', "force",            Arg_parser::no  },
    { 'h', "help",             Arg_parser::no  },
    { 'i', "ignore-errors",    Arg_parser::no  },
    { 'k', "keep",             Arg_parser::no  },
    { 'l', "list",             Arg_parser::no  },
    { 'm', "merge",            Arg_parser::no  },
    { 'n', "threads",          Arg_parser::yes },
    { 'o', "output",           Arg_parser::yes },
    { 'q', "quiet",            Arg_parser::no  },
    { 'R', "repair",           Arg_parser::no  },
    { 's', "split",            Arg_parser::no  },
    { 't', "test",             Arg_parser::no  },
    { 'v', "verbose",          Arg_parser::no  },
    { 'V', "version",          Arg_parser::no  },
    { 'W', "debug-decompress", Arg_parser::yes },
    { 'X', "show-packets",     Arg_parser::maybe },
    { 'Y', "debug-delay",      Arg_parser::yes },
    { 'Z', "debug-repair",     Arg_parser::yes },
    {  0 , 0,                  Arg_parser::no  } };

  const Arg_parser parser( argc, argv, options );
  if( parser.error().size() )				// bad option
    { show_error( parser.error().c_str(), 0, true ); return 1; }

  int argind = 0;
  for( ; argind < parser.arguments(); ++argind )
    {
    const int code = parser.code( argind );
    if( !code ) break;					// no more options
    const std::string & sarg = parser.argument( argind );
    const char * const arg = sarg.c_str();
    switch( code )
      {
      case 'a': ignore_trailing = false; break;
      case 'A': set_mode( program_mode, m_alone_to_lz ); break;
      case 'c': to_stdout = true; break;
      case 'd': set_mode( program_mode, m_decompress ); break;
      case 'D': set_mode( program_mode, m_range_dec );
                parse_range( arg, range ); break;
      case 'f': force = true; break;
      case 'h': show_help(); return 0;
      case 'i': ignore_errors = true; break;
      case 'k': keep_input_files = true; break;
      case 'l': set_mode( program_mode, m_list ); break;
      case 'm': set_mode( program_mode, m_merge ); break;
      case 'n': break;
      case 'o': default_output_filename = sarg; break;
      case 'q': verbosity = -1; break;
      case 'R': set_mode( program_mode, m_repair ); break;
      case 's': set_mode( program_mode, m_split ); break;
      case 't': set_mode( program_mode, m_test ); break;
      case 'v': if( verbosity < 4 ) ++verbosity; break;
      case 'V': show_version(); return 0;
      case 'W': set_mode( program_mode, m_debug_decompress );
                parse_pos_value( arg, bad_byte ); break;
      case 'X': set_mode( program_mode, m_show_packets );
                if( arg[0] ) { parse_pos_value( arg, bad_byte ); } break;
      case 'Y': set_mode( program_mode, m_debug_delay );
                parse_range( arg, range ); break;
      case 'Z': set_mode( program_mode, m_debug_repair );
                parse_pos_value( arg, bad_byte ); break;
      default : internal_error( "uncaught option." );
      }
    } // end process options

#if defined(__MSVCRT__) || defined(__OS2__)
  setmode( STDIN_FILENO, O_BINARY );
  setmode( STDOUT_FILENO, O_BINARY );
#endif

  if( program_mode == m_none )
    {
    show_error( "You must specify the operation to be performed.", 0, true );
    return 1;
    }

  bool filenames_given = false;
  for( ; argind < parser.arguments(); ++argind )
    {
    filenames.push_back( parser.argument( argind ) );
    if( filenames.back() != "-" ) filenames_given = true;
    }

  try {
  switch( program_mode )
    {
    case m_none: internal_error( "invalid operation." ); break;
    case m_alone_to_lz: break;
    case m_debug_decompress:
      one_file( filenames.size() );
      return debug_decompress( filenames[0], bad_byte, verbosity, false );
    case m_debug_delay:
      one_file( filenames.size() );
      return debug_delay( filenames[0], range, verbosity );
    case m_debug_repair:
      one_file( filenames.size() );
      return debug_repair( filenames[0], bad_byte, verbosity );
    case m_decompress: break;
    case m_list: break;
    case m_merge:
      if( filenames.size() < 2 )
        { show_error( "You must specify at least 2 files.", 0, true ); return 1; }
      set_signals();
      return merge_files( filenames, default_output_filename, verbosity, force );
    case m_range_dec:
      one_file( filenames.size() );
      set_signals();
      return range_decompress( filenames[0], default_output_filename, range,
               verbosity, force, ignore_errors, ignore_trailing, to_stdout );
    case m_repair:
      one_file( filenames.size() );
      set_signals();
      return repair_file( filenames[0], default_output_filename, verbosity,
                          force );
    case m_show_packets:
      one_file( filenames.size() );
      return debug_decompress( filenames[0], bad_byte, verbosity, true );
    case m_split:
      one_file( filenames.size() );
      set_signals();
      return split_file( filenames[0], default_output_filename, verbosity, force );
    case m_test: break;
    }
    }
  catch( std::bad_alloc )
    { show_error( "Not enough memory." ); cleanup_and_fail( 1 ); }
  catch( Error e ) { show_error( e.msg, errno ); cleanup_and_fail( 1 ); }

  if( filenames.empty() ) filenames.push_back("-");

  if( program_mode == m_list )
    return list_files( filenames, verbosity, ignore_trailing );

  if( program_mode == m_test )
    outfd = -1;
  else if( program_mode != m_alone_to_lz && program_mode != m_decompress )
    internal_error( "invalid decompressor operation." );

  if( !to_stdout && program_mode != m_test &&
      ( filenames_given || default_output_filename.size() ) )
    set_signals();

  Pretty_print pp( filenames, verbosity );

  int retval = 0;
  bool stdin_used = false;
  for( unsigned i = 0; i < filenames.size(); ++i )
    {
    std::string input_filename;
    struct stat in_stats;
    output_filename.clear();

    if( filenames[i].empty() || filenames[i] == "-" )
      {
      if( stdin_used ) continue; else stdin_used = true;
      infd = STDIN_FILENO;
      if( program_mode != m_test )
        {
        if( to_stdout || default_output_filename.empty() )
          outfd = STDOUT_FILENO;
        else
          {
          output_filename = default_output_filename;
          if( program_mode == m_alone_to_lz &&
              extension_index( default_output_filename ) < 0 )
            output_filename += known_extensions[0].from;
          if( !open_outstream( force, true ) )
            {
            if( retval < 1 ) retval = 1;
            close( infd ); infd = -1;
            continue;
            }
          }
        }
      }
    else
      {
      input_filename = filenames[i];
      infd = open_instream( input_filename.c_str(), &in_stats,
                            to_stdout || program_mode == m_test );
      if( infd < 0 ) { if( retval < 1 ) retval = 1; continue; }
      if( program_mode != m_test )
        {
        if( to_stdout ) outfd = STDOUT_FILENO;
        else
          {
          if( program_mode == m_alone_to_lz )
            set_a_outname( input_filename );
          else set_d_outname( input_filename, extension_index( input_filename ) );
          if( !open_outstream( force, false ) )
            {
            if( retval < 1 ) retval = 1;
            close( infd ); infd = -1;
            continue;
            }
          }
        }
      }

    pp.set_name( input_filename );
    if( !check_tty( pp.name(), infd, program_mode ) )
      {
      if( retval < 1 ) retval = 1;
      if( program_mode == m_test ) { close( infd ); infd = -1; continue; }
      cleanup_and_fail( retval );
      }

    const struct stat * const in_statsp = input_filename.size() ? &in_stats : 0;
    int tmp;
    if( program_mode == m_alone_to_lz )
      tmp = alone_to_lz( infd, pp );
    else
      tmp = decompress( infd, pp, ignore_trailing, program_mode == m_test );
    if( tmp > retval ) retval = tmp;
    if( tmp && program_mode != m_test ) cleanup_and_fail( retval );

    if( delete_output_on_interrupt )
      close_and_set_permissions( in_statsp );
    if( input_filename.size() )
      {
      close( infd ); infd = -1;
      if( !keep_input_files && !to_stdout && program_mode != m_test )
        std::remove( input_filename.c_str() );
      }
    }
  if( outfd >= 0 && close( outfd ) != 0 )
    {
    show_error( "Can't close stdout", errno );
    if( retval < 1 ) retval = 1;
    }
  return retval;
  }