/* Lunzip - Decompressor for the lzip format
   Copyright (C) 2010-2022 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
   (e.g., bug) which caused lunzip to panic.
*/

#define _FILE_OFFSET_BITS 64

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <utime.h>
#include <sys/stat.h>
#if defined __MSVCRT__ || defined __OS2__ || defined __DJGPP__
#include <io.h>
#if defined __MSVCRT__
#define fchmod(x,y) 0
#define fchown(x,y,z) 0
#define SIGHUP SIGTERM
#define S_ISSOCK(x) 0
#ifndef S_IRGRP
#define S_IRGRP 0
#define S_IWGRP 0
#define S_IROTH 0
#define S_IWOTH 0
#endif
#endif
#if defined __DJGPP__
#define S_ISSOCK(x) 0
#define S_ISVTX 0
#endif
#endif

#include "carg_parser.h"
#include "lzip.h"
#include "decoder.h"

#ifndef O_BINARY
#define O_BINARY 0
#endif

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

#if ( defined  SIZE_MAX &&  SIZE_MAX < UINT_MAX ) || \
    ( defined SSIZE_MAX && SSIZE_MAX <  INT_MAX )
#error "Environments where 'size_t' is narrower than 'int' are not supported."
#endif

int verbosity = 0;

static const char * const program_name = "lunzip";
static const char * const program_year = "2022";
static const char * invocation_name = "lunzip";		/* default value */

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

enum Mode { m_compress, m_decompress, m_list, m_test };

/* Variables used in signal handler context.
   They are not declared volatile because the handler never returns. */
static char * output_filename = 0;
static int outfd = -1;
static bool delete_output_on_interrupt = false;


static void show_help( void )
  {
  printf( "Lunzip is a decompressor for the lzip format written in C. Its small size\n"
          "makes it well suited for embedded devices or software installers that need\n"
          "to decompress files but don't need compression capabilities. Lunzip is fully\n"
          "compatible with lzip 1.4 or newer.\n"
          "\nLunzip provides a 'low memory' mode able to decompress any file using as\n"
          "little memory as 50 kB, irrespective of the dictionary size used to\n"
          "compress the file. To activate it, specify the size of the output buffer\n"
          "with the option --buffer-size and lunzip will use the decompressed\n"
          "file as dictionary for distances beyond the buffer size. Of course, the\n"
          "larger the difference between the buffer size and the dictionary size, the\n"
          "more accesses to disk are needed and the slower the decompression is.\n"
          "This 'low memory' mode only works when decompressing to a regular file\n"
          "and is intended for systems without enough memory (RAM + swap) to keep\n"
          "the whole dictionary at once.\n"
          "\nUsage: %s [options] [files]\n", invocation_name );
  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"
          "  -c, --stdout               write to standard output, keep input files\n"
          "  -d, --decompress           decompress (this is the default)\n"
          "  -f, --force                overwrite existing output files\n"
          "  -k, --keep                 keep (don't delete) input files\n"
          "  -l, --list                 print (un)compressed file sizes\n"
          "  -o, --output=<file>        write to <file>, keep input files\n"
          "  -q, --quiet                suppress all messages\n"
          "  -t, --test                 test compressed file integrity\n"
          "  -u, --buffer-size=<bytes>  set output buffer size in bytes\n"
          "  -v, --verbose              be verbose (a 2nd -v gives more)\n"
          "      --loose-trailing       allow trailing data seeming corrupt header\n"
          "\nIf no file names are given, or if a file is '-', lunzip 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"
          "Buffer sizes 12 to 29 are interpreted as powers of two, meaning 2^12\n"
          "to 2^29 bytes.\n"
          "\nTo extract all the files from archive 'foo.tar.lz', use the commands\n"
          "'tar -xf foo.tar.lz' or 'lunzip -cd foo.tar.lz | tar -xf -'.\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 (e.g., bug) which\n"
          "caused lunzip to panic.\n"
          "\nThe ideas embodied in lunzip are due to (at least) the following people:\n"
          "Abraham Lempel and Jacob Ziv (for the LZ algorithm), Andrey Markov (for the\n"
          "definition of Markov chains), G.N.N. Martin (for the definition of range\n"
          "encoding), Igor Pavlov (for putting all the above together in LZMA), and\n"
          "Julian Seward (for bzip2's CLI).\n"
          "\nReport bugs to lzip-bug@nongnu.org\n"
          "Lunzip home page: http://www.nongnu.org/lzip/lunzip.html\n" );
  }


static void show_version( void )
  {
  printf( "%s %s\n", program_name, PROGVERSION );
  printf( "Copyright (C) %s Antonio Diaz Diaz.\n", program_year );
  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" );
  }


/* assure at least a minimum size for buffer 'buf' */
void * resize_buffer( void * buf, const unsigned min_size )
  {
  if( buf ) buf = realloc( buf, min_size );
  else buf = malloc( min_size );
  if( !buf ) { show_error( mem_msg, 0, false ); cleanup_and_fail( 1 ); }
  return buf;
  }


struct Pretty_print
  {
  const char * name;
  char * padded_name;
  const char * stdin_name;
  unsigned longest_name;
  bool first_post;
  };

static void Pp_init( struct Pretty_print * const pp,
                     const char * const filenames[], const int num_filenames )
  {
  pp->name = 0;
  pp->padded_name = 0;
  pp->stdin_name = "(stdin)";
  pp->longest_name = 0;
  pp->first_post = false;

  if( verbosity <= 0 ) return;
  const unsigned stdin_name_len = strlen( pp->stdin_name );
  int i;
  for( i = 0; i < num_filenames; ++i )
    {
    const char * const s = filenames[i];
    const unsigned len = (strcmp( s, "-" ) == 0) ? stdin_name_len : strlen( s );
    if( pp->longest_name < len ) pp->longest_name = len;
    }
  if( pp->longest_name == 0 ) pp->longest_name = stdin_name_len;
  }

static void Pp_set_name( struct Pretty_print * const pp,
                         const char * const filename )
  {
  unsigned name_len, padded_name_len, i = 0;

  if( filename && filename[0] && strcmp( filename, "-" ) != 0 )
    pp->name = filename;
  else pp->name = pp->stdin_name;
  name_len = strlen( pp->name );
  padded_name_len = max( name_len, pp->longest_name ) + 4;
  pp->padded_name = resize_buffer( pp->padded_name, padded_name_len + 1 );
  while( i < 2 ) pp->padded_name[i++] = ' ';
  while( i < name_len + 2 ) { pp->padded_name[i] = pp->name[i-2]; ++i; }
  pp->padded_name[i++] = ':';
  while( i < padded_name_len ) pp->padded_name[i++] = ' ';
  pp->padded_name[i] = 0;
  pp->first_post = true;
  }

static void Pp_reset( struct Pretty_print * const pp )
  { if( pp->name && pp->name[0] ) pp->first_post = true; }

void Pp_show_msg( struct Pretty_print * const pp, const char * const msg )
  {
  if( verbosity < 0 ) return;
  if( pp->first_post )
    {
    pp->first_post = false;
    fputs( pp->padded_name, stderr );
    if( !msg ) fflush( stderr );
    }
  if( msg ) fprintf( stderr, "%s\n", msg );
  }


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 );

  int i; for( 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 )
  {
  fprintf( stderr, "dict %s, ", format_ds( dictionary_size ) );
  }


/* separate large numbers >= 100_000 in groups of 3 digits using '_' */
static const char * format_num3( unsigned long long num )
  {
  const char * const si_prefix = "kMGTPEZY";
  const char * const binary_prefix = "KMGTPEZY";
  enum { buffers = 8, bufsize = 4 * sizeof (long long) };
  static char buffer[buffers][bufsize];	/* circle of static buffers for printf */
  static int current = 0;
  int i;
  char * const buf = buffer[current++]; current %= buffers;
  char * p = buf + bufsize - 1;		/* fill the buffer backwards */
  *p = 0;	/* terminator */
  if( num > 1024 )
    {
    char prefix = 0;			/* try binary first, then si */
    for( i = 0; i < 8 && num >= 1024 && num % 1024 == 0; ++i )
      { num /= 1024; prefix = binary_prefix[i]; }
    if( prefix ) *(--p) = 'i';
    else
      for( i = 0; i < 8 && num >= 1000 && num % 1000 == 0; ++i )
        { num /= 1000; prefix = si_prefix[i]; }
    if( prefix ) *(--p) = prefix;
    }
  const bool split = num >= 100000;

  for( i = 0; ; )
    {
    *(--p) = num % 10 + '0'; num /= 10; if( num == 0 ) break;
    if( split && ++i >= 3 ) { i = 0; *(--p) = '_'; }
    }
  return p;
  }


static unsigned long getnum( const char * const arg,
                             const char * const option_name,
                             const unsigned long llimit,
                             const unsigned long ulimit )
  {
  char * tail;
  errno = 0;
  unsigned long long result = strtoul( arg, &tail, 0 );
  if( tail == arg )
    {
    if( verbosity >= 0 )
      fprintf( stderr, "%s: Bad or missing numerical argument in "
               "option '%s'.\n", program_name, option_name );
    exit( 1 );
    }

  if( !errno && tail[0] )
    {
    const unsigned factor = ( tail[1] == 'i' ) ? 1024 : 1000;
    int exponent = 0;				/* 0 = bad multiplier */
    int i;
    switch( tail[0] )
      {
      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;
      }
    if( exponent <= 0 )
      {
      if( verbosity >= 0 )
        fprintf( stderr, "%s: Bad multiplier in numerical argument of "
                 "option '%s'.\n", program_name, option_name );
      exit( 1 );
      }
    for( i = 0; i < exponent; ++i )
      {
      if( ulimit / factor >= result ) result *= factor;
      else { errno = ERANGE; break; }
      }
    }
  if( !errno && ( result < llimit || result > ulimit ) ) errno = ERANGE;
  if( errno )
    {
    if( verbosity >= 0 )
      fprintf( stderr, "%s: Numerical argument out of limits [%s,%s] "
               "in option '%s'.\n", program_name, format_num3( llimit ),
               format_num3( ulimit ), option_name );
    exit( 1 );
    }
  return result;
  }


static int get_dict_size( const char * const arg, const char * const option_name )
  {
  char * tail;
  const long bits = strtol( arg, &tail, 0 );
  if( bits >= min_dictionary_bits &&
      bits <= max_dictionary_bits && *tail == 0 )
    return 1 << bits;
  return getnum( arg, option_name, min_dictionary_size, max_dictionary_size );
  }


static void set_mode( enum Mode * const program_modep, const enum Mode new_mode )
  {
  if( *program_modep != m_compress && *program_modep != new_mode )
    {
    show_error( "Only one operation can be specified.", 0, true );
    exit( 1 );
    }
  *program_modep = new_mode;
  }


static int extension_index( const char * const name )
  {
  int eindex;
  for( eindex = 0; known_extensions[eindex].from; ++eindex )
    {
    const char * const ext = known_extensions[eindex].from;
    const unsigned name_len = strlen( name );
    const unsigned ext_len = strlen( ext );
    if( name_len > ext_len &&
        strncmp( name + name_len - ext_len, ext, ext_len ) == 0 )
      return eindex;
    }
  return -1;
  }


static void set_d_outname( const char * const name, const int eindex )
  {
  const unsigned name_len = strlen( name );
  if( eindex >= 0 )
    {
    const char * const from = known_extensions[eindex].from;
    const unsigned from_len = strlen( from );
    if( name_len > from_len )
      {
      output_filename = resize_buffer( output_filename, name_len +
                                       strlen( known_extensions[eindex].to ) + 1 );
      strcpy( output_filename, name );
      strcpy( output_filename + name_len - from_len, known_extensions[eindex].to );
      return;
      }
    }
  output_filename = resize_buffer( output_filename, name_len + 4 + 1 );
  strcpy( output_filename, name );
  strcat( output_filename, ".out" );
  if( verbosity >= 1 )
    fprintf( stderr, "%s: Can't guess original name for '%s' -- using '%s'\n",
             program_name, name, output_filename );
  }


int open_instream( const char * const name, struct stat * const in_statsp,
                   const bool one_to_one, 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 || one_to_one ) ) )
      {
      if( verbosity >= 0 )
        fprintf( stderr, "%s: Input file '%s' is not a regular file%s.\n",
                 program_name, name, ( can_read && one_to_one ) ?
                 ",\n        and neither '-c' nor '-o' were specified" : "" );
      close( infd );
      infd = -1;
      }
    }
  return infd;
  }


static bool open_outstream( const bool force, const bool protect )
  {
  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 = protect ? usr_rw : all_rw;
  int flags = O_APPEND | O_CREAT | O_RDWR | O_BINARY;
  if( force ) flags |= O_TRUNC; else flags |= O_EXCL;

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


static void set_signals( void (*action)(int) )
  {
  signal( SIGHUP, action );
  signal( SIGINT, action );
  signal( SIGTERM, action );
  }


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


static void signal_handler( int sig )
  {
  if( sig ) {}				/* keep compiler happy */
  show_error( "Control-C or similar caught, quitting.", 0, false );
  cleanup_and_fail( 1 );
  }


static bool check_tty_in( const char * const input_filename, const int infd,
                          const enum Mode program_mode, int * const retval )
  {
  if( isatty( infd ) )				/* for example /dev/tty */
    { show_file_error( input_filename,
                       "I won't read compressed data from a terminal.", 0 );
      close( infd ); set_retval( retval, 2 );
      if( program_mode != m_test ) cleanup_and_fail( *retval );
      return false; }
  return true;
  }


/* Set permissions, owner, and times. */
static 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, false );
    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, &t ) != 0 ) warning = true;
    }
  if( warning && verbosity >= 1 )
    show_error( "Can't change output file attributes.", 0, false );
  }


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


static bool show_trailing_data( const uint8_t * const data, const int size,
                                struct Pretty_print * const pp, const bool all,
                                const int ignore_trailing )	/* -1 = show */
  {
  if( verbosity >= 4 || ignore_trailing <= 0 )
    {
    int i;
    char buf[80];
    unsigned len = max( 0, snprintf( buf, sizeof buf, "%strailing data = ",
                                     all ? "" : "first bytes of " ) );
    for( i = 0; i < size && len + 2 < sizeof buf; ++i )
      {
      buf[len++] = xdigit( data[i] >> 4 );
      buf[len++] = xdigit( data[i] & 0x0F );
      buf[len++] = ' ';
      }
    if( len < sizeof buf ) buf[len++] = '\'';
    for( i = 0; i < size && len < sizeof buf; ++i )
      { if( isprint( data[i] ) ) buf[len++] = data[i]; else buf[len++] = '.'; }
    if( len < sizeof buf ) buf[len++] = '\'';
    if( len < sizeof buf ) buf[len] = 0; else buf[sizeof buf - 1] = 0;
    Pp_show_msg( pp, buf );
    if( ignore_trailing == 0 ) show_file_error( pp->name, trailing_msg, 0 );
    }
  return ( ignore_trailing > 0 );
  }


static int decompress( const unsigned long long cfile_size, const int infd,
                struct Pretty_print * const pp, const unsigned buffer_size,
                const bool ignore_trailing, const bool loose_trailing,
                const bool testing )
  {
  unsigned long long partial_file_pos = 0;
  struct Range_decoder rdec;
  int retval = 0;
  bool first_member;
  if( !Rd_init( &rdec, infd ) )
    { show_error( mem_msg, 0, false ); cleanup_and_fail( 1 ); }

  for( first_member = true; ; first_member = false )
    {
    Lzip_header header;
    Rd_reset_member_position( &rdec );
    const int size = Rd_read_data( &rdec, header, Lh_size );
    if( Rd_finished( &rdec ) )			/* End Of File */
      {
      if( first_member )
        { show_file_error( pp->name, "File ends unexpectedly at member header.", 0 );
          retval = 2; }
      else if( Lh_verify_prefix( header, size ) )
        { Pp_show_msg( pp, "Truncated header in multimember file." );
          show_trailing_data( header, size, pp, true, -1 );
          retval = 2; }
      else if( size > 0 && !show_trailing_data( header, size, pp,
                                                true, ignore_trailing ) )
        retval = 2;
      break;
      }
    if( !Lh_verify_magic( header ) )
      {
      if( first_member )
        { show_file_error( pp->name, bad_magic_msg, 0 ); retval = 2; }
      else if( !loose_trailing && Lh_verify_corrupt( header ) )
        { Pp_show_msg( pp, corrupt_mm_msg );
          show_trailing_data( header, size, pp, false, -1 );
          retval = 2; }
      else if( !show_trailing_data( header, size, pp, false, ignore_trailing ) )
        retval = 2;
      break;
      }
    if( !Lh_verify_version( header ) )
      { Pp_show_msg( pp, bad_version( Lh_version( header ) ) );
        retval = 2; break; }
    const unsigned dictionary_size = Lh_get_dictionary_size( header );
    if( !isvalid_ds( dictionary_size ) )
      { Pp_show_msg( pp, bad_dict_msg ); retval = 2; break; }

    if( verbosity >= 2 || ( verbosity == 1 && first_member ) )
      Pp_show_msg( pp, 0 );

    struct LZ_decoder decoder;
    if( !LZd_init( &decoder, &rdec, buffer_size, dictionary_size, outfd ) )
      {
      Pp_show_msg( pp, "Not enough memory. Try a smaller output buffer size." );
      retval = 1; break;
      }
    show_dprogress( cfile_size, partial_file_pos, &rdec, pp );	/* init */
    const int result = LZd_decode_member( &decoder, pp );
    partial_file_pos += Rd_member_position( &rdec );
    LZd_free( &decoder );
    if( result != 0 )
      {
      if( verbosity >= 0 && result <= 2 )
        {
        Pp_show_msg( pp, 0 );
        fprintf( stderr, "%s at pos %llu\n", ( result == 2 ) ?
                 "File ends unexpectedly" : "Decoder error",
                 partial_file_pos );
        }
      retval = 2; break;
      }
    if( verbosity >= 2 )
      { fputs( testing ? "ok\n" : "done\n", stderr ); Pp_reset( pp ); }
    }
  Rd_free( &rdec );
  if( verbosity == 1 && retval == 0 )
    fputs( testing ? "ok\n" : "done\n", stderr );
  return retval;
  }


void show_error( const char * const msg, const int errcode, const bool help )
  {
  if( verbosity < 0 ) return;
  if( msg && msg[0] )
    fprintf( stderr, "%s: %s%s%s\n", program_name, msg,
             ( errcode > 0 ) ? ": " : "",
             ( errcode > 0 ) ? strerror( errcode ) : "" );
  if( help )
    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 )
    fprintf( stderr, "%s: %s: %s%s%s\n", program_name, filename, msg,
             ( errcode > 0 ) ? ": " : "",
             ( errcode > 0 ) ? strerror( errcode ) : "" );
  }


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


void show_dprogress( const unsigned long long cfile_size,
                     const unsigned long long partial_size,
                     const struct Range_decoder * const d,
                     struct Pretty_print * const p )
  {
  static unsigned long long csize = 0;		/* file_size / 100 */
  static unsigned long long psize = 0;
  static const struct Range_decoder * rdec = 0;
  static struct Pretty_print * pp = 0;
  static int counter = 0;
  static bool enabled = true;

  if( !enabled ) return;
  if( p )					/* initialize static vars */
    {
    if( verbosity < 2 || !isatty( STDERR_FILENO ) ) { enabled = false; return; }
    csize = cfile_size; psize = partial_size; rdec = d; pp = p; counter = 0;
    }
  if( rdec && pp && --counter <= 0 )
    {
    const unsigned long long pos = psize + Rd_member_position( rdec );
    counter = 7;		/* update display every 114688 bytes */
    if( csize > 0 )
      fprintf( stderr, "%4llu%%  %.1f MB\r", pos / csize, pos / 1000000.0 );
    else
      fprintf( stderr, "  %.1f MB\r", pos / 1000000.0 );
    Pp_reset( pp ); Pp_show_msg( pp, 0 );	/* restore cursor position */
    }
  }


int main( const int argc, const char * const argv[] )
  {
  const char * default_output_filename = "";
  unsigned buffer_size = max_dictionary_size;
  enum Mode program_mode = m_compress;
  int i;
  bool force = false;
  bool ignore_trailing = true;
  bool keep_input_files = false;
  bool loose_trailing = false;
  bool to_stdout = false;
  if( argc > 0 ) invocation_name = argv[0];

  enum { opt_lt = 256 };
  const struct ap_Option options[] =
    {
    { 'a', "trailing-error",    ap_no  },
    { 'c', "stdout",            ap_no  },
    { 'd', "decompress",        ap_no  },
    { 'f', "force",             ap_no  },
    { 'h', "help",              ap_no  },
    { 'k', "keep",              ap_no  },
    { 'l', "list",              ap_no  },
    { 'n', "threads",           ap_yes },
    { 'o', "output",            ap_yes },
    { 'q', "quiet",             ap_no  },
    { 't', "test",              ap_no  },
    { 'u', "buffer-size",       ap_yes },
    { 'v', "verbose",           ap_no  },
    { 'V', "version",           ap_no  },
    { opt_lt, "loose-trailing", ap_no  },
    {  0 , 0,                   ap_no  } };

  CRC32_init();

  /* static because valgrind complains and memory management in C sucks */
  static struct Arg_parser parser;
  if( !ap_init( &parser, argc, argv, options, 0 ) )
    { show_error( mem_msg, 0, false ); return 1; }
  if( ap_error( &parser ) )				/* bad option */
    { show_error( ap_error( &parser ), 0, true ); return 1; }

  int argind = 0;
  for( ; argind < ap_arguments( &parser ); ++argind )
    {
    const int code = ap_code( &parser, argind );
    if( !code ) break;					/* no more options */
    const char * const pn = ap_parsed_name( &parser, argind );
    const char * const arg = ap_argument( &parser, argind );
    switch( code )
      {
      case 'a': ignore_trailing = false; break;
      case 'c': to_stdout = true; break;
      case 'd': set_mode( &program_mode, m_decompress ); break;
      case 'f': force = true; break;
      case 'h': show_help(); return 0;
      case 'k': keep_input_files = true; break;
      case 'l': set_mode( &program_mode, m_list ); break;
      case 'n': break;
      case 'o': if( strcmp( arg, "-" ) == 0 ) to_stdout = true;
                else { default_output_filename = arg; } break;
      case 'q': verbosity = -1; break;
      case 't': set_mode( &program_mode, m_test ); break;
      case 'u': buffer_size = get_dict_size( arg, pn ); break;
      case 'v': if( verbosity < 4 ) ++verbosity; break;
      case 'V': show_version(); return 0;
      case opt_lt: loose_trailing = true; break;
      default : internal_error( "uncaught option." );
      }
    } /* end process options */

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

  static const char ** filenames = 0;
  int num_filenames = max( 1, ap_arguments( &parser ) - argind );
  filenames = resize_buffer( filenames, num_filenames * sizeof filenames[0] );
  filenames[0] = "-";

  bool filenames_given = false;
  for( i = 0; argind + i < ap_arguments( &parser ); ++i )
    {
    filenames[i] = ap_argument( &parser, argind + i );
    if( strcmp( filenames[i], "-" ) != 0 ) filenames_given = true;
    }

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

  if( program_mode == m_compress )
    program_mode = m_decompress;			/* default mode */
  if( program_mode == m_test ) to_stdout = false;	/* apply overrides */
  if( program_mode == m_test || to_stdout ) default_output_filename = "";

  if( buffer_size < max_dictionary_size )
    {
    bool from_stdin = false;
    if( to_stdout || program_mode == m_test )
      { show_error( "'--buffer-size' is incompatible with '--stdout' and '--test'.",
                    0, false ); return 1; }
    for( i = 0; i < num_filenames; ++i )
      if( !filenames[i][0] || strcmp( filenames[i], "-" ) == 0 )
        { from_stdin = true; break; }
    if( from_stdin && !default_output_filename[0] )
      { show_error( "Output file must be specified when decompressing from standard input\n"
                    "        with a reduced buffer size.", 0, false ); return 1; }
    }

  output_filename = resize_buffer( output_filename, 1 );
  output_filename[0] = 0;
  if( to_stdout && program_mode != m_test ) outfd = STDOUT_FILENO;
  else outfd = -1;

  const bool to_file = !to_stdout && program_mode != m_test &&
                       default_output_filename[0];
  if( !to_stdout && program_mode != m_test && ( filenames_given || to_file ) )
    set_signals( signal_handler );

  static struct Pretty_print pp;
  Pp_init( &pp, filenames, num_filenames );

  int failed_tests = 0;
  int retval = 0;
  const bool one_to_one = !to_stdout && program_mode != m_test && !to_file;
  bool stdin_used = false;
  for( i = 0; i < num_filenames; ++i )
    {
    const char * input_filename = "";
    int infd;
    struct stat in_stats;

    Pp_set_name( &pp, filenames[i] );
    if( strcmp( filenames[i], "-" ) == 0 )
      {
      if( stdin_used ) continue; else stdin_used = true;
      infd = STDIN_FILENO;
      if( !check_tty_in( pp.name, infd, program_mode, &retval ) ) continue;
      if( one_to_one ) { outfd = STDOUT_FILENO; output_filename[0] = 0; }
      }
    else
      {
      input_filename = filenames[i];
      infd = open_instream( input_filename, &in_stats, one_to_one, false );
      if( infd < 0 ) { set_retval( &retval, 1 ); continue; }
      if( !check_tty_in( pp.name, infd, program_mode, &retval ) ) continue;
      if( one_to_one )			/* open outfd after verifying infd */
        {
        set_d_outname( input_filename, extension_index( input_filename ) );
        if( !open_outstream( force, true ) )
          { close( infd ); set_retval( &retval, 1 ); continue; }
        }
      }

    if( to_file && outfd < 0 )		/* open outfd after verifying infd */
      {
      output_filename = resize_buffer( output_filename,
                        strlen( default_output_filename ) + 1 );
      strcpy( output_filename, default_output_filename );
      if( !open_outstream( force, false ) ) return 1;
      }

    if( delete_output_on_interrupt && buffer_size < max_dictionary_size )
      {
      struct stat st;
      if( fstat( outfd, &st ) != 0 || !S_ISREG( st.st_mode ) )
        {
        if( verbosity >= 0 )
          fprintf( stderr, "%s: Output file '%s' is not a regular file,\n"
                   "        and 'low memory' mode has been requested.\n",
                   program_name, output_filename );
        set_retval( &retval, 1 );
        return retval;		/* don't try to delete a non-regular file */
        }
      }

    const struct stat * const in_statsp =
      ( input_filename[0] && one_to_one ) ? &in_stats : 0;
    const unsigned long long cfile_size =
      ( input_filename[0] && S_ISREG( in_stats.st_mode ) ) ?
        ( in_stats.st_size + 99 ) / 100 : 0;
    int tmp = decompress( cfile_size, infd, &pp, buffer_size, ignore_trailing,
                          loose_trailing, program_mode == m_test );
    if( close( infd ) != 0 )
      { show_file_error( pp.name, "Error closing input file", errno );
        set_retval( &tmp, 1 ); }
    set_retval( &retval, tmp );
    if( tmp )
      { if( program_mode != m_test ) cleanup_and_fail( retval );
        else ++failed_tests; }

    if( delete_output_on_interrupt && one_to_one )
      close_and_set_permissions( in_statsp );
    if( input_filename[0] && !keep_input_files && one_to_one )
      remove( input_filename );
    }
  if( delete_output_on_interrupt ) close_and_set_permissions( 0 );	/* -o */
  else if( outfd >= 0 && close( outfd ) != 0 )				/* -c */
    {
    show_error( "Error closing stdout", errno, false );
    set_retval( &retval, 1 );
    }
  if( failed_tests > 0 && verbosity >= 1 && num_filenames > 1 )
    fprintf( stderr, "%s: warning: %d %s failed the test.\n",
             program_name, failed_tests,
             ( failed_tests == 1 ) ? "file" : "files" );
  free( output_filename );
  free( filenames );
  ap_free( &parser );
  return retval;
  }