/*  Lunzip - Decompressor for the lzip format
    Copyright (C) 2010-2015 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 lunzip to panic.
*/

#define _FILE_OFFSET_BITS 64

#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__)
#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 "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


const char * const Program_name = "Lunzip";
const char * const program_name = "lunzip";
const char * const program_year = "2015";
const char * invocation_name = 0;

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

char * output_filename = 0;
int outfd = -1;
int verbosity = 0;
const mode_t usr_rw = S_IRUSR | S_IWUSR;
const mode_t all_rw = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
mode_t outfd_mode = S_IRUSR | S_IWUSR;
bool delete_output_on_interrupt = false;


static void show_help( void )
  {
  printf( "Lunzip is a decompressor for the lzip format. It is written in C and its\n"
          "small size makes it well suited for embedded devices or software\n"
          "installers that need to decompress files but do not need compression\n"
          "capabilities. Lunzip is fully 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 '--buffer-size' option and lunzip will use the decompressed\n"
          "file as dictionary for distances beyond the buffer size. Of course, the\n"
          "smaller the output buffer size used in relation to the dictionary size,\n"
          "the 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"
          "\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"
          "  -c, --stdout               send output to standard output\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"
          "  -o, --output=<file>        if reading stdin, place the output into <file>\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"
          "If no file names are given, lunzip decompresses from standard input to\n"
          "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 lunzip to panic.\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" );
  }


static void show_header( const unsigned dictionary_size )
  {
  if( verbosity >= 3 )
    {
    const char * const prefix[8] =
      { "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi", "Yi" };
    enum { factor = 1024 };
    const char * p = "";
    const char * np = "  ";
    unsigned num = dictionary_size, i;
    bool exact = ( num % factor == 0 );

    for( i = 0; i < 8 && ( num > 9999 || ( exact && num >= factor ) ); ++i )
      { num /= factor; if( num % factor != 0 ) exact = false;
        p = prefix[i]; np = ""; }
    fprintf( stderr, "dictionary size %s%4u %sB.  ", np, num, p );
    }
  }


static unsigned long getnum( const char * const ptr,
                             const unsigned long llimit,
                             const unsigned long ulimit )
  {
  unsigned long result;
  char * tail;
  errno = 0;
  result = strtoul( ptr, &tail, 0 );
  if( tail == ptr )
    {
    show_error( "Bad or missing numerical argument.", 0, true );
    exit( 1 );
    }

  if( !errno && tail[0] )
    {
    const int factor = ( tail[1] == 'i' ) ? 1024 : 1000;
    int exponent = 0, i;
    bool bad_multiplier = false;
    switch( tail[0] )
      {
      case ' ': break;
      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; else bad_multiplier = true;
                break;
      case 'k': if( factor == 1000 ) exponent = 1; else bad_multiplier = true;
                break;
      default : bad_multiplier = true;
      }
    if( bad_multiplier )
      {
      show_error( "Bad multiplier in numerical argument.", 0, true );
      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 )
    {
    show_error( "Numerical argument out of limits.", 0, false );
    exit( 1 );
    }
  return result;
  }


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


static int extension_index( const char * const name )
  {
  int i;
  for( i = 0; known_extensions[i].from; ++i )
    {
    const char * const ext = known_extensions[i].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 i;
    }
  return -1;
  }


static int open_instream( const char * const name, struct stat * const in_statsp,
                          const bool no_ofile )
  {
  int infd = open( name, O_RDONLY | O_BINARY );
  if( infd < 0 )
    {
    if( verbosity >= 0 )
      fprintf( stderr, "%s: Can't open input file '%s': %s\n",
               program_name, name, strerror( errno ) );
    }
  else
    {
    const int i = fstat( infd, in_statsp );
    const mode_t mode = in_statsp->st_mode;
    const bool can_read = ( i == 0 &&
                            ( 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 )
        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;
  }


/* assure at least a minimum size for buffer 'buf' */
static void * resize_buffer( void * buf, const int min_size )
  {
  if( buf ) buf = realloc( buf, min_size );
  else buf = malloc( min_size );
  if( !buf )
    {
    show_error( "Not enough memory.", 0, false );
    cleanup_and_fail( 1 );
    }
  return buf;
  }


static void set_d_outname( const char * const name, const int i )
  {
  const unsigned name_len = strlen( name );
  if( i >= 0 )
    {
    const char * const from = known_extensions[i].from;
    const unsigned from_len = strlen( from );
    if( name_len > from_len )
      {
      output_filename = resize_buffer( output_filename, name_len +
                                       strlen( known_extensions[0].to ) + 1 );
      strcpy( output_filename, name );
      strcpy( output_filename + name_len - from_len, known_extensions[i].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 );
  }


static bool open_outstream( const bool force )
  {
  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 && 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 );
  }


void cleanup_and_fail( const int retval )
  {
  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 );
  }


     /* 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 ) 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 int decompress( const int infd, struct Pretty_print * const pp,
                       const int buffer_size, 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( "Not enough memory.", 0, false );
    cleanup_and_fail( 1 );
    }

  for( first_member = true; ; first_member = false )
    {
    int result;
    unsigned dictionary_size;
    File_header header;
    struct LZ_decoder decoder;
    Rd_reset_member_position( &rdec );
    Rd_read_data( &rdec, header, Fh_size );
    if( Rd_finished( &rdec ) )			/* End Of File */
      {
      if( first_member )
        { Pp_show_msg( pp, "File ends unexpectedly at member header." );
          retval = 2; }
      break;
      }
    if( !Fh_verify_magic( header ) )
      {
      if( !first_member ) break;		/* trailing garbage */
      Pp_show_msg( pp, "Bad magic number (file not in lzip format)." );
      retval = 2; break;
      }
    if( !Fh_verify_version( header ) )
      {
      if( verbosity >= 0 )
        { Pp_show_msg( pp, 0 );
          fprintf( stderr, "Version %d member format not supported.\n",
                   Fh_version( header ) ); }
      retval = 2; break;
      }
    dictionary_size = Fh_get_dictionary_size( header );
    if( dictionary_size < min_dictionary_size ||
        dictionary_size > max_dictionary_size )
      { Pp_show_msg( pp, "Invalid dictionary size in member header." );
        retval = 2; break; }

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

    if( !LZd_init( &decoder, &rdec, buffer_size, dictionary_size, outfd ) )
      {
      show_error( "Not enough memory. Try a smaller output buffer size.", 0, false );
      cleanup_and_fail( 1 );
      }
    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 signal_handler( int sig )
  {
  if( sig ) {}				/* keep compiler happy */
  show_error( "Control-C or similar caught, quitting.", 0, false );
  cleanup_and_fail( 1 );
  }


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


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


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


int main( const int argc, const char * const argv[] )
  {
  const char * input_filename = "";
  const char * default_output_filename = "";
  const char ** filenames = 0;
  int num_filenames = 0;
  int buffer_size = max_dictionary_size;
  int infd = -1;
  int argind = 0;
  int retval = 0;
  int i;
  bool filenames_given = false;
  bool force = false;
  bool keep_input_files = false;
  bool testing = false;
  bool to_stdout = false;
  struct Pretty_print pp;

  const struct ap_Option options[] =
    {
    { 'c', "stdout",          ap_no  },
    { 'd', "decompress",      ap_no  },
    { 'f', "force",           ap_no  },
    { 'h', "help",            ap_no  },
    { 'k', "keep",            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  },
    {  0 ,  0,                ap_no  } };

  struct Arg_parser parser;

  invocation_name = argv[0];
  CRC32_init();

  if( !ap_init( &parser, argc, argv, options, 0 ) )
    { show_error( "Not enough memory.", 0, false ); return 1; }
  if( ap_error( &parser ) )				/* bad option */
    { show_error( ap_error( &parser ), 0, true ); return 1; }

  for( ; argind < ap_arguments( &parser ); ++argind )
    {
    const int code = ap_code( &parser, argind );
    const char * const arg = ap_argument( &parser, argind );
    if( !code ) break;					/* no more options */
    switch( code )
      {
      case 'c': to_stdout = true; break;
      case 'd': testing = false; break;
      case 'f': force = true; break;
      case 'h': show_help(); return 0;
      case 'k': keep_input_files = true; break;
      case 'n': break;
      case 'o': default_output_filename = arg; break;
      case 'q': verbosity = -1; break;
      case 't': testing = true; break;
      case 'u': buffer_size = get_dict_size( arg ); break;
      case 'v': if( verbosity < 4 ) ++verbosity; break;
      case 'V': show_version(); return 0;
      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( testing )
    outfd = -1;

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

  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( buffer_size < max_dictionary_size )
    {
    struct stat st;
    bool from_stdin = false;
    if( to_stdout || testing )
      { 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 stdin with a\n"
                    "        reduced buffer size.", 0, false ); return 1; }
    if( from_stdin && default_output_filename[0] &&
        stat( default_output_filename, &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, default_output_filename );
      return 1;
      }
    }

  if( !to_stdout && !testing &&
      ( filenames_given || default_output_filename[0] ) )
    set_signals();

  Pp_init( &pp, filenames, num_filenames );

  output_filename = resize_buffer( output_filename, 1 );
  for( i = 0; i < num_filenames; ++i )
    {
    int tmp;
    struct stat in_stats;
    const struct stat * in_statsp;
    output_filename[0] = 0;

    if( !filenames[i][0] || strcmp( filenames[i], "-" ) == 0 )
      {
      input_filename = "";
      infd = STDIN_FILENO;
      if( !testing )
        {
        if( to_stdout || !default_output_filename[0] )
          outfd = STDOUT_FILENO;
        else
          {
          output_filename = resize_buffer( output_filename,
                                           strlen( default_output_filename ) + 1 );
          strcpy( output_filename, default_output_filename );
          outfd_mode = all_rw;
          if( !open_outstream( force ) )
            {
            if( retval < 1 ) retval = 1;
            close( infd ); infd = -1;
            continue;
            }
          }
        }
      }
    else
      {
      input_filename = filenames[i];
      infd = open_instream( input_filename, &in_stats, to_stdout || testing );
      if( infd < 0 ) { if( retval < 1 ) retval = 1; continue; }
      if( !testing )
        {
        if( to_stdout ) outfd = STDOUT_FILENO;
        else
          {
          set_d_outname( input_filename, extension_index( input_filename ) );
          outfd_mode = usr_rw;
          if( !open_outstream( force ) )
            {
            if( retval < 1 ) retval = 1;
            close( infd ); infd = -1;
            continue;
            }
          }
        }
      }

    if( isatty( infd ) )
      {
      show_error( "I won't read compressed data from a terminal.", 0, true );
      return 1;
      }

    if( output_filename[0] && !to_stdout && !testing )
      delete_output_on_interrupt = true;
    in_statsp = input_filename[0] ? &in_stats : 0;
    Pp_set_name( &pp, input_filename );
    tmp = decompress( infd, &pp, buffer_size, testing );
    if( tmp > retval ) retval = tmp;
    if( tmp && !testing ) cleanup_and_fail( retval );

    if( delete_output_on_interrupt )
      close_and_set_permissions( in_statsp );
    if( input_filename[0] )
      {
      close( infd ); infd = -1;
      if( !keep_input_files && !to_stdout && !testing )
        remove( input_filename );
      }
    }
  if( outfd >= 0 && close( outfd ) != 0 )
    {
    show_error( "Can't close stdout", errno, false );
    if( retval < 1 ) retval = 1;
    }
  free( output_filename );
  free( filenames );
  ap_free( &parser );
  return retval;
  }