zutils/zcat.cc

/*  Zcat - decompress and concatenate files to standard output
    Copyright (C) 2010, 2011, 2012, 2013 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 3 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/>.
*/

struct Cat_options
  {
  int number_lines;		// 0 = no, 1 = nonblank, 2 = all
  bool show_ends;
  bool show_nonprinting;
  bool show_tabs;
  bool squeeze_blank;

  Cat_options()
    : number_lines( 0 ), show_ends( false ), show_nonprinting( false ),
      show_tabs( false ), squeeze_blank( false ) {}
  };


class Line_number		// unlimited size line counter
  {
  std::string str;
  unsigned first_digit_pos;

public:
  Line_number() : str( "     0\t" ), first_digit_pos( 5 ) {}

  void next()
    {
    for( unsigned i = str.size() - 1; i > first_digit_pos; )
      {
      if( str[--i] < '9' ) { ++str[i]; return; }
      str[i] = '0';
      }
    if( first_digit_pos > 0 ) str[--first_digit_pos] = '1';
    else str.insert( first_digit_pos, 1, '1' );
    }

  int sprint( uint8_t * const buf )
    {
    std::memcpy( buf, str.c_str(), str.size() );
    return str.size();
    }
  };

Line_number line_number;


void show_zcat_help()
  {
  std::printf( "Zcat copies each given file (\"-\" means standard input), to standard\n"
               "output. If any given file is compressed, its uncompressed content is\n"
               "used. If a given file does not exist, and its name does not end with one\n"
               "of the known extensions, zcat tries the compressed file names\n"
               "corresponding to the supported formats. If no files are specified,\n"
               "data is read from standard input, decompressed if needed, and sent to\n"
               "standard output. Data read from standard input must be of the same type;\n"
               "all uncompressed or all in the same compression format.\n"
               "\nThe supported formats are bzip2, gzip, lzip and xz.\n"
               "\nUsage: zcat [options] [files]\n"
               "\nExit status is 0 if no errors occurred, 1 otherwise.\n"
               "\nOptions:\n"
               "  -h, --help                 display this help and exit\n"
               "  -V, --version              output version information and exit\n"
               "  -A, --show-all             equivalent to '-vET'\n"
               "  -b, --number-nonblank      number nonblank output lines\n"
               "  -e                         equivalent to '-vE'\n"
               "  -E, --show-ends            display '$' at end of each line\n"
               "      --format=<fmt>         force given format (bz2, gz, lz, xz)\n"
               "  -n, --number               number all output lines\n"
               "  -q, --quiet                suppress all messages\n"
               "  -r, --recursive            operate recursively on directories\n"
               "  -s, --squeeze-blank        never more than one single blank line\n"
               "  -t                         equivalent to '-vT'\n"
               "  -T, --show-tabs            display TAB characters as '^I'\n"
               "  -v, --show-nonprinting     use '^' and 'M-' notation, except for LF and TAB\n"
               "      --verbose              verbose mode (show error messages)\n" );
  show_help_addr();
  }


int do_cat( const int infd, const int buffer_size,
            uint8_t * const inbuf, uint8_t * const outbuf,
            const std::string & input_filename,
            const Cat_options & cat_options )
  {
  static int at_bol = 1;	// at begin of line. 0 = false, 1 = true,
				// 2 = at begin of second blank line.
  int inpos = 0;		// positions in buffers
  int outpos = 0;
  int rd = -1;			// bytes read by the last readblock
  unsigned char c;

  while( true )
    {
    do {
      if( outpos >= buffer_size )
        {
        if( writeblock( STDOUT_FILENO, outbuf, outpos ) != outpos )
          { show_error( "Write error", errno ); return 1; }
        outpos = 0;
        }
      if( inpos > rd )			// inbuf is empty
        {
        rd = readblock( infd, inbuf, buffer_size );
        if( rd != buffer_size && errno )
          {
          show_error2( "Error reading file", input_filename.c_str() );
          return 1;
          }
        if( rd == 0 )
          {
          if( writeblock( STDOUT_FILENO, outbuf, outpos ) != outpos )
            { show_error( "Write error", errno ); return 1; }
          outpos = 0;
          return 0;
          }
        inpos = 0;
        inbuf[rd] = '\n';		// sentinel newline
        }
      else				// a real newline was found
        {
        if( at_bol > 1 )
          {
          if( cat_options.squeeze_blank ) { c = inbuf[inpos++]; continue; }
          }
        else ++at_bol;
        if( at_bol > 1 && cat_options.number_lines == 2 )
          {
          line_number.next();
          outpos += line_number.sprint( &outbuf[outpos] );
          }
        if( cat_options.show_ends ) outbuf[outpos++] = '$';
        outbuf[outpos++] = '\n';		// output the newline
        }
      c = inbuf[inpos++];
      }
    while( c == '\n' );

    if( at_bol > 0 && cat_options.number_lines )
      {
      line_number.next();
      outpos += line_number.sprint( &outbuf[outpos] );
      }
    at_bol = 0;

    // the loops below continue until a newline (real or sentinel) is found

    if( cat_options.show_nonprinting )
      while( true )
        {
        if( c < 32 || c >= 127 )
          {
          if( c == '\n' ) break;
          if( c != '\t' || cat_options.show_tabs )
            {
            if( c >= 128 )
              { c -= 128; outbuf[outpos++] = 'M'; outbuf[outpos++] = '-'; }
            if( c < 32 ) { c += 64; outbuf[outpos++] = '^'; }
            else if( c == 127 ) { c = '?'; outbuf[outpos++] = '^'; }
            }
          }
        outbuf[outpos++] = c;
        c = inbuf[inpos++];
        }
    else				// not quoting
      while( c != '\n' )
        {
        if( c == '\t' && cat_options.show_tabs )
          { c += 64; outbuf[outpos++] = '^'; }
        outbuf[outpos++] = c;
        c = inbuf[inpos++];
        }
    }
  }


int cat( int infd, const int format_type, const std::string & input_filename,
         const Cat_options & cat_options )
  {
  enum { buffer_size = 4096 };
  // buffer with space for sentinel newline at the end
  uint8_t * const inbuf = new uint8_t[buffer_size+1];
  // buffer with space for character quoting and 255-digit line number
  uint8_t * const outbuf = new uint8_t[(4*buffer_size)+256];
  pid_t pid = 0;
  int retval = 0;
  if( !set_data_feeder( &infd, &pid, format_type ) ) retval = 1;
  else
    retval = do_cat( infd, buffer_size, inbuf, outbuf,
                     input_filename, cat_options );
  if( retval == 0 )
    if( pid && wait_for_child( pid, "data feeder" ) != 0 ) retval = 1;
  if( retval == 0 )
    if( close( infd ) != 0 )
      { show_close_error( "data feeder" ); retval = 1; }
  delete[] inbuf; delete[] outbuf;
  return retval;
  }