Class: YEnc

Inherits:
Object
  • Object
show all
Defined in:
lib/y_enc.rb

Overview

yEnc

This gem allows you to decode and encode files using the yenc standard.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filepath, outputpath) ⇒ YEnc

Returns a new instance of YEnc.



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# File 'lib/y_enc.rb', line 11

def initialize filepath, outputpath
  @filepath = filepath
  @outputpath = outputpath
end

Instance Attribute Details

#filename ⇒ Object (readonly)

Returns the value of attribute filename.



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# File 'lib/y_enc.rb', line 9

def filename
  @filename
end

#filepath ⇒ Object (readonly)

Returns the value of attribute filepath.



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# File 'lib/y_enc.rb', line 9

def filepath
  @filepath
end

#filesize ⇒ Object (readonly)

Returns the value of attribute filesize.



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# File 'lib/y_enc.rb', line 9

def filesize
  @filesize
end

#line ⇒ Object (readonly)

Returns the value of attribute line.



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# File 'lib/y_enc.rb', line 9

def line
  @line
end

#outputpath ⇒ Object (readonly)

Returns the value of attribute outputpath.



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# File 'lib/y_enc.rb', line 9

def outputpath
  @outputpath
end

Instance Method Details

#crc32 ⇒ Object 



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# File 'lib/y_enc.rb', line 16

def crc32
  @crc32.upcase.strip
end

#decode ⇒ Object 



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# File 'lib/y_enc.rb', line 68

def decode
  if is_yenc?
          #Continue decoding
    begin_read = false

    File.open(@filepath, 'r').each_line do |line|

      if begin_read
        if line.start_with?("=yend")
          breakdown_endline line
          begin_read=false
          break #stop looking through the file we are done
        end
        #end of reading lines

        #puts "LINE COUNT: #{line.length}"
        #Decode and write to binary file
        esc = false
        line.each_byte do |c|
          next if c == 13 or c == 10

          if c == 61 and not esc #escape character hit goto the next one
            esc = true
            next
          else
            if esc
              esc = false
              c = c - 64
            end

            if c.between?(0,41)
              decoded = c + 214
            else
              decoded = c - 42
            end
          end
          @new_file.putc decoded
        end

      else
        if line.start_with?("=ybegin") #This is the begin size
          breakdown_header line
          begin_read = true
          next
        end
      end
    end
  else
    false
  end
  @new_file.close
end

#encode ⇒ Object

method only encodes given file and returns yenc encoded string; nothing more, nothing less Author: Tadeus Dobrovolskij



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# File 'lib/y_enc.rb', line 46

def encode
  sio = StringIO.new("","w:ASCII-8BIT")
  special = { 0 => nil, 10 => nil, 13 => nil, 61 => nil }
  File.open(@filepath,'rb') do |b|
    until b.eof?
      buffer = b.read(128)
      buffer.each_byte do |byte|
        char_to_write = (byte + 42) % 256
        if special.has_key?(char_to_write)
          sio.putc '='
          char_to_write = (char_to_write + 64) % 256
        end
        sio.putc char_to_write
      end
      sio.puts "\n"
    end
  end
  result = sio.string
  sio.close
  return result
end

#encode_to_file(outputfilename) ⇒ Object

Encode file into a yenc text file



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# File 'lib/y_enc.rb', line 21

def encode_to_file outputfilename
  outputfile = File.new(@outputpath + outputfilename, "w")
  outputfile.puts "=ybegin size=#{File.size?(@filepath)} line=128 name=#{File.basename @filepath}\n"
  special = { 0 => nil, 10 => nil, 13 => nil, 61 => nil }
  File.open(@filepath,'rb') do |f|
    until f.eof?
      #Read in 128 bytes at a time
      buffer = f.read(128)
      buffer.each_byte do |byte|
        char_to_write = (byte + 42) % 256
        if special.has_key?(char_to_write)
          outputfile.putc '='
          char_to_write = (char_to_write + 64) % 256
        end
        outputfile.putc char_to_write
      end
      outputfile.puts "\n"
    end
  end
  outputfile.puts "=yend size=312860 crc32=#{file_crc32(@filepath).upcase}\n"
  outputfile.close
end

#file_crc32(filepath) ⇒ Object

Get the CRC32 for a file



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# File 'lib/y_enc.rb', line 128

def file_crc32 filepath
  f = nil
  File.open( filepath, "rb") { |h| f = h.read }
  Zlib.crc32(f,0).to_s(16)
end

#pass_crc32? ⇒ Boolean

Does this pass the crc32 check

Returns:

  • (Boolean) 


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# File 'lib/y_enc.rb', line 122

def pass_crc32?
  crc32 = file_crc32 @outputpath + @filename
  crc32.eql?(@crc32.downcase.strip)
end