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.



11
12
13
14
 
# 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.



9
10
11
 
# File 'lib/y_enc.rb', line 9

def filename
  @filename
end

#filepath ⇒ Object (readonly)

Returns the value of attribute filepath.



9
10
11
 
# File 'lib/y_enc.rb', line 9

def filepath
  @filepath
end

#filesize ⇒ Object (readonly)

Returns the value of attribute filesize.



9
10
11
 
# File 'lib/y_enc.rb', line 9

def filesize
  @filesize
end

#line ⇒ Object (readonly)

Returns the value of attribute line.



9
10
11
 
# File 'lib/y_enc.rb', line 9

def line
  @line
end

#outputpath ⇒ Object (readonly)

Returns the value of attribute outputpath.



9
10
11
 
# File 'lib/y_enc.rb', line 9

def outputpath
  @outputpath
end

Instance Method Details

#crc32 ⇒ Object 



16
17
18
 
# File 'lib/y_enc.rb', line 16

def crc32
  @crc32.upcase.strip
end

#decode ⇒ Object 



43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
 
# File 'lib/y_enc.rb', line 43

def decode
  if is_yenc?
          #Continue decoding
    begin_read = false

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

        if line.include?("=ybegin") #This is the begin size
          breakdown_header line
          begin_read = true
          next
        end
        if line.include?("=yend")
          breakdown_endline line
          begin_read=false
          break #stop looking through the file we are done
        end
        #end of reading lines

        if begin_read
          #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
        end

    end
    @new_file.close
  else
    false
  end
end

#encode_to_file(outputfilename) ⇒ Object

Encode file into a yenc text file



21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
 
# 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"
  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 [0, 10, 13, 61].include?(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



102
103
104
105
106
 
# File 'lib/y_enc.rb', line 102

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) 


96
97
98
99
 
# File 'lib/y_enc.rb', line 96

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