Lib/encodings/uu_codec.py

   1 """ Python 'uu_codec' Codec - UU content transfer encoding
   2
   3     Unlike most of the other codecs which target Unicode, this codec
   4     will return Python string objects for both encode and decode.
   5
   6     Written by Marc-Andre Lemburg (mal@lemburg.com). Some details were
   7     adapted from uu.py which was written by Lance Ellinghouse and
   8     modified by Jack Jansen and Fredrik Lundh.
   9
  10 """
  11 import codecs, binascii
  12
  13 ### Codec APIs
  14
  15 def uu_encode(input,errors='strict',filename='<data>',mode=0666):
  16
  17     """ Encodes the object input and returns a tuple (output
  18         object, length consumed).
  19
  20         errors defines the error handling to apply. It defaults to
  21         'strict' handling which is the only currently supported
  22         error handling for this codec.
  23
  24     """
  25     assert errors == 'strict'
  26     from cStringIO import StringIO
  27     from binascii import b2a_uu
  28     infile = StringIO(input)
  29     outfile = StringIO()
  30     read = infile.read
  31     write = outfile.write
  32
  33     # Encode
  34     write('begin %o %s\n' % (mode & 0777, filename))
  35     chunk = read(45)
  36     while chunk:
  37         write(b2a_uu(chunk))
  38         chunk = read(45)
  39     write(' \nend\n')
  40
  41     return (outfile.getvalue(), len(input))
  42
  43 def uu_decode(input,errors='strict'):
  44
  45     """ Decodes the object input and returns a tuple (output
  46         object, length consumed).
  47
  48         input must be an object which provides the bf_getreadbuf
  49         buffer slot. Python strings, buffer objects and memory
  50         mapped files are examples of objects providing this slot.
  51
  52         errors defines the error handling to apply. It defaults to
  53         'strict' handling which is the only currently supported
  54         error handling for this codec.
  55
  56         Note: filename and file mode information in the input data is
  57         ignored.
  58
  59     """
  60     assert errors == 'strict'
  61     from cStringIO import StringIO
  62     from binascii import a2b_uu
  63     infile = StringIO(input)
  64     outfile = StringIO()
  65     readline = infile.readline
  66     write = outfile.write
  67
  68     # Find start of encoded data
  69     while 1:
  70         s = readline()
  71         if not s:
  72             raise ValueError, 'Missing "begin" line in input data'
  73         if s[:5] == 'begin':
  74             break
  75
  76     # Decode
  77     while 1:
  78         s = readline()
  79         if not s or \
  80            s == 'end\n':
  81             break
  82         try:
  83             data = a2b_uu(s)
  84         except binascii.Error, v:
  85             # Workaround for broken uuencoders by /Fredrik Lundh
  86             nbytes = (((ord(s[0])-32) & 63) * 4 + 5) / 3
  87             data = a2b_uu(s[:nbytes])
  88             #sys.stderr.write("Warning: %s\n" % str(v))
  89         write(data)
  90     if not s:
  91         raise ValueError, 'Truncated input data'
  92
  93     return (outfile.getvalue(), len(input))
  94
  95 class Codec(codecs.Codec):
  96
  97     def encode(self,input,errors='strict'):
  98         return uu_encode(input,errors)
  99     def decode(self,input,errors='strict'):
 100         return uu_decode(input,errors)
 101
 102 class StreamWriter(Codec,codecs.StreamWriter):
 103     pass
 104
 105 class StreamReader(Codec,codecs.StreamReader):
 106     pass
 107
 108 ### encodings module API
 109
 110 def getregentry():
 111
 112     return (uu_encode,uu_decode,StreamReader,StreamWriter)