Lib/base64.py

   1 #! /usr/bin/env python
   2
   3 # Conversions to/from base64 transport encoding as per RFC-MIME (Dec 1991
   4 # version).
   5
   6 # Parameters set by RFC-1421.
   7 #
   8 # Modified 04-Oct-95 by Jack to use binascii module
   9
  10 import binascii
  11
  12 MAXLINESIZE = 76 # Excluding the CRLF
  13 MAXBINSIZE = (MAXLINESIZE/4)*3
  14
  15 # Encode a file.
  16 def encode(input, output):
  17         while 1:
  18                 s = input.read(MAXBINSIZE)
  19                 if not s: break
  20                 while len(s) < MAXBINSIZE:
  21                     ns = input.read(MAXBINSIZE-len(s))
  22                     if not ns: break
  23                     s = s + ns
  24                 line = binascii.b2a_base64(s)
  25                 output.write(line)
  26
  27 # Decode a file.
  28 def decode(input, output):
  29         while 1:
  30                 line = input.readline()
  31                 if not line: break
  32                 s = binascii.a2b_base64(line)
  33                 output.write(s)
  34
  35 def encodestring(s):
  36         import StringIO
  37         f = StringIO.StringIO(s)
  38         g = StringIO.StringIO()
  39         encode(f, g)
  40         return g.getvalue()
  41
  42 def decodestring(s):
  43         import StringIO
  44         f = StringIO.StringIO(s)
  45         g = StringIO.StringIO()
  46         decode(f, g)
  47         return g.getvalue()
  48
  49 # Small test program
  50 def test():
  51         import sys, getopt
  52         try:
  53                 opts, args = getopt.getopt(sys.argv[1:], 'deut')
  54         except getopt.error, msg:
  55                 sys.stdout = sys.stderr
  56                 print msg
  57                 print """usage: basd64 [-d] [-e] [-u] [-t] [file|-]
  58                 -d, -u: decode
  59                 -e: encode (default)
  60                 -t: decode string 'Aladdin:open sesame'"""
  61                 sys.exit(2)
  62         func = encode
  63         for o, a in opts:
  64                 if o == '-e': func = encode
  65                 if o == '-d': func = decode
  66                 if o == '-u': func = decode
  67                 if o == '-t': test1(); return
  68         if args and args[0] != '-':
  69                 func(open(args[0], 'rb'), sys.stdout)
  70         else:
  71                 func(sys.stdin, sys.stdout)
  72
  73 def test1():
  74         s0 = "Aladdin:open sesame"
  75         s1 = encodestring(s0)
  76         s2 = decodestring(s1)
  77         print s0, `s1`, s2
  78
  79 if __name__ == '__main__':
  80         test()