Lib/base64.py

   1 #! /usr/bin/env python
   2
   3 """Conversions to/from base64 transport encoding as per RFC-1521."""
   4
   5 # Modified 04-Oct-95 by Jack to use binascii module
   6
   7 import binascii
   8
   9 MAXLINESIZE = 76 # Excluding the CRLF
  10 MAXBINSIZE = (MAXLINESIZE/4)*3
  11
  12 def encode(input, output):
  13     """Encode a file."""
  14     while 1:
  15         s = input.read(MAXBINSIZE)
  16         if not s: break
  17         while len(s) < MAXBINSIZE:
  18             ns = input.read(MAXBINSIZE-len(s))
  19             if not ns: break
  20             s = s + ns
  21         line = binascii.b2a_base64(s)
  22         output.write(line)
  23
  24 def decode(input, output):
  25     """Decode a file."""
  26     while 1:
  27         line = input.readline()
  28         if not line: break
  29         s = binascii.a2b_base64(line)
  30         output.write(s)
  31
  32 def encodestring(s):
  33     """Encode a string."""
  34     import StringIO
  35     f = StringIO.StringIO(s)
  36     g = StringIO.StringIO()
  37     encode(f, g)
  38     return g.getvalue()
  39
  40 def decodestring(s):
  41     """Decode a string."""
  42     import StringIO
  43     f = StringIO.StringIO(s)
  44     g = StringIO.StringIO()
  45     decode(f, g)
  46     return g.getvalue()
  47
  48 def test():
  49     """Small test program"""
  50     import sys, getopt
  51     try:
  52         opts, args = getopt.getopt(sys.argv[1:], 'deut')
  53     except getopt.error, msg:
  54         sys.stdout = sys.stderr
  55         print msg
  56         print """usage: basd64 [-d] [-e] [-u] [-t] [file|-]
  57         -d, -u: decode
  58         -e: encode (default)
  59         -t: decode string 'Aladdin:open sesame'"""
  60         sys.exit(2)
  61     func = encode
  62     for o, a in opts:
  63         if o == '-e': func = encode
  64         if o == '-d': func = decode
  65         if o == '-u': func = decode
  66         if o == '-t': test1(); return
  67     if args and args[0] != '-':
  68         func(open(args[0], 'rb'), sys.stdout)
  69     else:
  70         func(sys.stdin, sys.stdout)
  71
  72 def test1():
  73     s0 = "Aladdin:open sesame"
  74     s1 = encodestring(s0)
  75     s2 = decodestring(s1)
  76     print s0, `s1`, s2
  77
  78 if __name__ == '__main__':
  79     test()