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