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     pieces = []
  37     for i in range(0, len(s), MAXBINSIZE):
  38         chunk = s[i : i + MAXBINSIZE]
  39         pieces.append(binascii.b2a_base64(chunk))
  40     return "".join(pieces)
  41
  42 def decodestring(s):
  43     """Decode a string."""
  44     return binascii.a2b_base64(s)
  45
  46 def test():
  47     """Small test program"""
  48     import sys, getopt
  49     try:
  50         opts, args = getopt.getopt(sys.argv[1:], 'deut')
  51     except getopt.error, msg:
  52         sys.stdout = sys.stderr
  53         print msg
  54         print """usage: %s [-d|-e|-u|-t] [file|-]
  55         -d, -u: decode
  56         -e: encode (default)
  57         -t: encode and decode string 'Aladdin:open sesame'"""%sys.argv[0]
  58         sys.exit(2)
  59     func = encode
  60     for o, a in opts:
  61         if o == '-e': func = encode
  62         if o == '-d': func = decode
  63         if o == '-u': func = decode
  64         if o == '-t': test1(); return
  65     if args and args[0] != '-':
  66         func(open(args[0], 'rb'), sys.stdout)
  67     else:
  68         func(sys.stdin, sys.stdout)
  69
  70 def test1():
  71     s0 = "Aladdin:open sesame"
  72     s1 = encodestring(s0)
  73     s2 = decodestring(s1)
  74     print s0, `s1`, s2
  75
  76 if __name__ == '__main__':
  77     test()