Lib/base64.py

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