cpython/Lib/base64.py

# Conversions to/from base64 transport encoding as per RFC-MIME (Dec 1991
# version).

# Parameters set by RFX-XXXX.
#
# Modified 04-Oct-95 by Jack to use binascii module

import binascii

MAXLINESIZE = 76 # Excluding the CRLF
MAXBINSIZE = (MAXLINESIZE/4)*3

# Encode a file.
def encode(input, output):
	while 1:
		s = input.read(MAXBINSIZE)
		if not s: break
		while len(s) < MAXBINSIZE:
		    ns = input.read(MAXBINSIZE-len(s))
		    if not ns: break
		    s = s + ns
		line = binascii.b2a_base64(s)
		output.write(line)

# Decode a file.
def decode(input, output):
	while 1:
		line = input.readline()
		if not line: break
		s = binascii.a2b_base64(line)
		output.write(s)

def encodestring(s):
	import StringIO
	f = StringIO.StringIO(s)
	g = StringIO.StringIO()
	encode(f, g)
	return g.getvalue()

def decodestring(s):
	import StringIO
	f = StringIO.StringIO(s)
	g = StringIO.StringIO()
	decode(f, g)
	return g.getvalue()

# Small test program
def test():
	import sys, getopt
	try:
		opts, args = getopt.getopt(sys.argv[1:], 'deut')
	except getopt.error, msg:
		sys.stdout = sys.stderr
		print msg
		print """usage: basd64 [-d] [-e] [-u] [-t] [file|-]
		-d, -u: decode
		-e: encode (default)
		-t: decode string 'Aladdin:open sesame'"""
		sys.exit(2)
	func = encode
	for o, a in opts:
		if o == '-e': func = encode
		if o == '-d': func = decode
		if o == '-u': func = decode
		if o == '-t': test1(); return
	if args and args[0] != '-':
		func(open(args[0]), sys.stdout)
	else:
		func(sys.stdin, sys.stdout)

def test1():
	s0 = "Aladdin:open sesame"
	s1 = encodestring(s0)
	s2 = decodestring(s1)
	print s0, `s1`, s2

if __name__ == '__main__':
	test()