237 lines
6.8 KiB
Python
237 lines
6.8 KiB
Python
#! /usr/bin/env python
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"""Conversions to/from quoted-printable transport encoding as per RFC 1521."""
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# (Dec 1991 version).
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__all__ = ["encode", "decode", "encodestring", "decodestring"]
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ESCAPE = '='
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MAXLINESIZE = 76
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HEX = '0123456789ABCDEF'
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EMPTYSTRING = ''
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try:
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from binascii import a2b_qp, b2a_qp
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except ImportError:
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a2b_qp = None
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b2a_qp = None
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def needsquoting(c, quotetabs, header):
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"""Decide whether a particular character needs to be quoted.
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The 'quotetabs' flag indicates whether embedded tabs and spaces should be
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quoted. Note that line-ending tabs and spaces are always encoded, as per
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RFC 1521.
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"""
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if c in ' \t':
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return quotetabs
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# if header, we have to escape _ because _ is used to escape space
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if c == '_':
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return header
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return c == ESCAPE or not (' ' <= c <= '~')
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def quote(c):
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"""Quote a single character."""
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i = ord(c)
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return ESCAPE + HEX[i//16] + HEX[i%16]
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def encode(input, output, quotetabs, header = 0):
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"""Read 'input', apply quoted-printable encoding, and write to 'output'.
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'input' and 'output' are files with readline() and write() methods.
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The 'quotetabs' flag indicates whether embedded tabs and spaces should be
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quoted. Note that line-ending tabs and spaces are always encoded, as per
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RFC 1521.
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The 'header' flag indicates whether we are encoding spaces as _ as per
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RFC 1522.
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"""
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if b2a_qp is not None:
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data = input.read()
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odata = b2a_qp(data, quotetabs = quotetabs, header = header)
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output.write(odata)
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return
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def write(s, output=output, lineEnd='\n'):
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# RFC 1521 requires that the line ending in a space or tab must have
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# that trailing character encoded.
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if s and s[-1:] in ' \t':
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output.write(s[:-1] + quote(s[-1]) + lineEnd)
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elif s == '.':
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output.write(quote(s) + lineEnd)
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else:
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output.write(s + lineEnd)
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prevline = None
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while 1:
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line = input.readline()
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if not line:
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break
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outline = []
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# Strip off any readline induced trailing newline
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stripped = ''
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if line[-1:] == '\n':
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line = line[:-1]
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stripped = '\n'
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# Calculate the un-length-limited encoded line
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for c in line:
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if needsquoting(c, quotetabs, header):
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c = quote(c)
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if header and c == ' ':
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outline.append('_')
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else:
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outline.append(c)
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# First, write out the previous line
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if prevline is not None:
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write(prevline)
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# Now see if we need any soft line breaks because of RFC-imposed
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# length limitations. Then do the thisline->prevline dance.
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thisline = EMPTYSTRING.join(outline)
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while len(thisline) > MAXLINESIZE:
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# Don't forget to include the soft line break `=' sign in the
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# length calculation!
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write(thisline[:MAXLINESIZE-1], lineEnd='=\n')
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thisline = thisline[MAXLINESIZE-1:]
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# Write out the current line
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prevline = thisline
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# Write out the last line, without a trailing newline
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if prevline is not None:
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write(prevline, lineEnd=stripped)
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def encodestring(s, quotetabs = 0, header = 0):
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if b2a_qp is not None:
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return b2a_qp(s, quotetabs = quotetabs, header = header)
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from cStringIO import StringIO
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infp = StringIO(s)
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outfp = StringIO()
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encode(infp, outfp, quotetabs, header)
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return outfp.getvalue()
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def decode(input, output, header = 0):
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"""Read 'input', apply quoted-printable decoding, and write to 'output'.
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'input' and 'output' are files with readline() and write() methods.
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If 'header' is true, decode underscore as space (per RFC 1522)."""
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if a2b_qp is not None:
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data = input.read()
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odata = a2b_qp(data, header = header)
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output.write(odata)
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return
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new = ''
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while 1:
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line = input.readline()
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if not line: break
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i, n = 0, len(line)
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if n > 0 and line[n-1] == '\n':
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partial = 0; n = n-1
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# Strip trailing whitespace
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while n > 0 and line[n-1] in " \t\r":
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n = n-1
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else:
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partial = 1
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while i < n:
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c = line[i]
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if c == '_' and header:
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new = new + ' '; i = i+1
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elif c != ESCAPE:
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new = new + c; i = i+1
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elif i+1 == n and not partial:
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partial = 1; break
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elif i+1 < n and line[i+1] == ESCAPE:
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new = new + ESCAPE; i = i+2
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elif i+2 < n and ishex(line[i+1]) and ishex(line[i+2]):
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new = new + chr(unhex(line[i+1:i+3])); i = i+3
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else: # Bad escape sequence -- leave it in
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new = new + c; i = i+1
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if not partial:
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output.write(new + '\n')
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new = ''
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if new:
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output.write(new)
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def decodestring(s, header = 0):
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if a2b_qp is not None:
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return a2b_qp(s, header = header)
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from cStringIO import StringIO
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infp = StringIO(s)
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outfp = StringIO()
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decode(infp, outfp, header = header)
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return outfp.getvalue()
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# Other helper functions
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def ishex(c):
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"""Return true if the character 'c' is a hexadecimal digit."""
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return '0' <= c <= '9' or 'a' <= c <= 'f' or 'A' <= c <= 'F'
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def unhex(s):
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"""Get the integer value of a hexadecimal number."""
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bits = 0
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for c in s:
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if '0' <= c <= '9':
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i = ord('0')
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elif 'a' <= c <= 'f':
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i = ord('a')-10
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elif 'A' <= c <= 'F':
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i = ord('A')-10
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else:
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break
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bits = bits*16 + (ord(c) - i)
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return bits
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def main():
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import sys
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import getopt
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try:
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opts, args = getopt.getopt(sys.argv[1:], 'td')
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except getopt.error, msg:
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sys.stdout = sys.stderr
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print msg
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print "usage: quopri [-t | -d] [file] ..."
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print "-t: quote tabs"
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print "-d: decode; default encode"
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sys.exit(2)
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deco = 0
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tabs = 0
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for o, a in opts:
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if o == '-t': tabs = 1
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if o == '-d': deco = 1
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if tabs and deco:
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sys.stdout = sys.stderr
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print "-t and -d are mutually exclusive"
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sys.exit(2)
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if not args: args = ['-']
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sts = 0
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for file in args:
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if file == '-':
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fp = sys.stdin
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else:
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try:
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fp = open(file)
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except IOError, msg:
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sys.stderr.write("%s: can't open (%s)\n" % (file, msg))
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sts = 1
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continue
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if deco:
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decode(fp, sys.stdout)
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else:
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encode(fp, sys.stdout, tabs)
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if fp is not sys.stdin:
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fp.close()
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if sts:
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sys.exit(sts)
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if __name__ == '__main__':
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main()
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