Editing: quopri.py
#! /usr/bin/python2.7 """Conversions to/from quoted-printable transport encoding as per RFC 1521.""" # (Dec 1991 version). __all__ = ["encode", "decode", "encodestring", "decodestring"] ESCAPE = '=' MAXLINESIZE = 76 HEX = '0123456789ABCDEF' EMPTYSTRING = '' try: from binascii import a2b_qp, b2a_qp except ImportError: a2b_qp = None b2a_qp = None def needsquoting(c, quotetabs, header): """Decide whether a particular character needs to be quoted. The 'quotetabs' flag indicates whether embedded tabs and spaces should be quoted. Note that line-ending tabs and spaces are always encoded, as per RFC 1521. """ if c in ' \t': return quotetabs # if header, we have to escape _ because _ is used to escape space if c == '_': return header return c == ESCAPE or not (' ' <= c <= '~') def quote(c): """Quote a single character.""" i = ord(c) return ESCAPE + HEX[i//16] + HEX[i%16] def encode(input, output, quotetabs, header = 0): """Read 'input', apply quoted-printable encoding, and write to 'output'. 'input' and 'output' are files with readline() and write() methods. The 'quotetabs' flag indicates whether embedded tabs and spaces should be quoted. Note that line-ending tabs and spaces are always encoded, as per RFC 1521. The 'header' flag indicates whether we are encoding spaces as _ as per RFC 1522. """ if b2a_qp is not None: data = input.read() odata = b2a_qp(data, quotetabs = quotetabs, header = header) output.write(odata) return def write(s, output=output, lineEnd='\n'): # RFC 1521 requires that the line ending in a space or tab must have # that trailing character encoded. if s and s[-1:] in ' \t': output.write(s[:-1] + quote(s[-1]) + lineEnd) elif s == '.': output.write(quote(s) + lineEnd) else: output.write(s + lineEnd) prevline = None while 1: line = input.readline() if not line: break outline = [] # Strip off any readline induced trailing newline stripped = '' if line[-1:] == '\n': line = line[:-1] stripped = '\n' # Calculate the un-length-limited encoded line for c in line: if needsquoting(c, quotetabs, header): c = quote(c) if header and c == ' ': outline.append('_') else: outline.append(c) # First, write out the previous line if prevline is not None: write(prevline) # Now see if we need any soft line breaks because of RFC-imposed # length limitations. Then do the thisline->prevline dance. thisline = EMPTYSTRING.join(outline) while len(thisline) > MAXLINESIZE: # Don't forget to include the soft line break `=' sign in the # length calculation! write(thisline[:MAXLINESIZE-1], lineEnd='=\n') thisline = thisline[MAXLINESIZE-1:] # Write out the current line prevline = thisline # Write out the last line, without a trailing newline if prevline is not None: write(prevline, lineEnd=stripped) def encodestring(s, quotetabs = 0, header = 0): if b2a_qp is not None: return b2a_qp(s, quotetabs = quotetabs, header = header) from cStringIO import StringIO infp = StringIO(s) outfp = StringIO() encode(infp, outfp, quotetabs, header) return outfp.getvalue() def decode(input, output, header = 0): """Read 'input', apply quoted-printable decoding, and write to 'output'. 'input' and 'output' are files with readline() and write() methods. If 'header' is true, decode underscore as space (per RFC 1522).""" if a2b_qp is not None: data = input.read() odata = a2b_qp(data, header = header) output.write(odata) return new = '' while 1: line = input.readline() if not line: break i, n = 0, len(line) if n > 0 and line[n-1] == '\n': partial = 0; n = n-1 # Strip trailing whitespace while n > 0 and line[n-1] in " \t\r": n = n-1 else: partial = 1 while i < n: c = line[i] if c == '_' and header: new = new + ' '; i = i+1 elif c != ESCAPE: new = new + c; i = i+1 elif i+1 == n and not partial: partial = 1; break elif i+1 < n and line[i+1] == ESCAPE: new = new + ESCAPE; i = i+2 elif i+2 < n and ishex(line[i+1]) and ishex(line[i+2]): new = new + chr(unhex(line[i+1:i+3])); i = i+3 else: # Bad escape sequence -- leave it in new = new + c; i = i+1 if not partial: output.write(new + '\n') new = '' if new: output.write(new) def decodestring(s, header = 0): if a2b_qp is not None: return a2b_qp(s, header = header) from cStringIO import StringIO infp = StringIO(s) outfp = StringIO() decode(infp, outfp, header = header) return outfp.getvalue() # Other helper functions def ishex(c): """Return true if the character 'c' is a hexadecimal digit.""" return '0' <= c <= '9' or 'a' <= c <= 'f' or 'A' <= c <= 'F' def unhex(s): """Get the integer value of a hexadecimal number.""" bits = 0 for c in s: if '0' <= c <= '9': i = ord('0') elif 'a' <= c <= 'f': i = ord('a')-10 elif 'A' <= c <= 'F': i = ord('A')-10 else: break bits = bits*16 + (ord(c) - i) return bits def main(): import sys import getopt try: opts, args = getopt.getopt(sys.argv[1:], 'td') except getopt.error, msg: sys.stdout = sys.stderr print msg print "usage: quopri [-t | -d] [file] ..." print "-t: quote tabs" print "-d: decode; default encode" sys.exit(2) deco = 0 tabs = 0 for o, a in opts: if o == '-t': tabs = 1 if o == '-d': deco = 1 if tabs and deco: sys.stdout = sys.stderr print "-t and -d are mutually exclusive" sys.exit(2) if not args: args = ['-'] sts = 0 for file in args: if file == '-': fp = sys.stdin else: try: fp = open(file) except IOError, msg: sys.stderr.write("%s: can't open (%s)\n" % (file, msg)) sts = 1 continue if deco: decode(fp, sys.stdout) else: encode(fp, sys.stdout, tabs) if fp is not sys.stdin: fp.close() if sts: sys.exit(sts) if __name__ == '__main__': main()
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