Lib/quopri.py

   1 #! /usr/bin/env python
   2
   3 # Conversions to/from quoted-printable transport encoding as per RFC-1521
   4 # (Dec 1991 version).
   5
   6 ESCAPE = '='
   7 MAXLINESIZE = 76
   8 HEX = '0123456789ABCDEF'
   9
  10 def needsquoting(c, quotetabs):
  11         if c == '\t':
  12                 return not quotetabs
  13         return c == ESCAPE or not(' ' <= c <= '~')
  14
  15 def quote(c):
  16         if c == ESCAPE:
  17                 return ESCAPE * 2
  18         else:
  19                 i = ord(c)
  20                 return ESCAPE + HEX[i/16] + HEX[i%16]
  21
  22 def encode(input, output, quotetabs):
  23         while 1:
  24                 line = input.readline()
  25                 if not line: break
  26                 new = ''
  27                 last = line[-1:]
  28                 if last == '\n': line = line[:-1]
  29                 else: last = ''
  30                 prev = ''
  31                 for c in line:
  32                         if needsquoting(c, quotetabs):
  33                                 c = quote(c)
  34                         if len(new) + len(c) >= MAXLINESIZE:
  35                                 output.write(new + ESCAPE + '\n')
  36                                 new = ''
  37                         new = new + c
  38                         prev = c
  39                 if prev in (' ', '\t'):
  40                         output.write(new + ESCAPE + '\n\n')
  41                 else:
  42                         output.write(new + '\n')
  43
  44 def decode(input, output):
  45         new = ''
  46         while 1:
  47                 line = input.readline()
  48                 if not line: break
  49                 i, n = 0, len(line)
  50                 if n > 0 and line[n-1] == '\n':
  51                         partial = 0; n = n-1
  52                         # Strip trailing whitespace
  53                         while n > 0 and line[n-1] in (' ', '\t'):
  54                                 n = n-1
  55                 else:
  56                         partial = 1
  57                 while i < n:
  58                         c = line[i]
  59                         if c <> ESCAPE:
  60                                 new = new + c; i = i+1
  61                         elif i+1 == n and not partial:
  62                                 partial = 1; break
  63                         elif i+1 < n and line[i+1] == ESCAPE:
  64                                 new = new + ESCAPE; i = i+2
  65                         elif i+2 < n and ishex(line[i+1]) and ishex(line[i+2]):
  66                                 new = new + chr(unhex(line[i+1:i+3])); i = i+3
  67                         else: # Bad escape sequence -- leave it in
  68                                 new = new + c; i = i+1
  69                 if not partial:
  70                         output.write(new + '\n')
  71                         new = ''
  72         if new:
  73                 output.write(new)
  74
  75 def ishex(c):
  76         return '0' <= c <= '9' or 'a' <= c <= 'f' or 'A' <= c <= 'F'
  77
  78 def unhex(s):
  79         bits = 0
  80         for c in s:
  81                 if '0' <= c <= '9':
  82                         i = ord('0')
  83                 elif 'a' <= c <= 'f':
  84                         i = ord('a')-10
  85                 elif 'A' <= c <= 'F':
  86                         i = ord('A')-10
  87                 else:
  88                         break
  89                 bits = bits*16 + (ord(c) - i)
  90         return bits
  91
  92 def test():
  93         import sys
  94         import getopt
  95         try:
  96                 opts, args = getopt.getopt(sys.argv[1:], 'td')
  97         except getopt.error, msg:
  98                 sys.stdout = sys.stderr
  99                 print msg
 100                 print "usage: quopri [-t | -d] [file] ..."
 101                 print "-t: quote tabs"
 102                 print "-d: decode; default encode"
 103                 sys.exit(2)
 104         deco = 0
 105         tabs = 0
 106         for o, a in opts:
 107                 if o == '-t': tabs = 1
 108                 if o == '-d': deco = 1
 109         if tabs and deco:
 110                 sys.stdout = sys.stderr
 111                 print "-t and -d are mutually exclusive"
 112                 sys.exit(2)
 113         if not args: args = ['-']
 114         sts = 0
 115         for file in args:
 116                 if file == '-':
 117                         fp = sys.stdin
 118                 else:
 119                         try:
 120                                 fp = open(file)
 121                         except IOError, msg:
 122                                 sys.stderr.write("%s: can't open (%s)\n" % (file, msg))
 123                                 sts = 1
 124                                 continue
 125                 if deco:
 126                         decode(fp, sys.stdout)
 127                 else:
 128                         encode(fp, sys.stdout, tabs)
 129                 if fp is not sys.stdin:
 130                         fp.close()
 131         if sts:
 132                 sys.exit(sts)
 133
 134 if __name__ == '__main__':
 135         test()