1 | #! /usr/bin/env python |
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2 | |
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3 | """Conversions to/from quoted-printable transport encoding as per RFC 1521.""" |
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4 | |
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5 | # (Dec 1991 version). |
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6 | |
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7 | __all__ = ["encode", "decode", "encodestring", "decodestring"] |
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8 | |
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9 | ESCAPE = '=' |
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10 | MAXLINESIZE = 76 |
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11 | HEX = '0123456789ABCDEF' |
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12 | EMPTYSTRING = '' |
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13 | |
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14 | try: |
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15 | from binascii import a2b_qp, b2a_qp |
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16 | except ImportError: |
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17 | a2b_qp = None |
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18 | b2a_qp = None |
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19 | |
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20 | |
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21 | def needsquoting(c, quotetabs, header): |
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22 | """Decide whether a particular character needs to be quoted. |
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23 | |
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24 | The 'quotetabs' flag indicates whether embedded tabs and spaces should be |
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25 | quoted. Note that line-ending tabs and spaces are always encoded, as per |
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26 | RFC 1521. |
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27 | """ |
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28 | if c in ' \t': |
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29 | return quotetabs |
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30 | # if header, we have to escape _ because _ is used to escape space |
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31 | if c == '_': |
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32 | return header |
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33 | return c == ESCAPE or not (' ' <= c <= '~') |
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34 | |
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35 | def quote(c): |
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36 | """Quote a single character.""" |
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37 | i = ord(c) |
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38 | return ESCAPE + HEX[i//16] + HEX[i%16] |
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39 | |
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40 | |
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41 | |
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42 | def encode(input, output, quotetabs, header = 0): |
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43 | """Read 'input', apply quoted-printable encoding, and write to 'output'. |
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44 | |
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45 | 'input' and 'output' are files with readline() and write() methods. |
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46 | The 'quotetabs' flag indicates whether embedded tabs and spaces should be |
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47 | quoted. Note that line-ending tabs and spaces are always encoded, as per |
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48 | RFC 1521. |
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49 | The 'header' flag indicates whether we are encoding spaces as _ as per |
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50 | RFC 1522. |
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51 | """ |
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52 | |
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53 | if b2a_qp is not None: |
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54 | data = input.read() |
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55 | odata = b2a_qp(data, quotetabs = quotetabs, header = header) |
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56 | output.write(odata) |
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57 | return |
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58 | |
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59 | def write(s, output=output, lineEnd='\n'): |
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60 | # RFC 1521 requires that the line ending in a space or tab must have |
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61 | # that trailing character encoded. |
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62 | if s and s[-1:] in ' \t': |
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63 | output.write(s[:-1] + quote(s[-1]) + lineEnd) |
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64 | elif s == '.': |
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65 | output.write(quote(s) + lineEnd) |
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66 | else: |
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67 | output.write(s + lineEnd) |
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68 | |
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69 | prevline = None |
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70 | while 1: |
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71 | line = input.readline() |
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72 | if not line: |
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73 | break |
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74 | outline = [] |
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75 | # Strip off any readline induced trailing newline |
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76 | stripped = '' |
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77 | if line[-1:] == '\n': |
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78 | line = line[:-1] |
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79 | stripped = '\n' |
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80 | # Calculate the un-length-limited encoded line |
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81 | for c in line: |
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82 | if needsquoting(c, quotetabs, header): |
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83 | c = quote(c) |
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84 | if header and c == ' ': |
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85 | outline.append('_') |
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86 | else: |
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87 | outline.append(c) |
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88 | # First, write out the previous line |
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89 | if prevline is not None: |
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90 | write(prevline) |
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91 | # Now see if we need any soft line breaks because of RFC-imposed |
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92 | # length limitations. Then do the thisline->prevline dance. |
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93 | thisline = EMPTYSTRING.join(outline) |
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94 | while len(thisline) > MAXLINESIZE: |
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95 | # Don't forget to include the soft line break `=' sign in the |
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96 | # length calculation! |
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97 | write(thisline[:MAXLINESIZE-1], lineEnd='=\n') |
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98 | thisline = thisline[MAXLINESIZE-1:] |
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99 | # Write out the current line |
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100 | prevline = thisline |
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101 | # Write out the last line, without a trailing newline |
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102 | if prevline is not None: |
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103 | write(prevline, lineEnd=stripped) |
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104 | |
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105 | def encodestring(s, quotetabs = 0, header = 0): |
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106 | if b2a_qp is not None: |
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107 | return b2a_qp(s, quotetabs = quotetabs, header = header) |
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108 | from cStringIO import StringIO |
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109 | infp = StringIO(s) |
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110 | outfp = StringIO() |
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111 | encode(infp, outfp, quotetabs, header) |
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112 | return outfp.getvalue() |
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113 | |
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114 | |
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115 | |
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116 | def decode(input, output, header = 0): |
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117 | """Read 'input', apply quoted-printable decoding, and write to 'output'. |
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118 | 'input' and 'output' are files with readline() and write() methods. |
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119 | If 'header' is true, decode underscore as space (per RFC 1522).""" |
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120 | |
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121 | if a2b_qp is not None: |
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122 | data = input.read() |
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123 | odata = a2b_qp(data, header = header) |
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124 | output.write(odata) |
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125 | return |
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126 | |
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127 | new = '' |
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128 | while 1: |
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129 | line = input.readline() |
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130 | if not line: break |
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131 | i, n = 0, len(line) |
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132 | if n > 0 and line[n-1] == '\n': |
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133 | partial = 0; n = n-1 |
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134 | # Strip trailing whitespace |
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135 | while n > 0 and line[n-1] in " \t\r": |
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136 | n = n-1 |
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137 | else: |
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138 | partial = 1 |
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139 | while i < n: |
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140 | c = line[i] |
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141 | if c == '_' and header: |
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142 | new = new + ' '; i = i+1 |
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143 | elif c != ESCAPE: |
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144 | new = new + c; i = i+1 |
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145 | elif i+1 == n and not partial: |
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146 | partial = 1; break |
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147 | elif i+1 < n and line[i+1] == ESCAPE: |
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148 | new = new + ESCAPE; i = i+2 |
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149 | elif i+2 < n and ishex(line[i+1]) and ishex(line[i+2]): |
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150 | new = new + chr(unhex(line[i+1:i+3])); i = i+3 |
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151 | else: # Bad escape sequence -- leave it in |
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152 | new = new + c; i = i+1 |
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153 | if not partial: |
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154 | output.write(new + '\n') |
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155 | new = '' |
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156 | if new: |
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157 | output.write(new) |
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158 | |
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159 | def decodestring(s, header = 0): |
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160 | if a2b_qp is not None: |
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161 | return a2b_qp(s, header = header) |
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162 | from cStringIO import StringIO |
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163 | infp = StringIO(s) |
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164 | outfp = StringIO() |
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165 | decode(infp, outfp, header = header) |
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166 | return outfp.getvalue() |
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167 | |
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168 | |
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169 | |
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170 | # Other helper functions |
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171 | def ishex(c): |
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172 | """Return true if the character 'c' is a hexadecimal digit.""" |
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173 | return '0' <= c <= '9' or 'a' <= c <= 'f' or 'A' <= c <= 'F' |
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174 | |
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175 | def unhex(s): |
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176 | """Get the integer value of a hexadecimal number.""" |
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177 | bits = 0 |
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178 | for c in s: |
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179 | if '0' <= c <= '9': |
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180 | i = ord('0') |
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181 | elif 'a' <= c <= 'f': |
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182 | i = ord('a')-10 |
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183 | elif 'A' <= c <= 'F': |
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184 | i = ord('A')-10 |
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185 | else: |
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186 | break |
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187 | bits = bits*16 + (ord(c) - i) |
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188 | return bits |
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189 | |
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190 | |
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191 | |
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192 | def main(): |
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193 | import sys |
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194 | import getopt |
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195 | try: |
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196 | opts, args = getopt.getopt(sys.argv[1:], 'td') |
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197 | except getopt.error, msg: |
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198 | sys.stdout = sys.stderr |
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199 | print msg |
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200 | print "usage: quopri [-t | -d] [file] ..." |
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201 | print "-t: quote tabs" |
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202 | print "-d: decode; default encode" |
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203 | sys.exit(2) |
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204 | deco = 0 |
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205 | tabs = 0 |
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206 | for o, a in opts: |
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207 | if o == '-t': tabs = 1 |
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208 | if o == '-d': deco = 1 |
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209 | if tabs and deco: |
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210 | sys.stdout = sys.stderr |
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211 | print "-t and -d are mutually exclusive" |
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212 | sys.exit(2) |
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213 | if not args: args = ['-'] |
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214 | sts = 0 |
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215 | for file in args: |
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216 | if file == '-': |
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217 | fp = sys.stdin |
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218 | else: |
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219 | try: |
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220 | fp = open(file) |
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221 | except IOError, msg: |
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222 | sys.stderr.write("%s: can't open (%s)\n" % (file, msg)) |
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223 | sts = 1 |
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224 | continue |
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225 | if deco: |
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226 | decode(fp, sys.stdout) |
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227 | else: |
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228 | encode(fp, sys.stdout, tabs) |
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229 | if fp is not sys.stdin: |
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230 | fp.close() |
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231 | if sts: |
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232 | sys.exit(sts) |
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233 | |
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234 | |
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235 | |
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236 | if __name__ == '__main__': |
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237 | main() |
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