1 | from .constants import OutOfBandTags, IntegerTags, OctetStringTags, CharacterStringTags |
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2 | import sys |
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3 | import struct |
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4 | import logging |
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5 | |
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6 | # initialize logger |
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7 | logger = logging.getLogger(__name__) |
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8 | |
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9 | class Value(object): |
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10 | """An IPP value consists of a tag and a value. |
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11 | |
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12 | From RFC 2565: |
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13 | ----------------------------------------------- |
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14 | | value-tag | 1 byte |
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15 | ----------------------------------------------- |
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16 | | name-length (value is 0x0000) | 2 bytes |
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17 | ----------------------------------------------- |
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18 | | value-length (value is v) | 2 bytes |
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19 | ----------------------------------------------- |
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20 | | value | v bytes |
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21 | ----------------------------------------------- |
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22 | |
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23 | """ |
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24 | |
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25 | def __init__(self, tag=None, value=None): |
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26 | """Initialize a Value. There are three different ways you can |
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27 | call this method: |
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28 | |
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29 | Value() -- creates an empty Value instance |
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30 | |
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31 | Value(tag, value) -- creates a Value instance from |
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32 | a non-binary value |
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33 | |
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34 | If you create an empty Value instance, once you have set |
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35 | tag and value, you can retrieve the packed value from |
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36 | the packed_value property. |
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37 | |
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38 | Arguments: |
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39 | |
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40 | tag -- one byte, identifying the type of value |
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41 | |
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42 | value -- variable size, containing the actual value. |
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43 | It should be a string or number. |
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44 | |
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45 | """ |
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46 | |
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47 | # make sure the arguments are valid |
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48 | if value is not None and tag is None: |
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49 | raise ValueError("tag may not be None") |
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50 | |
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51 | # initialize member variables |
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52 | self.tag = tag # one byte, the type of value |
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53 | self.value = value # non-binary value of self.value |
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54 | |
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55 | def __cmp__(self, other): |
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56 | eq = (self.value == other.value) and (self.tag == other.tag) |
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57 | return 0 if eq else 1 |
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58 | |
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59 | @classmethod |
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60 | def unpack(cls, tag, packed_value): |
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61 | """Unpack a binary IPP value into a Value object. |
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62 | |
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63 | """ |
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64 | return cls(tag, cls._unpack(tag, packed_value)) |
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65 | |
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66 | @staticmethod |
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67 | def _unpack(tag, packed_value): |
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68 | """Given self.tag and self.packed_value, unpack the |
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69 | binary value into either a string or number. These values |
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70 | MUST NOT be null. |
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71 | |
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72 | Returns: unpacked value |
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73 | |
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74 | """ |
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75 | |
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76 | if tag is None: |
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77 | raise ValueError("cannot unpack values with no value tag") |
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78 | if packed_value is None: |
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79 | raise ValueError("cannot unpack null values") |
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80 | |
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81 | value = None |
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82 | |
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83 | # out-of-band value tags |
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84 | if tag == OutOfBandTags.UNSUPPORTED or \ |
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85 | tag == OutOfBandTags.DEFAULT or \ |
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86 | tag == OutOfBandTags.UNKNOWN or \ |
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87 | tag == OutOfBandTags.NO_VALUE: |
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88 | value_size = 0 |
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89 | value = '' |
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90 | |
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91 | # integer value tags |
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92 | elif tag == IntegerTags.INTEGER: |
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93 | value = struct.unpack('>i', packed_value)[0] |
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94 | elif tag == IntegerTags.BOOLEAN: |
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95 | value = struct.unpack('>b', packed_value)[0] |
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96 | elif tag == IntegerTags.ENUM: |
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97 | value = struct.unpack('>i', packed_value)[0] |
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98 | |
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99 | |
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100 | elif tag == OctetStringTags.DATETIME: |
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101 | # field octets contents range |
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102 | # ----- ------ -------- ----- |
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103 | # 1 1-2 year 0..65536 |
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104 | # 2 3 month 1..12 |
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105 | # 3 4 day 1..31 |
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106 | # 4 5 hour 0..23 |
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107 | # 5 6 minutes 0..59 |
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108 | # 6 7 seconds 0..60 |
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109 | # (use 60 for leap-second) |
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110 | # 7 8 deci-seconds 0..9 |
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111 | # 8 9 direction from UTC '+' / '-' |
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112 | # 9 10 hours from UTC 0..11 |
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113 | # 10 11 minutes from UTC 0..59 |
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114 | |
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115 | value = struct.unpack('>hbbbbbbcbb', packed_value) |
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116 | |
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117 | elif tag == OctetStringTags.RESOLUTION: |
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118 | # OCTET-STRING consisting of nine octets of 2 |
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119 | # SIGNED-INTEGERs followed by a SIGNED-BYTE. The first |
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120 | # SIGNED-INTEGER contains the value of cross feed |
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121 | # direction resolution. The second SIGNED-INTEGER contains |
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122 | # the value of feed direction resolution. The SIGNED-BYTE |
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123 | # contains the units |
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124 | |
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125 | value = struct.unpack('>iib', packed_value) |
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126 | |
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127 | elif tag == OctetStringTags.RANGE_OF_INTEGER: |
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128 | # Eight octets consisting of 2 SIGNED-INTEGERs. The first |
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129 | # SIGNED-INTEGER contains the lower bound and the second |
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130 | # SIGNED-INTEGER contains the upper bound. |
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131 | |
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132 | value = struct.unpack('>ii', packed_value) |
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133 | |
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134 | elif tag == OctetStringTags.TEXT_WITH_LANGUAGE or \ |
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135 | tag == OctetStringTags.NAME_WITH_LANGUAGE: |
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136 | a = struct.unpack('>h', packed_value[:2])[0] |
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137 | b = struct.unpack('>%ss' % a, packed_value[2:a+2])[0] |
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138 | c = struct.unpack('>h', packed_value[a+2:a+4])[0] |
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139 | d = struct.unpack('>%ss' % c, packed_value[a+4:][0]) |
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140 | value = (a, b, c, d) |
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141 | |
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142 | # character string value tags |
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143 | elif tag == \ |
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144 | CharacterStringTags.TEXT_WITHOUT_LANGUAGE or \ |
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145 | tag == \ |
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146 | CharacterStringTags.NAME_WITHOUT_LANGUAGE: |
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147 | value = str(packed_value) |
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148 | elif tag == CharacterStringTags.GENERIC or \ |
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149 | tag == CharacterStringTags.KEYWORD or \ |
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150 | tag == CharacterStringTags.URI or \ |
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151 | tag == CharacterStringTags.URI_SCHEME or \ |
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152 | tag == CharacterStringTags.CHARSET or \ |
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153 | tag == CharacterStringTags.NATURAL_LANGUAGE or \ |
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154 | tag == CharacterStringTags.MIME_MEDIA_TYPE: |
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155 | value = str(packed_value) |
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156 | |
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157 | # anything else that we didn't handle |
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158 | else: |
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159 | if value is None: |
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160 | value = packed_value |
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161 | |
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162 | return value |
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163 | |
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164 | @property |
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165 | def packed_value(self): |
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166 | """Given self.tag and self.value, pack the value into |
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167 | binary form. These values MUST NOT be null. |
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168 | |
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169 | Returns: packed_value |
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170 | |
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171 | """ |
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172 | |
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173 | if self.tag is None: |
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174 | raise ValueError("cannot pack value with null tag") |
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175 | if self.value is None: |
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176 | raise ValueError("cannot pack null value") |
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177 | |
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178 | packed_value = None |
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179 | |
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180 | # out-of-band value tags |
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181 | if self.tag == OutOfBandTags.UNSUPPORTED or \ |
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182 | self.tag == OutOfBandTags.DEFAULT or \ |
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183 | self.tag == OutOfBandTags.UNKNOWN or \ |
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184 | self.tag == OutOfBandTags.NO_VALUE: |
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185 | packed_value = '' |
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186 | |
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187 | # integer value tags |
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188 | elif self.tag == IntegerTags.INTEGER: |
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189 | packed_value = struct.pack('>i', self.value) |
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190 | elif self.tag == IntegerTags.BOOLEAN: |
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191 | packed_value = struct.pack('>b', self.value) |
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192 | elif self.tag == IntegerTags.ENUM: |
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193 | packed_value = struct.pack('>i', self.value) |
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194 | |
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195 | # octet string value tags |
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196 | elif self.tag == OctetStringTags.DATETIME: |
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197 | # field octets contents range |
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198 | # ----- ------ -------- ----- |
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199 | # 1 1-2 year 0..65536 |
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200 | # 2 3 month 1..12 |
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201 | # 3 4 day 1..31 |
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202 | # 4 5 hour 0..23 |
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203 | # 5 6 minutes 0..59 |
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204 | # 6 7 seconds 0..60 |
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205 | # (use 60 for leap-second) |
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206 | # 7 8 deci-seconds 0..9 |
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207 | # 8 9 direction from UTC '+' / '-' |
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208 | # 9 10 hours from UTC 0..11 |
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209 | # 10 11 minutes from UTC 0..59 |
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210 | |
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211 | packed_value = struct.pack('>hbbbbbbcbb', *self.value) |
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212 | |
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213 | elif self.tag == OctetStringTags.RESOLUTION: |
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214 | # OCTET-STRING consisting of nine octets of 2 |
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215 | # SIGNED-INTEGERs followed by a SIGNED-BYTE. The first |
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216 | # SIGNED-INTEGER contains the value of cross feed |
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217 | # direction resolution. The second SIGNED-INTEGER contains |
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218 | # the value of feed direction resolution. The SIGNED-BYTE |
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219 | # contains the units |
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220 | |
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221 | packed_value = struct.pack('>iib', *self.value) |
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222 | |
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223 | elif self.tag == OctetStringTags.RANGE_OF_INTEGER: |
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224 | # Eight octets consisting of 2 SIGNED-INTEGERs. The first |
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225 | # SIGNED-INTEGER contains the lower bound and the second |
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226 | # SIGNED-INTEGER contains the upper bound. |
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227 | |
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228 | packed_value = struct.pack('>ii', *self.value) |
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229 | |
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230 | elif self.tag == OctetStringTags.TEXT_WITH_LANGUAGE or \ |
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231 | self.tag == OctetStringTags.NAME_WITH_LANGUAGE: |
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232 | |
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233 | a_bin = struct.pack('>h', self.value[0]) |
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234 | b_bin = struct.pack('>%ss' % self.value[0], self.value[1]) |
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235 | c_bin = struct.pack('>h', self.value[2]) |
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236 | d_bin = struct.pack('>%ss' % self.value[2], self.value[3]) |
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237 | |
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238 | packed_value = a_bin + b_bin + c_bin + d_bin |
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239 | |
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240 | # character string value tags |
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241 | elif self.tag == \ |
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242 | CharacterStringTags.TEXT_WITHOUT_LANGUAGE or \ |
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243 | self.tag == \ |
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244 | CharacterStringTags.NAME_WITHOUT_LANGUAGE: |
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245 | |
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246 | packed_value = struct.pack('>%ss' % len(self.value), |
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247 | self.value) |
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248 | |
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249 | elif self.tag == CharacterStringTags.GENERIC or \ |
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250 | self.tag == CharacterStringTags.KEYWORD or \ |
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251 | self.tag == CharacterStringTags.URI or \ |
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252 | self.tag == CharacterStringTags.URI_SCHEME or \ |
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253 | self.tag == CharacterStringTags.CHARSET or \ |
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254 | self.tag == CharacterStringTags.NATURAL_LANGUAGE or \ |
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255 | self.tag == CharacterStringTags.MIME_MEDIA_TYPE: |
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256 | |
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257 | packed_value = struct.pack('>%ss' % len(self.value), |
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258 | self.value) |
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259 | |
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260 | else: |
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261 | packed_value = self.value |
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262 | |
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263 | return packed_value |
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264 | |
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265 | @packed_value.setter |
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266 | def packed_value(self, packed_value): |
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267 | """Replace a value using a new packed value |
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268 | |
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269 | Unpacks a new packed_value (of the same tag). |
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270 | |
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271 | """ |
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272 | self.value = self._unpack(self.tag, packed_value) |
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273 | |
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274 | @property |
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275 | def packed_value_size(self): |
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276 | """Get the size of the value in bytes. |
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277 | |
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278 | """ |
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279 | |
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280 | return len(self.packed_value) |
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281 | |
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282 | @property |
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283 | def total_size(self): |
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284 | """Get the total size of the IPP value. |
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285 | |
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286 | """ |
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287 | |
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288 | # 1 byte for the tag |
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289 | return self.packed_value_size + 1 |
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290 | |
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291 | def __str__(self): |
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292 | return str(self.value) |
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293 | |
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294 | def __repr__(self): |
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295 | return '<IPPValue (%x, %r)>' % (self.tag, self.value) |
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