| 1 | """Implements (a subset of) Sun XDR -- eXternal Data Representation. |
| 2 | |
| 3 | See: RFC 1014 |
| 4 | |
| 5 | """ |
| 6 | |
| 7 | import struct |
| 8 | try: |
| 9 | from cStringIO import StringIO as _StringIO |
| 10 | except ImportError: |
| 11 | from StringIO import StringIO as _StringIO |
| 12 | |
| 13 | __all__ = ["Error", "Packer", "Unpacker", "ConversionError"] |
| 14 | |
| 15 | # exceptions |
| 16 | class Error(Exception): |
| 17 | """Exception class for this module. Use: |
| 18 | |
| 19 | except xdrlib.Error, var: |
| 20 | # var has the Error instance for the exception |
| 21 | |
| 22 | Public ivars: |
| 23 | msg -- contains the message |
| 24 | |
| 25 | """ |
| 26 | def __init__(self, msg): |
| 27 | self.msg = msg |
| 28 | def __repr__(self): |
| 29 | return repr(self.msg) |
| 30 | def __str__(self): |
| 31 | return str(self.msg) |
| 32 | |
| 33 | |
| 34 | class ConversionError(Error): |
| 35 | pass |
| 36 | |
| 37 | |
| 38 | |
| 39 | class Packer: |
| 40 | """Pack various data representations into a buffer.""" |
| 41 | |
| 42 | def __init__(self): |
| 43 | self.reset() |
| 44 | |
| 45 | def reset(self): |
| 46 | self.__buf = _StringIO() |
| 47 | |
| 48 | def get_buffer(self): |
| 49 | return self.__buf.getvalue() |
| 50 | # backwards compatibility |
| 51 | get_buf = get_buffer |
| 52 | |
| 53 | def pack_uint(self, x): |
| 54 | self.__buf.write(struct.pack('>L', x)) |
| 55 | |
| 56 | pack_int = pack_uint |
| 57 | pack_enum = pack_int |
| 58 | |
| 59 | def pack_bool(self, x): |
| 60 | if x: self.__buf.write('\0\0\0\1') |
| 61 | else: self.__buf.write('\0\0\0\0') |
| 62 | |
| 63 | def pack_uhyper(self, x): |
| 64 | self.pack_uint(x>>32 & 0xffffffffL) |
| 65 | self.pack_uint(x & 0xffffffffL) |
| 66 | |
| 67 | pack_hyper = pack_uhyper |
| 68 | |
| 69 | def pack_float(self, x): |
| 70 | try: self.__buf.write(struct.pack('>f', x)) |
| 71 | except struct.error, msg: |
| 72 | raise ConversionError, msg |
| 73 | |
| 74 | def pack_double(self, x): |
| 75 | try: self.__buf.write(struct.pack('>d', x)) |
| 76 | except struct.error, msg: |
| 77 | raise ConversionError, msg |
| 78 | |
| 79 | def pack_fstring(self, n, s): |
| 80 | if n < 0: |
| 81 | raise ValueError, 'fstring size must be nonnegative' |
| 82 | n = ((n+3)/4)*4 |
| 83 | data = s[:n] |
| 84 | data = data + (n - len(data)) * '\0' |
| 85 | self.__buf.write(data) |
| 86 | |
| 87 | pack_fopaque = pack_fstring |
| 88 | |
| 89 | def pack_string(self, s): |
| 90 | n = len(s) |
| 91 | self.pack_uint(n) |
| 92 | self.pack_fstring(n, s) |
| 93 | |
| 94 | pack_opaque = pack_string |
| 95 | pack_bytes = pack_string |
| 96 | |
| 97 | def pack_list(self, list, pack_item): |
| 98 | for item in list: |
| 99 | self.pack_uint(1) |
| 100 | pack_item(item) |
| 101 | self.pack_uint(0) |
| 102 | |
| 103 | def pack_farray(self, n, list, pack_item): |
| 104 | if len(list) != n: |
| 105 | raise ValueError, 'wrong array size' |
| 106 | for item in list: |
| 107 | pack_item(item) |
| 108 | |
| 109 | def pack_array(self, list, pack_item): |
| 110 | n = len(list) |
| 111 | self.pack_uint(n) |
| 112 | self.pack_farray(n, list, pack_item) |
| 113 | |
| 114 | |
| 115 | |
| 116 | class Unpacker: |
| 117 | """Unpacks various data representations from the given buffer.""" |
| 118 | |
| 119 | def __init__(self, data): |
| 120 | self.reset(data) |
| 121 | |
| 122 | def reset(self, data): |
| 123 | self.__buf = data |
| 124 | self.__pos = 0 |
| 125 | |
| 126 | def get_position(self): |
| 127 | return self.__pos |
| 128 | |
| 129 | def set_position(self, position): |
| 130 | self.__pos = position |
| 131 | |
| 132 | def get_buffer(self): |
| 133 | return self.__buf |
| 134 | |
| 135 | def done(self): |
| 136 | if self.__pos < len(self.__buf): |
| 137 | raise Error('unextracted data remains') |
| 138 | |
| 139 | def unpack_uint(self): |
| 140 | i = self.__pos |
| 141 | self.__pos = j = i+4 |
| 142 | data = self.__buf[i:j] |
| 143 | if len(data) < 4: |
| 144 | raise EOFError |
| 145 | x = struct.unpack('>L', data)[0] |
| 146 | try: |
| 147 | return int(x) |
| 148 | except OverflowError: |
| 149 | return x |
| 150 | |
| 151 | def unpack_int(self): |
| 152 | i = self.__pos |
| 153 | self.__pos = j = i+4 |
| 154 | data = self.__buf[i:j] |
| 155 | if len(data) < 4: |
| 156 | raise EOFError |
| 157 | return struct.unpack('>l', data)[0] |
| 158 | |
| 159 | unpack_enum = unpack_int |
| 160 | unpack_bool = unpack_int |
| 161 | |
| 162 | def unpack_uhyper(self): |
| 163 | hi = self.unpack_uint() |
| 164 | lo = self.unpack_uint() |
| 165 | return long(hi)<<32 | lo |
| 166 | |
| 167 | def unpack_hyper(self): |
| 168 | x = self.unpack_uhyper() |
| 169 | if x >= 0x8000000000000000L: |
| 170 | x = x - 0x10000000000000000L |
| 171 | return x |
| 172 | |
| 173 | def unpack_float(self): |
| 174 | i = self.__pos |
| 175 | self.__pos = j = i+4 |
| 176 | data = self.__buf[i:j] |
| 177 | if len(data) < 4: |
| 178 | raise EOFError |
| 179 | return struct.unpack('>f', data)[0] |
| 180 | |
| 181 | def unpack_double(self): |
| 182 | i = self.__pos |
| 183 | self.__pos = j = i+8 |
| 184 | data = self.__buf[i:j] |
| 185 | if len(data) < 8: |
| 186 | raise EOFError |
| 187 | return struct.unpack('>d', data)[0] |
| 188 | |
| 189 | def unpack_fstring(self, n): |
| 190 | if n < 0: |
| 191 | raise ValueError, 'fstring size must be nonnegative' |
| 192 | i = self.__pos |
| 193 | j = i + (n+3)/4*4 |
| 194 | if j > len(self.__buf): |
| 195 | raise EOFError |
| 196 | self.__pos = j |
| 197 | return self.__buf[i:i+n] |
| 198 | |
| 199 | unpack_fopaque = unpack_fstring |
| 200 | |
| 201 | def unpack_string(self): |
| 202 | n = self.unpack_uint() |
| 203 | return self.unpack_fstring(n) |
| 204 | |
| 205 | unpack_opaque = unpack_string |
| 206 | unpack_bytes = unpack_string |
| 207 | |
| 208 | def unpack_list(self, unpack_item): |
| 209 | list = [] |
| 210 | while 1: |
| 211 | x = self.unpack_uint() |
| 212 | if x == 0: break |
| 213 | if x != 1: |
| 214 | raise ConversionError, '0 or 1 expected, got %r' % (x,) |
| 215 | item = unpack_item() |
| 216 | list.append(item) |
| 217 | return list |
| 218 | |
| 219 | def unpack_farray(self, n, unpack_item): |
| 220 | list = [] |
| 221 | for i in range(n): |
| 222 | list.append(unpack_item()) |
| 223 | return list |
| 224 | |
| 225 | def unpack_array(self, unpack_item): |
| 226 | n = self.unpack_uint() |
| 227 | return self.unpack_farray(n, unpack_item) |
| 228 | |
| 229 | |
| 230 | # test suite |
| 231 | def _test(): |
| 232 | p = Packer() |
| 233 | packtest = [ |
| 234 | (p.pack_uint, (9,)), |
| 235 | (p.pack_bool, (None,)), |
| 236 | (p.pack_bool, ('hello',)), |
| 237 | (p.pack_uhyper, (45L,)), |
| 238 | (p.pack_float, (1.9,)), |
| 239 | (p.pack_double, (1.9,)), |
| 240 | (p.pack_string, ('hello world',)), |
| 241 | (p.pack_list, (range(5), p.pack_uint)), |
| 242 | (p.pack_array, (['what', 'is', 'hapnin', 'doctor'], p.pack_string)), |
| 243 | ] |
| 244 | succeedlist = [1] * len(packtest) |
| 245 | count = 0 |
| 246 | for method, args in packtest: |
| 247 | print 'pack test', count, |
| 248 | try: |
| 249 | method(*args) |
| 250 | print 'succeeded' |
| 251 | except ConversionError, var: |
| 252 | print 'ConversionError:', var.msg |
| 253 | succeedlist[count] = 0 |
| 254 | count = count + 1 |
| 255 | data = p.get_buffer() |
| 256 | # now verify |
| 257 | up = Unpacker(data) |
| 258 | unpacktest = [ |
| 259 | (up.unpack_uint, (), lambda x: x == 9), |
| 260 | (up.unpack_bool, (), lambda x: not x), |
| 261 | (up.unpack_bool, (), lambda x: x), |
| 262 | (up.unpack_uhyper, (), lambda x: x == 45L), |
| 263 | (up.unpack_float, (), lambda x: 1.89 < x < 1.91), |
| 264 | (up.unpack_double, (), lambda x: 1.89 < x < 1.91), |
| 265 | (up.unpack_string, (), lambda x: x == 'hello world'), |
| 266 | (up.unpack_list, (up.unpack_uint,), lambda x: x == range(5)), |
| 267 | (up.unpack_array, (up.unpack_string,), |
| 268 | lambda x: x == ['what', 'is', 'hapnin', 'doctor']), |
| 269 | ] |
| 270 | count = 0 |
| 271 | for method, args, pred in unpacktest: |
| 272 | print 'unpack test', count, |
| 273 | try: |
| 274 | if succeedlist[count]: |
| 275 | x = method(*args) |
| 276 | print pred(x) and 'succeeded' or 'failed', ':', x |
| 277 | else: |
| 278 | print 'skipping' |
| 279 | except ConversionError, var: |
| 280 | print 'ConversionError:', var.msg |
| 281 | count = count + 1 |
| 282 | |
| 283 | |
| 284 | if __name__ == '__main__': |
| 285 | _test() |