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/Demo/rpc/xdr.py

http://unladen-swallow.googlecode.com/
Python | 200 lines | 191 code | 8 blank | 1 comment | 1 complexity | ed8b5f951f3b0f57e46a88632152dfe6 MD5 | raw file
  1# Implement (a subset of) Sun XDR -- RFC1014.
  2
  3
  4try:
  5    import struct
  6except ImportError:
  7    struct = None
  8
  9
 10Long = type(0L)
 11
 12
 13class Packer:
 14
 15    def __init__(self):
 16        self.reset()
 17
 18    def reset(self):
 19        self.buf = ''
 20
 21    def get_buf(self):
 22        return self.buf
 23
 24    def pack_uint(self, x):
 25        self.buf = self.buf + \
 26                (chr(int(x>>24 & 0xff)) + chr(int(x>>16 & 0xff)) + \
 27                 chr(int(x>>8 & 0xff)) + chr(int(x & 0xff)))
 28    if struct and struct.pack('l', 1) == '\0\0\0\1':
 29        def pack_uint(self, x):
 30            if type(x) == Long:
 31                x = int((x + 0x80000000L) % 0x100000000L \
 32                           - 0x80000000L)
 33            self.buf = self.buf + struct.pack('l', x)
 34
 35    pack_int = pack_uint
 36
 37    pack_enum = pack_int
 38
 39    def pack_bool(self, x):
 40        if x: self.buf = self.buf + '\0\0\0\1'
 41        else: self.buf = self.buf + '\0\0\0\0'
 42
 43    def pack_uhyper(self, x):
 44        self.pack_uint(int(x>>32 & 0xffffffff))
 45        self.pack_uint(int(x & 0xffffffff))
 46
 47    pack_hyper = pack_uhyper
 48
 49    def pack_float(self, x):
 50        # XXX
 51        self.buf = self.buf + struct.pack('f', x)
 52
 53    def pack_double(self, x):
 54        # XXX
 55        self.buf = self.buf + struct.pack('d', x)
 56
 57    def pack_fstring(self, n, s):
 58        if n < 0:
 59            raise ValueError, 'fstring size must be nonnegative'
 60        n = ((n + 3)//4)*4
 61        data = s[:n]
 62        data = data + (n - len(data)) * '\0'
 63        self.buf = self.buf + data
 64
 65    pack_fopaque = pack_fstring
 66
 67    def pack_string(self, s):
 68        n = len(s)
 69        self.pack_uint(n)
 70        self.pack_fstring(n, s)
 71
 72    pack_opaque = pack_string
 73
 74    def pack_list(self, list, pack_item):
 75        for item in list:
 76            self.pack_uint(1)
 77            pack_item(item)
 78        self.pack_uint(0)
 79
 80    def pack_farray(self, n, list, pack_item):
 81        if len(list) <> n:
 82            raise ValueError, 'wrong array size'
 83        for item in list:
 84            pack_item(item)
 85
 86    def pack_array(self, list, pack_item):
 87        n = len(list)
 88        self.pack_uint(n)
 89        self.pack_farray(n, list, pack_item)
 90
 91
 92class Unpacker:
 93
 94    def __init__(self, data):
 95        self.reset(data)
 96
 97    def reset(self, data):
 98        self.buf = data
 99        self.pos = 0
100
101    def done(self):
102        if self.pos < len(self.buf):
103            raise RuntimeError, 'unextracted data remains'
104
105    def unpack_uint(self):
106        i = self.pos
107        self.pos = j = i+4
108        data = self.buf[i:j]
109        if len(data) < 4:
110            raise EOFError
111        x = long(ord(data[0]))<<24 | ord(data[1])<<16 | \
112                ord(data[2])<<8 | ord(data[3])
113        # Return a Python long only if the value is not representable
114        # as a nonnegative Python int
115        if x < 0x80000000L: x = int(x)
116        return x
117    if struct and struct.unpack('l', '\0\0\0\1') == 1:
118        def unpack_uint(self):
119            i = self.pos
120            self.pos = j = i+4
121            data = self.buf[i:j]
122            if len(data) < 4:
123                raise EOFError
124            return struct.unpack('l', data)
125
126    def unpack_int(self):
127        x = self.unpack_uint()
128        if x >= 0x80000000L: x = x - 0x100000000L
129        return int(x)
130
131    unpack_enum = unpack_int
132
133    unpack_bool = unpack_int
134
135    def unpack_uhyper(self):
136        hi = self.unpack_uint()
137        lo = self.unpack_uint()
138        return long(hi)<<32 | lo
139
140    def unpack_hyper(self):
141        x = self.unpack_uhyper()
142        if x >= 0x8000000000000000L: x = x - 0x10000000000000000L
143        return x
144
145    def unpack_float(self):
146        # XXX
147        i = self.pos
148        self.pos = j = i+4
149        data = self.buf[i:j]
150        if len(data) < 4:
151            raise EOFError
152        return struct.unpack('f', data)[0]
153
154    def unpack_double(self):
155        # XXX
156        i = self.pos
157        self.pos = j = i+8
158        data = self.buf[i:j]
159        if len(data) < 8:
160            raise EOFError
161        return struct.unpack('d', data)[0]
162
163    def unpack_fstring(self, n):
164        if n < 0:
165            raise ValueError, 'fstring size must be nonnegative'
166        i = self.pos
167        j = i + (n+3)//4*4
168        if j > len(self.buf):
169            raise EOFError
170        self.pos = j
171        return self.buf[i:i+n]
172
173    unpack_fopaque = unpack_fstring
174
175    def unpack_string(self):
176        n = self.unpack_uint()
177        return self.unpack_fstring(n)
178
179    unpack_opaque = unpack_string
180
181    def unpack_list(self, unpack_item):
182        list = []
183        while 1:
184            x = self.unpack_uint()
185            if x == 0: break
186            if x <> 1:
187                raise RuntimeError, '0 or 1 expected, got %r' % (x, )
188            item = unpack_item()
189            list.append(item)
190        return list
191
192    def unpack_farray(self, n, unpack_item):
193        list = []
194        for i in range(n):
195            list.append(unpack_item())
196        return list
197
198    def unpack_array(self, unpack_item):
199        n = self.unpack_uint()
200        return self.unpack_farray(n, unpack_item)