# Implement (a subset of) Sun XDR -- RFC1014.  try:    import structexcept ImportError:    struct = None  Long = type(0L)  class Packer:     def __init__(self):        self.reset()     def reset(self):        self.buf = ''     def get_buf(self):        return self.buf     def pack_uint(self, x):        self.buf = self.buf + \                (chr(int(x>>24 & 0xff)) + chr(int(x>>16 & 0xff)) + \                 chr(int(x>>8 & 0xff)) + chr(int(x & 0xff)))    if struct and struct.pack('l', 1) == '\0\0\0\1':        def pack_uint(self, x):            if type(x) == Long:                x = int((x + 0x80000000L) % 0x100000000L \                           - 0x80000000L)            self.buf = self.buf + struct.pack('l', x)     pack_int = pack_uint     pack_enum = pack_int     def pack_bool(self, x):        if x: self.buf = self.buf + '\0\0\0\1'        else: self.buf = self.buf + '\0\0\0\0'     def pack_uhyper(self, x):        self.pack_uint(int(x>>32 & 0xffffffff))        self.pack_uint(int(x & 0xffffffff))     pack_hyper = pack_uhyper     def pack_float(self, x):        # XXX        self.buf = self.buf + struct.pack('f', x)     def pack_double(self, x):        # XXX        self.buf = self.buf + struct.pack('d', x)     def pack_fstring(self, n, s):        if n < 0:            raise ValueError, 'fstring size must be nonnegative'        n = ((n+3)/4)*4        data = s[:n]        data = data + (n - len(data)) * '\0'        self.buf = self.buf + data     pack_fopaque = pack_fstring     def pack_string(self, s):        n = len(s)        self.pack_uint(n)        self.pack_fstring(n, s)     pack_opaque = pack_string     def pack_list(self, list, pack_item):        for item in list:            self.pack_uint(1)            pack_item(item)        self.pack_uint(0)     def pack_farray(self, n, list, pack_item):        if len(list) <> n:            raise ValueError, 'wrong array size'        for item in list:            pack_item(item)     def pack_array(self, list, pack_item):        n = len(list)        self.pack_uint(n)        self.pack_farray(n, list, pack_item)  class Unpacker:     def __init__(self, data):        self.reset(data)     def reset(self, data):        self.buf = data        self.pos = 0     def done(self):        if self.pos < len(self.buf):            raise RuntimeError, 'unextracted data remains'     def unpack_uint(self):        i = self.pos        self.pos = j = i+4        data = self.buf[i:j]        if len(data) < 4:            raise EOFError        x = long(ord(data[0]))<<24 | ord(data[1])<<16 | \                ord(data[2])<<8 | ord(data[3])        # Return a Python long only if the value is not representable        # as a nonnegative Python int        if x < 0x80000000L: x = int(x)        return x    if struct and struct.unpack('l', '\0\0\0\1') == 1:        def unpack_uint(self):            i = self.pos            self.pos = j = i+4            data = self.buf[i:j]            if len(data) < 4:                raise EOFError            return struct.unpack('l', data)     def unpack_int(self):        x = self.unpack_uint()        if x >= 0x80000000L: x = x - 0x100000000L        return int(x)     unpack_enum = unpack_int     unpack_bool = unpack_int     def unpack_uhyper(self):        hi = self.unpack_uint()        lo = self.unpack_uint()        return long(hi)<<32 | lo     def unpack_hyper(self):        x = self.unpack_uhyper()        if x >= 0x8000000000000000L: x = x - 0x10000000000000000L        return x     def unpack_float(self):        # XXX        i = self.pos        self.pos = j = i+4        data = self.buf[i:j]        if len(data) < 4:            raise EOFError        return struct.unpack('f', data)[0]     def unpack_double(self):        # XXX        i = self.pos        self.pos = j = i+8        data = self.buf[i:j]        if len(data) < 8:            raise EOFError        return struct.unpack('d', data)[0]     def unpack_fstring(self, n):        if n < 0:            raise ValueError, 'fstring size must be nonnegative'        i = self.pos        j = i + (n+3)/4*4        if j > len(self.buf):            raise EOFError        self.pos = j        return self.buf[i:i+n]     unpack_fopaque = unpack_fstring     def unpack_string(self):        n = self.unpack_uint()        return self.unpack_fstring(n)     unpack_opaque = unpack_string     def unpack_list(self, unpack_item):        list = []        while 1:            x = self.unpack_uint()            if x == 0: break            if x <> 1:                raise RuntimeError, '0 or 1 expected, got %r' % (x, )            item = unpack_item()            list.append(item)        return list     def unpack_farray(self, n, unpack_item):        list = []        for i in range(n):            list.append(unpack_item())        return list     def unpack_array(self, unpack_item):        n = self.unpack_uint()        return self.unpack_farray(n, unpack_item)