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| """Implements (a subset of) Sun XDR -- eXternal Data Representation. | |
| See: RFC 1014 | |
| """ | |
| import struct | |
| from io import BytesIO | |
| from functools import wraps | |
| __all__ = ["Error", "Packer", "Unpacker", "ConversionError"] | |
| # exceptions | |
| class Error(Exception): | |
| """Exception class for this module. Use: | |
| except xdrlib.Error as var: | |
| # var has the Error instance for the exception | |
| Public ivars: | |
| msg -- contains the message | |
| """ | |
| def __init__(self, msg): | |
| self.msg = msg | |
| def __repr__(self): | |
| return repr(self.msg) | |
| def __str__(self): | |
| return str(self.msg) | |
| class ConversionError(Error): | |
| pass | |
| def raise_conversion_error(function): | |
| """ Wrap any raised struct.errors in a ConversionError. """ | |
| @wraps(function) | |
| def result(self, value): | |
| try: | |
| return function(self, value) | |
| except struct.error as e: | |
| raise ConversionError(e.args[0]) from None | |
| return result | |
| class Packer: | |
| """Pack various data representations into a buffer.""" | |
| def __init__(self): | |
| self.reset() | |
| def reset(self): | |
| self.__buf = BytesIO() | |
| def get_buffer(self): | |
| return self.__buf.getvalue() | |
| # backwards compatibility | |
| get_buf = get_buffer | |
| @raise_conversion_error | |
| def pack_uint(self, x): | |
| self.__buf.write(struct.pack('>L', x)) | |
| @raise_conversion_error | |
| def pack_int(self, x): | |
| self.__buf.write(struct.pack('>l', x)) | |
| pack_enum = pack_int | |
| def pack_bool(self, x): | |
| if x: self.__buf.write(b'\0\0\0\1') | |
| else: self.__buf.write(b'\0\0\0\0') | |
| def pack_uhyper(self, x): | |
| try: | |
| self.pack_uint(x>>32 & 0xffffffff) | |
| except (TypeError, struct.error) as e: | |
| raise ConversionError(e.args[0]) from None | |
| try: | |
| self.pack_uint(x & 0xffffffff) | |
| except (TypeError, struct.error) as e: | |
| raise ConversionError(e.args[0]) from None | |
| pack_hyper = pack_uhyper | |
| @raise_conversion_error | |
| def pack_float(self, x): | |
| self.__buf.write(struct.pack('>f', x)) | |
| @raise_conversion_error | |
| def pack_double(self, x): | |
| self.__buf.write(struct.pack('>d', x)) | |
| def pack_fstring(self, n, s): | |
| if n < 0: | |
| raise ValueError('fstring size must be nonnegative') | |
| data = s[:n] | |
| n = ((n+3)//4)*4 | |
| data = data + (n - len(data)) * b'\0' | |
| self.__buf.write(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 | |
| pack_bytes = 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: | |
| """Unpacks various data representations from the given buffer.""" | |
| def __init__(self, data): | |
| self.reset(data) | |
| def reset(self, data): | |
| self.__buf = data | |
| self.__pos = 0 | |
| def get_position(self): | |
| return self.__pos | |
| def set_position(self, position): | |
| self.__pos = position | |
| def get_buffer(self): | |
| return self.__buf | |
| def done(self): | |
| if self.__pos < len(self.__buf): | |
| raise Error('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 | |
| return struct.unpack('>L', data)[0] | |
| def unpack_int(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)[0] | |
| unpack_enum = unpack_int | |
| def unpack_bool(self): | |
| return bool(self.unpack_int()) | |
| def unpack_uhyper(self): | |
| hi = self.unpack_uint() | |
| lo = self.unpack_uint() | |
| return int(hi)<<32 | lo | |
| def unpack_hyper(self): | |
| x = self.unpack_uhyper() | |
| if x >= 0x8000000000000000: | |
| x = x - 0x10000000000000000 | |
| return x | |
| def unpack_float(self): | |
| 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): | |
| 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 | |
| unpack_bytes = unpack_string | |
| def unpack_list(self, unpack_item): | |
| list = [] | |
| while 1: | |
| x = self.unpack_uint() | |
| if x == 0: break | |
| if x != 1: | |
| raise ConversionError('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) |