| Guido van Rossum | e3cafbe | 1992-12-14 23:25:04 +0000 | [diff] [blame] | 1 | # Implement (a subset of) Sun XDR -- RFC1014. |
| 2 | |
| 3 | |
| 4 | import struct |
| 5 | |
| 6 | |
| 7 | class Packer: |
| 8 | |
| 9 | def init(self): |
| 10 | self.reset() |
| 11 | return self |
| 12 | |
| 13 | def reset(self): |
| 14 | self.buf = '' |
| 15 | |
| 16 | def get_buf(self): |
| 17 | return self.buf |
| 18 | |
| 19 | def pack_uint(self, x): |
| 20 | self.buf = self.buf + \ |
| 21 | (chr(int(x>>24 & 0xff)) + chr(int(x>>16 & 0xff)) + \ |
| 22 | chr(int(x>>8 & 0xff)) + chr(int(x & 0xff))) |
| 23 | if struct.pack('i', 1) == '\0\0\0\1': |
| 24 | def pack_uint(self, x): |
| 25 | self.buf = self.buf + struct.pack('i', x) |
| 26 | |
| 27 | pack_int = pack_uint |
| 28 | |
| 29 | pack_enum = pack_int |
| 30 | |
| 31 | def pack_bool(self, x): |
| 32 | if x: self.buf = self.buf + '\0\0\0\1' |
| 33 | else: self.buf = self.buf + '\0\0\0\0' |
| 34 | |
| 35 | def pack_uhyper(self, x): |
| 36 | self.pack_uint(x>>32 & 0xffffffff) |
| 37 | self.pack_uint(x & 0xffffffff) |
| 38 | |
| 39 | pack_hyper = pack_uhyper |
| 40 | |
| 41 | def pack_fstring(self, n, s): |
| 42 | if n < 0: |
| 43 | raise ValueError, 'fstring size must be nonnegative' |
| 44 | n = ((n+3)/4)*4 |
| 45 | data = s[:n] |
| 46 | data = data + (n - len(data)) * '\0' |
| 47 | self.buf = self.buf + data |
| 48 | |
| 49 | pack_fopaque = pack_fstring |
| 50 | |
| 51 | def pack_string(self, s): |
| 52 | n = len(s) |
| 53 | self.pack_uint(n) |
| 54 | self.pack_fstring(n, s) |
| 55 | |
| 56 | pack_opaque = pack_string |
| 57 | |
| 58 | def pack_list(self, list, pack_item): |
| 59 | for item in list: |
| 60 | self.pack_uint(1) |
| 61 | pack_item(list) |
| 62 | self.pack_uint(0) |
| 63 | |
| 64 | |
| 65 | class Unpacker: |
| 66 | |
| 67 | def init(self, data): |
| 68 | self.reset(data) |
| 69 | return self |
| 70 | |
| 71 | def reset(self, data): |
| 72 | self.buf = data |
| 73 | self.pos = 0 |
| 74 | |
| 75 | def done(self): |
| 76 | if self.pos < len(self.buf): |
| 77 | raise RuntimeError, 'unextracted data remains' |
| 78 | |
| 79 | def unpack_uint(self): |
| 80 | i = self.pos |
| 81 | self.pos = j = i+4 |
| 82 | data = self.buf[i:j] |
| 83 | x = long(ord(data[0]))<<24 | ord(data[1])<<16 | \ |
| 84 | ord(data[2])<<8 | ord(data[3]) |
| 85 | # Return a Python long only if the value is not representable |
| 86 | # as a nonnegative Python int |
| 87 | if x < 0x80000000L: x = int(x) |
| 88 | return x |
| 89 | if struct.unpack('i', '\0\0\0\1') == 1: |
| 90 | def unpack_uint(self): |
| 91 | i = self.pos |
| 92 | self.pos = j = i+4 |
| 93 | return struct.unpack('i', self.buf[i:j]) |
| 94 | |
| 95 | def unpack_int(self): |
| 96 | x = self.unpack_uint() |
| 97 | if x >= 0x80000000L: x = x - 0x100000000L |
| 98 | return int(x) |
| 99 | |
| 100 | unpack_enum = unpack_int |
| 101 | |
| 102 | unpack_bool = unpack_int |
| 103 | |
| 104 | def unpack_uhyper(self): |
| 105 | hi = self.unpack_uint() |
| 106 | lo = self.unpack_uint() |
| 107 | return long(hi)<<32 | lo |
| 108 | |
| 109 | def unpack_hyper(self): |
| 110 | x = self.unpack_uhyper() |
| 111 | if x >= 0x8000000000000000L: x = x - 0x10000000000000000L |
| 112 | return x |
| 113 | |
| 114 | def unpack_fstring(self, n): |
| 115 | if n < 0: |
| 116 | raise ValueError, 'fstring size must be nonnegative' |
| 117 | i = self.pos |
| 118 | j = i + (n+3)/4*4 |
| 119 | if j > len(self.buf): |
| 120 | raise RuntimeError, 'buffer overrun' |
| 121 | self.pos = j |
| 122 | return self.buf[i:i+n] |
| 123 | |
| 124 | unpack_fopaque = unpack_fstring |
| 125 | |
| 126 | def unpack_string(self): |
| 127 | n = self.unpack_uint() |
| 128 | return self.unpack_fstring(n) |
| 129 | |
| 130 | unpack_opaque = unpack_string |
| 131 | |
| 132 | def unpack_list(self, unpack_item): |
| 133 | list = [] |
| 134 | while 1: |
| 135 | x = self.unpack_uint() |
| 136 | if not x: break |
| 137 | if x <> 1: |
| 138 | raise RuntimeError, \ |
| 139 | '0 or 1 expected, got ' + `x` |
| 140 | list.append(unpack_item()) |
| 141 | return list |