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pybser.py
359 lines | 12.0 KiB | text/x-python | PythonLexer
# Copyright 2015 Facebook, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# * Neither the name Facebook nor the names of its contributors may be used to
# endorse or promote products derived from this software without specific
# prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import collections
import ctypes
import struct
import sys
BSER_ARRAY = '\x00'
BSER_OBJECT = '\x01'
BSER_STRING = '\x02'
BSER_INT8 = '\x03'
BSER_INT16 = '\x04'
BSER_INT32 = '\x05'
BSER_INT64 = '\x06'
BSER_REAL = '\x07'
BSER_TRUE = '\x08'
BSER_FALSE = '\x09'
BSER_NULL = '\x0a'
BSER_TEMPLATE = '\x0b'
BSER_SKIP = '\x0c'
# Leave room for the serialization header, which includes
# our overall length. To make things simpler, we'll use an
# int32 for the header
EMPTY_HEADER = "\x00\x01\x05\x00\x00\x00\x00"
# Python 3 conditional for supporting Python 2's int/long types
if sys.version_info > (3,):
long = int
def _int_size(x):
"""Return the smallest size int that can store the value"""
if -0x80 <= x <= 0x7F:
return 1
elif -0x8000 <= x <= 0x7FFF:
return 2
elif -0x80000000 <= x <= 0x7FFFFFFF:
return 4
elif long(-0x8000000000000000) <= x <= long(0x7FFFFFFFFFFFFFFF):
return 8
else:
raise RuntimeError('Cannot represent value: ' + str(x))
class _bser_buffer(object):
def __init__(self):
self.buf = ctypes.create_string_buffer(8192)
struct.pack_into(str(len(EMPTY_HEADER)) + 's', self.buf, 0, EMPTY_HEADER)
self.wpos = len(EMPTY_HEADER)
def ensure_size(self, size):
while ctypes.sizeof(self.buf) - self.wpos < size:
ctypes.resize(self.buf, ctypes.sizeof(self.buf) * 2)
def append_long(self, val):
size = _int_size(val)
to_write = size + 1
self.ensure_size(to_write)
if size == 1:
struct.pack_into('=cb', self.buf, self.wpos, BSER_INT8, val)
elif size == 2:
struct.pack_into('=ch', self.buf, self.wpos, BSER_INT16, val)
elif size == 4:
struct.pack_into('=ci', self.buf, self.wpos, BSER_INT32, val)
elif size == 8:
struct.pack_into('=cq', self.buf, self.wpos, BSER_INT64, val)
else:
raise RuntimeError('Cannot represent this long value')
self.wpos += to_write
def append_string(self, s):
if isinstance(s, unicode):
s = s.encode('utf-8')
s_len = len(s)
size = _int_size(s_len)
to_write = 2 + size + s_len
self.ensure_size(to_write)
if size == 1:
struct.pack_into('=ccb' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT8, s_len, s)
elif size == 2:
struct.pack_into('=cch' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT16, s_len, s)
elif size == 4:
struct.pack_into('=cci' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT32, s_len, s)
elif size == 8:
struct.pack_into('=ccq' + str(s_len) + 's', self.buf, self.wpos, BSER_STRING, BSER_INT64, s_len, s)
else:
raise RuntimeError('Cannot represent this string value')
self.wpos += to_write
def append_recursive(self, val):
if isinstance(val, bool):
needed = 1
self.ensure_size(needed)
if val:
to_encode = BSER_TRUE
else:
to_encode = BSER_FALSE
struct.pack_into('=c', self.buf, self.wpos, to_encode)
self.wpos += needed
elif val is None:
needed = 1
self.ensure_size(needed)
struct.pack_into('=c', self.buf, self.wpos, BSER_NULL)
self.wpos += needed
elif isinstance(val, (int, long)):
self.append_long(val)
elif isinstance(val, (str, unicode)):
self.append_string(val)
elif isinstance(val, float):
needed = 9
self.ensure_size(needed)
struct.pack_into('=cd', self.buf, self.wpos, BSER_REAL, val)
self.wpos += needed
elif isinstance(val, collections.Mapping) and isinstance(val, collections.Sized):
val_len = len(val)
size = _int_size(val_len)
needed = 2 + size
self.ensure_size(needed)
if size == 1:
struct.pack_into('=ccb', self.buf, self.wpos, BSER_OBJECT, BSER_INT8, val_len)
elif size == 2:
struct.pack_into('=cch', self.buf, self.wpos, BSER_OBJECT, BSER_INT16, val_len)
elif size == 4:
struct.pack_into('=cci', self.buf, self.wpos, BSER_OBJECT, BSER_INT32, val_len)
elif size == 8:
struct.pack_into('=ccq', self.buf, self.wpos, BSER_OBJECT, BSER_INT64, val_len)
else:
raise RuntimeError('Cannot represent this mapping value')
self.wpos += needed
for k, v in val.iteritems():
self.append_string(k)
self.append_recursive(v)
elif isinstance(val, collections.Iterable) and isinstance(val, collections.Sized):
val_len = len(val)
size = _int_size(val_len)
needed = 2 + size
self.ensure_size(needed)
if size == 1:
struct.pack_into('=ccb', self.buf, self.wpos, BSER_ARRAY, BSER_INT8, val_len)
elif size == 2:
struct.pack_into('=cch', self.buf, self.wpos, BSER_ARRAY, BSER_INT16, val_len)
elif size == 4:
struct.pack_into('=cci', self.buf, self.wpos, BSER_ARRAY, BSER_INT32, val_len)
elif size == 8:
struct.pack_into('=ccq', self.buf, self.wpos, BSER_ARRAY, BSER_INT64, val_len)
else:
raise RuntimeError('Cannot represent this sequence value')
self.wpos += needed
for v in val:
self.append_recursive(v)
else:
raise RuntimeError('Cannot represent unknown value type')
def dumps(obj):
bser_buf = _bser_buffer()
bser_buf.append_recursive(obj)
# Now fill in the overall length
obj_len = bser_buf.wpos - len(EMPTY_HEADER)
struct.pack_into('=i', bser_buf.buf, 3, obj_len)
return bser_buf.buf.raw[:bser_buf.wpos]
def _bunser_int(buf, pos):
try:
int_type = buf[pos]
except IndexError:
raise ValueError('Invalid bser int encoding, pos out of range')
if int_type == BSER_INT8:
needed = 2
fmt = '=b'
elif int_type == BSER_INT16:
needed = 3
fmt = '=h'
elif int_type == BSER_INT32:
needed = 5
fmt = '=i'
elif int_type == BSER_INT64:
needed = 9
fmt = '=q'
else:
raise ValueError('Invalid bser int encoding 0x%02x' % int(int_type))
int_val = struct.unpack_from(fmt, buf, pos + 1)[0]
return (int_val, pos + needed)
def _bunser_string(buf, pos):
str_len, pos = _bunser_int(buf, pos + 1)
str_val = struct.unpack_from(str(str_len) + 's', buf, pos)[0]
return (str_val, pos + str_len)
def _bunser_array(buf, pos, mutable=True):
arr_len, pos = _bunser_int(buf, pos + 1)
arr = []
for i in range(arr_len):
arr_item, pos = _bser_loads_recursive(buf, pos, mutable)
arr.append(arr_item)
if not mutable:
arr = tuple(arr)
return arr, pos
# This is a quack-alike with the bserObjectType in bser.c
# It provides by getattr accessors and getitem for both index
# and name.
class _BunserDict(object):
__slots__ = ('_keys', '_values')
def __init__(self, keys, values):
self._keys = keys
self._values = values
def __getattr__(self, name):
return self.__getitem__(name)
def __getitem__(self, key):
if isinstance(key, (int, long)):
return self._values[key]
elif key.startswith('st_'):
# hack^Wfeature to allow mercurial to use "st_size" to
# reference "size"
key = key[3:]
try:
return self._values[self._keys.index(key)]
except ValueError as ex:
raise KeyError('_BunserDict has no key %s' % key)
def __len__(self):
return len(self._keys)
def _bunser_object(buf, pos, mutable=True):
obj_len, pos = _bunser_int(buf, pos + 1)
if mutable:
obj = {}
else:
keys = []
vals = []
for i in range(obj_len):
key, pos = _bunser_string(buf, pos)
val, pos = _bser_loads_recursive(buf, pos, mutable)
if mutable:
obj[key] = val
else:
keys.append(key)
vals.append(val)
if not mutable:
obj = _BunserDict(keys, vals)
return obj, pos
def _bunser_template(buf, pos, mutable=True):
if buf[pos + 1] != BSER_ARRAY:
raise RuntimeError('Expect ARRAY to follow TEMPLATE')
keys, pos = _bunser_array(buf, pos + 1)
nitems, pos = _bunser_int(buf, pos)
arr = []
for i in range(nitems):
if mutable:
obj = {}
else:
vals = []
for keyidx in range(len(keys)):
if buf[pos] == BSER_SKIP:
pos += 1
ele = None
else:
ele, pos = _bser_loads_recursive(buf, pos, mutable)
if mutable:
key = keys[keyidx]
obj[key] = ele
else:
vals.append(ele)
if not mutable:
obj = _BunserDict(keys, vals)
arr.append(obj)
return arr, pos
def _bser_loads_recursive(buf, pos, mutable=True):
val_type = buf[pos]
if (val_type == BSER_INT8 or val_type == BSER_INT16 or
val_type == BSER_INT32 or val_type == BSER_INT64):
return _bunser_int(buf, pos)
elif val_type == BSER_REAL:
val = struct.unpack_from('=d', buf, pos + 1)[0]
return (val, pos + 9)
elif val_type == BSER_TRUE:
return (True, pos + 1)
elif val_type == BSER_FALSE:
return (False, pos + 1)
elif val_type == BSER_NULL:
return (None, pos + 1)
elif val_type == BSER_STRING:
return _bunser_string(buf, pos)
elif val_type == BSER_ARRAY:
return _bunser_array(buf, pos, mutable)
elif val_type == BSER_OBJECT:
return _bunser_object(buf, pos, mutable)
elif val_type == BSER_TEMPLATE:
return _bunser_template(buf, pos, mutable)
else:
raise RuntimeError('unhandled bser opcode 0x%02x' % (val_type,))
def pdu_len(buf):
if buf[0:2] != EMPTY_HEADER[0:2]:
raise RuntimeError('Invalid BSER header')
expected_len, pos = _bunser_int(buf, 2)
return expected_len + pos
def loads(buf, mutable=True):
if buf[0:2] != EMPTY_HEADER[0:2]:
raise RuntimeError('Invalid BSER header')
expected_len, pos = _bunser_int(buf, 2)
if len(buf) != expected_len + pos:
raise RuntimeError('bser data len != header len')
return _bser_loads_recursive(buf, pos, mutable)[0]
# no-check-code -- this is a 3rd party library