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cpython/Lib/pickle.py

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"""Create portable serialized representations of Python objects.
See module cPickle for a (much) faster implementation.
See module copy_reg for a mechanism for registering custom picklers.
Classes:
Pickler
Unpickler
Functions:
dump(object, file)
dumps(object) -> string
load(file) -> object
loads(string) -> object
Misc variables:
__version__
format_version
compatible_formats
"""
__version__ = "$Revision$" # Code version
from types import *
from copy_reg import dispatch_table, safe_constructors
import marshal
import sys
import struct
import re
__all__ = ["PickleError", "PicklingError", "UnpicklingError", "Pickler",
"Unpickler", "dump", "dumps", "load", "loads"]
format_version = "1.3" # File format version we write
compatible_formats = ["1.0", "1.1", "1.2"] # Old format versions we can read
mdumps = marshal.dumps
mloads = marshal.loads
class PickleError(Exception):
"""A common base class for the other pickling exceptions."""
pass
class PicklingError(PickleError):
"""This exception is raised when an unpicklable object is passed to the
dump() method.
"""
pass
class UnpicklingError(PickleError):
"""This exception is raised when there is a problem unpickling an object,
such as a security violation.
Note that other exceptions may also be raised during unpickling, including
(but not necessarily limited to) AttributeError, EOFError, ImportError,
and IndexError.
"""
pass
class _Stop(Exception):
def __init__(self, value):
self.value = value
try:
from org.python.core import PyStringMap
except ImportError:
PyStringMap = None
try:
UnicodeType
except NameError:
UnicodeType = None
MARK = '('
STOP = '.'
POP = '0'
POP_MARK = '1'
DUP = '2'
FLOAT = 'F'
INT = 'I'
BININT = 'J'
BININT1 = 'K'
LONG = 'L'
BININT2 = 'M'
NONE = 'N'
PERSID = 'P'
BINPERSID = 'Q'
REDUCE = 'R'
STRING = 'S'
BINSTRING = 'T'
SHORT_BINSTRING = 'U'
UNICODE = 'V'
BINUNICODE = 'X'
APPEND = 'a'
BUILD = 'b'
GLOBAL = 'c'
DICT = 'd'
EMPTY_DICT = '}'
APPENDS = 'e'
GET = 'g'
BINGET = 'h'
INST = 'i'
LONG_BINGET = 'j'
LIST = 'l'
EMPTY_LIST = ']'
OBJ = 'o'
PUT = 'p'
BINPUT = 'q'
LONG_BINPUT = 'r'
SETITEM = 's'
TUPLE = 't'
EMPTY_TUPLE = ')'
SETITEMS = 'u'
BINFLOAT = 'G'
TRUE = 'I01\n'
FALSE = 'I00\n'
__all__.extend([x for x in dir() if re.match("[A-Z][A-Z0-9_]+$",x)])
del x
class Pickler:
def __init__(self, file, bin = 0):
"""This takes a file-like object for writing a pickle data stream.
The optional bin parameter if true, tells the pickler to use the more
efficient binary pickle format, otherwise the ASCII format is used
(this is the default).
The file parameter must have a write() method that accepts a single
string argument. It can thus be an open file object, a StringIO
object, or any other custom object that meets this interface.
"""
self.write = file.write
self.memo = {}
self.bin = bin
def clear_memo(self):
"""Clears the pickler's "memo".
The memo is the data structure that remembers which objects the
pickler has already seen, so that shared or recursive objects pickled
by reference and not by value. This method is useful when re-using
picklers.
"""
self.memo.clear()
def dump(self, object):
"""Write a pickled representation of object to the open file object.
Either the binary or ASCII format will be used, depending on the
value of the bin flag passed to the constructor.
"""
self.save(object)
self.write(STOP)
def put(self, i):
if self.bin:
s = mdumps(i)[1:]
if i < 256:
return BINPUT + s[0]
return LONG_BINPUT + s
return PUT + `i` + '\n'
def get(self, i):
if self.bin:
s = mdumps(i)[1:]
if i < 256:
return BINGET + s[0]
return LONG_BINGET + s
return GET + `i` + '\n'
def save(self, object, pers_save = 0):
memo = self.memo
if not pers_save:
pid = self.persistent_id(object)
if pid is not None:
self.save_pers(pid)
return
d = id(object)
t = type(object)
if (t is TupleType) and (len(object) == 0):
if self.bin:
self.save_empty_tuple(object)
else:
self.save_tuple(object)
return
if d in memo:
self.write(self.get(memo[d][0]))
return
try:
f = self.dispatch[t]
except KeyError:
try:
issc = issubclass(t, TypeType)
except TypeError: # t is not a class
issc = 0
if issc:
self.save_global(object)
return
pid = self.inst_persistent_id(object)
if pid is not None:
self.save_pers(pid)
return
try:
reduce = dispatch_table[t]
except KeyError:
try:
reduce = object.__reduce__
except AttributeError:
raise PicklingError, \
"can't pickle %s object: %s" % (`t.__name__`,
`object`)
else:
tup = reduce()
else:
tup = reduce(object)
if type(tup) is StringType:
self.save_global(object, tup)
return
if type(tup) is not TupleType:
raise PicklingError, "Value returned by %s must be a " \
"tuple" % reduce
l = len(tup)
if (l != 2) and (l != 3):
raise PicklingError, "tuple returned by %s must contain " \
"only two or three elements" % reduce
callable = tup[0]
arg_tup = tup[1]
if l > 2:
state = tup[2]
else:
state = None
if type(arg_tup) is not TupleType and arg_tup is not None:
raise PicklingError, "Second element of tuple returned " \
"by %s must be a tuple" % reduce
self.save_reduce(callable, arg_tup, state)
memo_len = len(memo)
self.write(self.put(memo_len))
memo[d] = (memo_len, object)
return
f(self, object)
def persistent_id(self, object):
return None
def inst_persistent_id(self, object):
return None
def save_pers(self, pid):
if not self.bin:
self.write(PERSID + str(pid) + '\n')
else:
self.save(pid, 1)
self.write(BINPERSID)
def save_reduce(self, callable, arg_tup, state = None):
write = self.write
save = self.save
save(callable)
save(arg_tup)
write(REDUCE)
if state is not None:
save(state)
write(BUILD)
dispatch = {}
def save_none(self, object):
self.write(NONE)
dispatch[NoneType] = save_none
def save_bool(self, object):
if object:
self.write(TRUE)
else:
self.write(FALSE)
dispatch[bool] = save_bool
def save_int(self, object):
if self.bin:
# If the int is small enough to fit in a signed 4-byte 2's-comp
# format, we can store it more efficiently than the general
# case.
high_bits = object >> 31 # note that Python shift sign-extends
if high_bits == 0 or high_bits == -1:
# All high bits are copies of bit 2**31, so the value
# fits in a 4-byte signed int.
i = mdumps(object)[1:]
assert len(i) == 4
if i[-2:] == '\000\000': # fits in 2-byte unsigned int
if i[-3] == '\000': # fits in 1-byte unsigned int
self.write(BININT1 + i[0])
else:
self.write(BININT2 + i[:2])
else:
self.write(BININT + i)
return
# Text pickle, or int too big to fit in signed 4-byte format.
self.write(INT + `object` + '\n')
dispatch[IntType] = save_int
def save_long(self, object):
self.write(LONG + `object` + '\n')
dispatch[LongType] = save_long
def save_float(self, object, pack=struct.pack):
if self.bin:
self.write(BINFLOAT + pack('>d', object))
else:
self.write(FLOAT + `object` + '\n')
dispatch[FloatType] = save_float
def save_string(self, object):
d = id(object)
memo = self.memo
if self.bin:
l = len(object)
s = mdumps(l)[1:]
if l < 256:
self.write(SHORT_BINSTRING + s[0] + object)
else:
self.write(BINSTRING + s + object)
else:
self.write(STRING + `object` + '\n')
memo_len = len(memo)
self.write(self.put(memo_len))
memo[d] = (memo_len, object)
dispatch[StringType] = save_string
def save_unicode(self, object):
d = id(object)
memo = self.memo
if self.bin:
encoding = object.encode('utf-8')
l = len(encoding)
s = mdumps(l)[1:]
self.write(BINUNICODE + s + encoding)
else:
object = object.replace("\\", "\\u005c")
object = object.replace("\n", "\\u000a")
self.write(UNICODE + object.encode('raw-unicode-escape') + '\n')
memo_len = len(memo)
self.write(self.put(memo_len))
memo[d] = (memo_len, object)
dispatch[UnicodeType] = save_unicode
if StringType == UnicodeType:
# This is true for Jython
def save_string(self, object):
d = id(object)
memo = self.memo
unicode = object.isunicode()
if self.bin:
if unicode:
object = object.encode("utf-8")
l = len(object)
s = mdumps(l)[1:]
if l < 256 and not unicode:
self.write(SHORT_BINSTRING + s[0] + object)
else:
if unicode:
self.write(BINUNICODE + s + object)
else:
self.write(BINSTRING + s + object)
else:
if unicode:
object = object.replace("\\", "\\u005c")
object = object.replace("\n", "\\u000a")
object = object.encode('raw-unicode-escape')
self.write(UNICODE + object + '\n')
else:
self.write(STRING + `object` + '\n')
memo_len = len(memo)
self.write(self.put(memo_len))
memo[d] = (memo_len, object)
dispatch[StringType] = save_string
def save_tuple(self, object):
write = self.write
save = self.save
memo = self.memo
d = id(object)
write(MARK)
for element in object:
save(element)
if len(object) and d in memo:
if self.bin:
write(POP_MARK + self.get(memo[d][0]))
return
write(POP * (len(object) + 1) + self.get(memo[d][0]))
return
memo_len = len(memo)
self.write(TUPLE + self.put(memo_len))
memo[d] = (memo_len, object)
dispatch[TupleType] = save_tuple
def save_empty_tuple(self, object):
self.write(EMPTY_TUPLE)
def save_list(self, object):
d = id(object)
write = self.write
save = self.save
memo = self.memo
if self.bin:
write(EMPTY_LIST)
else:
write(MARK + LIST)
memo_len = len(memo)
write(self.put(memo_len))
memo[d] = (memo_len, object)
using_appends = (self.bin and (len(object) > 1))
if using_appends:
write(MARK)
for element in object:
save(element)
if not using_appends:
write(APPEND)
if using_appends:
write(APPENDS)
dispatch[ListType] = save_list
def save_dict(self, object):
d = id(object)
write = self.write
save = self.save
memo = self.memo
if self.bin:
write(EMPTY_DICT)
else:
write(MARK + DICT)
memo_len = len(memo)
self.write(self.put(memo_len))
memo[d] = (memo_len, object)
using_setitems = (self.bin and (len(object) > 1))
if using_setitems:
write(MARK)
items = object.items()
for key, value in items:
save(key)
save(value)
if not using_setitems:
write(SETITEM)
if using_setitems:
write(SETITEMS)
dispatch[DictionaryType] = save_dict
if not PyStringMap is None:
dispatch[PyStringMap] = save_dict
def save_inst(self, object):
d = id(object)
cls = object.__class__
memo = self.memo
write = self.write
save = self.save
if hasattr(object, '__getinitargs__'):
args = object.__getinitargs__()
len(args) # XXX Assert it's a sequence
_keep_alive(args, memo)
else:
args = ()
write(MARK)
if self.bin:
save(cls)
for arg in args:
save(arg)
memo_len = len(memo)
if self.bin:
write(OBJ + self.put(memo_len))
else:
write(INST + cls.__module__ + '\n' + cls.__name__ + '\n' +
self.put(memo_len))
memo[d] = (memo_len, object)
try:
getstate = object.__getstate__
except AttributeError:
stuff = object.__dict__
else:
stuff = getstate()
_keep_alive(stuff, memo)
save(stuff)
write(BUILD)
dispatch[InstanceType] = save_inst
def save_global(self, object, name = None):
write = self.write
memo = self.memo
if name is None:
name = object.__name__
try:
module = object.__module__
except AttributeError:
module = whichmodule(object, name)
try:
__import__(module)
mod = sys.modules[module]
klass = getattr(mod, name)
except (ImportError, KeyError, AttributeError):
raise PicklingError(
"Can't pickle %r: it's not found as %s.%s" %
(object, module, name))
else:
if klass is not object:
raise PicklingError(
"Can't pickle %r: it's not the same object as %s.%s" %
(object, module, name))
memo_len = len(memo)
write(GLOBAL + module + '\n' + name + '\n' +
self.put(memo_len))
memo[id(object)] = (memo_len, object)
dispatch[ClassType] = save_global
dispatch[FunctionType] = save_global
dispatch[BuiltinFunctionType] = save_global
dispatch[TypeType] = save_global
def _keep_alive(x, memo):
"""Keeps a reference to the object x in the memo.
Because we remember objects by their id, we have
to assure that possibly temporary objects are kept
alive by referencing them.
We store a reference at the id of the memo, which should
normally not be used unless someone tries to deepcopy
the memo itself...
"""
try:
memo[id(memo)].append(x)
except KeyError:
# aha, this is the first one :-)
memo[id(memo)]=[x]
classmap = {}
# This is no longer used to find classes, but still for functions
def whichmodule(cls, clsname):
"""Figure out the module in which a class occurs.
Search sys.modules for the module.
Cache in classmap.
Return a module name.
If the class cannot be found, return __main__.
"""
if cls in classmap:
return classmap[cls]
for name, module in sys.modules.items():
if name != '__main__' and \
hasattr(module, clsname) and \
getattr(module, clsname) is cls:
break
else:
name = '__main__'
classmap[cls] = name
return name
class Unpickler:
def __init__(self, file):
"""This takes a file-like object for reading a pickle data stream.
This class automatically determines whether the data stream was
written in binary mode or not, so it does not need a flag as in
the Pickler class factory.
The file-like object must have two methods, a read() method that
takes an integer argument, and a readline() method that requires no
arguments. Both methods should return a string. Thus file-like
object can be a file object opened for reading, a StringIO object,
or any other custom object that meets this interface.
"""
self.readline = file.readline
self.read = file.read
self.memo = {}
def load(self):
"""Read a pickled object representation from the open file object.
Return the reconstituted object hierarchy specified in the file
object.
"""
self.mark = object() # any new unique object
self.stack = []
self.append = self.stack.append
read = self.read
dispatch = self.dispatch
try:
while 1:
key = read(1)
dispatch[key](self)
except _Stop, stopinst:
return stopinst.value
def marker(self):
stack = self.stack
mark = self.mark
k = len(stack)-1
while stack[k] is not mark: k = k-1
return k
dispatch = {}
def load_eof(self):
raise EOFError
dispatch[''] = load_eof
def load_persid(self):
pid = self.readline()[:-1]
self.append(self.persistent_load(pid))
dispatch[PERSID] = load_persid
def load_binpersid(self):
pid = self.stack.pop()
self.append(self.persistent_load(pid))
dispatch[BINPERSID] = load_binpersid
def load_none(self):
self.append(None)
dispatch[NONE] = load_none
def load_int(self):
data = self.readline()
if data == FALSE[1:]:
val = False
elif data == TRUE[1:]:
val = True
else:
try:
val = int(data)
except ValueError:
val = long(data)
self.append(val)
dispatch[INT] = load_int
def load_binint(self):
self.append(mloads('i' + self.read(4)))
dispatch[BININT] = load_binint
def load_binint1(self):
self.append(mloads('i' + self.read(1) + '\000\000\000'))
dispatch[BININT1] = load_binint1
def load_binint2(self):
self.append(mloads('i' + self.read(2) + '\000\000'))
dispatch[BININT2] = load_binint2
def load_long(self):
self.append(long(self.readline()[:-1], 0))
dispatch[LONG] = load_long
def load_float(self):
self.append(float(self.readline()[:-1]))
dispatch[FLOAT] = load_float
def load_binfloat(self, unpack=struct.unpack):
self.append(unpack('>d', self.read(8))[0])
dispatch[BINFLOAT] = load_binfloat
def load_string(self):
rep = self.readline()[:-1]
if not self._is_string_secure(rep):
raise ValueError, "insecure string pickle"
self.append(eval(rep,
{'__builtins__': {}})) # Let's be careful
dispatch[STRING] = load_string
def _is_string_secure(self, s):
"""Return true if s contains a string that is safe to eval
The definition of secure string is based on the implementation
in cPickle. s is secure as long as it only contains a quoted
string and optional trailing whitespace.
"""
q = s[0]
if q not in ("'", '"'):
return 0
# find the closing quote
offset = 1
i = None
while 1:
try:
i = s.index(q, offset)
except ValueError:
# if there is an error the first time, there is no
# close quote
if offset == 1:
return 0
if s[i-1] != '\\':
break
# check to see if this one is escaped
nslash = 0
j = i - 1
while j >= offset and s[j] == '\\':
j = j - 1
nslash = nslash + 1
if nslash % 2 == 0:
break
offset = i + 1
for c in s[i+1:]:
if ord(c) > 32:
return 0
return 1
def load_binstring(self):
len = mloads('i' + self.read(4))
self.append(self.read(len))
dispatch[BINSTRING] = load_binstring
def load_unicode(self):
self.append(unicode(self.readline()[:-1],'raw-unicode-escape'))
dispatch[UNICODE] = load_unicode
def load_binunicode(self):
len = mloads('i' + self.read(4))
self.append(unicode(self.read(len),'utf-8'))
dispatch[BINUNICODE] = load_binunicode
def load_short_binstring(self):
len = mloads('i' + self.read(1) + '\000\000\000')
self.append(self.read(len))
dispatch[SHORT_BINSTRING] = load_short_binstring
def load_tuple(self):
k = self.marker()
self.stack[k:] = [tuple(self.stack[k+1:])]
dispatch[TUPLE] = load_tuple
def load_empty_tuple(self):
self.stack.append(())
dispatch[EMPTY_TUPLE] = load_empty_tuple
def load_empty_list(self):
self.stack.append([])
dispatch[EMPTY_LIST] = load_empty_list
def load_empty_dictionary(self):
self.stack.append({})
dispatch[EMPTY_DICT] = load_empty_dictionary
def load_list(self):
k = self.marker()
self.stack[k:] = [self.stack[k+1:]]
dispatch[LIST] = load_list
def load_dict(self):
k = self.marker()
d = {}
items = self.stack[k+1:]
for i in range(0, len(items), 2):
key = items[i]
value = items[i+1]
d[key] = value
self.stack[k:] = [d]
dispatch[DICT] = load_dict
def load_inst(self):
k = self.marker()
args = tuple(self.stack[k+1:])
del self.stack[k:]
module = self.readline()[:-1]
name = self.readline()[:-1]
klass = self.find_class(module, name)
instantiated = 0
if (not args and type(klass) is ClassType and
not hasattr(klass, "__getinitargs__")):
try:
value = _EmptyClass()
value.__class__ = klass
instantiated = 1
except RuntimeError:
# In restricted execution, assignment to inst.__class__ is
# prohibited
pass
if not instantiated:
try:
if not hasattr(klass, '__safe_for_unpickling__'):
raise UnpicklingError('%s is not safe for unpickling' %
klass)
value = apply(klass, args)
except TypeError, err:
raise TypeError, "in constructor for %s: %s" % (
klass.__name__, str(err)), sys.exc_info()[2]
self.append(value)
dispatch[INST] = load_inst
def load_obj(self):
stack = self.stack
k = self.marker()
klass = stack[k + 1]
del stack[k + 1]
args = tuple(stack[k + 1:])
del stack[k:]
instantiated = 0
if (not args and type(klass) is ClassType and
not hasattr(klass, "__getinitargs__")):
try:
value = _EmptyClass()
value.__class__ = klass
instantiated = 1
except RuntimeError:
# In restricted execution, assignment to inst.__class__ is
# prohibited
pass
if not instantiated:
value = apply(klass, args)
self.append(value)
dispatch[OBJ] = load_obj
def load_global(self):
module = self.readline()[:-1]
name = self.readline()[:-1]
klass = self.find_class(module, name)
self.append(klass)
dispatch[GLOBAL] = load_global
def find_class(self, module, name):
__import__(module)
mod = sys.modules[module]
klass = getattr(mod, name)
return klass
def load_reduce(self):
stack = self.stack
callable = stack[-2]
arg_tup = stack[-1]
del stack[-2:]
if type(callable) is not ClassType:
if not callable in safe_constructors:
try:
safe = callable.__safe_for_unpickling__
except AttributeError:
safe = None
if not safe:
raise UnpicklingError, "%s is not safe for " \
"unpickling" % callable
if arg_tup is None:
import warnings
warnings.warn("The None return argument form of __reduce__ is "
"deprecated. Return a tuple of arguments instead.",
DeprecationWarning)
value = callable.__basicnew__()
else:
value = apply(callable, arg_tup)
self.append(value)
dispatch[REDUCE] = load_reduce
def load_pop(self):
del self.stack[-1]
dispatch[POP] = load_pop
def load_pop_mark(self):
k = self.marker()
del self.stack[k:]
dispatch[POP_MARK] = load_pop_mark
def load_dup(self):
self.append(self.stack[-1])
dispatch[DUP] = load_dup
def load_get(self):
self.append(self.memo[self.readline()[:-1]])
dispatch[GET] = load_get
def load_binget(self):
i = mloads('i' + self.read(1) + '\000\000\000')
self.append(self.memo[`i`])
dispatch[BINGET] = load_binget
def load_long_binget(self):
i = mloads('i' + self.read(4))
self.append(self.memo[`i`])
dispatch[LONG_BINGET] = load_long_binget
def load_put(self):
self.memo[self.readline()[:-1]] = self.stack[-1]
dispatch[PUT] = load_put
def load_binput(self):
i = mloads('i' + self.read(1) + '\000\000\000')
self.memo[`i`] = self.stack[-1]
dispatch[BINPUT] = load_binput
def load_long_binput(self):
i = mloads('i' + self.read(4))
self.memo[`i`] = self.stack[-1]
dispatch[LONG_BINPUT] = load_long_binput
def load_append(self):
stack = self.stack
value = stack.pop()
list = stack[-1]
list.append(value)
dispatch[APPEND] = load_append
def load_appends(self):
stack = self.stack
mark = self.marker()
list = stack[mark - 1]
for i in range(mark + 1, len(stack)):
list.append(stack[i])
del stack[mark:]
dispatch[APPENDS] = load_appends
def load_setitem(self):
stack = self.stack
value = stack.pop()
key = stack.pop()
dict = stack[-1]
dict[key] = value
dispatch[SETITEM] = load_setitem
def load_setitems(self):
stack = self.stack
mark = self.marker()
dict = stack[mark - 1]
for i in range(mark + 1, len(stack), 2):
dict[stack[i]] = stack[i + 1]
del stack[mark:]
dispatch[SETITEMS] = load_setitems
def load_build(self):
stack = self.stack
value = stack.pop()
inst = stack[-1]
try:
setstate = inst.__setstate__
except AttributeError:
try:
inst.__dict__.update(value)
except RuntimeError:
# XXX In restricted execution, the instance's __dict__ is not
# accessible. Use the old way of unpickling the instance
# variables. This is a semantic different when unpickling in
# restricted vs. unrestricted modes.
for k, v in value.items():
setattr(inst, k, v)
else:
setstate(value)
dispatch[BUILD] = load_build
def load_mark(self):
self.append(self.mark)
dispatch[MARK] = load_mark
def load_stop(self):
value = self.stack.pop()
raise _Stop(value)
dispatch[STOP] = load_stop
# Helper class for load_inst/load_obj
class _EmptyClass:
pass
# Shorthands
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
def dump(object, file, bin = 0):
Pickler(file, bin).dump(object)
def dumps(object, bin = 0):
file = StringIO()
Pickler(file, bin).dump(object)
return file.getvalue()
def load(file):
return Unpickler(file).load()
def loads(str):
file = StringIO(str)
return Unpickler(file).load()
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