CasperSecurity
# -*- test-case-name: twisted.test.test_persisted -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
AOT: Abstract Object Trees
The source-code-marshallin'est abstract-object-serializin'est persister
this side of Marmalade!
"""
import copyreg as copy_reg
import re
import types
from tokenize import generate_tokens as tokenize
from twisted.persisted import crefutil
from twisted.python import log, reflect
from twisted.python.compat import _constructMethod
###########################
# Abstract Object Classes #
###########################
# "\0" in a getSource means "insert variable-width indention here".
# see `indentify'.
class Named:
def __init__(self, name):
self.name = name
class Class(Named):
def getSource(self):
return "Class(%r)" % self.name
class Function(Named):
def getSource(self):
return "Function(%r)" % self.name
class Module(Named):
def getSource(self):
return "Module(%r)" % self.name
class InstanceMethod:
def __init__(self, name, klass, inst):
if not (
isinstance(inst, Ref)
or isinstance(inst, Instance)
or isinstance(inst, Deref)
):
raise TypeError("%s isn't an Instance, Ref, or Deref!" % inst)
self.name = name
self.klass = klass
self.instance = inst
def getSource(self):
return "InstanceMethod({!r}, {!r}, \n\0{})".format(
self.name,
self.klass,
prettify(self.instance),
)
class _NoStateObj:
pass
NoStateObj = _NoStateObj()
_SIMPLE_BUILTINS = [
bool,
bytes,
str,
int,
float,
complex,
type(None),
slice,
type(Ellipsis),
]
class Instance:
def __init__(self, className, __stateObj__=NoStateObj, **state):
if not isinstance(className, str):
raise TypeError("%s isn't a string!" % className)
self.klass = className
if __stateObj__ is not NoStateObj:
self.state = __stateObj__
self.stateIsDict = 0
else:
self.state = state
self.stateIsDict = 1
def getSource(self):
# XXX make state be foo=bar instead of a dict.
if self.stateIsDict:
stateDict = self.state
elif isinstance(self.state, Ref) and isinstance(self.state.obj, dict):
stateDict = self.state.obj
else:
stateDict = None
if stateDict is not None:
try:
return f"Instance({self.klass!r}, {dictToKW(stateDict)})"
except NonFormattableDict:
return f"Instance({self.klass!r}, {prettify(stateDict)})"
return f"Instance({self.klass!r}, {prettify(self.state)})"
class Ref:
def __init__(self, *args):
# blargh, lame.
if len(args) == 2:
self.refnum = args[0]
self.obj = args[1]
elif not args:
self.refnum = None
self.obj = None
def setRef(self, num):
if self.refnum:
raise ValueError(f"Error setting id {num}, I already have {self.refnum}")
self.refnum = num
def setObj(self, obj):
if self.obj:
raise ValueError(f"Error setting obj {obj}, I already have {self.obj}")
self.obj = obj
def getSource(self):
if self.obj is None:
raise RuntimeError(
"Don't try to display me before setting an object on me!"
)
if self.refnum:
return "Ref(%d, \n\0%s)" % (self.refnum, prettify(self.obj))
return prettify(self.obj)
class Deref:
def __init__(self, num):
self.refnum = num
def getSource(self):
return "Deref(%d)" % self.refnum
__repr__ = getSource
class Copyreg:
def __init__(self, loadfunc, state):
self.loadfunc = loadfunc
self.state = state
def getSource(self):
return f"Copyreg({self.loadfunc!r}, {prettify(self.state)})"
###############
# Marshalling #
###############
def getSource(ao):
"""Pass me an AO, I'll return a nicely-formatted source representation."""
return indentify("app = " + prettify(ao))
class NonFormattableDict(Exception):
"""A dictionary was not formattable."""
r = re.compile("[a-zA-Z_][a-zA-Z0-9_]*$")
def dictToKW(d):
out = []
items = list(d.items())
items.sort()
for k, v in items:
if not isinstance(k, str):
raise NonFormattableDict("%r ain't a string" % k)
if not r.match(k):
raise NonFormattableDict("%r ain't an identifier" % k)
out.append(f"\n\0{k}={prettify(v)},")
return "".join(out)
def prettify(obj):
if hasattr(obj, "getSource"):
return obj.getSource()
else:
# basic type
t = type(obj)
if t in _SIMPLE_BUILTINS:
return repr(obj)
elif t is dict:
out = ["{"]
for k, v in obj.items():
out.append(f"\n\0{prettify(k)}: {prettify(v)},")
out.append(len(obj) and "\n\0}" or "}")
return "".join(out)
elif t is list:
out = ["["]
for x in obj:
out.append("\n\0%s," % prettify(x))
out.append(len(obj) and "\n\0]" or "]")
return "".join(out)
elif t is tuple:
out = ["("]
for x in obj:
out.append("\n\0%s," % prettify(x))
out.append(len(obj) and "\n\0)" or ")")
return "".join(out)
else:
raise TypeError(f"Unsupported type {t} when trying to prettify {obj}.")
def indentify(s):
out = []
stack = []
l = ["", s]
for (
tokenType,
tokenString,
(startRow, startColumn),
(endRow, endColumn),
logicalLine,
) in tokenize(l.pop):
if tokenString in ["[", "(", "{"]:
stack.append(tokenString)
elif tokenString in ["]", ")", "}"]:
stack.pop()
if tokenString == "\0":
out.append(" " * len(stack))
else:
out.append(tokenString)
return "".join(out)
###########
# Unjelly #
###########
def unjellyFromAOT(aot):
"""
Pass me an Abstract Object Tree, and I'll unjelly it for you.
"""
return AOTUnjellier().unjelly(aot)
def unjellyFromSource(stringOrFile):
"""
Pass me a string of code or a filename that defines an 'app' variable (in
terms of Abstract Objects!), and I'll execute it and unjelly the resulting
AOT for you, returning a newly unpersisted Application object!
"""
ns = {
"Instance": Instance,
"InstanceMethod": InstanceMethod,
"Class": Class,
"Function": Function,
"Module": Module,
"Ref": Ref,
"Deref": Deref,
"Copyreg": Copyreg,
}
if hasattr(stringOrFile, "read"):
source = stringOrFile.read()
else:
source = stringOrFile
code = compile(source, "<source>", "exec")
eval(code, ns, ns)
if "app" in ns:
return unjellyFromAOT(ns["app"])
else:
raise ValueError("%s needs to define an 'app', it didn't!" % stringOrFile)
class AOTUnjellier:
"""I handle the unjellying of an Abstract Object Tree.
See AOTUnjellier.unjellyAO
"""
def __init__(self):
self.references = {}
self.stack = []
self.afterUnjelly = []
##
# unjelly helpers (copied pretty much directly from (now deleted) marmalade)
##
def unjellyLater(self, node):
"""Unjelly a node, later."""
d = crefutil._Defer()
self.unjellyInto(d, 0, node)
return d
def unjellyInto(self, obj, loc, ao):
"""Utility method for unjellying one object into another.
This automates the handling of backreferences.
"""
o = self.unjellyAO(ao)
obj[loc] = o
if isinstance(o, crefutil.NotKnown):
o.addDependant(obj, loc)
return o
def callAfter(self, callable, result):
if isinstance(result, crefutil.NotKnown):
listResult = [None]
result.addDependant(listResult, 1)
else:
listResult = [result]
self.afterUnjelly.append((callable, listResult))
def unjellyAttribute(self, instance, attrName, ao):
# XXX this is unused????
"""Utility method for unjellying into instances of attributes.
Use this rather than unjellyAO unless you like surprising bugs!
Alternatively, you can use unjellyInto on your instance's __dict__.
"""
self.unjellyInto(instance.__dict__, attrName, ao)
def unjellyAO(self, ao):
"""Unjelly an Abstract Object and everything it contains.
I return the real object.
"""
self.stack.append(ao)
t = type(ao)
if t in _SIMPLE_BUILTINS:
return ao
elif t is list:
l = []
for x in ao:
l.append(None)
self.unjellyInto(l, len(l) - 1, x)
return l
elif t is tuple:
l = []
tuple_ = tuple
for x in ao:
l.append(None)
if isinstance(self.unjellyInto(l, len(l) - 1, x), crefutil.NotKnown):
tuple_ = crefutil._Tuple
return tuple_(l)
elif t is dict:
d = {}
for k, v in ao.items():
kvd = crefutil._DictKeyAndValue(d)
self.unjellyInto(kvd, 0, k)
self.unjellyInto(kvd, 1, v)
return d
else:
# Abstract Objects
c = ao.__class__
if c is Module:
return reflect.namedModule(ao.name)
elif c in [Class, Function] or issubclass(c, type):
return reflect.namedObject(ao.name)
elif c is InstanceMethod:
im_name = ao.name
im_class = reflect.namedObject(ao.klass)
im_self = self.unjellyAO(ao.instance)
if im_name in im_class.__dict__:
if im_self is None:
return getattr(im_class, im_name)
elif isinstance(im_self, crefutil.NotKnown):
return crefutil._InstanceMethod(im_name, im_self, im_class)
else:
return _constructMethod(im_class, im_name, im_self)
else:
raise TypeError("instance method changed")
elif c is Instance:
klass = reflect.namedObject(ao.klass)
state = self.unjellyAO(ao.state)
inst = klass.__new__(klass)
if hasattr(klass, "__setstate__"):
self.callAfter(inst.__setstate__, state)
else:
inst.__dict__ = state
return inst
elif c is Ref:
o = self.unjellyAO(ao.obj) # THIS IS CHANGING THE REF OMG
refkey = ao.refnum
ref = self.references.get(refkey)
if ref is None:
self.references[refkey] = o
elif isinstance(ref, crefutil.NotKnown):
ref.resolveDependants(o)
self.references[refkey] = o
elif refkey is None:
# This happens when you're unjellying from an AOT not read from source
pass
else:
raise ValueError(
"Multiple references with the same ID: %s, %s, %s!"
% (ref, refkey, ao)
)
return o
elif c is Deref:
num = ao.refnum
ref = self.references.get(num)
if ref is None:
der = crefutil._Dereference(num)
self.references[num] = der
return der
return ref
elif c is Copyreg:
loadfunc = reflect.namedObject(ao.loadfunc)
d = self.unjellyLater(ao.state).addCallback(
lambda result, _l: _l(*result), loadfunc
)
return d
else:
raise TypeError("Unsupported AOT type: %s" % t)
def unjelly(self, ao):
try:
l = [None]
self.unjellyInto(l, 0, ao)
for func, v in self.afterUnjelly:
func(v[0])
return l[0]
except BaseException:
log.msg("Error jellying object! Stacktrace follows::")
log.msg("\n".join(map(repr, self.stack)))
raise
#########
# Jelly #
#########
def jellyToAOT(obj):
"""Convert an object to an Abstract Object Tree."""
return AOTJellier().jelly(obj)
def jellyToSource(obj, file=None):
"""
Pass me an object and, optionally, a file object.
I'll convert the object to an AOT either return it (if no file was
specified) or write it to the file.
"""
aot = jellyToAOT(obj)
if file:
file.write(getSource(aot).encode("utf-8"))
else:
return getSource(aot)
def _classOfMethod(methodObject):
"""
Get the associated class of the given method object.
@param methodObject: a bound method
@type methodObject: L{types.MethodType}
@return: a class
@rtype: L{type}
"""
return methodObject.__self__.__class__
def _funcOfMethod(methodObject):
"""
Get the associated function of the given method object.
@param methodObject: a bound method
@type methodObject: L{types.MethodType}
@return: the function implementing C{methodObject}
@rtype: L{types.FunctionType}
"""
return methodObject.__func__
def _selfOfMethod(methodObject):
"""
Get the object that a bound method is bound to.
@param methodObject: a bound method
@type methodObject: L{types.MethodType}
@return: the C{self} passed to C{methodObject}
@rtype: L{object}
"""
return methodObject.__self__
class AOTJellier:
def __init__(self):
# dict of {id(obj): (obj, node)}
self.prepared = {}
self._ref_id = 0
self.stack = []
def prepareForRef(self, aoref, object):
"""I prepare an object for later referencing, by storing its id()
and its _AORef in a cache."""
self.prepared[id(object)] = aoref
def jellyToAO(self, obj):
"""I turn an object into an AOT and return it."""
objType = type(obj)
self.stack.append(repr(obj))
# immutable: We don't care if these have multiple refs!
if objType in _SIMPLE_BUILTINS:
retval = obj
elif issubclass(objType, types.MethodType):
# TODO: make methods 'prefer' not to jelly the object internally,
# so that the object will show up where it's referenced first NOT
# by a method.
retval = InstanceMethod(
_funcOfMethod(obj).__name__,
reflect.qual(_classOfMethod(obj)),
self.jellyToAO(_selfOfMethod(obj)),
)
elif issubclass(objType, types.ModuleType):
retval = Module(obj.__name__)
elif issubclass(objType, type):
retval = Class(reflect.qual(obj))
elif objType is types.FunctionType:
retval = Function(reflect.fullFuncName(obj))
else: # mutable! gotta watch for refs.
# Marmalade had the nicety of being able to just stick a 'reference' attribute
# on any Node object that was referenced, but in AOT, the referenced object
# is *inside* of a Ref call (Ref(num, obj) instead of
# <objtype ... reference="1">). The problem is, especially for built-in types,
# I can't just assign some attribute to them to give them a refnum. So, I have
# to "wrap" a Ref(..) around them later -- that's why I put *everything* that's
# mutable inside one. The Ref() class will only print the "Ref(..)" around an
# object if it has a Reference explicitly attached.
if id(obj) in self.prepared:
oldRef = self.prepared[id(obj)]
if oldRef.refnum:
# it's been referenced already
key = oldRef.refnum
else:
# it hasn't been referenced yet
self._ref_id = self._ref_id + 1
key = self._ref_id
oldRef.setRef(key)
return Deref(key)
retval = Ref()
def _stateFrom(state):
retval.setObj(
Instance(reflect.qual(obj.__class__), self.jellyToAO(state))
)
self.prepareForRef(retval, obj)
if objType is list:
retval.setObj([self.jellyToAO(o) for o in obj]) # hah!
elif objType is tuple:
retval.setObj(tuple(map(self.jellyToAO, obj)))
elif objType is dict:
d = {}
for k, v in obj.items():
d[self.jellyToAO(k)] = self.jellyToAO(v)
retval.setObj(d)
elif objType in copy_reg.dispatch_table:
unpickleFunc, state = copy_reg.dispatch_table[objType](obj)
retval.setObj(
Copyreg(reflect.fullFuncName(unpickleFunc), self.jellyToAO(state))
)
elif hasattr(obj, "__getstate__"):
_stateFrom(obj.__getstate__())
elif hasattr(obj, "__dict__"):
_stateFrom(obj.__dict__)
else:
raise TypeError("Unsupported type: %s" % objType.__name__)
del self.stack[-1]
return retval
def jelly(self, obj):
try:
ao = self.jellyToAO(obj)
return ao
except BaseException:
log.msg("Error jellying object! Stacktrace follows::")
log.msg("\n".join(self.stack))
raise