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# -*- test-case-name: twisted.test.test_sob -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
#
"""
Save and load Small OBjects to and from files, using various formats.
Maintainer: Moshe Zadka
"""
from __future__ import division, absolute_import
import os
import sys
import warnings
try:
import cPickle as pickle
except ImportError:
import pickle
from io import BytesIO
from hashlib import md5
from twisted.python import log, runtime
from twisted.persisted import styles
from zope.interface import implementer, Interface
# Note:
# These encrypt/decrypt functions only work for data formats
# which are immune to having spaces tucked at the end.
# All data formats which persist saves hold that condition.
def _encrypt(passphrase, data):
from Crypto.Cipher import AES as cipher
warnings.warn(
'Saving encrypted persisted data is deprecated since Twisted 15.5.0',
DeprecationWarning, stacklevel=2)
leftover = len(data) % cipher.block_size
if leftover:
data += b' ' * (cipher.block_size - leftover)
return cipher.new(md5(passphrase).digest()[:16]).encrypt(data)
def _decrypt(passphrase, data):
from Crypto.Cipher import AES
warnings.warn(
'Loading encrypted persisted data is deprecated since Twisted 15.5.0',
DeprecationWarning, stacklevel=2)
return AES.new(md5(passphrase).digest()[:16]).decrypt(data)
class IPersistable(Interface):
"""An object which can be saved in several formats to a file"""
def setStyle(style):
"""Set desired format.
@type style: string (one of 'pickle' or 'source')
"""
def save(tag=None, filename=None, passphrase=None):
"""Save object to file.
@type tag: string
@type filename: string
@type passphrase: string
"""
@implementer(IPersistable)
class Persistent:
style = "pickle"
def __init__(self, original, name):
self.original = original
self.name = name
def setStyle(self, style):
"""Set desired format.
@type style: string (one of 'pickle' or 'source')
"""
self.style = style
def _getFilename(self, filename, ext, tag):
if filename:
finalname = filename
filename = finalname + "-2"
elif tag:
filename = "%s-%s-2.%s" % (self.name, tag, ext)
finalname = "%s-%s.%s" % (self.name, tag, ext)
else:
filename = "%s-2.%s" % (self.name, ext)
finalname = "%s.%s" % (self.name, ext)
return finalname, filename
def _saveTemp(self, filename, passphrase, dumpFunc):
f = open(filename, 'wb')
if passphrase is None:
dumpFunc(self.original, f)
else:
s = BytesIO()
dumpFunc(self.original, s)
f.write(_encrypt(passphrase, s.getvalue()))
f.close()
def _getStyle(self):
if self.style == "source":
from twisted.persisted.aot import jellyToSource as dumpFunc
ext = "tas"
else:
def dumpFunc(obj, file):
pickle.dump(obj, file, 2)
ext = "tap"
return ext, dumpFunc
def save(self, tag=None, filename=None, passphrase=None):
"""Save object to file.
@type tag: string
@type filename: string
@type passphrase: string
"""
ext, dumpFunc = self._getStyle()
if passphrase:
ext = 'e' + ext
finalname, filename = self._getFilename(filename, ext, tag)
log.msg("Saving "+self.name+" application to "+finalname+"...")
self._saveTemp(filename, passphrase, dumpFunc)
if runtime.platformType == "win32" and os.path.isfile(finalname):
os.remove(finalname)
os.rename(filename, finalname)
log.msg("Saved.")
# "Persistant" has been present since 1.0.7, so retain it for compatibility
Persistant = Persistent
class _EverythingEphemeral(styles.Ephemeral):
initRun = 0
def __init__(self, mainMod):
"""
@param mainMod: The '__main__' module that this class will proxy.
"""
self.mainMod = mainMod
def __getattr__(self, key):
try:
return getattr(self.mainMod, key)
except AttributeError:
if self.initRun:
raise
else:
log.msg("Warning! Loading from __main__: %s" % key)
return styles.Ephemeral()
def load(filename, style, passphrase=None):
"""Load an object from a file.
Deserialize an object from a file. The file can be encrypted.
@param filename: string
@param style: string (one of 'pickle' or 'source')
@param passphrase: string
"""
mode = 'r'
if style=='source':
from twisted.persisted.aot import unjellyFromSource as _load
else:
_load, mode = pickle.load, 'rb'
if passphrase:
with open(filename, 'rb') as loadedFile:
fp = BytesIO(_decrypt(passphrase, loadedFile.read()))
else:
fp = open(filename, mode)
ee = _EverythingEphemeral(sys.modules['__main__'])
sys.modules['__main__'] = ee
ee.initRun = 1
try:
value = _load(fp)
finally:
# restore __main__ if an exception is raised.
sys.modules['__main__'] = ee.mainMod
fp.close()
styles.doUpgrade()
ee.initRun = 0
persistable = IPersistable(value, None)
if persistable is not None:
persistable.setStyle(style)
return value
def loadValueFromFile(filename, variable, passphrase=None):
"""Load the value of a variable in a Python file.
Run the contents of the file, after decrypting if C{passphrase} is
given, in a namespace and return the result of the variable
named C{variable}.
@param filename: string
@param variable: string
@param passphrase: string
"""
if passphrase:
mode = 'rb'
else:
mode = 'r'
with open(filename, mode) as fileObj:
data = fileObj.read()
d = {'__file__': filename}
if passphrase:
data = _decrypt(passphrase, data)
codeObj = compile(data, filename, "exec")
eval(codeObj, d, d)
value = d[variable]
return value
def guessType(filename):
ext = os.path.splitext(filename)[1]
return {
'.tac': 'python',
'.etac': 'python',
'.py': 'python',
'.tap': 'pickle',
'.etap': 'pickle',
'.tas': 'source',
'.etas': 'source',
}[ext]
__all__ = ['loadValueFromFile', 'load', 'Persistent', 'Persistant',
'IPersistable', 'guessType']
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