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##############################################################################
#
# Copyright (c) 2004 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""compile() equivalent that produces restricted code.
Only 'eval' is supported at this time.
$Id$
"""
import compiler.pycodegen
import RestrictedPython.RCompile
from RestrictedPython.SelectCompiler import ast, OP_ASSIGN, OP_DELETE, OP_APPLY
def compile(text, filename, mode):
if not isinstance(text, basestring):
raise TypeError("Compiled source must be string")
gen = RExpression(text, str(filename), mode)
gen.compile()
return gen.getCode()
class RExpression(RestrictedPython.RCompile.RestrictedCompileMode):
CodeGeneratorClass = compiler.pycodegen.ExpressionCodeGenerator
def __init__(self, source, filename, mode = "eval"):
self.mode = mode
RestrictedPython.RCompile.RestrictedCompileMode.__init__(
self, source, filename)
self.rm = RestrictionMutator()
# The security checks are performed by a set of six functions that
# must be provided by the restricted environment.
_getattr_name = ast.Name("getattr")
class RestrictionMutator:
def __init__(self):
self.errors = []
self.warnings = []
self.used_names = {}
def error(self, node, info):
"""Records a security error discovered during compilation."""
lineno = getattr(node, 'lineno', None)
if lineno is not None and lineno > 0:
self.errors.append('Line %d: %s' % (lineno, info))
else:
self.errors.append(info)
def visitGetattr(self, node, walker):
"""Converts attribute access to a function call.
'foo.bar' becomes 'getattr(foo, "bar")'.
Also prevents augmented assignment of attributes, which would
be difficult to support correctly.
"""
node = walker.defaultVisitNode(node)
return ast.CallFunc(_getattr_name,
[node.expr, ast.Const(node.attrname)])
def visitExec(self, node, walker):
self.error(node, "exec statements are not supported")
def visitPrint(self, node, walker):
"""Make sure prints always have a destination
If we get a print without a destination, make the default destination
untrusted_output.
"""
node = walker.defaultVisitNode(node)
if node.dest is None:
node.dest = ast.Name('untrusted_output')
return node
visitPrintnl = visitPrint
def visitRaise(self, node, walker):
self.error(node, "raise statements are not supported")
def visitTryExcept(self, node, walker):
self.error(node, "try/except statements are not supported")
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