PythonLib/min added, missing .pyd files for PythonLib/full

Author: bruderstein

PythonLib/full/bz2.pyd

@@ -0,0 +1,180 @@
+"""Bastionification utility.
+
+A bastion (for another object -- the 'original') is an object that has
+the same methods as the original but does not give access to its
+instance variables.  Bastions have a number of uses, but the most
+obvious one is to provide code executing in restricted mode with a
+safe interface to an object implemented in unrestricted mode.
+
+The bastionification routine has an optional second argument which is
+a filter function.  Only those methods for which the filter method
+(called with the method name as argument) returns true are accessible.
+The default filter method returns true unless the method name begins
+with an underscore.
+
+There are a number of possible implementations of bastions.  We use a
+'lazy' approach where the bastion's __getattr__() discipline does all
+the work for a particular method the first time it is used.  This is
+usually fastest, especially if the user doesn't call all available
+methods.  The retrieved methods are stored as instance variables of
+the bastion, so the overhead is only occurred on the first use of each
+method.
+
+Detail: the bastion class has a __repr__() discipline which includes
+the repr() of the original object.  This is precomputed when the
+bastion is created.
+
+"""
+from warnings import warnpy3k
+warnpy3k("the Bastion module has been removed in Python 3.0", stacklevel=2)
+del warnpy3k
+
+__all__ = ["BastionClass", "Bastion"]
+
+from types import MethodType
+
+
+class BastionClass:
+
+    """Helper class used by the Bastion() function.
+
+    You could subclass this and pass the subclass as the bastionclass
+    argument to the Bastion() function, as long as the constructor has
+    the same signature (a get() function and a name for the object).
+
+    """
+
+    def __init__(self, get, name):
+        """Constructor.
+
+        Arguments:
+
+        get - a function that gets the attribute value (by name)
+        name - a human-readable name for the original object
+               (suggestion: use repr(object))
+
+        """
+        self._get_ = get
+        self._name_ = name
+
+    def __repr__(self):
+        """Return a representation string.
+
+        This includes the name passed in to the constructor, so that
+        if you print the bastion during debugging, at least you have
+        some idea of what it is.
+
+        """
+        return "<Bastion for %s>" % self._name_
+
+    def __getattr__(self, name):
+        """Get an as-yet undefined attribute value.
+
+        This calls the get() function that was passed to the
+        constructor.  The result is stored as an instance variable so
+        that the next time the same attribute is requested,
+        __getattr__() won't be invoked.
+
+        If the get() function raises an exception, this is simply
+        passed on -- exceptions are not cached.
+
+        """
+        attribute = self._get_(name)
+        self.__dict__[name] = attribute
+        return attribute
+
+
+def Bastion(object, filter = lambda name: name[:1] != '_',
+            name=None, bastionclass=BastionClass):
+    """Create a bastion for an object, using an optional filter.
+
+    See the Bastion module's documentation for background.
+
+    Arguments:
+
+    object - the original object
+    filter - a predicate that decides whether a function name is OK;
+             by default all names are OK that don't start with '_'
+    name - the name of the object; default repr(object)
+    bastionclass - class used to create the bastion; default BastionClass
+
+    """
+
+    raise RuntimeError, "This code is not secure in Python 2.2 and later"
+
+    # Note: we define *two* ad-hoc functions here, get1 and get2.
+    # Both are intended to be called in the same way: get(name).
+    # It is clear that the real work (getting the attribute
+    # from the object and calling the filter) is done in get1.
+    # Why can't we pass get1 to the bastion?  Because the user
+    # would be able to override the filter argument!  With get2,
+    # overriding the default argument is no security loophole:
+    # all it does is call it.
+    # Also notice that we can't place the object and filter as
+    # instance variables on the bastion object itself, since
+    # the user has full access to all instance variables!
+
+    def get1(name, object=object, filter=filter):
+        """Internal function for Bastion().  See source comments."""
+        if filter(name):
+            attribute = getattr(object, name)
+            if type(attribute) == MethodType:
+                return attribute
+        raise AttributeError, name
+
+    def get2(name, get1=get1):
+        """Internal function for Bastion().  See source comments."""
+        return get1(name)
+
+    if name is None:
+        name = repr(object)
+    return bastionclass(get2, name)
+
+
+def _test():
+    """Test the Bastion() function."""
+    class Original:
+        def __init__(self):
+            self.sum = 0
+        def add(self, n):
+            self._add(n)
+        def _add(self, n):
+            self.sum = self.sum + n
+        def total(self):
+            return self.sum
+    o = Original()
+    b = Bastion(o)
+    testcode = """if 1:
+    b.add(81)
+    b.add(18)
+    print "b.total() =", b.total()
+    try:
+        print "b.sum =", b.sum,
+    except:
+        print "inaccessible"
+    else:
+        print "accessible"
+    try:
+        print "b._add =", b._add,
+    except:
+        print "inaccessible"
+    else:
+        print "accessible"
+    try:
+        print "b._get_.func_defaults =", map(type, b._get_.func_defaults),
+    except:
+        print "inaccessible"
+    else:
+        print "accessible"
+    \n"""
+    exec testcode
+    print '='*20, "Using rexec:", '='*20
+    import rexec
+    r = rexec.RExec()
+    m = r.add_module('__main__')
+    m.b = b
+    r.r_exec(testcode)
+
+
+if __name__ == '__main__':
+    _test()