feat: add protected_inplacevar function extracted from AccessControl

Extracted from 17a5ceb0ae/src/AccessControl/ZopeGuards.py

frappe/utils/inplacevar.py

@@ -0,0 +1,127 @@
+#############################################################################
+#
+# Copyright (c) 2002 Zope Foundation and Contributors.
+#
+# 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
+#
+##############################################################################
+
+# Extracted from AccessControl.ZopeGuards
+# https://github.com/zopefoundation/AccessControl
+
+valid_inplace_types = (list, set)
+
+
+inplace_slots = {
+    '+=': '__iadd__',
+    '-=': '__isub__',
+    '*=': '__imul__',
+    '/=': (1 / 2 == 0) and '__idiv__' or '__itruediv__',
+    '//=': '__ifloordiv__',
+    '%=': '__imod__',
+    '**=': '__ipow__',
+    '<<=': '__ilshift__',
+    '>>=': '__irshift__',
+    '&=': '__iand__',
+    '^=': '__ixor__',
+    '|=': '__ior__',
+}
+
+
+def __iadd__(x, y):
+    x += y
+    return x
+
+
+def __isub__(x, y):
+    x -= y
+    return x
+
+
+def __imul__(x, y):
+    x *= y
+    return x
+
+
+def __idiv__(x, y):
+    x /= y
+    return x
+
+
+def __ifloordiv__(x, y):
+    x //= y
+    return x
+
+
+def __imod__(x, y):
+    x %= y
+    return x
+
+
+def __ipow__(x, y):
+    x **= y
+    return x
+
+
+def __ilshift__(x, y):
+    x <<= y
+    return x
+
+
+def __irshift__(x, y):
+    x >>= y
+    return x
+
+
+def __iand__(x, y):
+    x &= y
+    return x
+
+
+def __ixor__(x, y):
+    x ^= y
+    return x
+
+
+def __ior__(x, y):
+    x |= y
+    return x
+
+
+inplace_ops = {
+    '+=': __iadd__,
+    '-=': __isub__,
+    '*=': __imul__,
+    '/=': __idiv__,
+    '//=': __ifloordiv__,
+    '%=': __imod__,
+    '**=': __ipow__,
+    '<<=': __ilshift__,
+    '>>=': __irshift__,
+    '&=': __iand__,
+    '^=': __ixor__,
+    '|=': __ior__,
+}
+
+
+def protected_inplacevar(op, var, expr):
+    """Do an inplace operation
+
+    If the var has an inplace slot, then disallow the operation
+    unless the var an instance of ``valid_inplace_types``.
+    """
+    if hasattr(var, inplace_slots[op]) and \
+       not isinstance(var, valid_inplace_types):
+        try:
+            cls = var.__class__
+        except AttributeError:
+            cls = type(var)
+        raise TypeError(
+            "Augmented assignment to %s objects is not allowed"
+            " in untrusted code" % cls.__name__)
+    return inplace_ops[op](var, expr)