bpo-42990: Functions inherit current builtins (GH-24564)
The types.FunctionType constructor now inherits the current builtins
if the globals dictionary has no "__builtins__" key, rather than
using {"None": None} as builtins: same behavior as eval() and exec()
functions.
Defining a function with "def function(...): ..." in Python is not
affected, globals cannot be overriden with this syntax: it also
inherits the current builtins.
PyFrame_New(), PyEval_EvalCode(), PyEval_EvalCodeEx(),
PyFunction_New() and PyFunction_NewWithQualName() now inherits the
current builtins namespace if the globals dictionary has no
"__builtins__" key.
* Add _PyEval_GetBuiltins() function.
* _PyEval_BuiltinsFromGlobals() now uses _PyEval_GetBuiltins() if
builtins cannot be found in globals.
* Add tstate parameter to _PyEval_BuiltinsFromGlobals().diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst
index c4a79b6..2ceb26f 100644
--- a/Doc/whatsnew/3.10.rst
+++ b/Doc/whatsnew/3.10.rst
@@ -282,7 +282,8 @@
* Functions have a new ``__builtins__`` attribute which is used to look for
builtin symbols when a function is executed, instead of looking into
- ``__globals__['__builtins__']``.
+ ``__globals__['__builtins__']``. The attribute is initialized from
+ ``__globals__["__builtins__"]`` if it exists, else from the current builtins.
(Contributed by Mark Shannon in :issue:`42990`.)
@@ -789,6 +790,14 @@
(Contributed by Yurii Karabas, Andrew Svetlov, Yury Selivanov and Kyle Stanley
in :issue:`42392`.)
+* The :data:`types.FunctionType` constructor now inherits the current builtins
+ if the *globals* dictionary has no ``"__builtins__"`` key, rather than using
+ ``{"None": None}`` as builtins: same behavior as :func:`eval` and
+ :func:`exec` functions. Defining a function with ``def function(...): ...``
+ in Python is not affected, globals cannot be overriden with this syntax: it
+ also inherits the current builtins.
+ (Contributed by Victor Stinner in :issue:`42990`.)
+
CPython bytecode changes
========================
diff --git a/Include/internal/pycore_ceval.h b/Include/internal/pycore_ceval.h
index 78a7056..f07959d 100644
--- a/Include/internal/pycore_ceval.h
+++ b/Include/internal/pycore_ceval.h
@@ -34,7 +34,10 @@ PyAPI_FUNC(void) _PyEval_SetCoroutineOriginTrackingDepth(
void _PyEval_Fini(void);
-extern PyObject *_PyEval_BuiltinsFromGlobals(PyObject *globals);
+extern PyObject* _PyEval_GetBuiltins(PyThreadState *tstate);
+extern PyObject *_PyEval_BuiltinsFromGlobals(
+ PyThreadState *tstate,
+ PyObject *globals);
static inline PyObject*
diff --git a/Lib/test/test_funcattrs.py b/Lib/test/test_funcattrs.py
index 15cf250..77977d0 100644
--- a/Lib/test/test_funcattrs.py
+++ b/Lib/test/test_funcattrs.py
@@ -1,3 +1,4 @@
+import textwrap
import types
import unittest
@@ -78,6 +79,32 @@ def test___builtins__(self):
self.cannot_set_attr(self.b, '__builtins__', 2,
(AttributeError, TypeError))
+ # bpo-42990: If globals is specified and has no "__builtins__" key,
+ # a function inherits the current builtins namespace.
+ def func(s): return len(s)
+ ns = {}
+ func2 = type(func)(func.__code__, ns)
+ self.assertIs(func2.__globals__, ns)
+ self.assertIs(func2.__builtins__, __builtins__)
+
+ # Make sure that the function actually works.
+ self.assertEqual(func2("abc"), 3)
+ self.assertEqual(ns, {})
+
+ # Define functions using exec() with different builtins,
+ # and test inheritance when globals has no "__builtins__" key
+ code = textwrap.dedent("""
+ def func3(s): pass
+ func4 = type(func3)(func3.__code__, {})
+ """)
+ safe_builtins = {'None': None}
+ ns = {'type': type, '__builtins__': safe_builtins}
+ exec(code, ns)
+ self.assertIs(ns['func3'].__builtins__, safe_builtins)
+ self.assertIs(ns['func4'].__builtins__, safe_builtins)
+ self.assertIs(ns['func3'].__globals__['__builtins__'], safe_builtins)
+ self.assertNotIn('__builtins__', ns['func4'].__globals__)
+
def test___closure__(self):
a = 12
def f(): print(a)
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-02-18-15-12-30.bpo-42990.toAqBH.rst b/Misc/NEWS.d/next/Core and Builtins/2021-02-18-15-12-30.bpo-42990.toAqBH.rst
new file mode 100644
index 0000000..b9e6647
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-02-18-15-12-30.bpo-42990.toAqBH.rst
@@ -0,0 +1,7 @@
+The :data:`types.FunctionType` constructor now inherits the current builtins if
+the *globals* dictionary has no ``"__builtins__"`` key, rather than using
+``{"None": None}`` as builtins: same behavior as :func:`eval` and :func:`exec`
+functions. Defining a function with ``def function(...): ...`` in Python is
+not affected, globals cannot be overriden with this syntax: it also inherits
+the current builtins.
+Patch by Victor Stinner.
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 0571bfe..056d42a 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -847,7 +847,7 @@ PyFrameObject*
PyFrame_New(PyThreadState *tstate, PyCodeObject *code,
PyObject *globals, PyObject *locals)
{
- PyObject *builtins = _PyEval_BuiltinsFromGlobals(globals);
+ PyObject *builtins = _PyEval_BuiltinsFromGlobals(tstate, globals);
if (builtins == NULL) {
return NULL;
}
@@ -862,7 +862,6 @@ PyFrame_New(PyThreadState *tstate, PyCodeObject *code,
.fc_closure = NULL
};
PyFrameObject *f = _PyFrame_New_NoTrack(tstate, &desc, locals);
- Py_DECREF(builtins);
if (f) {
_PyObject_GC_TRACK(f);
}
@@ -1163,7 +1162,7 @@ PyFrame_GetBack(PyFrameObject *frame)
}
PyObject*
-_PyEval_BuiltinsFromGlobals(PyObject *globals)
+_PyEval_BuiltinsFromGlobals(PyThreadState *tstate, PyObject *globals)
{
PyObject *builtins = _PyDict_GetItemIdWithError(globals, &PyId___builtins__);
if (builtins) {
@@ -1171,21 +1170,11 @@ _PyEval_BuiltinsFromGlobals(PyObject *globals)
builtins = PyModule_GetDict(builtins);
assert(builtins != NULL);
}
- return Py_NewRef(builtins);
+ return builtins;
}
-
if (PyErr_Occurred()) {
return NULL;
}
- /* No builtins! Make up a minimal one. Give them 'None', at least. */
- builtins = PyDict_New();
- if (builtins == NULL) {
- return NULL;
- }
- if (PyDict_SetItemString(builtins, "None", Py_None) < 0) {
- Py_DECREF(builtins);
- return NULL;
- }
- return builtins;
+ return _PyEval_GetBuiltins(tstate);
}
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
index 4b92f6c..36df88a 100644
--- a/Objects/funcobject.c
+++ b/Objects/funcobject.c
@@ -4,6 +4,7 @@
#include "Python.h"
#include "pycore_ceval.h" // _PyEval_BuiltinsFromGlobals()
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
+#include "pycore_pyerrors.h" // _PyErr_Occurred()
#include "structmember.h" // PyMemberDef
PyObject *
@@ -13,6 +14,8 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
assert(PyDict_Check(globals));
Py_INCREF(globals);
+ PyThreadState *tstate = _PyThreadState_GET();
+
PyCodeObject *code_obj = (PyCodeObject *)code;
Py_INCREF(code_obj);
@@ -42,15 +45,16 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
_Py_IDENTIFIER(__name__);
PyObject *module = _PyDict_GetItemIdWithError(globals, &PyId___name__);
PyObject *builtins = NULL;
- if (module == NULL && PyErr_Occurred()) {
+ if (module == NULL && _PyErr_Occurred(tstate)) {
goto error;
}
Py_XINCREF(module);
- builtins = _PyEval_BuiltinsFromGlobals(globals);
+ builtins = _PyEval_BuiltinsFromGlobals(tstate, globals);
if (builtins == NULL) {
goto error;
}
+ Py_INCREF(builtins);
PyFunctionObject *op = PyObject_GC_New(PyFunctionObject, &PyFunction_Type);
if (op == NULL) {
diff --git a/Python/ceval.c b/Python/ceval.c
index 7ccb8fc..e2b2d21 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -889,10 +889,11 @@ static int unpack_iterable(PyThreadState *, PyObject *, int, int, PyObject **);
PyObject *
PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals)
{
+ PyThreadState *tstate = PyThreadState_GET();
if (locals == NULL) {
locals = globals;
}
- PyObject *builtins = _PyEval_BuiltinsFromGlobals(globals);
+ PyObject *builtins = _PyEval_BuiltinsFromGlobals(tstate, globals);
if (builtins == NULL) {
return NULL;
}
@@ -906,10 +907,7 @@ PyEval_EvalCode(PyObject *co, PyObject *globals, PyObject *locals)
.fc_kwdefaults = NULL,
.fc_closure = NULL
};
- PyThreadState *tstate = PyThreadState_GET();
- PyObject *res = _PyEval_Vector(tstate, &desc, locals, NULL, 0, NULL);
- Py_DECREF(builtins);
- return res;
+ return _PyEval_Vector(tstate, &desc, locals, NULL, 0, NULL);
}
@@ -4733,12 +4731,13 @@ PyEval_EvalCodeEx(PyObject *_co, PyObject *globals, PyObject *locals,
PyObject *const *defs, int defcount,
PyObject *kwdefs, PyObject *closure)
{
+ PyThreadState *tstate = _PyThreadState_GET();
PyObject *res;
PyObject *defaults = _PyTuple_FromArray(defs, defcount);
if (defaults == NULL) {
return NULL;
}
- PyObject *builtins = _PyEval_BuiltinsFromGlobals(globals);
+ PyObject *builtins = _PyEval_BuiltinsFromGlobals(tstate, globals);
if (builtins == NULL) {
Py_DECREF(defaults);
return NULL;
@@ -4797,7 +4796,6 @@ PyEval_EvalCodeEx(PyObject *_co, PyObject *globals, PyObject *locals,
.fc_kwdefaults = kwdefs,
.fc_closure = closure
};
- PyThreadState *tstate = _PyThreadState_GET();
res = _PyEval_Vector(tstate, &constr, locals,
allargs, argcount,
kwnames);
@@ -5316,14 +5314,20 @@ PyEval_GetFrame(void)
}
PyObject *
+_PyEval_GetBuiltins(PyThreadState *tstate)
+{
+ PyFrameObject *frame = tstate->frame;
+ if (frame != NULL) {
+ return frame->f_builtins;
+ }
+ return tstate->interp->builtins;
+}
+
+PyObject *
PyEval_GetBuiltins(void)
{
PyThreadState *tstate = _PyThreadState_GET();
- PyFrameObject *current_frame = tstate->frame;
- if (current_frame == NULL)
- return tstate->interp->builtins;
- else
- return current_frame->f_builtins;
+ return _PyEval_GetBuiltins(tstate);
}
/* Convenience function to get a builtin from its name */