SF Bug #215126: Over restricted type checking on eval() function

The builtin eval() function now accepts any mapping for the locals argument.
Time sensitive steps guarded by PyDict_CheckExact() to keep from slowing
down the normal case.  My timings so no measurable impact.

2 files changed, 29 insertions, 10 deletions

diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index b3c8b09..f4f8b7a 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -455,11 +455,17 @@ builtin_eval(PyObject *self, PyObject *args)
 	char *str;
 	PyCompilerFlags cf;
 
-	if (!PyArg_ParseTuple(args, "O|O!O!:eval",
-			&cmd,
-			&PyDict_Type, &globals,
-			&PyDict_Type, &locals))
+	if (!PyArg_UnpackTuple(args, "eval", 1, 3, &cmd, &globals, &locals))
 		return NULL;
+	if (locals != Py_None && !PyMapping_Check(locals)) {
+		PyErr_SetString(PyExc_TypeError, "locals must be a mapping");
+			return NULL;
+	}
+	if (globals != Py_None && !PyDict_Check(globals)) {
+		PyErr_SetString(PyExc_TypeError, PyMapping_Check(globals) ? 
+			"globals must be a real dict; try eval(expr, {}, mapping)"
+			: "globals must be a dict");
+	}
 	if (globals == Py_None) {
 		globals = PyEval_GetGlobals();
 		if (locals == Py_None)
@@ -517,8 +523,9 @@ PyDoc_STRVAR(eval_doc,
 Evaluate the source in the context of globals and locals.\n\
 The source may be a string representing a Python expression\n\
 or a code object as returned by compile().\n\
-The globals and locals are dictionaries, defaulting to the current\n\
-globals and locals.  If only globals is given, locals defaults to it.");
+The globals must be a dictionary and locals can be any mappping,\n\
+defaulting to the current globals and locals.\n\
+If only globals is given, locals defaults to it.\n");
 
 
 static PyObject *
diff --git a/Python/ceval.c b/Python/ceval.c
index ca7cea8..0c3a93d 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1643,7 +1643,10 @@ PyEval_EvalFrame(PyFrameObject *f)
 			w = GETITEM(names, oparg);
 			v = POP();
 			if ((x = f->f_locals) != NULL) {
-				err = PyDict_SetItem(x, w, v);
+				if (PyDict_CheckExact(v))
+					err = PyDict_SetItem(x, w, v);
+				else
+					err = PyObject_SetItem(x, w, v);
 				Py_DECREF(v);
 				if (err == 0) continue;
 				break;
@@ -1656,7 +1659,7 @@ PyEval_EvalFrame(PyFrameObject *f)
 		case DELETE_NAME:
 			w = GETITEM(names, oparg);
 			if ((x = f->f_locals) != NULL) {
-				if ((err = PyDict_DelItem(x, w)) != 0)
+				if ((err = PyObject_DelItem(x, w)) != 0)
 					format_exc_check_arg(PyExc_NameError,
 								NAME_ERROR_MSG ,w);
 				break;
@@ -1733,13 +1736,22 @@ PyEval_EvalFrame(PyFrameObject *f)
 
 		case LOAD_NAME:
 			w = GETITEM(names, oparg);
-			if ((x = f->f_locals) == NULL) {
+			if ((v = f->f_locals) == NULL) {
 				PyErr_Format(PyExc_SystemError,
 					     "no locals when loading %s",
 					     PyObject_REPR(w));
 				break;
 			}
-			x = PyDict_GetItem(x, w);
+			if (PyDict_CheckExact(v))
+				x = PyDict_GetItem(v, w);
+			else {
+				x = PyObject_GetItem(v, w);
+				if (x == NULL && PyErr_Occurred()) {
+					if (!PyErr_ExceptionMatches(PyExc_KeyError))
+						break;
+					PyErr_Clear();
+				}
+			}
 			if (x == NULL) {
 				x = PyDict_GetItem(f->f_globals, w);
 				if (x == NULL) {