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.
diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index fa9cd55..0c5b0e3 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -291,8 +291,12 @@
\end{funcdesc}
\begin{funcdesc}{eval}{expression\optional{, globals\optional{, locals}}}
- The arguments are a string and two optional dictionaries. The
- \var{expression} argument is parsed and evaluated as a Python
+ The arguments are a string and optional globals and locals. If provided,
+ \var{globals} must be a dictionary. If provided, \var{locals} can be
+ any mapping object. \versionchanged[formerly \var{locals} was required
+ to be a dictionary]{2.4}
+
+ The \var{expression} argument is parsed and evaluated as a Python
expression (technically speaking, a condition list) using the
\var{globals} and \var{locals} dictionaries as global and local name
space. If the \var{globals} dictionary is present and lacks
diff --git a/Include/frameobject.h b/Include/frameobject.h
index 2820e88..7dc14e3 100644
--- a/Include/frameobject.h
+++ b/Include/frameobject.h
@@ -19,7 +19,7 @@
PyCodeObject *f_code; /* code segment */
PyObject *f_builtins; /* builtin symbol table (PyDictObject) */
PyObject *f_globals; /* global symbol table (PyDictObject) */
- PyObject *f_locals; /* local symbol table (PyDictObject) */
+ PyObject *f_locals; /* local symbol table (any mapping) */
PyObject **f_valuestack; /* points after the last local */
/* Next free slot in f_valuestack. Frame creation sets to f_valuestack.
Frame evaluation usually NULLs it, but a frame that yields sets it
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 9aa24c2..8fea0ca 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -3,7 +3,7 @@
import test.test_support, unittest
from test.test_support import fcmp, have_unicode, TESTFN, unlink
-import sys, warnings, cStringIO, random
+import sys, warnings, cStringIO, random, UserDict
warnings.filterwarnings("ignore", "hex../oct.. of negative int",
FutureWarning, __name__)
warnings.filterwarnings("ignore", "integer argument expected",
@@ -262,6 +262,60 @@
self.assertRaises(TypeError, eval)
self.assertRaises(TypeError, eval, ())
+ def test_general_eval(self):
+ # Tests that general mappings can be used for the locals argument
+
+ class M:
+ "Test mapping interface versus possible calls from eval()."
+ def __getitem__(self, key):
+ if key == 'a':
+ return 12
+ raise KeyError
+ def keys(self):
+ return list('xyz')
+
+ m = M()
+ g = globals()
+ self.assertEqual(eval('a', g, m), 12)
+ self.assertRaises(NameError, eval, 'b', g, m)
+ self.assertEqual(eval('dir()', g, m), list('xyz'))
+ self.assertEqual(eval('globals()', g, m), g)
+ self.assertEqual(eval('locals()', g, m), m)
+
+ # Verify that dict subclasses work as well
+ class D(dict):
+ def __getitem__(self, key):
+ if key == 'a':
+ return 12
+ return dict.__getitem__(self, key)
+ def keys(self):
+ return list('xyz')
+
+ d = D()
+ self.assertEqual(eval('a', g, d), 12)
+ self.assertRaises(NameError, eval, 'b', g, d)
+ self.assertEqual(eval('dir()', g, d), list('xyz'))
+ self.assertEqual(eval('globals()', g, d), g)
+ self.assertEqual(eval('locals()', g, d), d)
+
+ # Verify locals stores (used by list comps)
+ eval('[locals() for i in (2,3)]', g, d)
+ eval('[locals() for i in (2,3)]', g, UserDict.UserDict())
+
+ class SpreadSheet:
+ "Sample application showing nested, calculated lookups."
+ _cells = {}
+ def __setitem__(self, key, formula):
+ self._cells[key] = formula
+ def __getitem__(self, key ):
+ return eval(self._cells[key], globals(), self)
+
+ ss = SpreadSheet()
+ ss['a1'] = '5'
+ ss['a2'] = 'a1*6'
+ ss['a3'] = 'a2*7'
+ self.assertEqual(ss['a3'], 210)
+
# Done outside of the method test_z to get the correct scope
z = 0
f = open(TESTFN, 'w')
diff --git a/Lib/test/test_descrtut.py b/Lib/test/test_descrtut.py
index 58b7451..851ce4a 100644
--- a/Lib/test/test_descrtut.py
+++ b/Lib/test/test_descrtut.py
@@ -78,16 +78,6 @@
3
>>>
-However, our __getitem__() method is not used for variable access by the
-interpreter:
-
- >>> exec "print foo" in a
- Traceback (most recent call last):
- File "<stdin>", line 1, in ?
- File "<string>", line 1, in ?
- NameError: name 'foo' is not defined
- >>>
-
Now I'll show that defaultdict instances have dynamic instance variables,
just like classic classes:
diff --git a/Misc/NEWS b/Misc/NEWS
index 7d21994..d01f20b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@
Core and builtins
-----------------
+- Bug #215126. The locals argument to eval() now accepts any mapping type.
+
- marshal now shares interned strings. This change introduces
a new .pyc magic.
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 81b3819..bc8cae9 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -544,7 +544,7 @@
#ifdef Py_DEBUG
if (code == NULL || globals == NULL || !PyDict_Check(globals) ||
- (locals != NULL && !PyDict_Check(locals))) {
+ (locals != NULL && !PyMapping_Check(locals))) {
PyErr_BadInternalCall();
return NULL;
}
@@ -688,11 +688,11 @@
if (deref)
value = PyCell_GET(value);
if (value == NULL) {
- if (PyDict_DelItem(dict, key) != 0)
+ if (PyObject_DelItem(dict, key) != 0)
PyErr_Clear();
}
else {
- if (PyDict_SetItem(dict, key, value) != 0)
+ if (PyObject_SetItem(dict, key, value) != 0)
PyErr_Clear();
}
}
@@ -705,7 +705,9 @@
int j;
for (j = nmap; --j >= 0; ) {
PyObject *key = PyTuple_GET_ITEM(map, j);
- PyObject *value = PyDict_GetItem(dict, key);
+ PyObject *value = PyObject_GetItem(dict, key);
+ if (value == NULL)
+ PyErr_Clear();
if (deref) {
if (value || clear) {
if (PyCell_GET(values[j]) != value) {
@@ -720,6 +722,7 @@
values[j] = value;
}
}
+ Py_XDECREF(value);
}
}
@@ -742,7 +745,7 @@
}
}
map = f->f_code->co_varnames;
- if (!PyDict_Check(locals) || !PyTuple_Check(map))
+ if (!PyTuple_Check(map))
return;
PyErr_Fetch(&error_type, &error_value, &error_traceback);
fast = f->f_localsplus;
@@ -780,7 +783,7 @@
map = f->f_code->co_varnames;
if (locals == NULL)
return;
- if (!PyDict_Check(locals) || !PyTuple_Check(map))
+ if (!PyTuple_Check(map))
return;
PyErr_Fetch(&error_type, &error_value, &error_traceback);
fast = f->f_localsplus;
diff --git a/Objects/object.c b/Objects/object.c
index 22196d7..1c0efdd 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1621,7 +1621,7 @@
PyObject *locals = PyEval_GetLocals();
if (locals == NULL)
goto error;
- result = PyDict_Keys(locals);
+ result = PyMapping_Keys(locals);
if (result == NULL)
goto error;
}
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 @@
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 @@
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 @@
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 @@
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 @@
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) {