Add PySys_GetAttrString()

Author: vstinner

Doc/c-api/sys.rst

@@ -258,13 +258,24 @@ These are utility functions that make functionality from the :mod:`sys` module
 accessible to C code.  They all work with the current interpreter thread's
 :mod:`sys` module's dict, which is contained in the internal thread state structure.
 
-.. c:function:: PyObject *PySys_GetAttr(const char *name)
+.. c:function:: PyObject *PySys_GetAttr(PyObject *name)
 
    Return the object *name* from the :mod:`sys` module.
 
    Return a new object on success. Set an exception and return ``NULL`` on
    error.
 
+   .. versionadded:: next
+
+
+.. c:function:: PyObject *PySys_GetAttrString(const char *name)
+
+   Similar to :c:func:`PySys_GetAttrString`, but *name* is an UTF-8 encoded
+   string.
+
+   .. versionadded:: next
+
+
 .. c:function:: PyObject *PySys_GetObject(const char *name)
 
    Return the object *name* from the :mod:`sys` module or ``NULL`` if it does

Doc/data/refcounts.dat

@@ -3054,4 +3054,7 @@ _Py_c_sum:Py_complex:left::
 _Py_c_sum:Py_complex:right::
 
 PySys_GetAttr:PyObject*::+1:
-PySys_GetAttr:const char*:name::
+PySys_GetAttr:PyObject*:name:0:
+
+PySys_GetAttrString:PyObject*::+1:
+PySys_GetAttrString:const char*:name::

Doc/whatsnew/3.14.rst

@@ -1330,9 +1330,10 @@ New features
   bit-packing Python version numbers.
   (Contributed by Petr Viktorin in :gh:`128629`.)
 
-* Add :c:func:`PySys_GetAttr` function to get an attribute of the :mod:`sys`
-  module. Compared to :c:func:`PySys_GetObject`, it doesn't ignore errors and
-  it returns a :term:`strong reference`.
+* Add :c:func:`PySys_GetAttr` and :c:func:`PySys_GetAttrString` functions to
+  get an attribute of the :mod:`sys` module. Compared to
+  :c:func:`PySys_GetObject`, they don't ignore errors and return a
+  :term:`strong reference`.
   (Contributed by Victor Stinner in :gh:`129367`.)
 
 

Include/cpython/sysmodule.h

@@ -2,4 +2,5 @@
 #  error "this header file must not be included directly"
 #endif
 
-PyAPI_FUNC(PyObject *) PySys_GetAttr(const char *);
+PyAPI_FUNC(PyObject *) PySys_GetAttr(PyObject *name);
+PyAPI_FUNC(PyObject *) PySys_GetAttrString(const char *name);

Lib/test/test_capi/test_sys.py

@@ -18,14 +18,20 @@ class CAPITest(unittest.TestCase):
 
     maxDiff = None
 
+    def check_sys_getattr_common(self, sys_getattr, use_bytes=True):
+        self.assertIs(sys_getattr('stdout'), sys.stdout)
+
+        name = '\U0001f40d'
+        with support.swap_attr(sys, name, 42):
+            key = (name.encode() if use_bytes else name)
+            self.assertEqual(sys_getattr(key), 42)
+
     @support.cpython_only
     def test_sys_getobject(self):
         # Test PySys_GetObject()
         getobject = _testlimitedcapi.sys_getobject
 
-        self.assertIs(getobject(b'stdout'), sys.stdout)
-        with support.swap_attr(sys, '\U0001f40d', 42):
-            self.assertEqual(getobject('\U0001f40d'.encode()), 42)
+        self.check_sys_getattr_common(getobject)
 
         self.assertIs(getobject(b'nonexisting'), AttributeError)
         with support.catch_unraisable_exception() as cm:
@@ -35,21 +41,36 @@ def test_sys_getobject(self):
                              "'utf-8' codec can't decode")
         # CRASHES getobject(NULL)
 
+    def check_sys_getattr(self, sys_getattr):
+        self.check_sys_getattr_common(sys_getattr, use_bytes=False)
+
+        with self.assertRaises(AttributeError):
+            sys_getattr(b'nonexisting')
+
     def test_sys_getattr(self):
         # Test PySys_GetAttr()
         sys_getattr = _testcapi.PySys_GetAttr
 
-        self.assertIs(sys_getattr('stdout'), sys.stdout)
-        with support.swap_attr(sys, '\U0001f40d', 42):
-            self.assertEqual(sys_getattr('\U0001f40d'.encode()), 42)
+        self.check_sys_getattr(sys_getattr)
 
-        with self.assertRaises(AttributeError):
-            sys_getattr(b'nonexisting')
-        with self.assertRaises(UnicodeDecodeError):
-            self.assertIs(sys_getattr(b'\xff'), AttributeError)
+        with self.assertRaises(TypeError):
+            for invalid_name in (123, [], object()):
+                with self.assertRaises(AttributeError):
+                    sys_getattr(invalid_name)
 
         # CRASHES sys_getattr(NULL)
 
+    def test_sys_getattrstring(self):
+        # Test PySys_GetAttr()
+        sys_getattrstring = _testcapi.PySys_GetAttrString
+
+        self.check_sys_getattr(sys_getattrstring)
+
+        with self.assertRaises(UnicodeDecodeError):
+            self.assertIs(sys_getattrstring(b'\xff'), AttributeError)
+
+        # CRASHES sys_getattrstring(NULL)
+
     @support.cpython_only
     def test_sys_setobject(self):
         # Test PySys_SetObject()

Misc/NEWS.d/next/C_API/2025-01-27-17-40-20.gh-issue-129367.sm8DvA.rst

@@ -1,3 +1,4 @@
-Add :c:func:`PySys_GetAttr` function to get an attribute of the :mod:`sys`
-module. Compared to :c:func:`PySys_GetObject`, it doesn't ignore errors and
-it returns a :term:`strong reference`. Patch by Victor Stinner.
+Add :c:func:`PySys_GetAttr` and :c:func:`PySys_GetAttrString` functions to get
+an attribute of the :mod:`sys` module. Compared to :c:func:`PySys_GetObject`,
+they don't ignore errors and return a :term:`strong reference`. Patch by Victor
+Stinner.

Modules/_testcapi/sys.c

@@ -3,20 +3,29 @@
 
 
 static PyObject *
-pysys_getattr(PyObject *self, PyObject *arg)
+pysys_getattr(PyObject *self, PyObject *name)
+{
+    NULLABLE(name);
+    return PySys_GetAttr(name);
+}
+
+
+static PyObject *
+pysys_getattrstring(PyObject *self, PyObject *arg)
 {
     const char *name;
     Py_ssize_t size;
     if (!PyArg_Parse(arg, "z#", &name, &size)) {
         return NULL;
     }
 
-    return PySys_GetAttr(name);
+    return PySys_GetAttrString(name);
 }
 
 
 static PyMethodDef test_methods[] = {
     {"PySys_GetAttr", pysys_getattr, METH_O},
+    {"PySys_GetAttrString", pysys_getattrstring, METH_O},
     {NULL},
 };
 

Python/sysmodule.c

@@ -88,16 +88,16 @@ _PySys_GetAttr(PyThreadState *tstate, PyObject *name)
 
 
 PyObject*
-PySys_GetAttr(const char *name)
+PySys_GetAttr(PyObject *name)
 {
     PyInterpreterState *interp = _PyInterpreterState_GET();
-    PyObject *sysdict = interp->sysdict;
-    if (sysdict == NULL) {
+    PyObject *sys_dict = interp->sysdict;
+    if (sys_dict == NULL) {
         PyErr_SetString(PyExc_RuntimeError, "lost sys module");
         return NULL;
     }
     PyObject *value;
-    if (PyDict_GetItemStringRef(sysdict, name, &value) < 0) {
+    if (PyDict_GetItemRef(sys_dict, name, &value) < 0) {
         return NULL;
     }
     if (value == NULL) {
@@ -108,6 +108,20 @@ PySys_GetAttr(const char *name)
 }
 
 
+PyObject*
+PySys_GetAttrString(const char *name)
+{
+    PyObject *name_obj = PyUnicode_FromString(name);
+    if (name_obj == NULL) {
+        return NULL;
+    }
+
+    PyObject *value = PySys_GetAttr(name_obj);
+    Py_DECREF(name_obj);
+    return value;
+}
+
+
 static PyObject *
 _PySys_GetObject(PyInterpreterState *interp, const char *name)
 {
@@ -3172,7 +3186,7 @@ sys_set_flag(PyObject *flags, Py_ssize_t pos, PyObject *value)
 int
 _PySys_SetFlagObj(Py_ssize_t pos, PyObject *value)
 {
-    PyObject *flags = PySys_GetAttr("flags");
+    PyObject *flags = PySys_GetAttrString("flags");
     if (flags == NULL) {
         return -1;
     }
@@ -3732,7 +3746,7 @@ _PySys_UpdateConfig(PyThreadState *tstate)
 #undef COPY_WSTR
 
     // sys.flags
-    PyObject *flags = PySys_GetAttr("flags");
+    PyObject *flags = PySys_GetAttrString("flags");
     if (flags == NULL) {
         return -1;
     }