gh-108512: Add and use new replacements for PySys_GetObject() (GH-111035)

Add functions PySys_GetAttr(), PySys_GetAttrString(),
PySys_GetOptionalAttr() and PySys_GetOptionalAttrString().

Author: serhiy-storchaka

Doc/c-api/init_config.rst

@@ -2111,7 +2111,7 @@ initialization::
 
         /* Specify sys.path explicitly */
         /* If you want to modify the default set of paths, finish
-           initialization first and then use PySys_GetObject("path") */
+           initialization first and then use PySys_GetAttrString("path") */
         config.module_search_paths_set = 1;
         status = PyWideStringList_Append(&config.module_search_paths,
                                          L"/path/to/stdlib");

Doc/c-api/sys.rst

@@ -258,10 +258,57 @@ 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(PyObject *name)
+
+   Get the attribute *name* of the :mod:`sys` module.
+   Return a :term:`strong reference`.
+   Raise :exc:`RuntimeError` and return ``NULL`` if it does not exist or
+   if the :mod:`sys` module cannot be found.
+
+   If the non-existing object should not be treated as a failure, you can use
+   :c:func:`PySys_GetOptionalAttr` instead.
+
+   .. versionadded:: next
+
+.. c:function:: PyObject *PySys_GetAttrString(const char *name)
+
+   This is the same as :c:func:`PySys_GetAttr`, but *name* is
+   specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
+   rather than a :c:expr:`PyObject*`.
+
+   If the non-existing object should not be treated as a failure, you can use
+   :c:func:`PySys_GetOptionalAttrString` instead.
+
+   .. versionadded:: next
+
+.. c:function:: int PySys_GetOptionalAttr(PyObject *name, PyObject **result)
+
+   Variant of :c:func:`PySys_GetAttr` which doesn't raise
+   exception if the object does not exist.
+
+   * Set *\*result* to a new :term:`strong reference` to the object and
+     return ``1`` if the object exists.
+   * Set *\*result* to ``NULL`` and return ``0`` without setting an exception
+     if the object does not exist.
+   * Set an exception, set *\*result* to ``NULL``, and return ``-1``,
+     if an error occurred.
+
+   .. versionadded:: next
+
+.. c:function:: int PySys_GetOptionalAttrString(const char *name, PyObject **result)
+
+   This is the same as :c:func:`PySys_GetOptionalAttr`, but *name* is
+   specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
+   rather than a :c:expr:`PyObject*`.
+
+   .. versionadded:: next
+
 .. c:function:: PyObject *PySys_GetObject(const char *name)
 
-   Return the object *name* from the :mod:`sys` module or ``NULL`` if it does
-   not exist, without setting an exception.
+   Similar to :c:func:`PySys_GetAttrString`, but return a :term:`borrowed
+   reference` and return ``NULL`` *without* setting exception on failure.
+
+   Preserves exception that was set before the call.
 
 .. c:function:: int PySys_SetObject(const char *name, PyObject *v)
 

Doc/data/stable_abi.dat

@@ -213,7 +213,10 @@ C API changes
 New features
 ------------
 
-* TODO
+* Add :c:func:`PySys_GetAttr`, :c:func:`PySys_GetAttrString`,
+  :c:func:`PySys_GetOptionalAttr`, and :c:func:`PySys_GetOptionalAttrString`
+  functions as replacements for :c:func:`PySys_GetObject`.
+  (Contributed by Serhiy Storchaka in :gh:`108512`.)
 
 Porting to Python 3.15
 ----------------------

Doc/whatsnew/3.15.rst

@@ -8,11 +8,6 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE define"
 #endif
 
-PyAPI_FUNC(int) _PySys_GetOptionalAttr(PyObject *, PyObject **);
-PyAPI_FUNC(int) _PySys_GetOptionalAttrString(const char *, PyObject **);
-PyAPI_FUNC(PyObject *) _PySys_GetRequiredAttr(PyObject *);
-PyAPI_FUNC(PyObject *) _PySys_GetRequiredAttrString(const char *);
-
 // Export for '_pickle' shared extension
 PyAPI_FUNC(size_t) _PySys_GetSizeOf(PyObject *);
 

Include/internal/pycore_sysmodule.h

@@ -4,6 +4,12 @@
 extern "C" {
 #endif
 
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030f0000
+PyAPI_FUNC(PyObject *) PySys_GetAttr(PyObject *);
+PyAPI_FUNC(PyObject *) PySys_GetAttrString(const char *);
+PyAPI_FUNC(int) PySys_GetOptionalAttr(PyObject *, PyObject **);
+PyAPI_FUNC(int) PySys_GetOptionalAttrString(const char *, PyObject **);
+#endif
 PyAPI_FUNC(PyObject *) PySys_GetObject(const char *);
 PyAPI_FUNC(int) PySys_SetObject(const char *, PyObject *);
 

Include/sysmodule.h

@@ -19,6 +19,68 @@ class CAPITest(unittest.TestCase):
 
     maxDiff = None
 
+    @unittest.skipIf(_testlimitedcapi is None, 'need _testlimitedcapi module')
+    def test_sys_getattr(self):
+        # Test PySys_GetAttr()
+        sys_getattr = _testlimitedcapi.sys_getattr
+
+        self.assertIs(sys_getattr('stdout'), sys.stdout)
+        with support.swap_attr(sys, '\U0001f40d', 42):
+            self.assertEqual(sys_getattr('\U0001f40d'), 42)
+
+        with self.assertRaisesRegex(RuntimeError, r'lost sys\.nonexistent'):
+            sys_getattr('nonexistent')
+        with self.assertRaisesRegex(RuntimeError, r'lost sys\.\U0001f40d'):
+            sys_getattr('\U0001f40d')
+        self.assertRaises(TypeError, sys_getattr, 1)
+        self.assertRaises(TypeError, sys_getattr, [])
+        # CRASHES sys_getattr(NULL)
+
+    @unittest.skipIf(_testlimitedcapi is None, 'need _testlimitedcapi module')
+    def test_sys_getattrstring(self):
+        # Test PySys_GetAttrString()
+        getattrstring = _testlimitedcapi.sys_getattrstring
+
+        self.assertIs(getattrstring(b'stdout'), sys.stdout)
+        with support.swap_attr(sys, '\U0001f40d', 42):
+            self.assertEqual(getattrstring('\U0001f40d'.encode()), 42)
+
+        with self.assertRaisesRegex(RuntimeError, r'lost sys\.nonexistent'):
+            getattrstring(b'nonexistent')
+        with self.assertRaisesRegex(RuntimeError, r'lost sys\.\U0001f40d'):
+            getattrstring('\U0001f40d'.encode())
+        self.assertRaises(UnicodeDecodeError, getattrstring, b'\xff')
+        # CRASHES getattrstring(NULL)
+
+    @unittest.skipIf(_testlimitedcapi is None, 'need _testlimitedcapi module')
+    def test_sys_getoptionalattr(self):
+        # Test PySys_GetOptionalAttr()
+        getoptionalattr = _testlimitedcapi.sys_getoptionalattr
+
+        self.assertIs(getoptionalattr('stdout'), sys.stdout)
+        with support.swap_attr(sys, '\U0001f40d', 42):
+            self.assertEqual(getoptionalattr('\U0001f40d'), 42)
+
+        self.assertIs(getoptionalattr('nonexistent'), AttributeError)
+        self.assertIs(getoptionalattr('\U0001f40d'), AttributeError)
+        self.assertRaises(TypeError, getoptionalattr, 1)
+        self.assertRaises(TypeError, getoptionalattr, [])
+        # CRASHES getoptionalattr(NULL)
+
+    @unittest.skipIf(_testlimitedcapi is None, 'need _testlimitedcapi module')
+    def test_sys_getoptionalattrstring(self):
+        # Test PySys_GetOptionalAttrString()
+        getoptionalattrstring = _testlimitedcapi.sys_getoptionalattrstring
+
+        self.assertIs(getoptionalattrstring(b'stdout'), sys.stdout)
+        with support.swap_attr(sys, '\U0001f40d', 42):
+            self.assertEqual(getoptionalattrstring('\U0001f40d'.encode()), 42)
+
+        self.assertIs(getoptionalattrstring(b'nonexistent'), AttributeError)
+        self.assertIs(getoptionalattrstring('\U0001f40d'.encode()), AttributeError)
+        self.assertRaises(UnicodeDecodeError, getoptionalattrstring, b'\xff')
+        # CRASHES getoptionalattrstring(NULL)
+
     @support.cpython_only
     @unittest.skipIf(_testlimitedcapi is None, 'need _testlimitedcapi module')
     def test_sys_getobject(self):
@@ -29,7 +91,7 @@ def test_sys_getobject(self):
         with support.swap_attr(sys, '\U0001f40d', 42):
             self.assertEqual(getobject('\U0001f40d'.encode()), 42)
 
-        self.assertIs(getobject(b'nonexisting'), AttributeError)
+        self.assertIs(getobject(b'nonexistent'), AttributeError)
         with support.catch_unraisable_exception() as cm:
             self.assertIs(getobject(b'\xff'), AttributeError)
             self.assertEqual(cm.unraisable.exc_type, UnicodeDecodeError)

Lib/test/test_capi/test_sys.py

@@ -0,0 +1,2 @@
+Add functions :c:func:`PySys_GetAttr`, :c:func:`PySys_GetAttrString`,
+:c:func:`PySys_GetOptionalAttr` and :c:func:`PySys_GetOptionalAttrString`.

Lib/test/test_stable_abi_ctypes.py

@@ -2575,3 +2575,11 @@
     added = '3.14'
 [function.Py_PACK_VERSION]
     added = '3.14'
+[function.PySys_GetAttr]
+    added = '3.15'
+[function.PySys_GetAttrString]
+    added = '3.15'
+[function.PySys_GetOptionalAttr]
+    added = '3.15'
+[function.PySys_GetOptionalAttrString]
+    added = '3.15'

Misc/NEWS.d/next/C_API/2023-10-18-14-36-35.gh-issue-108512.fMZLfr.rst

@@ -108,7 +108,6 @@ static const char PyCursesVersion[] = "2.2";
 #include "pycore_capsule.h"     // _PyCapsule_SetTraverse()
 #include "pycore_long.h"        // _PyLong_GetZero()
 #include "pycore_structseq.h"   // _PyStructSequence_NewType()
-#include "pycore_sysmodule.h"   // _PySys_GetOptionalAttrString()
 #include "pycore_fileutils.h"   // _Py_set_inheritable
 
 #ifdef __hpux
@@ -3847,7 +3846,7 @@ _curses_setupterm_impl(PyObject *module, const char *term, int fd)
     if (fd == -1) {
         PyObject* sys_stdout;
 
-        if (_PySys_GetOptionalAttrString("stdout", &sys_stdout) < 0) {
+        if (PySys_GetOptionalAttrString("stdout", &sys_stdout) < 0) {
             return NULL;
         }
 

Misc/stable_abi.toml

@@ -782,7 +782,7 @@ _lsprof_Profiler_enable_impl(ProfilerObject *self, int subcalls,
         return NULL;
     }
 
-    PyObject* monitoring = PyImport_ImportModuleAttrString("sys", "monitoring");
+    PyObject* monitoring = PySys_GetAttrString("monitoring");
     if (!monitoring) {
         return NULL;
     }
@@ -864,7 +864,7 @@ _lsprof_Profiler_disable_impl(ProfilerObject *self)
     }
     if (self->flags & POF_ENABLED) {
         PyObject* result = NULL;
-        PyObject* monitoring = PyImport_ImportModuleAttrString("sys", "monitoring");
+        PyObject* monitoring = PySys_GetAttrString("monitoring");
 
         if (!monitoring) {
             return NULL;
@@ -983,7 +983,7 @@ profiler_init_impl(ProfilerObject *self, PyObject *timer, double timeunit,
     Py_XSETREF(self->externalTimer, Py_XNewRef(timer));
     self->tool_id = PY_MONITORING_PROFILER_ID;
 
-    PyObject* monitoring = PyImport_ImportModuleAttrString("sys", "monitoring");
+    PyObject* monitoring = PySys_GetAttrString("monitoring");
     if (!monitoring) {
         return -1;
     }

Modules/_cursesmodule.c

@@ -1915,7 +1915,7 @@ whichmodule(PickleState *st, PyObject *global, PyObject *global_name, PyObject *
            __module__ can be None. If it is so, then search sys.modules for
            the module of global. */
         Py_CLEAR(module_name);
-        modules = _PySys_GetRequiredAttr(&_Py_ID(modules));
+        modules = PySys_GetAttr(&_Py_ID(modules));
         if (modules == NULL) {
             return NULL;
         }

Modules/_lsprof.c

@@ -1,7 +1,76 @@
+#include "pyconfig.h"   // Py_GIL_DISABLED
+// Need limited C API version 3.15 for PySys_GetAttr() etc
+#if !defined(Py_GIL_DISABLED) && !defined(Py_LIMITED_API)
+#  define Py_LIMITED_API 0x030f0000
+#endif
 #include "parts.h"
 #include "util.h"
 
 
+static PyObject *
+sys_getattr(PyObject *Py_UNUSED(module), PyObject *name)
+{
+    NULLABLE(name);
+    return PySys_GetAttr(name);
+}
+
+static PyObject *
+sys_getattrstring(PyObject *Py_UNUSED(module), PyObject *arg)
+{
+    const char *name;
+    Py_ssize_t size;
+    if (!PyArg_Parse(arg, "z#", &name, &size)) {
+        return NULL;
+    }
+    return PySys_GetAttrString(name);
+}
+
+static PyObject *
+sys_getoptionalattr(PyObject *Py_UNUSED(module), PyObject *name)
+{
+    PyObject *value = UNINITIALIZED_PTR;
+    NULLABLE(name);
+
+    switch (PySys_GetOptionalAttr(name, &value)) {
+        case -1:
+            assert(value == NULL);
+            assert(PyErr_Occurred());
+            return NULL;
+        case 0:
+            assert(value == NULL);
+            return Py_NewRef(PyExc_AttributeError);
+        case 1:
+            return value;
+        default:
+            Py_FatalError("PySys_GetOptionalAttr() returned invalid code");
+    }
+}
+
+static PyObject *
+sys_getoptionalattrstring(PyObject *Py_UNUSED(module), PyObject *arg)
+{
+    PyObject *value = UNINITIALIZED_PTR;
+    const char *name;
+    Py_ssize_t size;
+    if (!PyArg_Parse(arg, "z#", &name, &size)) {
+        return NULL;
+    }
+
+    switch (PySys_GetOptionalAttrString(name, &value)) {
+        case -1:
+            assert(value == NULL);
+            assert(PyErr_Occurred());
+            return NULL;
+        case 0:
+            assert(value == NULL);
+            return Py_NewRef(PyExc_AttributeError);
+        case 1:
+            return value;
+        default:
+            Py_FatalError("PySys_GetOptionalAttrString() returned invalid code");
+    }
+}
+
 static PyObject *
 sys_getobject(PyObject *Py_UNUSED(module), PyObject *arg)
 {
@@ -39,6 +108,10 @@ sys_getxoptions(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(ignored))
 
 
 static PyMethodDef test_methods[] = {
+    {"sys_getattr", sys_getattr, METH_O},
+    {"sys_getattrstring", sys_getattrstring, METH_O},
+    {"sys_getoptionalattr", sys_getoptionalattr, METH_O},
+    {"sys_getoptionalattrstring", sys_getoptionalattrstring, METH_O},
     {"sys_getobject", sys_getobject, METH_O},
     {"sys_setobject", sys_setobject, METH_VARARGS},
     {"sys_getxoptions", sys_getxoptions, METH_NOARGS},

Modules/_pickle.c

@@ -10,7 +10,6 @@
 #include "pycore_object_deferred.h" // _PyObject_SetDeferredRefcount()
 #include "pycore_pylifecycle.h"
 #include "pycore_pystate.h"       // _PyThreadState_SetCurrent()
-#include "pycore_sysmodule.h"     // _PySys_GetOptionalAttr()
 #include "pycore_time.h"          // _PyTime_FromSeconds()
 #include "pycore_weakref.h"       // _PyWeakref_GET_REF()
 
@@ -2290,7 +2289,7 @@ thread_excepthook(PyObject *module, PyObject *args)
     PyObject *thread = PyStructSequence_GET_ITEM(args, 3);
 
     PyObject *file;
-    if (_PySys_GetOptionalAttr( &_Py_ID(stderr), &file) < 0) {
+    if (PySys_GetOptionalAttr( &_Py_ID(stderr), &file) < 0) {
         return NULL;
     }
     if (file == NULL || file == Py_None) {