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

Doc/c-api/init_config.rst

@@ -2098,7 +2098,7 @@ 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

@@ -258,11 +258,36 @@ 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:: int PySys_GetAttr(PyObject *name, PyObject **result);
+
+   Get the attribute *name* of the :mod:`sys` module.
+
+   If the object exists, set *\*result* to a new :term:`strong reference`
+   to the object and return ``1``.
+   If the object does not exist, set *\*result* to ``NULL`` and return ``0``,
+   without setting an exception.
+   If other error occurred, set an exception, set *\*result* to ``NULL`` and
+   return ``-1``.
+
+   .. versionadded:: next
+
+.. c:function:: int PySys_GetAttrString(const char *name, PyObject **result);
+
+   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*`.
+
+   .. 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.
 
+   Preserves exception that was set before the call.
+
+   It is recommended to use :c:func:`PySys_GetAttrString` instead.
+
 .. c:function:: int PySys_SetObject(const char *name, PyObject *v)
 
    Set *name* in the :mod:`sys` module to *v* unless *v* is ``NULL``, in which

Doc/whatsnew/3.14.rst

@@ -1491,6 +1491,10 @@ New features
 
   (Contributed by Sergey B Kirpichev and Victor Stinner in :gh:`102471`.)
 
+* Add :c:func:`PySys_GetAttr` and :c:func:`PySys_GetAttrString`
+  functions as replacements for :c:func:`PySys_GetObject`.
+  (Contributed by Serhiy Storchaka in :gh:`108512`.)
+
 * Add :c:func:`PyType_GetBaseByToken` and :c:data:`Py_tp_token` slot for easier
   superclass identification, which attempts to resolve the `type checking issue
   <https://peps.python.org/pep-0630/#type-checking>`__ mentioned in :pep:`630`

Include/internal/pycore_sysmodule.h

@@ -8,8 +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 *);
 

Include/sysmodule.h

@@ -4,6 +4,10 @@
 extern "C" {
 #endif
 
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030e0000
+PyAPI_FUNC(int) PySys_GetAttr(PyObject *, PyObject **);
+PyAPI_FUNC(int) PySys_GetAttrString(const char *, PyObject **);
+#endif
 PyAPI_FUNC(PyObject *) PySys_GetObject(const char *);
 PyAPI_FUNC(int) PySys_SetObject(const char *, PyObject *);
 

Lib/test/test_capi/test_sys.py

@@ -9,6 +9,11 @@
 except ImportError:
     _testlimitedcapi = None
 
+try:
+    import _testinternalcapi
+except ImportError:
+    _testinternalcapi = None
+
 NULL = None
 
 class CAPITest(unittest.TestCase):
@@ -19,6 +24,33 @@ 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)
+
+        self.assertIs(sys_getattr('nonexisting'), AttributeError)
+        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)
+
+        self.assertIs(getattrstring(b'nonexisting'), AttributeError)
+        self.assertRaises(UnicodeDecodeError, getattrstring, b'\xff')
+        # CRASHES getattrstring(NULL)
+
     @support.cpython_only
     @unittest.skipIf(_testlimitedcapi is None, 'need _testlimitedcapi module')
     def test_sys_getobject(self):

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

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

Misc/stable_abi.toml

@@ -2545,3 +2545,7 @@
     added = '3.14'
 [function.Py_PACK_VERSION]
     added = '3.14'
+[function.PySys_GetAttr]
+    added = '3.14'
+[function.PySys_GetAttrString]
+    added = '3.14'

Modules/_cursesmodule.c

@@ -108,7 +108,7 @@ 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_sysmodule.h"   // PySys_GetAttrString()
 
 #ifdef __hpux
 #define STRICT_SYSV_CURSES
@@ -3543,7 +3543,7 @@ _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_GetAttrString("stdout", &sys_stdout) < 0) {
             return NULL;
         }
 

Modules/_lsprof.c

@@ -6,6 +6,7 @@
 #include "pycore_call.h"          // _PyObject_CallNoArgs()
 #include "pycore_ceval.h"         // _PyEval_SetProfile()
 #include "pycore_pystate.h"       // _PyThreadState_GET()
+#include "pycore_sysmodule.h"     // _PySys_GetRequiredAttrString()
 #include "pycore_time.h"          // _PyTime_FromLong()
 
 #include "rotatingtree.h"
@@ -779,7 +780,7 @@ _lsprof_Profiler_enable_impl(ProfilerObject *self, int subcalls,
         return NULL;
     }
 
-    PyObject* monitoring = PyImport_ImportModuleAttrString("sys", "monitoring");
+    PyObject* monitoring = _PySys_GetRequiredAttrString("monitoring");
     if (!monitoring) {
         return NULL;
     }
@@ -861,7 +862,7 @@ _lsprof_Profiler_disable_impl(ProfilerObject *self)
     }
     if (self->flags & POF_ENABLED) {
         PyObject* result = NULL;
-        PyObject* monitoring = PyImport_ImportModuleAttrString("sys", "monitoring");
+        PyObject* monitoring = _PySys_GetRequiredAttrString("monitoring");
 
         if (!monitoring) {
             return NULL;
@@ -980,7 +981,7 @@ 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_GetRequiredAttrString("monitoring");
     if (!monitoring) {
         return -1;
     }

Modules/_testlimitedcapi/sys.c

@@ -1,7 +1,58 @@
+#include "pyconfig.h"   // Py_GIL_DISABLED
+// Need limited C API version 3.14 for PySys_GetAttr() etc
+#if !defined(Py_GIL_DISABLED) && !defined(Py_LIMITED_API)
+#  define Py_LIMITED_API 0x030e0000
+#endif
 #include "parts.h"
 #include "util.h"
 
 
+static PyObject *
+sys_getattr(PyObject *Py_UNUSED(module), PyObject *name)
+{
+    PyObject *value = UNINITIALIZED_PTR;
+    NULLABLE(name);
+
+    switch (PySys_GetAttr(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_GetAttr() returned invalid code");
+    }
+}
+
+static PyObject *
+sys_getattrstring(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_GetAttrString(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_GetAttrString() returned invalid code");
+    }
+}
+
 static PyObject *
 sys_getobject(PyObject *Py_UNUSED(module), PyObject *arg)
 {
@@ -39,6 +90,8 @@ 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_getobject", sys_getobject, METH_O},
     {"sys_setobject", sys_setobject, METH_VARARGS},
     {"sys_getxoptions", sys_getxoptions, METH_NOARGS},

Modules/_threadmodule.c

@@ -8,7 +8,6 @@
 #include "pycore_modsupport.h"    // _PyArg_NoKeywords()
 #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()
 
@@ -2250,7 +2249,7 @@ 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_GetAttr( &_Py_ID(stderr), &file) < 0) {
         return NULL;
     }
     if (file == NULL || file == Py_None) {

Modules/_tkinter.c

@@ -31,7 +31,6 @@ Copyright (C) 1994 Steen Lumholt.
 #endif
 
 #include "pycore_long.h"          // _PyLong_IsNegative()
-#include "pycore_sysmodule.h"     // _PySys_GetOptionalAttrString()
 
 #ifdef MS_WINDOWS
 #  include <windows.h>
@@ -145,7 +144,7 @@ _get_tcl_lib_path(void)
         int stat_return_value;
         PyObject *prefix;
 
-        (void) _PySys_GetOptionalAttrString("base_prefix", &prefix);
+        (void) PySys_GetAttrString("base_prefix", &prefix);
         if (prefix == NULL) {
             return NULL;
         }
@@ -3520,7 +3519,7 @@ PyInit__tkinter(void)
 
     /* This helps the dynamic loader; in Unicode aware Tcl versions
        it also helps Tcl find its encodings. */
-    (void) _PySys_GetOptionalAttrString("executable", &uexe);
+    (void) PySys_GetAttrString("executable", &uexe);
     if (uexe && PyUnicode_Check(uexe)) {   // sys.executable can be None
         cexe = PyUnicode_EncodeFSDefault(uexe);
         Py_DECREF(uexe);

Modules/main.c

@@ -481,16 +481,13 @@ pymain_run_startup(PyConfig *config, int *exitcode)
 static int
 pymain_run_interactive_hook(int *exitcode)
 {
-    PyObject *hook = PyImport_ImportModuleAttrString("sys",
-                                                     "__interactivehook__");
-    if (hook == NULL) {
-        if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
-            // no sys.__interactivehook__ attribute
-            PyErr_Clear();
-            return 0;
-        }
+    PyObject *hook;
+    if (PySys_GetAttrString("__interactivehook__", &hook) < 0) {
         goto error;
     }
+    if (hook == NULL) {
+        return 0;
+    }
 
     if (PySys_Audit("cpython.run_interactivehook", "O", hook) < 0) {
         goto error;

Modules/syslogmodule.c

@@ -56,7 +56,6 @@ Revision history:
 
 #include "Python.h"
 #include "osdefs.h"               // SEP
-#include "pycore_sysmodule.h"     // _PySys_GetOptionalAttrString()
 
 #include <syslog.h>
 
@@ -92,7 +91,7 @@ syslog_get_argv(void)
     Py_ssize_t slash;
     PyObject *argv;
 
-    if (_PySys_GetOptionalAttrString("argv", &argv) <= 0) {
+    if (PySys_GetAttrString("argv", &argv) <= 0) {
         return NULL;
     }
 

Objects/moduleobject.c

@@ -12,7 +12,7 @@
 #include "pycore_object.h"        // _PyType_AllocNoTrack
 #include "pycore_pyerrors.h"      // _PyErr_FormatFromCause()
 #include "pycore_pystate.h"       // _PyInterpreterState_GET()
-#include "pycore_sysmodule.h"     // _PySys_GetOptionalAttrString()
+#include "pycore_sysmodule.h"     // PySys_GetAttrString()
 
 #include "osdefs.h"               // MAXPATHLEN
 
@@ -1005,7 +1005,7 @@ _Py_module_getattro_impl(PyModuleObject *m, PyObject *name, int suppress)
     int is_possibly_shadowing_stdlib = 0;
     if (is_possibly_shadowing) {
         PyObject *stdlib_modules;
-        if (_PySys_GetOptionalAttrString("stdlib_module_names", &stdlib_modules) < 0) {
+        if (PySys_GetAttrString("stdlib_module_names", &stdlib_modules) < 0) {
             goto done;
         }
         if (stdlib_modules && PyAnySet_Check(stdlib_modules)) {

Python/_warnings.c

@@ -5,7 +5,6 @@
 #include "pycore_pyerrors.h"      // _PyErr_Occurred()
 #include "pycore_pylifecycle.h"   // _Py_IsInterpreterFinalizing()
 #include "pycore_pystate.h"       // _PyThreadState_GET()
-#include "pycore_sysmodule.h"     // _PySys_GetOptionalAttr()
 #include "pycore_traceback.h"     // _Py_DisplaySourceLine()
 
 #include <stdbool.h>
@@ -563,7 +562,7 @@ show_warning(PyThreadState *tstate, PyObject *filename, int lineno,
         goto error;
     }
 
-    if (_PySys_GetOptionalAttr(&_Py_ID(stderr), &f_stderr) <= 0) {
+    if (PySys_GetAttr(&_Py_ID(stderr), &f_stderr) <= 0) {
         fprintf(stderr, "lost sys.stderr\n");
         goto error;
     }