From 758b74e71eb22e1e83a9eb937d1c015e461745a1 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Tue, 7 Dec 2021 18:56:06 -0700
Subject: bpo-46008: Add _PyInterpreterState_Main(). (gh-29978)

PyInterpreterState_Main() is a plain function exposed in the public C-API. For internal usage we can take the more efficient approach in this PR.

https://bugs.python.org/issue46008
---
 Include/internal/pycore_pystate.h | 14 +++++++++-----
 Modules/posixmodule.c             |  4 ++--
 Python/pylifecycle.c              |  2 +-
 Python/pystate.c                  |  2 +-
 4 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/Include/internal/pycore_pystate.h b/Include/internal/pycore_pystate.h
index f139fa9..06f58fb 100644
--- a/Include/internal/pycore_pystate.h
+++ b/Include/internal/pycore_pystate.h
@@ -21,19 +21,23 @@ _Py_IsMainThread(void)
 }
 
 
+static inline PyInterpreterState *
+_PyInterpreterState_Main(void)
+{
+    return _PyRuntime.interpreters.main;
+}
+
 static inline int
 _Py_IsMainInterpreter(PyInterpreterState *interp)
 {
-    /* Use directly _PyRuntime rather than tstate->interp->runtime, since
-       this function is used in performance critical code path (ceval) */
-    return (interp == _PyRuntime.interpreters.main);
+    return (interp == _PyInterpreterState_Main());
 }
 
 
 static inline const PyConfig *
 _Py_GetMainConfig(void)
 {
-    PyInterpreterState *interp = _PyRuntime.interpreters.main;
+    PyInterpreterState *interp = _PyInterpreterState_Main();
     if (interp == NULL) {
         return NULL;
     }
@@ -45,7 +49,7 @@ _Py_GetMainConfig(void)
 static inline int
 _Py_ThreadCanHandleSignals(PyInterpreterState *interp)
 {
-    return (_Py_IsMainThread() && interp == _PyRuntime.interpreters.main);
+    return (_Py_IsMainThread() && _Py_IsMainInterpreter(interp));
 }
 
 
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index b1c2914..2d95efe 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -6696,7 +6696,7 @@ os_fork1_impl(PyObject *module)
 {
     pid_t pid;
 
-    if (_PyInterpreterState_GET() != PyInterpreterState_Main()) {
+    if (!_Py_IsMainInterpreter(_PyInterpreterState_GET())) {
         PyErr_SetString(PyExc_RuntimeError, "fork not supported for subinterpreters");
         return NULL;
     }
@@ -7348,7 +7348,7 @@ os_forkpty_impl(PyObject *module)
     int master_fd = -1;
     pid_t pid;
 
-    if (_PyInterpreterState_GET() != PyInterpreterState_Main()) {
+    if (!_Py_IsMainInterpreter(_PyInterpreterState_GET())) {
         PyErr_SetString(PyExc_RuntimeError, "fork not supported for subinterpreters");
         return NULL;
     }
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index f648dda..2b386a1 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1953,7 +1953,7 @@ new_interpreter(PyThreadState **tstate_p, int isolated_subinterpreter)
 #endif
     {
         /* No current thread state, copy from the main interpreter */
-        PyInterpreterState *main_interp = PyInterpreterState_Main();
+        PyInterpreterState *main_interp = _PyInterpreterState_Main();
         config = _PyInterpreterState_GetConfig(main_interp);
     }
 
diff --git a/Python/pystate.c b/Python/pystate.c
index f94019d..f21673e 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -1204,7 +1204,7 @@ PyInterpreterState_Head(void)
 PyInterpreterState *
 PyInterpreterState_Main(void)
 {
-    return _PyRuntime.interpreters.main;
+    return _PyInterpreterState_Main();
 }
 
 PyInterpreterState *
-- 
cgit v0.12