From 70ba3abd0c3c354e7e1214b70ab129c9e27b89a4 Mon Sep 17 00:00:00 2001
From: alperyoney <alperyoney@fb.com>
Date: Thu, 5 Jun 2025 16:39:52 -0700
Subject: [PATCH 1/3] gh-116738: Inline append for local PyList

---
 Modules/grpmodule.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Modules/grpmodule.c b/Modules/grpmodule.c
index 29da9936b65504..3fb5b1e666e9a6 100644
--- a/Modules/grpmodule.c
+++ b/Modules/grpmodule.c
@@ -7,6 +7,7 @@
 
 #include "Python.h"
 #include "posixmodule.h"
+#include "pycore_list.h"          // _PyList_AppendTakeRef()
 
 #include <errno.h>                // ERANGE
 #include <grp.h>                  // getgrgid_r()
@@ -295,8 +296,12 @@ grp_getgrall_impl(PyObject *module)
         // setgrent()/endgrent() are not reentrant / thread-safe. A deadlock
         // is unlikely since mkgrent() should not be able to call arbitrary
         // Python code.
+        // `d` is a local list; append to it without a lock using
+        // _PyList_AppendTakeRef().
         PyObject *v = mkgrent(module, p);
-        if (v == NULL || PyList_Append(d, v) != 0) {
+        if (v == NULL
+            || _PyList_AppendTakeRef((PyListObject *)d, Py_NewRef(v)) != 0)
+        {
             Py_XDECREF(v);
             Py_CLEAR(d);
             goto done;

From d47b85cb96aab8b05918f94719d86c1a02350091 Mon Sep 17 00:00:00 2001
From: Alper <alperyoney@fb.com>
Date: Tue, 10 Jun 2025 08:19:42 -0500
Subject: [PATCH 2/3] gh-116738: Assert list is uniquely referenced

---
 Modules/grpmodule.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Modules/grpmodule.c b/Modules/grpmodule.c
index 3fb5b1e666e9a6..dde4aa85159b95 100644
--- a/Modules/grpmodule.c
+++ b/Modules/grpmodule.c
@@ -8,6 +8,7 @@
 #include "Python.h"
 #include "posixmodule.h"
 #include "pycore_list.h"          // _PyList_AppendTakeRef()
+#include "pycore_object.h"        // _PyObject_IsUniquelyReferenced()
 
 #include <errno.h>                // ERANGE
 #include <grp.h>                  // getgrgid_r()
@@ -291,13 +292,14 @@ grp_getgrall_impl(PyObject *module)
     setgrent();
 
     struct group *p;
+    // `d` is a local list; append items without a lock using
+    // _PyList_AppendTakeRef() within the loop.
+    assert(_PyObject_IsUniquelyReferenced(d));
     while ((p = getgrent()) != NULL) {
         // gh-126316: Don't release the mutex around mkgrent() since
         // setgrent()/endgrent() are not reentrant / thread-safe. A deadlock
         // is unlikely since mkgrent() should not be able to call arbitrary
         // Python code.
-        // `d` is a local list; append to it without a lock using
-        // _PyList_AppendTakeRef().
         PyObject *v = mkgrent(module, p);
         if (v == NULL
             || _PyList_AppendTakeRef((PyListObject *)d, Py_NewRef(v)) != 0)

From cf5d8ec8a604b40fab080697e0c6fb84c3f48de9 Mon Sep 17 00:00:00 2001
From: alperyoney <alperyoney@fb.com>
Date: Tue, 10 Jun 2025 14:48:29 -0700
Subject: [PATCH 3/3] gh-116738: Let _PyList_AppendTakeRef() steal the
 reference

---
 Modules/grpmodule.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/Modules/grpmodule.c b/Modules/grpmodule.c
index dde4aa85159b95..e71f4ea8cb6b45 100644
--- a/Modules/grpmodule.c
+++ b/Modules/grpmodule.c
@@ -301,14 +301,10 @@ grp_getgrall_impl(PyObject *module)
         // is unlikely since mkgrent() should not be able to call arbitrary
         // Python code.
         PyObject *v = mkgrent(module, p);
-        if (v == NULL
-            || _PyList_AppendTakeRef((PyListObject *)d, Py_NewRef(v)) != 0)
-        {
-            Py_XDECREF(v);
+        if (v == NULL || _PyList_AppendTakeRef((PyListObject *)d, v) != 0) {
             Py_CLEAR(d);
             goto done;
         }
-        Py_DECREF(v);
     }
 
 done: