diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index 9465be9..9a605e4 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -3247,6 +3247,118 @@
 
 #endif /* defined(HAVE_GETPID) */
 
+#if defined(HAVE_GETGROUPLIST) && defined(__APPLE__)
+
+PyDoc_STRVAR(os_getgrouplist__doc__,
+"getgrouplist($module, user, group, /)\n"
+"--\n"
+"\n"
+"Returns a list of groups to which a user belongs.\n"
+"\n"
+"  user\n"
+"    username to lookup\n"
+"  group\n"
+"    base group id of the user");
+
+#define OS_GETGROUPLIST_METHODDEF    \
+    {"getgrouplist", (PyCFunction)(void(*)(void))os_getgrouplist, METH_FASTCALL, os_getgrouplist__doc__},
+
+static PyObject *
+os_getgrouplist_impl(PyObject *module, const char *user, int basegid);
+
+static PyObject *
+os_getgrouplist(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    const char *user;
+    int basegid;
+
+    if (!_PyArg_CheckPositional("getgrouplist", nargs, 2, 2)) {
+        goto exit;
+    }
+    if (!PyUnicode_Check(args[0])) {
+        _PyArg_BadArgument("getgrouplist", "argument 1", "str", args[0]);
+        goto exit;
+    }
+    Py_ssize_t user_length;
+    user = PyUnicode_AsUTF8AndSize(args[0], &user_length);
+    if (user == NULL) {
+        goto exit;
+    }
+    if (strlen(user) != (size_t)user_length) {
+        PyErr_SetString(PyExc_ValueError, "embedded null character");
+        goto exit;
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    basegid = _PyLong_AsInt(args[1]);
+    if (basegid == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    return_value = os_getgrouplist_impl(module, user, basegid);
+
+exit:
+    return return_value;
+}
+
+#endif /* defined(HAVE_GETGROUPLIST) && defined(__APPLE__) */
+
+#if defined(HAVE_GETGROUPLIST) && !defined(__APPLE__)
+
+PyDoc_STRVAR(os_getgrouplist__doc__,
+"getgrouplist($module, user, group, /)\n"
+"--\n"
+"\n"
+"Returns a list of groups to which a user belongs.\n"
+"\n"
+"  user\n"
+"    username to lookup\n"
+"  group\n"
+"    base group id of the user");
+
+#define OS_GETGROUPLIST_METHODDEF    \
+    {"getgrouplist", (PyCFunction)(void(*)(void))os_getgrouplist, METH_FASTCALL, os_getgrouplist__doc__},
+
+static PyObject *
+os_getgrouplist_impl(PyObject *module, const char *user, gid_t basegid);
+
+static PyObject *
+os_getgrouplist(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    const char *user;
+    gid_t basegid;
+
+    if (!_PyArg_CheckPositional("getgrouplist", nargs, 2, 2)) {
+        goto exit;
+    }
+    if (!PyUnicode_Check(args[0])) {
+        _PyArg_BadArgument("getgrouplist", "argument 1", "str", args[0]);
+        goto exit;
+    }
+    Py_ssize_t user_length;
+    user = PyUnicode_AsUTF8AndSize(args[0], &user_length);
+    if (user == NULL) {
+        goto exit;
+    }
+    if (strlen(user) != (size_t)user_length) {
+        PyErr_SetString(PyExc_ValueError, "embedded null character");
+        goto exit;
+    }
+    if (!_Py_Gid_Converter(args[1], &basegid)) {
+        goto exit;
+    }
+    return_value = os_getgrouplist_impl(module, user, basegid);
+
+exit:
+    return return_value;
+}
+
+#endif /* defined(HAVE_GETGROUPLIST) && !defined(__APPLE__) */
+
 #if defined(HAVE_GETGROUPS)
 
 PyDoc_STRVAR(os_getgroups__doc__,
@@ -3269,6 +3381,102 @@
 
 #endif /* defined(HAVE_GETGROUPS) */
 
+#if defined(HAVE_INITGROUPS) && defined(__APPLE__)
+
+PyDoc_STRVAR(os_initgroups__doc__,
+"initgroups($module, username, gid, /)\n"
+"--\n"
+"\n"
+"Initialize the group access list.\n"
+"\n"
+"Call the system initgroups() to initialize the group access list with all of\n"
+"the groups of which the specified username is a member, plus the specified\n"
+"group id.");
+
+#define OS_INITGROUPS_METHODDEF    \
+    {"initgroups", (PyCFunction)(void(*)(void))os_initgroups, METH_FASTCALL, os_initgroups__doc__},
+
+static PyObject *
+os_initgroups_impl(PyObject *module, PyObject *oname, int gid);
+
+static PyObject *
+os_initgroups(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    PyObject *oname = NULL;
+    int gid;
+
+    if (!_PyArg_CheckPositional("initgroups", nargs, 2, 2)) {
+        goto exit;
+    }
+    if (!PyUnicode_FSConverter(args[0], &oname)) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    gid = _PyLong_AsInt(args[1]);
+    if (gid == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    return_value = os_initgroups_impl(module, oname, gid);
+
+exit:
+    /* Cleanup for oname */
+    Py_XDECREF(oname);
+
+    return return_value;
+}
+
+#endif /* defined(HAVE_INITGROUPS) && defined(__APPLE__) */
+
+#if defined(HAVE_INITGROUPS) && !defined(__APPLE__)
+
+PyDoc_STRVAR(os_initgroups__doc__,
+"initgroups($module, username, gid, /)\n"
+"--\n"
+"\n"
+"Initialize the group access list.\n"
+"\n"
+"Call the system initgroups() to initialize the group access list with all of\n"
+"the groups of which the specified username is a member, plus the specified\n"
+"group id.");
+
+#define OS_INITGROUPS_METHODDEF    \
+    {"initgroups", (PyCFunction)(void(*)(void))os_initgroups, METH_FASTCALL, os_initgroups__doc__},
+
+static PyObject *
+os_initgroups_impl(PyObject *module, PyObject *oname, gid_t gid);
+
+static PyObject *
+os_initgroups(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    PyObject *oname = NULL;
+    gid_t gid;
+
+    if (!_PyArg_CheckPositional("initgroups", nargs, 2, 2)) {
+        goto exit;
+    }
+    if (!PyUnicode_FSConverter(args[0], &oname)) {
+        goto exit;
+    }
+    if (!_Py_Gid_Converter(args[1], &gid)) {
+        goto exit;
+    }
+    return_value = os_initgroups_impl(module, oname, gid);
+
+exit:
+    /* Cleanup for oname */
+    Py_XDECREF(oname);
+
+    return return_value;
+}
+
+#endif /* defined(HAVE_INITGROUPS) && !defined(__APPLE__) */
+
 #if defined(HAVE_GETPGID)
 
 PyDoc_STRVAR(os_getpgid__doc__,
@@ -5021,6 +5229,283 @@
     return return_value;
 }
 
+#if defined(HAVE_SENDFILE) && defined(__APPLE__)
+
+PyDoc_STRVAR(os_sendfile__doc__,
+"sendfile($module, /, out_fd, in_fd, offset, count, headers=(),\n"
+"         trailers=(), flags=0)\n"
+"--\n"
+"\n"
+"Copy count bytes from file descriptor in_fd to file descriptor out_fd.");
+
+#define OS_SENDFILE_METHODDEF    \
+    {"sendfile", (PyCFunction)(void(*)(void))os_sendfile, METH_FASTCALL|METH_KEYWORDS, os_sendfile__doc__},
+
+static PyObject *
+os_sendfile_impl(PyObject *module, int out_fd, int in_fd, Py_off_t offset,
+                 Py_off_t sbytes, PyObject *headers, PyObject *trailers,
+                 int flags);
+
+static PyObject *
+os_sendfile(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"out_fd", "in_fd", "offset", "count", "headers", "trailers", "flags", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "sendfile", 0};
+    PyObject *argsbuf[7];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 4;
+    int out_fd;
+    int in_fd;
+    Py_off_t offset;
+    Py_off_t sbytes;
+    PyObject *headers = NULL;
+    PyObject *trailers = NULL;
+    int flags = 0;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 4, 7, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[0])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    out_fd = _PyLong_AsInt(args[0]);
+    if (out_fd == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    in_fd = _PyLong_AsInt(args[1]);
+    if (in_fd == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    if (!Py_off_t_converter(args[2], &offset)) {
+        goto exit;
+    }
+    if (!Py_off_t_converter(args[3], &sbytes)) {
+        goto exit;
+    }
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[4]) {
+        headers = args[4];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (args[5]) {
+        trailers = args[5];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[6])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    flags = _PyLong_AsInt(args[6]);
+    if (flags == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = os_sendfile_impl(module, out_fd, in_fd, offset, sbytes, headers, trailers, flags);
+
+exit:
+    return return_value;
+}
+
+#endif /* defined(HAVE_SENDFILE) && defined(__APPLE__) */
+
+#if defined(HAVE_SENDFILE) && !defined(__APPLE__) && (defined(__FreeBSD__) || defined(__DragonFly__))
+
+PyDoc_STRVAR(os_sendfile__doc__,
+"sendfile($module, /, out_fd, in_fd, offset, count, headers=(),\n"
+"         trailers=(), flags=0)\n"
+"--\n"
+"\n"
+"Copy count bytes from file descriptor in_fd to file descriptor out_fd.");
+
+#define OS_SENDFILE_METHODDEF    \
+    {"sendfile", (PyCFunction)(void(*)(void))os_sendfile, METH_FASTCALL|METH_KEYWORDS, os_sendfile__doc__},
+
+static PyObject *
+os_sendfile_impl(PyObject *module, int out_fd, int in_fd, Py_off_t offset,
+                 Py_ssize_t count, PyObject *headers, PyObject *trailers,
+                 int flags);
+
+static PyObject *
+os_sendfile(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"out_fd", "in_fd", "offset", "count", "headers", "trailers", "flags", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "sendfile", 0};
+    PyObject *argsbuf[7];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 4;
+    int out_fd;
+    int in_fd;
+    Py_off_t offset;
+    Py_ssize_t count;
+    PyObject *headers = NULL;
+    PyObject *trailers = NULL;
+    int flags = 0;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 4, 7, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[0])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    out_fd = _PyLong_AsInt(args[0]);
+    if (out_fd == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    in_fd = _PyLong_AsInt(args[1]);
+    if (in_fd == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    if (!Py_off_t_converter(args[2], &offset)) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[3])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    {
+        Py_ssize_t ival = -1;
+        PyObject *iobj = PyNumber_Index(args[3]);
+        if (iobj != NULL) {
+            ival = PyLong_AsSsize_t(iobj);
+            Py_DECREF(iobj);
+        }
+        if (ival == -1 && PyErr_Occurred()) {
+            goto exit;
+        }
+        count = ival;
+    }
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[4]) {
+        headers = args[4];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (args[5]) {
+        trailers = args[5];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[6])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    flags = _PyLong_AsInt(args[6]);
+    if (flags == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = os_sendfile_impl(module, out_fd, in_fd, offset, count, headers, trailers, flags);
+
+exit:
+    return return_value;
+}
+
+#endif /* defined(HAVE_SENDFILE) && !defined(__APPLE__) && (defined(__FreeBSD__) || defined(__DragonFly__)) */
+
+#if defined(HAVE_SENDFILE) && !defined(__APPLE__) && !(defined(__FreeBSD__) || defined(__DragonFly__))
+
+PyDoc_STRVAR(os_sendfile__doc__,
+"sendfile($module, /, out_fd, in_fd, offset, count)\n"
+"--\n"
+"\n"
+"Copy count bytes from file descriptor in_fd to file descriptor out_fd.");
+
+#define OS_SENDFILE_METHODDEF    \
+    {"sendfile", (PyCFunction)(void(*)(void))os_sendfile, METH_FASTCALL|METH_KEYWORDS, os_sendfile__doc__},
+
+static PyObject *
+os_sendfile_impl(PyObject *module, int out_fd, int in_fd, PyObject *offobj,
+                 Py_ssize_t count);
+
+static PyObject *
+os_sendfile(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"out_fd", "in_fd", "offset", "count", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "sendfile", 0};
+    PyObject *argsbuf[4];
+    int out_fd;
+    int in_fd;
+    PyObject *offobj;
+    Py_ssize_t count;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 4, 4, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[0])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    out_fd = _PyLong_AsInt(args[0]);
+    if (out_fd == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    in_fd = _PyLong_AsInt(args[1]);
+    if (in_fd == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+    offobj = args[2];
+    if (PyFloat_Check(args[3])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    {
+        Py_ssize_t ival = -1;
+        PyObject *iobj = PyNumber_Index(args[3]);
+        if (iobj != NULL) {
+            ival = PyLong_AsSsize_t(iobj);
+            Py_DECREF(iobj);
+        }
+        if (ival == -1 && PyErr_Occurred()) {
+            goto exit;
+        }
+        count = ival;
+    }
+    return_value = os_sendfile_impl(module, out_fd, in_fd, offobj, count);
+
+exit:
+    return return_value;
+}
+
+#endif /* defined(HAVE_SENDFILE) && !defined(__APPLE__) && !(defined(__FreeBSD__) || defined(__DragonFly__)) */
+
 #if defined(__APPLE__)
 
 PyDoc_STRVAR(os__fcopyfile__doc__,
@@ -7568,6 +8053,62 @@
 
 #endif /* defined(HAVE_MEMFD_CREATE) */
 
+#if (defined(TERMSIZE_USE_CONIO) || defined(TERMSIZE_USE_IOCTL))
+
+PyDoc_STRVAR(os_get_terminal_size__doc__,
+"get_terminal_size($module, fd=<unrepresentable>, /)\n"
+"--\n"
+"\n"
+"Return the size of the terminal window as (columns, lines).\n"
+"\n"
+"The optional argument fd (default standard output) specifies\n"
+"which file descriptor should be queried.\n"
+"\n"
+"If the file descriptor is not connected to a terminal, an OSError\n"
+"is thrown.\n"
+"\n"
+"This function will only be defined if an implementation is\n"
+"available for this system.\n"
+"\n"
+"shutil.get_terminal_size is the high-level function which should\n"
+"normally be used, os.get_terminal_size is the low-level implementation.");
+
+#define OS_GET_TERMINAL_SIZE_METHODDEF    \
+    {"get_terminal_size", (PyCFunction)(void(*)(void))os_get_terminal_size, METH_FASTCALL, os_get_terminal_size__doc__},
+
+static PyObject *
+os_get_terminal_size_impl(PyObject *module, int fd);
+
+static PyObject *
+os_get_terminal_size(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    int fd = fileno(stdout);
+
+    if (!_PyArg_CheckPositional("get_terminal_size", nargs, 0, 1)) {
+        goto exit;
+    }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    if (PyFloat_Check(args[0])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    fd = _PyLong_AsInt(args[0]);
+    if (fd == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional:
+    return_value = os_get_terminal_size_impl(module, fd);
+
+exit:
+    return return_value;
+}
+
+#endif /* (defined(TERMSIZE_USE_CONIO) || defined(TERMSIZE_USE_IOCTL)) */
+
 PyDoc_STRVAR(os_cpu_count__doc__,
 "cpu_count($module, /)\n"
 "--\n"
@@ -8522,10 +9063,18 @@
     #define OS_GETPID_METHODDEF
 #endif /* !defined(OS_GETPID_METHODDEF) */
 
+#ifndef OS_GETGROUPLIST_METHODDEF
+    #define OS_GETGROUPLIST_METHODDEF
+#endif /* !defined(OS_GETGROUPLIST_METHODDEF) */
+
 #ifndef OS_GETGROUPS_METHODDEF
     #define OS_GETGROUPS_METHODDEF
 #endif /* !defined(OS_GETGROUPS_METHODDEF) */
 
+#ifndef OS_INITGROUPS_METHODDEF
+    #define OS_INITGROUPS_METHODDEF
+#endif /* !defined(OS_INITGROUPS_METHODDEF) */
+
 #ifndef OS_GETPGID_METHODDEF
     #define OS_GETPGID_METHODDEF
 #endif /* !defined(OS_GETPGID_METHODDEF) */
@@ -8662,6 +9211,10 @@
     #define OS_PREADV_METHODDEF
 #endif /* !defined(OS_PREADV_METHODDEF) */
 
+#ifndef OS_SENDFILE_METHODDEF
+    #define OS_SENDFILE_METHODDEF
+#endif /* !defined(OS_SENDFILE_METHODDEF) */
+
 #ifndef OS__FCOPYFILE_METHODDEF
     #define OS__FCOPYFILE_METHODDEF
 #endif /* !defined(OS__FCOPYFILE_METHODDEF) */
@@ -8838,6 +9391,10 @@
     #define OS_MEMFD_CREATE_METHODDEF
 #endif /* !defined(OS_MEMFD_CREATE_METHODDEF) */
 
+#ifndef OS_GET_TERMINAL_SIZE_METHODDEF
+    #define OS_GET_TERMINAL_SIZE_METHODDEF
+#endif /* !defined(OS_GET_TERMINAL_SIZE_METHODDEF) */
+
 #ifndef OS_GET_HANDLE_INHERITABLE_METHODDEF
     #define OS_GET_HANDLE_INHERITABLE_METHODDEF
 #endif /* !defined(OS_GET_HANDLE_INHERITABLE_METHODDEF) */
@@ -8869,4 +9426,4 @@
 #ifndef OS_WAITSTATUS_TO_EXITCODE_METHODDEF
     #define OS_WAITSTATUS_TO_EXITCODE_METHODDEF
 #endif /* !defined(OS_WAITSTATUS_TO_EXITCODE_METHODDEF) */
-/*[clinic end generated code: output=ca63e471c11dc6e7 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=545c08f76d7a6286 input=a9049054013a1b77]*/
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 4085b92..2157cbb 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -6947,23 +6947,46 @@
 
 #ifdef HAVE_GETGROUPLIST
 
-/* AC 3.5: funny apple logic below */
-PyDoc_STRVAR(posix_getgrouplist__doc__,
-"getgrouplist(user, group) -> list of groups to which a user belongs\n\n\
-Returns a list of groups to which a user belongs.\n\n\
-    user: username to lookup\n\
-    group: base group id of the user");
+#ifdef __APPLE__
+/*[clinic input]
+os.getgrouplist
+
+    user: str
+        username to lookup
+    group as basegid: int
+        base group id of the user
+    /
+
+Returns a list of groups to which a user belongs.
+[clinic start generated code]*/
 
 static PyObject *
-posix_getgrouplist(PyObject *self, PyObject *args)
+os_getgrouplist_impl(PyObject *module, const char *user, int basegid)
+/*[clinic end generated code: output=6e734697b8c26de0 input=f8d870374b09a490]*/
+#else
+/*[clinic input]
+os.getgrouplist
+
+    user: str
+        username to lookup
+    group as basegid: gid_t
+        base group id of the user
+    /
+
+Returns a list of groups to which a user belongs.
+[clinic start generated code]*/
+
+static PyObject *
+os_getgrouplist_impl(PyObject *module, const char *user, gid_t basegid)
+/*[clinic end generated code: output=0ebd7fb70115575b input=cc61d5c20b08958d]*/
+#endif
 {
-    const char *user;
     int i, ngroups;
     PyObject *list;
 #ifdef __APPLE__
-    int *groups, basegid;
+    int *groups;
 #else
-    gid_t *groups, basegid;
+    gid_t *groups;
 #endif
 
     /*
@@ -6976,15 +6999,6 @@
      */
     ngroups = 1 + MAX_GROUPS;
 
-#ifdef __APPLE__
-    if (!PyArg_ParseTuple(args, "si:getgrouplist", &user, &basegid))
-        return NULL;
-#else
-    if (!PyArg_ParseTuple(args, "sO&:getgrouplist", &user,
-                          _Py_Gid_Converter, &basegid))
-        return NULL;
-#endif
-
     while (1) {
 #ifdef __APPLE__
         groups = PyMem_New(int, ngroups);
@@ -7155,40 +7169,47 @@
 #endif /* HAVE_GETGROUPS */
 
 #ifdef HAVE_INITGROUPS
-PyDoc_STRVAR(posix_initgroups__doc__,
-"initgroups(username, gid) -> None\n\n\
-Call the system initgroups() to initialize the group access list with all of\n\
-the groups of which the specified username is a member, plus the specified\n\
-group id.");
+#ifdef __APPLE__
+/*[clinic input]
+os.initgroups
 
-/* AC 3.5: funny apple logic */
+    username as oname: FSConverter
+    gid: int
+    /
+
+Initialize the group access list.
+
+Call the system initgroups() to initialize the group access list with all of
+the groups of which the specified username is a member, plus the specified
+group id.
+[clinic start generated code]*/
+
 static PyObject *
-posix_initgroups(PyObject *self, PyObject *args)
+os_initgroups_impl(PyObject *module, PyObject *oname, int gid)
+/*[clinic end generated code: output=7f074d30a425fd3a input=df3d54331b0af204]*/
+#else
+/*[clinic input]
+os.initgroups
+
+    username as oname: FSConverter
+    gid: gid_t
+    /
+
+Initialize the group access list.
+
+Call the system initgroups() to initialize the group access list with all of
+the groups of which the specified username is a member, plus the specified
+group id.
+[clinic start generated code]*/
+
+static PyObject *
+os_initgroups_impl(PyObject *module, PyObject *oname, gid_t gid)
+/*[clinic end generated code: output=59341244521a9e3f input=0cb91bdc59a4c564]*/
+#endif
 {
-    PyObject *oname;
-    const char *username;
-    int res;
-#ifdef __APPLE__
-    int gid;
-#else
-    gid_t gid;
-#endif
+    const char *username = PyBytes_AS_STRING(oname);
 
-#ifdef __APPLE__
-    if (!PyArg_ParseTuple(args, "O&i:initgroups",
-                          PyUnicode_FSConverter, &oname,
-                          &gid))
-#else
-    if (!PyArg_ParseTuple(args, "O&O&:initgroups",
-                          PyUnicode_FSConverter, &oname,
-                          _Py_Gid_Converter, &gid))
-#endif
-        return NULL;
-    username = PyBytes_AS_STRING(oname);
-
-    res = initgroups(username, gid);
-    Py_DECREF(oname);
-    if (res == -1)
+    if (initgroups(username, gid) == -1)
         return PyErr_SetFromErrno(PyExc_OSError);
 
     Py_RETURN_NONE;
@@ -9220,46 +9241,77 @@
 }
 
 #ifdef HAVE_SENDFILE
-PyDoc_STRVAR(posix_sendfile__doc__,
-"sendfile(out_fd, in_fd, offset, count) -> byteswritten\n\
-sendfile(out_fd, in_fd, offset, count[, headers][, trailers], flags=0)\n\
-            -> byteswritten\n\
-Copy count bytes from file descriptor in_fd to file descriptor out_fd.");
+#ifdef __APPLE__
+/*[clinic input]
+os.sendfile
 
-/* AC 3.5: don't bother converting, has optional group*/
+    out_fd: int
+    in_fd: int
+    offset: Py_off_t
+    count as sbytes: Py_off_t
+    headers: object(c_default="NULL") = ()
+    trailers: object(c_default="NULL") = ()
+    flags: int = 0
+
+Copy count bytes from file descriptor in_fd to file descriptor out_fd.
+[clinic start generated code]*/
+
 static PyObject *
-posix_sendfile(PyObject *self, PyObject *args, PyObject *kwdict)
+os_sendfile_impl(PyObject *module, int out_fd, int in_fd, Py_off_t offset,
+                 Py_off_t sbytes, PyObject *headers, PyObject *trailers,
+                 int flags)
+/*[clinic end generated code: output=81c4bcd143f5c82b input=b0d72579d4c69afa]*/
+#elif defined(__FreeBSD__) || defined(__DragonFly__)
+/*[clinic input]
+os.sendfile
+
+    out_fd: int
+    in_fd: int
+    offset: Py_off_t
+    count: Py_ssize_t
+    headers: object(c_default="NULL") = ()
+    trailers: object(c_default="NULL") = ()
+    flags: int = 0
+
+Copy count bytes from file descriptor in_fd to file descriptor out_fd.
+[clinic start generated code]*/
+
+static PyObject *
+os_sendfile_impl(PyObject *module, int out_fd, int in_fd, Py_off_t offset,
+                 Py_ssize_t count, PyObject *headers, PyObject *trailers,
+                 int flags)
+/*[clinic end generated code: output=329ea009bdd55afc input=338adb8ff84ae8cd]*/
+#else
+/*[clinic input]
+os.sendfile
+
+    out_fd: int
+    in_fd: int
+    offset as offobj: object
+    count: Py_ssize_t
+
+Copy count bytes from file descriptor in_fd to file descriptor out_fd.
+[clinic start generated code]*/
+
+static PyObject *
+os_sendfile_impl(PyObject *module, int out_fd, int in_fd, PyObject *offobj,
+                 Py_ssize_t count)
+/*[clinic end generated code: output=ae81216e40f167d8 input=76d64058c74477ba]*/
+#endif
 {
-    int in, out;
     Py_ssize_t ret;
     int async_err = 0;
-    off_t offset;
 
 #if defined(__FreeBSD__) || defined(__DragonFly__) || defined(__APPLE__)
 #ifndef __APPLE__
-    Py_ssize_t len;
-#endif
-    PyObject *headers = NULL, *trailers = NULL;
-    Py_buffer *hbuf, *tbuf;
     off_t sbytes;
+#endif
+    Py_buffer *hbuf, *tbuf;
     struct sf_hdtr sf;
-    int flags = 0;
-    static char *keywords[] = {"out_fd", "in_fd",
-                                "offset", "count",
-                                "headers", "trailers", "flags", NULL};
 
     sf.headers = NULL;
     sf.trailers = NULL;
 
-#ifdef __APPLE__
-    if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iiO&O&|OOi:sendfile",
-        keywords, &out, &in, Py_off_t_converter, &offset, Py_off_t_converter, &sbytes,
-#else
-    if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iiO&n|OOi:sendfile",
-        keywords, &out, &in, Py_off_t_converter, &offset, &len,
-#endif
-                &headers, &trailers, &flags))
-            return NULL;
     if (headers != NULL) {
         if (!PySequence_Check(headers)) {
             PyErr_SetString(PyExc_TypeError,
@@ -9321,9 +9373,9 @@
     do {
         Py_BEGIN_ALLOW_THREADS
 #ifdef __APPLE__
-        ret = sendfile(in, out, offset, &sbytes, &sf, flags);
+        ret = sendfile(in_fd, out_fd, offset, &sbytes, &sf, flags);
 #else
-        ret = sendfile(in, out, offset, len, &sf, &sbytes, flags);
+        ret = sendfile(in_fd, out_fd, offset, count, &sf, &sbytes, flags);
 #endif
         Py_END_ALLOW_THREADS
     } while (ret < 0 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
@@ -9358,18 +9410,11 @@
     #endif
 
 #else
-    Py_ssize_t count;
-    PyObject *offobj;
-    static char *keywords[] = {"out_fd", "in_fd",
-                                "offset", "count", NULL};
-    if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iiOn:sendfile",
-            keywords, &out, &in, &offobj, &count))
-        return NULL;
 #ifdef __linux__
     if (offobj == Py_None) {
         do {
             Py_BEGIN_ALLOW_THREADS
-            ret = sendfile(out, in, NULL, count);
+            ret = sendfile(out_fd, in_fd, NULL, count);
             Py_END_ALLOW_THREADS
         } while (ret < 0 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
         if (ret < 0)
@@ -9377,12 +9422,13 @@
         return Py_BuildValue("n", ret);
     }
 #endif
+    off_t offset;
     if (!Py_off_t_converter(offobj, &offset))
         return NULL;
 
     do {
         Py_BEGIN_ALLOW_THREADS
-        ret = sendfile(out, in, &offset, count);
+        ret = sendfile(out_fd, in_fd, &offset, count);
         Py_END_ALLOW_THREADS
     } while (ret < 0 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
     if (ret < 0)
@@ -12360,29 +12406,34 @@
 };
 
 #if defined(TERMSIZE_USE_CONIO) || defined(TERMSIZE_USE_IOCTL)
-/* AC 3.5: fd should accept None */
-PyDoc_STRVAR(termsize__doc__,
-    "Return the size of the terminal window as (columns, lines).\n"        \
-    "\n"                                                                   \
-    "The optional argument fd (default standard output) specifies\n"       \
-    "which file descriptor should be queried.\n"                           \
-    "\n"                                                                   \
-    "If the file descriptor is not connected to a terminal, an OSError\n"  \
-    "is thrown.\n"                                                         \
-    "\n"                                                                   \
-    "This function will only be defined if an implementation is\n"         \
-    "available for this system.\n"                                         \
-    "\n"                                                                   \
-    "shutil.get_terminal_size is the high-level function which should\n"  \
-    "normally be used, os.get_terminal_size is the low-level implementation.");
+/*[clinic input]
+os.get_terminal_size
 
-static PyObject*
-get_terminal_size(PyObject *self, PyObject *args)
+    fd: int(c_default="fileno(stdout)", py_default="<unrepresentable>") = -1
+    /
+
+Return the size of the terminal window as (columns, lines).
+
+The optional argument fd (default standard output) specifies
+which file descriptor should be queried.
+
+If the file descriptor is not connected to a terminal, an OSError
+is thrown.
+
+This function will only be defined if an implementation is
+available for this system.
+
+shutil.get_terminal_size is the high-level function which should
+normally be used, os.get_terminal_size is the low-level implementation.
+[clinic start generated code]*/
+
+static PyObject *
+os_get_terminal_size_impl(PyObject *module, int fd)
+/*[clinic end generated code: output=fbab93acef980508 input=ead5679b82ddb920]*/
 {
     int columns, lines;
     PyObject *termsize;
 
-    int fd = fileno(stdout);
     /* Under some conditions stdout may not be connected and
      * fileno(stdout) may point to an invalid file descriptor. For example
      * GUI apps don't have valid standard streams by default.
@@ -12391,9 +12442,6 @@
      * the ioctl below will fail returning EBADF. This is what we want.
      */
 
-    if (!PyArg_ParseTuple(args, "|i", &fd))
-        return NULL;
-
 #ifdef TERMSIZE_USE_IOCTL
     {
         struct winsize w;
@@ -12433,7 +12481,7 @@
     }
 #endif /* TERMSIZE_USE_CONIO */
 
-    PyObject *TerminalSizeType = get_posix_state(self)->TerminalSizeType;
+    PyObject *TerminalSizeType = get_posix_state(module)->TerminalSizeType;
     termsize = PyStructSequence_New((PyTypeObject *)TerminalSizeType);
     if (termsize == NULL)
         return NULL;
@@ -13912,9 +13960,7 @@
     OS_GETEGID_METHODDEF
     OS_GETEUID_METHODDEF
     OS_GETGID_METHODDEF
-#ifdef HAVE_GETGROUPLIST
-    {"getgrouplist",    posix_getgrouplist, METH_VARARGS, posix_getgrouplist__doc__},
-#endif
+    OS_GETGROUPLIST_METHODDEF
     OS_GETGROUPS_METHODDEF
     OS_GETPID_METHODDEF
     OS_GETPGRP_METHODDEF
@@ -13924,9 +13970,7 @@
     OS_KILL_METHODDEF
     OS_KILLPG_METHODDEF
     OS_PLOCK_METHODDEF
-#ifdef MS_WINDOWS
     OS_STARTFILE_METHODDEF
-#endif
     OS_SETUID_METHODDEF
     OS_SETEUID_METHODDEF
     OS_SETREUID_METHODDEF
@@ -13934,9 +13978,7 @@
     OS_SETEGID_METHODDEF
     OS_SETREGID_METHODDEF
     OS_SETGROUPS_METHODDEF
-#ifdef HAVE_INITGROUPS
-    {"initgroups",      posix_initgroups, METH_VARARGS, posix_initgroups__doc__},
-#endif /* HAVE_INITGROUPS */
+    OS_INITGROUPS_METHODDEF
     OS_GETPGID_METHODDEF
     OS_SETPGRP_METHODDEF
     OS_WAIT_METHODDEF
@@ -13966,10 +14008,7 @@
     OS_WRITEV_METHODDEF
     OS_PWRITE_METHODDEF
     OS_PWRITEV_METHODDEF
-#ifdef HAVE_SENDFILE
-    {"sendfile",        (PyCFunction)(void(*)(void))posix_sendfile, METH_VARARGS | METH_KEYWORDS,
-                            posix_sendfile__doc__},
-#endif
+    OS_SENDFILE_METHODDEF
     OS_FSTAT_METHODDEF
     OS_ISATTY_METHODDEF
     OS_PIPE_METHODDEF
@@ -14021,26 +14060,20 @@
     OS_REMOVEXATTR_METHODDEF
     OS_LISTXATTR_METHODDEF
 
-#if defined(TERMSIZE_USE_CONIO) || defined(TERMSIZE_USE_IOCTL)
-    {"get_terminal_size", get_terminal_size, METH_VARARGS, termsize__doc__},
-#endif
+    OS_GET_TERMINAL_SIZE_METHODDEF
     OS_CPU_COUNT_METHODDEF
     OS_GET_INHERITABLE_METHODDEF
     OS_SET_INHERITABLE_METHODDEF
     OS_GET_HANDLE_INHERITABLE_METHODDEF
     OS_SET_HANDLE_INHERITABLE_METHODDEF
-#ifndef MS_WINDOWS
     OS_GET_BLOCKING_METHODDEF
     OS_SET_BLOCKING_METHODDEF
-#endif
     OS_SCANDIR_METHODDEF
     OS_FSPATH_METHODDEF
     OS_GETRANDOM_METHODDEF
     OS_MEMFD_CREATE_METHODDEF
-#ifdef MS_WINDOWS
     OS__ADD_DLL_DIRECTORY_METHODDEF
     OS__REMOVE_DLL_DIRECTORY_METHODDEF
-#endif
     OS_WAITSTATUS_TO_EXITCODE_METHODDEF
     {NULL,              NULL}            /* Sentinel */
 };