From 773c4d96d890d083c8f159ad99c82ba65cf6e9ae Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Wed, 11 Dec 2024 12:57:59 +0100
Subject: [PATCH 01/18] gh-127350: Add Py_fopen() function

Rename _Py_fopen_obj() to Py_fopen(). The function now also accepts
bytes path on Windows.

Remove the private, undocumented, and untested function
_Py_fopen_obj().
---
 Doc/c-api/sys.rst                             |  16 +++
 Doc/whatsnew/3.14.rst                         |   5 +
 Include/cpython/fileutils.h                   |   3 +-
 Lib/test/test_capi/test_file.py               |  23 ++++
 Lib/test/test_ssl.py                          |   3 +-
 ...-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst |   3 +
 Modules/_ssl.c                                |   2 +-
 Modules/_ssl/debughelpers.c                   |   4 +-
 Modules/_testcapi/clinic/file.c.h             |  48 +++++++++
 Modules/_testcapi/file.c                      |  35 ++++++
 Modules/_testcapi/object.c                    |   8 +-
 Modules/_testcapimodule.c                     |  12 +--
 Modules/main.c                                |   4 +-
 Python/errors.c                               |   2 +-
 Python/fileutils.c                            | 100 ++++++++----------
 Python/import.c                               |   2 +-
 Python/pythonrun.c                            |   2 +-
 17 files changed, 197 insertions(+), 75 deletions(-)
 create mode 100644 Lib/test/test_capi/test_file.py
 create mode 100644 Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst
 create mode 100644 Modules/_testcapi/clinic/file.c.h

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index c688afdca8231d..d51e66d45d22b3 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -216,6 +216,22 @@ Operating System Utilities
       The function now uses the UTF-8 encoding on Windows if
       :c:member:`PyPreConfig.legacy_windows_fs_encoding` is zero.
 
+.. c:function:: FILE* Py_fopen(PyObject *path, const char *mode)
+
+   Similar to the :c:func:`!fopen` function, but *path* is a Python object and
+   an exception is set on error.
+
+   *path* must be a :class:`str` object or a :class:`bytes` object.
+
+   On success, return the new file object.
+   On error, set an exception and return ``NULL``.
+
+   The file descriptor is created non-inheritable (:pep:`446`).
+
+   The caller must hold the GIL.
+
+   .. versionadded:: next
+
 
 .. _systemfunctions:
 
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index b71d31f9742fe0..2ce1bcdad75fbc 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -1034,6 +1034,11 @@ New features
 * Add :c:func:`PyUnstable_Object_EnableDeferredRefcount` for enabling
   deferred reference counting, as outlined in :pep:`703`.
 
+* Add :c:func:`Py_fopen` function to open a file. Similar to the
+  :c:func:`!fopen` function, but the *path* parameter is a Python object and an
+  exception is set on error.
+  (Contributed by Victor Stinner in :gh:`127350`.)
+
 Porting to Python 3.14
 ----------------------
 
diff --git a/Include/cpython/fileutils.h b/Include/cpython/fileutils.h
index b386ad107bde1f..3a2bfae1add88e 100644
--- a/Include/cpython/fileutils.h
+++ b/Include/cpython/fileutils.h
@@ -2,7 +2,6 @@
 #  error "this header file must not be included directly"
 #endif
 
-// Used by _testcapi which must not use the internal C API
-PyAPI_FUNC(FILE*) _Py_fopen_obj(
+PyAPI_FUNC(FILE*) Py_fopen(
     PyObject *path,
     const char *mode);
diff --git a/Lib/test/test_capi/test_file.py b/Lib/test/test_capi/test_file.py
new file mode 100644
index 00000000000000..68e63ad2a3e490
--- /dev/null
+++ b/Lib/test/test_capi/test_file.py
@@ -0,0 +1,23 @@
+import os
+import unittest
+from test.support import import_helper
+
+_testcapi = import_helper.import_module('_testcapi')
+
+
+class CAPIFileTest(unittest.TestCase):
+    def test_py_fopen(self):
+        for filename in (__file__, os.fsencode(__file__)):
+            with self.subTest(filename=filename):
+                content = _testcapi.py_fopen(filename, "rb")
+                with open(filename, "rb") as fp:
+                    self.assertEqual(fp.read(256), content)
+
+        for invalid_type in (123, object()):
+            with self.subTest(filename=invalid_type):
+                with self.assertRaises(TypeError):
+                    _testcapi.py_fopen(invalid_type, "r")
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 59f37b3f9a7575..122c1e7882864f 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -1325,8 +1325,7 @@ def test_load_verify_cadata(self):
     def test_load_dh_params(self):
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
         ctx.load_dh_params(DHFILE)
-        if os.name != 'nt':
-            ctx.load_dh_params(BYTES_DHFILE)
+        ctx.load_dh_params(BYTES_DHFILE)
         self.assertRaises(TypeError, ctx.load_dh_params)
         self.assertRaises(TypeError, ctx.load_dh_params, None)
         with self.assertRaises(FileNotFoundError) as cm:
diff --git a/Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst b/Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst
new file mode 100644
index 00000000000000..e3a914188ca680
--- /dev/null
+++ b/Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst
@@ -0,0 +1,3 @@
+Add :c:func:`Py_fopen` function to open a file. Similar to the :c:func:`!fopen`
+function, but the *path* parameter is a Python object and an exception is set
+on error. Patch by Victor Stinner.
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index e7df132869fee6..accc9b7a3ac481 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -4377,7 +4377,7 @@ _ssl__SSLContext_load_dh_params_impl(PySSLContext *self, PyObject *filepath)
     FILE *f;
     DH *dh;
 
-    f = _Py_fopen_obj(filepath, "rb");
+    f = Py_fopen(filepath, "rb");
     if (f == NULL)
         return NULL;
 
diff --git a/Modules/_ssl/debughelpers.c b/Modules/_ssl/debughelpers.c
index 9c87f8b4d21e68..318c045a0eec3c 100644
--- a/Modules/_ssl/debughelpers.c
+++ b/Modules/_ssl/debughelpers.c
@@ -180,8 +180,8 @@ _PySSLContext_set_keylog_filename(PySSLContext *self, PyObject *arg, void *c) {
         return 0;
     }
 
-    /* _Py_fopen_obj() also checks that arg is of proper type. */
-    fp = _Py_fopen_obj(arg, "a" PY_STDIOTEXTMODE);
+    /* Py_fopen() also checks that arg is of proper type. */
+    fp = Py_fopen(arg, "a" PY_STDIOTEXTMODE);
     if (fp == NULL)
         return -1;
 
diff --git a/Modules/_testcapi/clinic/file.c.h b/Modules/_testcapi/clinic/file.c.h
new file mode 100644
index 00000000000000..9856b6161cdfa0
--- /dev/null
+++ b/Modules/_testcapi/clinic/file.c.h
@@ -0,0 +1,48 @@
+/*[clinic input]
+preserve
+[clinic start generated code]*/
+
+#include "pycore_modsupport.h"    // _PyArg_CheckPositional()
+
+PyDoc_STRVAR(_testcapi_py_fopen__doc__,
+"py_fopen($module, path, mode, /)\n"
+"--\n"
+"\n"
+"Call Py_fopen() and return fread(256).");
+
+#define _TESTCAPI_PY_FOPEN_METHODDEF    \
+    {"py_fopen", _PyCFunction_CAST(_testcapi_py_fopen), METH_FASTCALL, _testcapi_py_fopen__doc__},
+
+static PyObject *
+_testcapi_py_fopen_impl(PyObject *module, PyObject *path, const char *mode);
+
+static PyObject *
+_testcapi_py_fopen(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    PyObject *path;
+    const char *mode;
+
+    if (!_PyArg_CheckPositional("py_fopen", nargs, 2, 2)) {
+        goto exit;
+    }
+    path = args[0];
+    if (!PyUnicode_Check(args[1])) {
+        _PyArg_BadArgument("py_fopen", "argument 2", "str", args[1]);
+        goto exit;
+    }
+    Py_ssize_t mode_length;
+    mode = PyUnicode_AsUTF8AndSize(args[1], &mode_length);
+    if (mode == NULL) {
+        goto exit;
+    }
+    if (strlen(mode) != (size_t)mode_length) {
+        PyErr_SetString(PyExc_ValueError, "embedded null character");
+        goto exit;
+    }
+    return_value = _testcapi_py_fopen_impl(module, path, mode);
+
+exit:
+    return return_value;
+}
+/*[clinic end generated code: output=968f4f4a620f13cf input=a9049054013a1b77]*/
diff --git a/Modules/_testcapi/file.c b/Modules/_testcapi/file.c
index 634563f6ea12cb..b163ec0efcb78b 100644
--- a/Modules/_testcapi/file.c
+++ b/Modules/_testcapi/file.c
@@ -1,8 +1,43 @@
+// clinic/file.c.h uses internal pycore_modsupport.h API
+#define PYTESTCAPI_NEED_INTERNAL_API
+
 #include "parts.h"
 #include "util.h"
+#include "clinic/file.c.h"
+
+/*[clinic input]
+module _testcapi
+[clinic start generated code]*/
+/*[clinic end generated code: output=da39a3ee5e6b4b0d input=6361033e795369fc]*/
+
+/*[clinic input]
+_testcapi.py_fopen
+
+    path: object
+    mode: str
+    /
+
+Call Py_fopen() and return fread(256).
+[clinic start generated code]*/
 
+static PyObject *
+_testcapi_py_fopen_impl(PyObject *module, PyObject *path, const char *mode)
+/*[clinic end generated code: output=5a900af000f759de input=0878c2f9333abd60]*/
+{
+    FILE *fp = Py_fopen(path, mode);
+    if (fp == NULL) {
+        return NULL;
+    }
+
+    char buffer[256];
+    size_t size = fread(buffer, 1, Py_ARRAY_LENGTH(buffer), fp);
+    fclose(fp);
+
+    return PyBytes_FromStringAndSize(buffer, size);
+}
 
 static PyMethodDef test_methods[] = {
+    _TESTCAPI_PY_FOPEN_METHODDEF
     {NULL},
 };
 
diff --git a/Modules/_testcapi/object.c b/Modules/_testcapi/object.c
index 3af5429ef00985..841410c52b3ce2 100644
--- a/Modules/_testcapi/object.c
+++ b/Modules/_testcapi/object.c
@@ -15,7 +15,7 @@ call_pyobject_print(PyObject *self, PyObject * args)
         return NULL;
     }
 
-    fp = _Py_fopen_obj(filename, "w+");
+    fp = Py_fopen(filename, "w+");
 
     if (Py_IsTrue(print_raw)) {
         flags = Py_PRINT_RAW;
@@ -41,7 +41,7 @@ pyobject_print_null(PyObject *self, PyObject *args)
         return NULL;
     }
 
-    fp = _Py_fopen_obj(filename, "w+");
+    fp = Py_fopen(filename, "w+");
 
     if (PyObject_Print(NULL, fp, 0) < 0) {
         fclose(fp);
@@ -72,7 +72,7 @@ pyobject_print_noref_object(PyObject *self, PyObject *args)
         return NULL;
     }
 
-    fp = _Py_fopen_obj(filename, "w+");
+    fp = Py_fopen(filename, "w+");
 
     if (PyObject_Print(test_string, fp, 0) < 0){
         fclose(fp);
@@ -103,7 +103,7 @@ pyobject_print_os_error(PyObject *self, PyObject *args)
     }
 
     // open file in read mode to induce OSError
-    fp = _Py_fopen_obj(filename, "r");
+    fp = Py_fopen(filename, "r");
 
     if (PyObject_Print(test_string, fp, 0) < 0) {
         fclose(fp);
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 8d86b535effb9a..994785191c4bb5 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -1744,7 +1744,7 @@ pymarshal_write_long_to_file(PyObject* self, PyObject *args)
                           &value, &filename, &version))
         return NULL;
 
-    fp = _Py_fopen_obj(filename, "wb");
+    fp = Py_fopen(filename, "wb");
     if (fp == NULL) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;
@@ -1769,7 +1769,7 @@ pymarshal_write_object_to_file(PyObject* self, PyObject *args)
                           &obj, &filename, &version))
         return NULL;
 
-    fp = _Py_fopen_obj(filename, "wb");
+    fp = Py_fopen(filename, "wb");
     if (fp == NULL) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;
@@ -1793,7 +1793,7 @@ pymarshal_read_short_from_file(PyObject* self, PyObject *args)
     if (!PyArg_ParseTuple(args, "O:pymarshal_read_short_from_file", &filename))
         return NULL;
 
-    fp = _Py_fopen_obj(filename, "rb");
+    fp = Py_fopen(filename, "rb");
     if (fp == NULL) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;
@@ -1818,7 +1818,7 @@ pymarshal_read_long_from_file(PyObject* self, PyObject *args)
     if (!PyArg_ParseTuple(args, "O:pymarshal_read_long_from_file", &filename))
         return NULL;
 
-    fp = _Py_fopen_obj(filename, "rb");
+    fp = Py_fopen(filename, "rb");
     if (fp == NULL) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;
@@ -1840,7 +1840,7 @@ pymarshal_read_last_object_from_file(PyObject* self, PyObject *args)
     if (!PyArg_ParseTuple(args, "O:pymarshal_read_last_object_from_file", &filename))
         return NULL;
 
-    FILE *fp = _Py_fopen_obj(filename, "rb");
+    FILE *fp = Py_fopen(filename, "rb");
     if (fp == NULL) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;
@@ -1863,7 +1863,7 @@ pymarshal_read_object_from_file(PyObject* self, PyObject *args)
     if (!PyArg_ParseTuple(args, "O:pymarshal_read_object_from_file", &filename))
         return NULL;
 
-    FILE *fp = _Py_fopen_obj(filename, "rb");
+    FILE *fp = Py_fopen(filename, "rb");
     if (fp == NULL) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;
diff --git a/Modules/main.c b/Modules/main.c
index 15ea49a1bad19e..29b944aab84bec 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -370,7 +370,7 @@ pymain_run_file_obj(PyObject *program_name, PyObject *filename,
         return pymain_exit_err_print();
     }
 
-    FILE *fp = _Py_fopen_obj(filename, "rb");
+    FILE *fp = Py_fopen(filename, "rb");
     if (fp == NULL) {
         // Ignore the OSError
         PyErr_Clear();
@@ -464,7 +464,7 @@ pymain_run_startup(PyConfig *config, int *exitcode)
         goto error;
     }
 
-    FILE *fp = _Py_fopen_obj(startup, "r");
+    FILE *fp = Py_fopen(startup, "r");
     if (fp == NULL) {
         int save_errno = errno;
         PyErr_Clear();
diff --git a/Python/errors.c b/Python/errors.c
index 7f3b4aabc432d7..3376012dca4d01 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -1972,7 +1972,7 @@ _PyErr_ProgramDecodedTextObject(PyObject *filename, int lineno, const char* enco
         return NULL;
     }
 
-    FILE *fp = _Py_fopen_obj(filename, "r" PY_STDIOTEXTMODE);
+    FILE *fp = Py_fopen(filename, "r" PY_STDIOTEXTMODE);
     if (fp == NULL) {
         PyErr_Clear();
         return NULL;
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 9529b14d377c60..c039fdc8f3309e 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1748,8 +1748,10 @@ _Py_wfopen(const wchar_t *path, const wchar_t *mode)
 }
 
 
-/* Open a file. Call _wfopen() on Windows, or encode the path to the filesystem
-   encoding and call fopen() otherwise.
+/* Open a file.
+
+   On Windows, if 'path' is a Unicode string, call _wfopen(). Otherwise, encode
+   the path to the filesystem encoding and call fopen().
 
    Return the new file object on success. Raise an exception and return NULL
    on error.
@@ -1762,72 +1764,64 @@ _Py_wfopen(const wchar_t *path, const wchar_t *mode)
    Release the GIL to call _wfopen() or fopen(). The caller must hold
    the GIL. */
 FILE*
-_Py_fopen_obj(PyObject *path, const char *mode)
+Py_fopen(PyObject *path, const char *mode)
 {
-    FILE *f;
-    int async_err = 0;
-#ifdef MS_WINDOWS
-    wchar_t wmode[10];
-    int usize;
-
     assert(PyGILState_Check());
 
     if (PySys_Audit("open", "Osi", path, mode, 0) < 0) {
         return NULL;
     }
-    if (!PyUnicode_Check(path)) {
-        PyErr_Format(PyExc_TypeError,
-                     "str file path expected under Windows, got %R",
-                     Py_TYPE(path));
-        return NULL;
-    }
 
-    wchar_t *wpath = PyUnicode_AsWideCharString(path, NULL);
-    if (wpath == NULL)
-        return NULL;
+    FILE *f;
+    int async_err = 0;
+    int saved_errno;
+#ifdef MS_WINDOWS
+    if (PyUnicode_Check(path)) {
+        wchar_t *wpath = PyUnicode_AsWideCharString(path, NULL);
+        if (wpath == NULL) {
+            return NULL;
+        }
 
-    usize = MultiByteToWideChar(CP_ACP, 0, mode, -1,
-                                wmode, Py_ARRAY_LENGTH(wmode));
-    if (usize == 0) {
-        PyErr_SetFromWindowsErr(0);
+        wchar_t wmode[10];
+        int usize = MultiByteToWideChar(CP_ACP, 0, mode, -1,
+                                        wmode, Py_ARRAY_LENGTH(wmode));
+        if (usize == 0) {
+            PyErr_SetFromWindowsErr(0);
+            PyMem_Free(wpath);
+            return NULL;
+        }
+
+        do {
+            Py_BEGIN_ALLOW_THREADS
+            f = _wfopen(wpath, wmode);
+            Py_END_ALLOW_THREADS
+        } while (f == NULL
+                 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
+        saved_errno = errno;
         PyMem_Free(wpath);
-        return NULL;
     }
+    else
+#endif
+    {
+        PyObject *bytes;
+        if (!PyUnicode_FSConverter(path, &bytes)) {
+            return NULL;
+        }
+        const char *path_bytes = PyBytes_AS_STRING(bytes);
 
-    do {
-        Py_BEGIN_ALLOW_THREADS
-        f = _wfopen(wpath, wmode);
-        Py_END_ALLOW_THREADS
-    } while (f == NULL
-             && errno == EINTR && !(async_err = PyErr_CheckSignals()));
-    int saved_errno = errno;
-    PyMem_Free(wpath);
-#else
-    PyObject *bytes;
-    const char *path_bytes;
-
-    assert(PyGILState_Check());
-
-    if (!PyUnicode_FSConverter(path, &bytes))
-        return NULL;
-    path_bytes = PyBytes_AS_STRING(bytes);
-
-    if (PySys_Audit("open", "Osi", path, mode, 0) < 0) {
+        do {
+            Py_BEGIN_ALLOW_THREADS
+            f = fopen(path_bytes, mode);
+            Py_END_ALLOW_THREADS
+        } while (f == NULL
+                 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
+        saved_errno = errno;
         Py_DECREF(bytes);
-        return NULL;
     }
 
-    do {
-        Py_BEGIN_ALLOW_THREADS
-        f = fopen(path_bytes, mode);
-        Py_END_ALLOW_THREADS
-    } while (f == NULL
-             && errno == EINTR && !(async_err = PyErr_CheckSignals()));
-    int saved_errno = errno;
-    Py_DECREF(bytes);
-#endif
-    if (async_err)
+    if (async_err) {
         return NULL;
+    }
 
     if (f == NULL) {
         errno = saved_errno;
diff --git a/Python/import.c b/Python/import.c
index b3c384c27718ce..9566b596703884 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -4687,7 +4687,7 @@ _imp_create_dynamic_impl(PyObject *module, PyObject *spec, PyObject *file)
      * code relies on fp still being open. */
     FILE *fp;
     if (file != NULL) {
-        fp = _Py_fopen_obj(info.filename, "r");
+        fp = Py_fopen(info.filename, "r");
         if (fp == NULL) {
             goto finally;
         }
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 8b57018321c070..8b8a9e72a9ac61 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -467,7 +467,7 @@ _PyRun_SimpleFileObject(FILE *fp, PyObject *filename, int closeit,
             fclose(fp);
         }
 
-        pyc_fp = _Py_fopen_obj(filename, "rb");
+        pyc_fp = Py_fopen(filename, "rb");
         if (pyc_fp == NULL) {
             fprintf(stderr, "python: Can't reopen .pyc file\n");
             goto done;

From b80f4245e4635306c6c7e3fda08323d5e859390d Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Fri, 13 Dec 2024 14:13:59 +0100
Subject: [PATCH 02/18] Add Py_fclose() function

---
 Doc/c-api/sys.rst                                 | 15 +++++++++++++++
 Doc/whatsnew/3.14.rst                             |  3 ++-
 Include/cpython/fileutils.h                       |  2 ++
 ...2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst |  4 +++-
 Modules/_testcapi/file.c                          |  4 ++--
 Python/fileutils.c                                | 13 +++++++++++++
 6 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index d51e66d45d22b3..21f5c813c5dcdd 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -226,6 +226,9 @@ Operating System Utilities
    On success, return the new file object.
    On error, set an exception and return ``NULL``.
 
+   The file must be closed by :c:func:`Py_fclose` rather than calling directly
+   ``fclose()``.
+
    The file descriptor is created non-inheritable (:pep:`446`).
 
    The caller must hold the GIL.
@@ -233,6 +236,18 @@ Operating System Utilities
    .. versionadded:: next
 
 
+.. c:function:: int Py_fclose(FILE *file)
+
+   Call ``fclose(file)``.
+
+   This function is needed on Windows: ``FILE*`` files opened by
+   :c:func:`Py_fopen` in the Python DLL must be closed by the Python DLL to use
+   the same C runtime version. Otherwise, calling ``fclose()`` directly can
+   cause undefined behavior.
+
+   .. versionadded:: next
+
+
 .. _systemfunctions:
 
 System Functions
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index 2ce1bcdad75fbc..22221cc51675ec 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -1036,7 +1036,8 @@ New features
 
 * Add :c:func:`Py_fopen` function to open a file. Similar to the
   :c:func:`!fopen` function, but the *path* parameter is a Python object and an
-  exception is set on error.
+  exception is set on error. Add also :c:func:`Py_fclose` function to close a
+  file, function needed for Windows support.
   (Contributed by Victor Stinner in :gh:`127350`.)
 
 Porting to Python 3.14
diff --git a/Include/cpython/fileutils.h b/Include/cpython/fileutils.h
index 3a2bfae1add88e..c65e5d807266d6 100644
--- a/Include/cpython/fileutils.h
+++ b/Include/cpython/fileutils.h
@@ -5,3 +5,5 @@
 PyAPI_FUNC(FILE*) Py_fopen(
     PyObject *path,
     const char *mode);
+
+PyAPI_FUNC(int) Py_fclose(FILE *file);
diff --git a/Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst b/Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst
index e3a914188ca680..d1b528c673442f 100644
--- a/Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst
+++ b/Misc/NEWS.d/next/C_API/2024-12-11-13-01-26.gh-issue-127350.uEBZZ4.rst
@@ -1,3 +1,5 @@
 Add :c:func:`Py_fopen` function to open a file. Similar to the :c:func:`!fopen`
 function, but the *path* parameter is a Python object and an exception is set
-on error. Patch by Victor Stinner.
+on error. Add also :c:func:`Py_fclose` function to close a file, function
+needed for Windows support.
+Patch by Victor Stinner.
diff --git a/Modules/_testcapi/file.c b/Modules/_testcapi/file.c
index b163ec0efcb78b..0ce0780623b9cd 100644
--- a/Modules/_testcapi/file.c
+++ b/Modules/_testcapi/file.c
@@ -17,7 +17,7 @@ _testcapi.py_fopen
     mode: str
     /
 
-Call Py_fopen() and return fread(256).
+Call Py_fopen(), fread(256) and Py_fclose(). Return read bytes.
 [clinic start generated code]*/
 
 static PyObject *
@@ -31,7 +31,7 @@ _testcapi_py_fopen_impl(PyObject *module, PyObject *path, const char *mode)
 
     char buffer[256];
     size_t size = fread(buffer, 1, Py_ARRAY_LENGTH(buffer), fp);
-    fclose(fp);
+    Py_fclose(fp);
 
     return PyBytes_FromStringAndSize(buffer, size);
 }
diff --git a/Python/fileutils.c b/Python/fileutils.c
index c039fdc8f3309e..7075e6a6938efe 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1836,6 +1836,19 @@ Py_fopen(PyObject *path, const char *mode)
     return f;
 }
 
+
+// Call fclose().
+//
+// This function is needed on Windows: FILE* files opened by Py_fopen() in the
+// Python DLL must be closed by the Python DLL to use the same C runtime
+// version. Otherwise, calling fclose() directly can cause undefined behavior.
+int
+Py_fclose(FILE *file)
+{
+    return fclose(file);
+}
+
+
 /* Read count bytes from fd into buf.
 
    On success, return the number of read bytes, it can be lower than count.

From 7390c5e6ff85f713b2ba1728f058eac3a8496889 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Fri, 13 Dec 2024 14:37:55 +0100
Subject: [PATCH 03/18] Replace _Py_fopen_obj() with Py_fopen() in sysmodule.c

---
 Python/sysmodule.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index d6719f9bb0af91..887591a681b25c 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -2356,7 +2356,7 @@ static PyObject *
 sys__dump_tracelets_impl(PyObject *module, PyObject *outpath)
 /*[clinic end generated code: output=a7fe265e2bc3b674 input=5bff6880cd28ffd1]*/
 {
-    FILE *out = _Py_fopen_obj(outpath, "wb");
+    FILE *out = Py_fopen(outpath, "wb");
     if (out == NULL) {
         return NULL;
     }

From 26a5a5698e43419f52ad831cd3706916fc525907 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Fri, 13 Dec 2024 15:44:50 +0100
Subject: [PATCH 04/18] Simplify Py_fclose() documentation

---
 Doc/c-api/sys.rst     | 5 -----
 Doc/whatsnew/3.14.rst | 2 +-
 Python/fileutils.c    | 6 +++---
 3 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index 21f5c813c5dcdd..b132988aeac875 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -240,11 +240,6 @@ Operating System Utilities
 
    Call ``fclose(file)``.
 
-   This function is needed on Windows: ``FILE*`` files opened by
-   :c:func:`Py_fopen` in the Python DLL must be closed by the Python DLL to use
-   the same C runtime version. Otherwise, calling ``fclose()`` directly can
-   cause undefined behavior.
-
    .. versionadded:: next
 
 
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index c12dd3aa13f936..918d34b3ed40b6 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -1048,7 +1048,7 @@ New features
 * Add :c:func:`Py_fopen` function to open a file. Similar to the
   :c:func:`!fopen` function, but the *path* parameter is a Python object and an
   exception is set on error. Add also :c:func:`Py_fclose` function to close a
-  file, function needed for Windows support.
+  file.
   (Contributed by Victor Stinner in :gh:`127350`.)
 
 Porting to Python 3.14
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 7075e6a6938efe..a3f889cb8a65e7 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1839,9 +1839,9 @@ Py_fopen(PyObject *path, const char *mode)
 
 // Call fclose().
 //
-// This function is needed on Windows: FILE* files opened by Py_fopen() in the
-// Python DLL must be closed by the Python DLL to use the same C runtime
-// version. Otherwise, calling fclose() directly can cause undefined behavior.
+// On Windows, files opened by Py_fopen() in the Python DLL must be closed by
+// the Python DLL to use the same C runtime version. Otherwise, calling
+// fclose() directly can cause undefined behavior.
 int
 Py_fclose(FILE *file)
 {

From 4375566a429ad288331a7f92e2462d7bace887b7 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Fri, 13 Dec 2024 16:09:37 +0100
Subject: [PATCH 05/18] Run make clinic

---
 Modules/_testcapi/clinic/file.c.h | 4 ++--
 Modules/_testcapi/file.c          | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Modules/_testcapi/clinic/file.c.h b/Modules/_testcapi/clinic/file.c.h
index 9856b6161cdfa0..2ca21fffcef680 100644
--- a/Modules/_testcapi/clinic/file.c.h
+++ b/Modules/_testcapi/clinic/file.c.h
@@ -8,7 +8,7 @@ PyDoc_STRVAR(_testcapi_py_fopen__doc__,
 "py_fopen($module, path, mode, /)\n"
 "--\n"
 "\n"
-"Call Py_fopen() and return fread(256).");
+"Call Py_fopen(), fread(256) and Py_fclose(). Return read bytes.");
 
 #define _TESTCAPI_PY_FOPEN_METHODDEF    \
     {"py_fopen", _PyCFunction_CAST(_testcapi_py_fopen), METH_FASTCALL, _testcapi_py_fopen__doc__},
@@ -45,4 +45,4 @@ _testcapi_py_fopen(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=968f4f4a620f13cf input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c9fe964c3e5a0c32 input=a9049054013a1b77]*/
diff --git a/Modules/_testcapi/file.c b/Modules/_testcapi/file.c
index 0ce0780623b9cd..4bad43010fd440 100644
--- a/Modules/_testcapi/file.c
+++ b/Modules/_testcapi/file.c
@@ -22,7 +22,7 @@ Call Py_fopen(), fread(256) and Py_fclose(). Return read bytes.
 
 static PyObject *
 _testcapi_py_fopen_impl(PyObject *module, PyObject *path, const char *mode)
-/*[clinic end generated code: output=5a900af000f759de input=0878c2f9333abd60]*/
+/*[clinic end generated code: output=5a900af000f759de input=d7e7b8f0fd151953]*/
 {
     FILE *fp = Py_fopen(path, mode);
     if (fp == NULL) {

From a7793215dfce7819ab82f726815b29ebdfef0236 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Fri, 13 Dec 2024 19:11:13 +0100
Subject: [PATCH 06/18] Update Doc/c-api/sys.rst

Co-authored-by: Steve Dower <steve.dower@microsoft.com>
---
 Doc/c-api/sys.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index b132988aeac875..10178bbd42cbb6 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -238,7 +238,7 @@ Operating System Utilities
 
 .. c:function:: int Py_fclose(FILE *file)
 
-   Call ``fclose(file)``.
+   Closes files that were opened by :c:func:`Py_fopen`.
 
    .. versionadded:: next
 

From e6133740e832018ea35888e43a88d009c35a2782 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 16 Dec 2024 13:41:42 +0100
Subject: [PATCH 07/18] Document Py_fclose() return value

---
 Doc/c-api/sys.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index 10178bbd42cbb6..2d044dbb30afcd 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -240,6 +240,11 @@ Operating System Utilities
 
    Closes files that were opened by :c:func:`Py_fopen`.
 
+   On success, return ``0``.
+   On error, return ``EOF`` and ``errno`` is set to indicate the error.
+   In either case, any further access (including another call to
+   :c:func:`Py_fclose`) to the stream results in undefined behavior.
+
    .. versionadded:: next
 
 

From 2af4d2b3c24e73d0ecafed22e9fddf9745c1f4e5 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 11:31:37 +0100
Subject: [PATCH 08/18] Address some of Serhiy's review

---
 Doc/c-api/sys.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index 2d044dbb30afcd..daa4ab06e647b6 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -223,7 +223,7 @@ Operating System Utilities
 
    *path* must be a :class:`str` object or a :class:`bytes` object.
 
-   On success, return the new file object.
+   On success, return the new file pointer.
    On error, set an exception and return ``NULL``.
 
    The file must be closed by :c:func:`Py_fclose` rather than calling directly

From 8e9170ea2c1ee50fc68b3113b6829b0b8aa13e2a Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 11:32:56 +0100
Subject: [PATCH 09/18] Address Erlend's review

---
 Doc/c-api/sys.rst | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index daa4ab06e647b6..ef62849505bf2a 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -218,7 +218,7 @@ Operating System Utilities
 
 .. c:function:: FILE* Py_fopen(PyObject *path, const char *mode)
 
-   Similar to the :c:func:`!fopen` function, but *path* is a Python object and
+   Similar to :c:func:`!fopen`, but *path* is a Python object and
    an exception is set on error.
 
    *path* must be a :class:`str` object or a :class:`bytes` object.
@@ -227,7 +227,7 @@ Operating System Utilities
    On error, set an exception and return ``NULL``.
 
    The file must be closed by :c:func:`Py_fclose` rather than calling directly
-   ``fclose()``.
+   :c:func:`!fclose`.
 
    The file descriptor is created non-inheritable (:pep:`446`).
 
@@ -238,7 +238,7 @@ Operating System Utilities
 
 .. c:function:: int Py_fclose(FILE *file)
 
-   Closes files that were opened by :c:func:`Py_fopen`.
+   Close a file that was opened by :c:func:`Py_fopen`.
 
    On success, return ``0``.
    On error, return ``EOF`` and ``errno`` is set to indicate the error.

From a8c26b2707e74c6b1ca593d4123cc7f283e2d5c5 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 11:51:03 +0100
Subject: [PATCH 10/18] Add more tests

---
 Lib/test/test_capi/test_file.py | 34 ++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_capi/test_file.py b/Lib/test/test_capi/test_file.py
index 68e63ad2a3e490..bae4bce3dcc0a9 100644
--- a/Lib/test/test_capi/test_file.py
+++ b/Lib/test/test_capi/test_file.py
@@ -1,23 +1,55 @@
 import os
 import unittest
-from test.support import import_helper
+from test import support
+from test.support import import_helper, os_helper
 
 _testcapi = import_helper.import_module('_testcapi')
 
 
 class CAPIFileTest(unittest.TestCase):
     def test_py_fopen(self):
+        # Test Py_fopen() and Py_fclose()
         for filename in (__file__, os.fsencode(__file__)):
             with self.subTest(filename=filename):
                 content = _testcapi.py_fopen(filename, "rb")
                 with open(filename, "rb") as fp:
                     self.assertEqual(fp.read(256), content)
 
+        with open(__file__, "rb") as fp:
+            content = fp.read()
+        for filename in (
+            os_helper.TESTFN,
+            os.fsencode(os_helper.TESTFN),
+            os_helper.TESTFN_UNDECODABLE,
+            os_helper.TESTFN_UNENCODABLE,
+        ):
+            with self.subTest(filename=filename):
+                try:
+                    with open(filename, "wb") as fp:
+                        fp.write(content)
+
+                    content = _testcapi.py_fopen(filename, "rb")
+                    with open(filename, "rb") as fp:
+                        self.assertEqual(fp.read(256), content[:256])
+                finally:
+                    os_helper.unlink(filename)
+
+        # embedded null character/byte in the filename
+        with self.assertRaises(ValueError):
+            _testcapi.py_fopen("a\x00b", "rb")
+        with self.assertRaises(ValueError):
+            _testcapi.py_fopen(b"a\x00b", "rb")
+
         for invalid_type in (123, object()):
             with self.subTest(filename=invalid_type):
                 with self.assertRaises(TypeError):
                     _testcapi.py_fopen(invalid_type, "r")
 
+        if support.MS_WINDOWS:
+            with self.assertRaises(OSError):
+                # On Windows, the file mode is limited to 10 characters
+                _testcapi.py_fopen(__file__, "rt+, ccs=UTF-8")
+
 
 if __name__ == "__main__":
     unittest.main()

From 5b52a4e63dcd5ca445bdb721feb44f3d622c6e70 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 12:08:40 +0100
Subject: [PATCH 11/18] Support __fspath__() protocol on Windows

Test also non-ASCII mode.
---
 Lib/test/test_capi/test_file.py | 33 +++++++++++++++++++++++----------
 Python/fileutils.c              |  6 ++++++
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/Lib/test/test_capi/test_file.py b/Lib/test/test_capi/test_file.py
index bae4bce3dcc0a9..66a7e18f59a108 100644
--- a/Lib/test/test_capi/test_file.py
+++ b/Lib/test/test_capi/test_file.py
@@ -9,14 +9,23 @@
 class CAPIFileTest(unittest.TestCase):
     def test_py_fopen(self):
         # Test Py_fopen() and Py_fclose()
+        class FSPath:
+            def __init__(self, path):
+                self.path = path
+            def __fspath__(self):
+                return self.path
+
+        with open(__file__, "rb") as fp:
+            source = fp.read()
+
         for filename in (__file__, os.fsencode(__file__)):
             with self.subTest(filename=filename):
-                content = _testcapi.py_fopen(filename, "rb")
-                with open(filename, "rb") as fp:
-                    self.assertEqual(fp.read(256), content)
+                data = _testcapi.py_fopen(filename, "rb")
+                self.assertEqual(data, source[:256])
+
+                data = _testcapi.py_fopen(FSPath(filename), "rb")
+                self.assertEqual(data, source[:256])
 
-        with open(__file__, "rb") as fp:
-            content = fp.read()
         for filename in (
             os_helper.TESTFN,
             os.fsencode(os_helper.TESTFN),
@@ -26,11 +35,10 @@ def test_py_fopen(self):
             with self.subTest(filename=filename):
                 try:
                     with open(filename, "wb") as fp:
-                        fp.write(content)
+                        fp.write(source)
 
-                    content = _testcapi.py_fopen(filename, "rb")
-                    with open(filename, "rb") as fp:
-                        self.assertEqual(fp.read(256), content[:256])
+                    data = _testcapi.py_fopen(filename, "rb")
+                    self.assertEqual(data, source[:256])
                 finally:
                     os_helper.unlink(filename)
 
@@ -40,10 +48,15 @@ def test_py_fopen(self):
         with self.assertRaises(ValueError):
             _testcapi.py_fopen(b"a\x00b", "rb")
 
+        # non-ASCII mode failing with "Invalid argument"
+        with self.assertRaises(OSError):
+            _testcapi.py_fopen(__file__, "\xe9")
+
+        # invalid filename type
         for invalid_type in (123, object()):
             with self.subTest(filename=invalid_type):
                 with self.assertRaises(TypeError):
-                    _testcapi.py_fopen(invalid_type, "r")
+                    _testcapi.py_fopen(invalid_type, "rb")
 
         if support.MS_WINDOWS:
             with self.assertRaises(OSError):
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 746f86aeaeab54..0d3baeccdf4013 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1776,6 +1776,12 @@ Py_fopen(PyObject *path, const char *mode)
     int async_err = 0;
     int saved_errno;
 #ifdef MS_WINDOWS
+    PyObject *fspath = PyOS_FSPath(arg);
+    if (fspath == NULL) {
+        return NULL;
+    }
+    Py_SETREF(path, fspath);
+
     if (PyUnicode_Check(path)) {
         wchar_t *wpath = PyUnicode_AsWideCharString(path, NULL);
         if (wpath == NULL) {

From e6a53feda01b5d47675de112c596e24773562585 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 12:10:27 +0100
Subject: [PATCH 12/18] Update doc for path-like object

---
 Doc/c-api/sys.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Doc/c-api/sys.rst b/Doc/c-api/sys.rst
index ef62849505bf2a..7a7d39aea20baf 100644
--- a/Doc/c-api/sys.rst
+++ b/Doc/c-api/sys.rst
@@ -221,7 +221,8 @@ Operating System Utilities
    Similar to :c:func:`!fopen`, but *path* is a Python object and
    an exception is set on error.
 
-   *path* must be a :class:`str` object or a :class:`bytes` object.
+   *path* must be a :class:`str` object, a :class:`bytes` object,
+   or a :term:`path-like object`.
 
    On success, return the new file pointer.
    On error, set an exception and return ``NULL``.

From 1d1e7f4985ae0dcd177e5bccc41b174192f44ed5 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 12:15:45 +0100
Subject: [PATCH 13/18] Keep _Py_fopen_obj() function

---
 Include/cpython/fileutils.h | 5 +++++
 Python/fileutils.c          | 8 ++++++++
 2 files changed, 13 insertions(+)

diff --git a/Include/cpython/fileutils.h b/Include/cpython/fileutils.h
index c65e5d807266d6..702f89aca324c5 100644
--- a/Include/cpython/fileutils.h
+++ b/Include/cpython/fileutils.h
@@ -6,4 +6,9 @@ PyAPI_FUNC(FILE*) Py_fopen(
     PyObject *path,
     const char *mode);
 
+// Deprecated alias to Py_fopen() kept for backward compatibility
+Py_DEPRECATED(3.14) PyAPI_FUNC(FILE*) _Py_fopen_obj(
+    PyObject *path,
+    const char *mode);
+
 PyAPI_FUNC(int) Py_fclose(FILE *file);
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 0d3baeccdf4013..e05eda7c6108b2 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1843,6 +1843,14 @@ Py_fopen(PyObject *path, const char *mode)
 }
 
 
+// Deprecated alias to Py_fopen() kept for backward compatibility
+FILE*
+_Py_fopen_obj(PyObject *path, const char *mode)
+{
+    return Py_fopen(path, mode);
+}
+
+
 // Call fclose().
 //
 // On Windows, files opened by Py_fopen() in the Python DLL must be closed by

From 335c1bc5e2ea677b79b0a1e751b73f9f508174e3 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 12:16:53 +0100
Subject: [PATCH 14/18] Fix typo

---
 Python/fileutils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Python/fileutils.c b/Python/fileutils.c
index e05eda7c6108b2..246ea27227717d 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1776,7 +1776,7 @@ Py_fopen(PyObject *path, const char *mode)
     int async_err = 0;
     int saved_errno;
 #ifdef MS_WINDOWS
-    PyObject *fspath = PyOS_FSPath(arg);
+    PyObject *fspath = PyOS_FSPath(path);
     if (fspath == NULL) {
         return NULL;
     }

From 82414221f5b0386a0464173c5cb48a4c880a8d73 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 12:34:36 +0100
Subject: [PATCH 15/18] Fix test on macOS and WASI

* Skip TESTFN_UNENCODABLE if it's None.
* Remove TESTFN_UNDECODABLE test.
---
 Lib/test/test_capi/test_file.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/Lib/test/test_capi/test_file.py b/Lib/test/test_capi/test_file.py
index 66a7e18f59a108..d0a7b3d3d75441 100644
--- a/Lib/test/test_capi/test_file.py
+++ b/Lib/test/test_capi/test_file.py
@@ -26,12 +26,14 @@ def __fspath__(self):
                 data = _testcapi.py_fopen(FSPath(filename), "rb")
                 self.assertEqual(data, source[:256])
 
-        for filename in (
+        filenames = [
             os_helper.TESTFN,
             os.fsencode(os_helper.TESTFN),
-            os_helper.TESTFN_UNDECODABLE,
-            os_helper.TESTFN_UNENCODABLE,
-        ):
+        ]
+        # TESTFN_UNDECODABLE cannot be used to create a file on macOS/WASI.
+        if os_helper.TESTFN_UNENCODABLE is not None:
+            filenames.append(os_helper.TESTFN_UNENCODABLE)
+        for filename in filenames:
             with self.subTest(filename=filename):
                 try:
                     with open(filename, "wb") as fp:

From c91aa82dc4a059126c9730d5c03ee3ba6dd883ef Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 13:13:43 +0100
Subject: [PATCH 16/18] Rewrite the Windows implementation

---
 Python/fileutils.c | 78 ++++++++++++++++++++++------------------------
 1 file changed, 38 insertions(+), 40 deletions(-)

diff --git a/Python/fileutils.c b/Python/fileutils.c
index 246ea27227717d..6bc3a44c3c1313 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1776,54 +1776,52 @@ Py_fopen(PyObject *path, const char *mode)
     int async_err = 0;
     int saved_errno;
 #ifdef MS_WINDOWS
-    PyObject *fspath = PyOS_FSPath(path);
-    if (fspath == NULL) {
+    PyObject *unicode;
+    if (!PyUnicode_FSDecoder(path, &unicode)) {
         return NULL;
     }
-    Py_SETREF(path, fspath);
 
-    if (PyUnicode_Check(path)) {
-        wchar_t *wpath = PyUnicode_AsWideCharString(path, NULL);
-        if (wpath == NULL) {
-            return NULL;
-        }
-
-        wchar_t wmode[10];
-        int usize = MultiByteToWideChar(CP_ACP, 0, mode, -1,
-                                        wmode, Py_ARRAY_LENGTH(wmode));
-        if (usize == 0) {
-            PyErr_SetFromWindowsErr(0);
-            PyMem_Free(wpath);
-            return NULL;
-        }
+    wchar_t *wpath = PyUnicode_AsWideCharString(unicode, NULL);
+    Py_DECREF(unicode);
+    if (wpath == NULL) {
+        return NULL;
+    }
 
-        do {
-            Py_BEGIN_ALLOW_THREADS
-            f = _wfopen(wpath, wmode);
-            Py_END_ALLOW_THREADS
-        } while (f == NULL
-                 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
-        saved_errno = errno;
+    wchar_t wmode[10];
+    int usize = MultiByteToWideChar(CP_ACP, 0, mode, -1,
+                                    wmode, Py_ARRAY_LENGTH(wmode));
+    if (usize == 0) {
+        PyErr_SetFromWindowsErr(0);
         PyMem_Free(wpath);
+        return NULL;
     }
-    else
-#endif
-    {
-        PyObject *bytes;
-        if (!PyUnicode_FSConverter(path, &bytes)) {
-            return NULL;
-        }
-        const char *path_bytes = PyBytes_AS_STRING(bytes);
 
-        do {
-            Py_BEGIN_ALLOW_THREADS
-            f = fopen(path_bytes, mode);
-            Py_END_ALLOW_THREADS
-        } while (f == NULL
-                 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
-        saved_errno = errno;
-        Py_DECREF(bytes);
+    do {
+        Py_BEGIN_ALLOW_THREADS
+        _Py_BEGIN_SUPPRESS_IPH
+        f = _wfopen(wpath, wmode);
+        _Py_END_SUPPRESS_IPH
+        Py_END_ALLOW_THREADS
+    } while (f == NULL
+             && errno == EINTR && !(async_err = PyErr_CheckSignals()));
+    saved_errno = errno;
+    PyMem_Free(wpath);
+#else
+    PyObject *bytes;
+    if (!PyUnicode_FSConverter(path, &bytes)) {
+        return NULL;
     }
+    const char *path_bytes = PyBytes_AS_STRING(bytes);
+
+    do {
+        Py_BEGIN_ALLOW_THREADS
+        f = fopen(path_bytes, mode);
+        Py_END_ALLOW_THREADS
+    } while (f == NULL
+             && errno == EINTR && !(async_err = PyErr_CheckSignals()));
+    saved_errno = errno;
+    Py_DECREF(bytes);
+#endif
 
     if (async_err) {
         return NULL;

From 0fc6dc10d767f93ead306cb06cb06fdedeacaf98 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 13:17:03 +0100
Subject: [PATCH 17/18] Use FakePath

---
 Lib/test/test_capi/test_file.py | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/Lib/test/test_capi/test_file.py b/Lib/test/test_capi/test_file.py
index d0a7b3d3d75441..3f25a1e7fe0588 100644
--- a/Lib/test/test_capi/test_file.py
+++ b/Lib/test/test_capi/test_file.py
@@ -9,11 +9,6 @@
 class CAPIFileTest(unittest.TestCase):
     def test_py_fopen(self):
         # Test Py_fopen() and Py_fclose()
-        class FSPath:
-            def __init__(self, path):
-                self.path = path
-            def __fspath__(self):
-                return self.path
 
         with open(__file__, "rb") as fp:
             source = fp.read()
@@ -23,7 +18,7 @@ def __fspath__(self):
                 data = _testcapi.py_fopen(filename, "rb")
                 self.assertEqual(data, source[:256])
 
-                data = _testcapi.py_fopen(FSPath(filename), "rb")
+                data = _testcapi.py_fopen(os_helper.FakePath(filename), "rb")
                 self.assertEqual(data, source[:256])
 
         filenames = [

From dda433569a6ecdae30495cf90fd6c24ef26db2f0 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Jan 2025 13:19:18 +0100
Subject: [PATCH 18/18] NULL mode does crash

---
 Lib/test/test_capi/test_file.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/test/test_capi/test_file.py b/Lib/test/test_capi/test_file.py
index 3f25a1e7fe0588..8a08a0a93eb8b7 100644
--- a/Lib/test/test_capi/test_file.py
+++ b/Lib/test/test_capi/test_file.py
@@ -60,6 +60,8 @@ def test_py_fopen(self):
                 # On Windows, the file mode is limited to 10 characters
                 _testcapi.py_fopen(__file__, "rt+, ccs=UTF-8")
 
+        # CRASHES py_fopen(__file__, None)
+
 
 if __name__ == "__main__":
     unittest.main()