Mar 2, 2026 · Mar 1, 2026 · Mar 1, 2026 · Mar 2, 2026 · Mar 2, 2026
diff --git a/Lib/test/test_os/test_os.py b/Lib/test/test_os/test_os.py
        self.check(os.pathconf, "PC_NAME_MAX")
        self.check(os.fpathconf, "PC_NAME_MAX")

    @unittest.skipUnless(hasattr(os, 'pathconf'), 'test needs os.pathconf()')
    @unittest.skipIf(
        support.linked_to_musl(),
        'musl fpathconf ignores the file descriptor and returns a constant',
        )
    def test_pathconf_negative_fd_uses_fd_semantics(self):
        with self.assertRaises(OSError) as ctx:
            os.pathconf(-1, 1)
        self.assertEqual(ctx.exception.errno, errno.EBADF)

    @unittest.skipUnless(hasattr(os, 'ftruncate'), 'test needs os.ftruncate()')
    def test_ftruncate(self):
        self.check(os.truncate, 0)
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-03-01-13-37-31.gh-issue-145335.e36kPJ.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-01-13-37-31.gh-issue-145335.e36kPJ.rst
 Fix a crash in :func:`os.pathconf` when called with ``-1`` as the path
 argument.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
 *     Contains a file descriptor if path.accept_fd was true
 *     and the caller provided a signed integer instead of any
 *     sort of string.
 *   path.is_fd
 *     True if path was provided as a file descriptor.
 *
 *     WARNING: if your "path" parameter is optional, and is
 *     unspecified, path_converter will never get called.
    const wchar_t *wide;
    const char *narrow;
    int fd;
    bool is_fd;
    int value_error;
    Py_ssize_t length;
    PyObject *object;
 #define PATH_T_INITIALIZE(function_name, argument_name, nullable, nonstrict, \
                          make_wide, suppress_value_error, allow_fd) \
    {function_name, argument_name, nullable, nonstrict, make_wide, \
     suppress_value_error, allow_fd, NULL, NULL, -1, 0, 0, NULL, NULL}
     suppress_value_error, allow_fd, NULL, NULL, -1,false,0, 0, NULL, NULL}
 #ifdef MS_WINDOWS
 #define PATH_T_INITIALIZE_P(function_name, argument_name, nullable, \
                            nonstrict, suppress_value_error, allow_fd) \
        }
        path->wide = NULL;
        path->narrow = NULL;
        path->is_fd = true;
        goto success_exit;
    }
    else {

    errno = 0;
 #ifdef HAVE_FPATHCONF
    if (path->fd != -1)
    if (path->is_fd) {
        limit = fpathconf(path->fd, name);
    }
    else
 #endif
        limit = pathconf(path->narrow, name);
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2778,6 +2778,16 @@ def test_fpathconf_bad_fd(self):
		self.check(os.pathconf, "PC_NAME_MAX")
		self.check(os.fpathconf, "PC_NAME_MAX")

		@unittest.skipUnless(hasattr(os, 'pathconf'), 'test needs os.pathconf()')
		@unittest.skipIf(
		support.linked_to_musl(),
		'musl fpathconf ignores the file descriptor and returns a constant',
		)
		def test_pathconf_negative_fd_uses_fd_semantics(self):
		with self.assertRaises(OSError) as ctx:
		os.pathconf(-1, 1)
		self.assertEqual(ctx.exception.errno, errno.EBADF)

		@unittest.skipUnless(hasattr(os, 'ftruncate'), 'test needs os.ftruncate()')
		def test_ftruncate(self):
		self.check(os.truncate, 0)
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Fix a crash in :func:`os.pathconf` when called with ``-1`` as the path
		argument.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1280,6 +1280,8 @@ get_posix_state(PyObject *module)
		* Contains a file descriptor if path.accept_fd was true
		* and the caller provided a signed integer instead of any
		* sort of string.
		* path.is_fd
		* True if path was provided as a file descriptor.
		*
		* WARNING: if your "path" parameter is optional, and is
		* unspecified, path_converter will never get called.
Expand DownExpand Up		@@ -1332,6 +1334,7 @@ typedef struct {
		const wchar_t *wide;
		const char *narrow;
		int fd;
		bool is_fd;
		int value_error;
		Py_ssize_t length;
		PyObject *object;
Expand All		@@ -1341,7 +1344,7 @@ typedef struct {
		#define PATH_T_INITIALIZE(function_name, argument_name, nullable, nonstrict, \
		make_wide, suppress_value_error, allow_fd) \
		{function_name, argument_name, nullable, nonstrict, make_wide, \
		suppress_value_error, allow_fd, NULL, NULL, -1, 0, 0, NULL, NULL}
		suppress_value_error, allow_fd, NULL, NULL, -1,false,0, 0, NULL, NULL}
		#ifdef MS_WINDOWS
		#define PATH_T_INITIALIZE_P(function_name, argument_name, nullable, \
		nonstrict, suppress_value_error, allow_fd) \
Expand DownExpand Up		@@ -1475,6 +1478,7 @@ path_converter(PyObject o, void p)
		}
		path->wide = NULL;
		path->narrow = NULL;
		path->is_fd = true;
		goto success_exit;
		}
		else {
Expand DownExpand Up		@@ -14328,8 +14332,9 @@ os_pathconf_impl(PyObject module, path_t path, int name)

		errno = 0;
		#ifdef HAVE_FPATHCONF
		if (path->fd != -1)
		if (path->is_fd) {
		limit = fpathconf(path->fd, name);
		}
		else
		#endif
		limit = pathconf(path->narrow, name);
Expand Down