issue27186: add C version of os.fspath(); patch by Jelle Zijlstra

Include/Python.h

@@ -116,6 +116,7 @@
 #include "pylifecycle.h"
 #include "ceval.h"
 #include "sysmodule.h"
+#include "osmodule.h"
 #include "intrcheck.h"
 #include "import.h"
 

Include/osmodule.h

@@ -0,0 +1,15 @@
+
+/* os module interface */
+
+#ifndef Py_OSMODULE_H
+#define Py_OSMODULE_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+PyAPI_FUNC(PyObject *) PyOS_FSPath(PyObject *path);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_OSMODULE_H */

Lib/os.py

@@ -1104,8 +1104,9 @@ def fdopen(fd, *args, **kwargs):
     import io
     return io.open(fd, *args, **kwargs)
 
-# Supply os.fspath()
-def fspath(path):
+# Supply os.fspath() if not defined in C
+if not _exists('fspath'):
+    def fspath(path):
         """Return the string representation of the path.
 
         If str or bytes is passed in, it is returned unchanged.

Lib/test/test_os.py

@@ -3121,6 +3121,13 @@ class TestPEP519(unittest.TestCase):
             self.assertEqual(b"path/like/object", os.fsencode(pathlike))
             self.assertEqual("path/like/object", os.fsdecode(pathlike))
 
+    def test_fspathlike(self):
+        class PathLike(object):
+            def __fspath__(self):
+                return '#feelthegil'
+
+        self.assertEqual('#feelthegil', os.fspath(PathLike()))
+
     def test_garbage_in_exception_out(self):
         vapor = type('blah', (), {})
         for o in int, type, os, vapor():

Modules/clinic/posixmodule.c.h

@@ -5321,6 +5321,38 @@ exit:
 
 #endif /* defined(MS_WINDOWS) */
 
+PyDoc_STRVAR(os_fspath__doc__,
+"fspath($module, /, path)\n"
+"--\n"
+"\n"
+"Return the file system path representation of the object.\n"
+"\n"
+"If the object is str or bytes, then allow it to pass through with\n"
+"an incremented refcount. If the object defines __fspath__(), then\n"
+"return the result of that method. All other types raise a TypeError.");
+
+#define OS_FSPATH_METHODDEF    \
+    {"fspath", (PyCFunction)os_fspath, METH_VARARGS|METH_KEYWORDS, os_fspath__doc__},
+
+static PyObject *
+os_fspath_impl(PyModuleDef *module, PyObject *path);
+
+static PyObject *
+os_fspath(PyModuleDef *module, PyObject *args, PyObject *kwargs)
+{
+    PyObject *return_value = NULL;
+    static char *_keywords[] = {"path", NULL};
+    PyObject *path;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O:fspath", _keywords,
+        &path))
+        goto exit;
+    return_value = os_fspath_impl(module, path);
+
+exit:
+    return return_value;
+}
+
 #ifndef OS_TTYNAME_METHODDEF
     #define OS_TTYNAME_METHODDEF
 #endif /* !defined(OS_TTYNAME_METHODDEF) */
@@ -5792,4 +5824,4 @@ exit:
 #ifndef OS_SET_HANDLE_INHERITABLE_METHODDEF
     #define OS_SET_HANDLE_INHERITABLE_METHODDEF
 #endif /* !defined(OS_SET_HANDLE_INHERITABLE_METHODDEF) */
-/*[clinic end generated code: output=a5c9bef9ad11a20b input=a9049054013a1b77]*/
+/*[clinic end generated code: output=e64e246b8270abda input=a9049054013a1b77]*/

Modules/posixmodule.c

@@ -12284,6 +12284,56 @@ error:
     return NULL;
 }
 
+/*
+    Return the file system path representation of the object.
+
+    If the object is str or bytes, then allow it to pass through with
+    an incremented refcount. If the object defines __fspath__(), then
+    return the result of that method. All other types raise a TypeError.
+*/
+PyObject *
+PyOS_FSPath(PyObject *path)
+{
+    _Py_IDENTIFIER(__fspath__);
+    PyObject *func = NULL;
+    PyObject *path_repr = NULL;
+
+    if (PyUnicode_Check(path) || PyBytes_Check(path)) {
+        Py_INCREF(path);
+        return path;
+    }
+
+    func = _PyObject_LookupSpecial(path, &PyId___fspath__);
+    if (NULL == func) {
+        return PyErr_Format(PyExc_TypeError,
+                            "expected str, bytes or os.PathLike object, "
+                            "not %S",
+                            path->ob_type);
+    }
+
+    path_repr = PyObject_CallFunctionObjArgs(func, NULL);
+    Py_DECREF(func);
+    return path_repr;
+}
+
+/*[clinic input]
+os.fspath
+
+    path: object
+
+Return the file system path representation of the object.
+
+If the object is str or bytes, then allow it to pass through with
+an incremented refcount. If the object defines __fspath__(), then
+return the result of that method. All other types raise a TypeError.
+[clinic start generated code]*/
+
+static PyObject *
+os_fspath_impl(PyModuleDef *module, PyObject *path)
+/*[clinic end generated code: output=51ef0c2772c1932a input=652c7c37e4be1c13]*/
+{
+    return PyOS_FSPath(path);
+}
 
 #include "clinic/posixmodule.c.h"
 
@@ -12484,6 +12534,7 @@ static PyMethodDef posix_methods[] = {
     {"scandir",         (PyCFunction)posix_scandir,
                         METH_VARARGS | METH_KEYWORDS,
                         posix_scandir__doc__},
+    OS_FSPATH_METHODDEF
     {NULL,              NULL}            /* Sentinel */
 };