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bpo-35942: Improve the error message if __fspath__ returns invalid types in path_converter #11831

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Merged
pablogsal merged 4 commits into from
Feb 18, 2019
Merged

bpo-35942: Improve the error message if __fspath__ returns invalid types in path_converter #11831

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a59ad45
bpo-35942: Delegate on PyOS_FSPath when checking for __fspath__ in pa…
pablogsal Feb 12, 2019
34a2448
Change only the error when __fspath__ returns an invalid type
pablogsal Feb 17, 2019
477daf8
fixup! Change only the error when __fspath__ returns an invalid type
pablogsal Feb 18, 2019
808801f
Add NEWS entry
pablogsal Feb 18, 2019
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19 changes: 18 additions & 1 deletion Lib/test/test_os.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3344,7 +3344,7 @@ def test_path_t_converter(self):
cleanup_fn(result)

with self.assertRaisesRegex(
TypeError, 'should be string, bytes'):
TypeError, 'to return str or bytes'):
fn(int_fspath, *extra_args)

if allow_fd:
Expand All @@ -3357,6 +3357,23 @@ def test_path_t_converter(self):
'os.PathLike'):
fn(fd, *extra_args)

def test_path_t_converter_and_custom_class(self):
with self.assertRaisesRegex(
TypeError,
'__fspath__\(\) to return str or bytes, not int'
):
os.stat(FakePath(2))
with self.assertRaisesRegex(
TypeError,
'__fspath__\(\) to return str or bytes, not float'
):
os.stat(FakePath(2.34))
with self.assertRaisesRegex(
TypeError,
'__fspath__\(\) to return str or bytes, not object'
):
os.stat(FakePath(object()))


@unittest.skipUnless(hasattr(os, 'get_blocking'),
'needs os.get_blocking() and os.set_blocking()')
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2019-02-18-09-30-55.bpo-35942.oLhL2v.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
The error message emmited when returning invalid types from ``__fspath__``
in interfaces that allow passing :class:`~os.PathLike` objects has been
improved and now it does explain the origin of the error.
23 changes: 15 additions & 8 deletions Modules/posixmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -954,28 +954,35 @@ path_converter(PyObject *o, void *p)
if (!is_index && !is_buffer && !is_unicode && !is_bytes) {
/* Inline PyOS_FSPath() for better error messages. */
_Py_IDENTIFIER(__fspath__);
PyObject *func = NULL;
PyObject *func, *res;

func = _PyObject_LookupSpecial(o, &PyId___fspath__);
if (NULL == func) {
goto error_format;
}
/* still owns a reference to the original object */
Py_DECREF(o);
o = _PyObject_CallNoArg(func);
res = _PyObject_CallNoArg(func);
Py_DECREF(func);
if (NULL == o) {
if (NULL == res) {
goto error_exit;
}
else if (PyUnicode_Check(o)) {
else if (PyUnicode_Check(res)) {
is_unicode = 1;
}
else if (PyBytes_Check(o)) {
else if (PyBytes_Check(res)) {
is_bytes = 1;
}
else {
goto error_format;
PyErr_Format(PyExc_TypeError,
"expected %.200s.__fspath__() to return str or bytes, "
"not %.200s", Py_TYPE(o)->tp_name,
Py_TYPE(res)->tp_name);
Py_DECREF(res);
goto error_exit;
}

/* still owns a reference to the original object */
Py_DECREF(o);
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@eamanu eamanu Feb 18, 2019

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A little question, Why don't make Py_DECREF(res); too?

o = res;
}

if (is_unicode) {
Expand Down