bpo-43916: PyStdPrinter_Type uses Py_TPFLAGS_DISALLOW_INSTANTIATION (GH-25749)

The PyStdPrinter_Type type now uses the
Py_TPFLAGS_DISALLOW_INSTANTIATION flag to disallow instantiation,
rather than seting a tp_init method which always fail.

Write also unit tests for PyStdPrinter_Type.
This commit is contained in:
Victor Stinner 2021-04-30 14:56:27 +02:00 committed by GitHub
parent 0cad068ec1
commit 4908fae3d5
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 61 additions and 28 deletions

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@ -1473,11 +1473,67 @@ class AuditingTests(EmbeddingTestsMixin, unittest.TestCase):
timeout=support.SHORT_TIMEOUT,
returncode=1)
class MiscTests(EmbeddingTestsMixin, unittest.TestCase):
def test_unicode_id_init(self):
# bpo-42882: Test that _PyUnicode_FromId() works
# when Python is initialized multiples times.
self.run_embedded_interpreter("test_unicode_id_init")
class StdPrinterTests(EmbeddingTestsMixin, unittest.TestCase):
# Test PyStdPrinter_Type which is used by _PySys_SetPreliminaryStderr():
# "Set up a preliminary stderr printer until we have enough
# infrastructure for the io module in place."
def get_stdout_fd(self):
return sys.__stdout__.fileno()
def create_printer(self, fd):
ctypes = import_helper.import_module('ctypes')
PyFile_NewStdPrinter = ctypes.pythonapi.PyFile_NewStdPrinter
PyFile_NewStdPrinter.argtypes = (ctypes.c_int,)
PyFile_NewStdPrinter.restype = ctypes.py_object
return PyFile_NewStdPrinter(fd)
def test_write(self):
message = "unicode:\xe9-\u20ac-\udc80!\n"
stdout_fd = self.get_stdout_fd()
stdout_fd_copy = os.dup(stdout_fd)
self.addCleanup(os.close, stdout_fd_copy)
rfd, wfd = os.pipe()
self.addCleanup(os.close, rfd)
self.addCleanup(os.close, wfd)
try:
# PyFile_NewStdPrinter() only accepts fileno(stdout)
# or fileno(stderr) file descriptor.
os.dup2(wfd, stdout_fd)
printer = self.create_printer(stdout_fd)
printer.write(message)
finally:
os.dup2(stdout_fd_copy, stdout_fd)
data = os.read(rfd, 100)
self.assertEqual(data, message.encode('utf8', 'backslashreplace'))
def test_methods(self):
fd = self.get_stdout_fd()
printer = self.create_printer(fd)
self.assertEqual(printer.fileno(), fd)
self.assertEqual(printer.isatty(), os.isatty(fd))
printer.flush() # noop
printer.close() # noop
def test_disallow_instantiation(self):
fd = self.get_stdout_fd()
printer = self.create_printer(fd)
PyStdPrinter_Type = type(printer)
with self.assertRaises(TypeError):
PyStdPrinter_Type(fd)
if __name__ == "__main__":
unittest.main()

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@ -325,29 +325,6 @@ typedef struct {
int fd;
} PyStdPrinter_Object;
static PyObject *
stdprinter_new(PyTypeObject *type, PyObject *args, PyObject *kews)
{
PyStdPrinter_Object *self;
assert(type != NULL && type->tp_alloc != NULL);
self = (PyStdPrinter_Object *) type->tp_alloc(type, 0);
if (self != NULL) {
self->fd = -1;
}
return (PyObject *) self;
}
static int
stdprinter_init(PyObject *self, PyObject *args, PyObject *kwds)
{
PyErr_SetString(PyExc_TypeError,
"cannot create 'stderrprinter' instances");
return -1;
}
PyObject *
PyFile_NewStdPrinter(int fd)
{
@ -390,7 +367,7 @@ stdprinter_write(PyStdPrinter_Object *self, PyObject *args)
return NULL;
}
/* Encode Unicode to UTF-8/surrogateescape */
/* Encode Unicode to UTF-8/backslashreplace */
str = PyUnicode_AsUTF8AndSize(unicode, &n);
if (str == NULL) {
PyErr_Clear();
@ -507,7 +484,7 @@ PyTypeObject PyStdPrinter_Type = {
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
@ -523,9 +500,9 @@ PyTypeObject PyStdPrinter_Type = {
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
stdprinter_init, /* tp_init */
0, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
stdprinter_new, /* tp_new */
0, /* tp_new */
PyObject_Del, /* tp_free */
};

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@ -3007,7 +3007,7 @@ err_occurred:
/* Set up a preliminary stderr printer until we have enough
infrastructure for the io module in place.
Use UTF-8/surrogateescape and ignore EAGAIN errors. */
Use UTF-8/backslashreplace and ignore EAGAIN errors. */
static PyStatus
_PySys_SetPreliminaryStderr(PyObject *sysdict)
{