Oct 3, 2022 · Oct 3, 2022
diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
    def _send(self, cmd, name, rtype):
        self.ensure_running()
        msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('ascii')
        if len(name) > 512:
        if len(msg) > 512:
            # posix guarantees that writes to a pipe of less than PIPE_BUF
            # bytes are atomic, and that PIPE_BUF >= 512
            raise ValueError('name too long')
            raise ValueError('msg too long')
        nbytes = os.write(self._fd, msg)
        assert nbytes == len(msg), "nbytes {0:n} but len(msg) {1:n}".format(
            nbytes, len(msg))
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py

        self.assertTrue(is_resource_tracker_reused)

    def test_too_long_name_resource(self):
        # gh-96819: Resource names that will make the length of a write to a pipe
        # greater than PIPE_BUF are not allowed
        rtype = "shared_memory"
        too_long_name_resource = "a" * (512 - len(rtype))
        with self.assertRaises(ValueError):
            resource_tracker.register(too_long_name_resource, rtype)


 class TestSimpleQueue(unittest.TestCase):

diff --git a/Misc/NEWS.d/next/Library/2022-09-17-13-15-10.gh-issue-96819.6RfqM7.rst b/Misc/NEWS.d/next/Library/2022-09-17-13-15-10.gh-issue-96819.6RfqM7.rst
 Fixed check in :mod:`multiprocessing.resource_tracker` that guarantees that the length of a write to a pipe is not greater than ``PIPE_BUF``.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -161,10 +161,10 @@ def unregister(self, name, rtype):
		def _send(self, cmd, name, rtype):
		self.ensure_running()
		msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('ascii')
		if len(name) > 512:
		if len(msg) > 512:
		# posix guarantees that writes to a pipe of less than PIPE_BUF
		# bytes are atomic, and that PIPE_BUF >= 512
		raise ValueError('name too long')
		raise ValueError('msg too long')
		nbytes = os.write(self._fd, msg)
		assert nbytes == len(msg), "nbytes {0:n} but len(msg) {1:n}".format(
		nbytes, len(msg))
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -5377,6 +5377,14 @@ def test_resource_tracker_reused(self):

		self.assertTrue(is_resource_tracker_reused)

		def test_too_long_name_resource(self):
		# gh-96819: Resource names that will make the length of a write to a pipe
		# greater than PIPE_BUF are not allowed
		rtype = "shared_memory"
		too_long_name_resource = "a" * (512 - len(rtype))
		with self.assertRaises(ValueError):
		resource_tracker.register(too_long_name_resource, rtype)


		class TestSimpleQueue(unittest.TestCase):

Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fixed check in :mod:`multiprocessing.resource_tracker` that guarantees that the length of a write to a pipe is not greater than ``PIPE_BUF``.