mirror of
https://github.com/python/cpython.git
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281 lines
10 KiB
Python
281 lines
10 KiB
Python
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import errno
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import os
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import signal
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import threading
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import unittest
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from test import support
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from test.support import import_helper
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from .utils import PyTestCase, CTestCase
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requires_alarm = unittest.skipUnless(
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hasattr(signal, "alarm"), "test requires signal.alarm()"
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)
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@unittest.skipIf(os.name == 'nt', 'POSIX signals required for this test.')
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class SignalsTest:
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def setUp(self):
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self.oldalrm = signal.signal(signal.SIGALRM, self.alarm_interrupt)
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def tearDown(self):
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signal.signal(signal.SIGALRM, self.oldalrm)
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def alarm_interrupt(self, sig, frame):
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1/0
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def check_interrupted_write(self, item, bytes, **fdopen_kwargs):
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"""Check that a partial write, when it gets interrupted, properly
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invokes the signal handler, and bubbles up the exception raised
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in the latter."""
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# XXX This test has three flaws that appear when objects are
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# XXX not reference counted.
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# - if wio.write() happens to trigger a garbage collection,
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# the signal exception may be raised when some __del__
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# method is running; it will not reach the assertRaises()
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# call.
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# - more subtle, if the wio object is not destroyed at once
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# and survives this function, the next opened file is likely
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# to have the same fileno (since the file descriptor was
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# actively closed). When wio.__del__ is finally called, it
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# will close the other's test file... To trigger this with
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# CPython, try adding "global wio" in this function.
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# - This happens only for streams created by the _pyio module,
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# because a wio.close() that fails still consider that the
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# file needs to be closed again. You can try adding an
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# "assert wio.closed" at the end of the function.
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# Fortunately, a little gc.collect() seems to be enough to
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# work around all these issues.
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support.gc_collect() # For PyPy or other GCs.
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read_results = []
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def _read():
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s = os.read(r, 1)
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read_results.append(s)
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t = threading.Thread(target=_read)
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t.daemon = True
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r, w = os.pipe()
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fdopen_kwargs["closefd"] = False
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large_data = item * (support.PIPE_MAX_SIZE // len(item) + 1)
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try:
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wio = self.io.open(w, **fdopen_kwargs)
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if hasattr(signal, 'pthread_sigmask'):
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# create the thread with SIGALRM signal blocked
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signal.pthread_sigmask(signal.SIG_BLOCK, [signal.SIGALRM])
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t.start()
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signal.pthread_sigmask(signal.SIG_UNBLOCK, [signal.SIGALRM])
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else:
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t.start()
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# Fill the pipe enough that the write will be blocking.
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# It will be interrupted by the timer armed above. Since the
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# other thread has read one byte, the low-level write will
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# return with a successful (partial) result rather than an EINTR.
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# The buffered IO layer must check for pending signal
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# handlers, which in this case will invoke alarm_interrupt().
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signal.alarm(1)
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try:
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self.assertRaises(ZeroDivisionError, wio.write, large_data)
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finally:
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signal.alarm(0)
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t.join()
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# We got one byte, get another one and check that it isn't a
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# repeat of the first one.
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read_results.append(os.read(r, 1))
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self.assertEqual(read_results, [bytes[0:1], bytes[1:2]])
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finally:
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os.close(w)
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os.close(r)
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# This is deliberate. If we didn't close the file descriptor
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# before closing wio, wio would try to flush its internal
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# buffer, and block again.
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try:
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wio.close()
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except OSError as e:
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if e.errno != errno.EBADF:
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raise
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@requires_alarm
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@unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
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def test_interrupted_write_unbuffered(self):
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self.check_interrupted_write(b"xy", b"xy", mode="wb", buffering=0)
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@requires_alarm
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@unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
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def test_interrupted_write_buffered(self):
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self.check_interrupted_write(b"xy", b"xy", mode="wb")
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@requires_alarm
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@unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
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def test_interrupted_write_text(self):
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self.check_interrupted_write("xy", b"xy", mode="w", encoding="ascii")
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@support.no_tracing
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def check_reentrant_write(self, data, **fdopen_kwargs):
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def on_alarm(*args):
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# Will be called reentrantly from the same thread
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wio.write(data)
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1/0
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signal.signal(signal.SIGALRM, on_alarm)
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r, w = os.pipe()
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wio = self.io.open(w, **fdopen_kwargs)
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try:
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signal.alarm(1)
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# Either the reentrant call to wio.write() fails with RuntimeError,
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# or the signal handler raises ZeroDivisionError.
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with self.assertRaises((ZeroDivisionError, RuntimeError)) as cm:
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while 1:
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for i in range(100):
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wio.write(data)
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wio.flush()
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# Make sure the buffer doesn't fill up and block further writes
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os.read(r, len(data) * 100)
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exc = cm.exception
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if isinstance(exc, RuntimeError):
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self.assertStartsWith(str(exc), "reentrant call")
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finally:
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signal.alarm(0)
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wio.close()
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os.close(r)
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@requires_alarm
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def test_reentrant_write_buffered(self):
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self.check_reentrant_write(b"xy", mode="wb")
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@requires_alarm
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def test_reentrant_write_text(self):
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self.check_reentrant_write("xy", mode="w", encoding="ascii")
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def check_interrupted_read_retry(self, decode, **fdopen_kwargs):
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"""Check that a buffered read, when it gets interrupted (either
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returning a partial result or EINTR), properly invokes the signal
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handler and retries if the latter returned successfully."""
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r, w = os.pipe()
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fdopen_kwargs["closefd"] = False
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def alarm_handler(sig, frame):
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os.write(w, b"bar")
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signal.signal(signal.SIGALRM, alarm_handler)
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try:
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rio = self.io.open(r, **fdopen_kwargs)
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os.write(w, b"foo")
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signal.alarm(1)
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# Expected behaviour:
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# - first raw read() returns partial b"foo"
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# - second raw read() returns EINTR
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# - third raw read() returns b"bar"
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self.assertEqual(decode(rio.read(6)), "foobar")
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finally:
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signal.alarm(0)
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rio.close()
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os.close(w)
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os.close(r)
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@requires_alarm
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@support.requires_resource('walltime')
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def test_interrupted_read_retry_buffered(self):
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self.check_interrupted_read_retry(lambda x: x.decode('latin1'),
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mode="rb")
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@requires_alarm
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@support.requires_resource('walltime')
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def test_interrupted_read_retry_text(self):
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self.check_interrupted_read_retry(lambda x: x,
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mode="r", encoding="latin1")
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def check_interrupted_write_retry(self, item, **fdopen_kwargs):
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"""Check that a buffered write, when it gets interrupted (either
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returning a partial result or EINTR), properly invokes the signal
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handler and retries if the latter returned successfully."""
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select = import_helper.import_module("select")
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# A quantity that exceeds the buffer size of an anonymous pipe's
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# write end.
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N = support.PIPE_MAX_SIZE
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r, w = os.pipe()
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fdopen_kwargs["closefd"] = False
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# We need a separate thread to read from the pipe and allow the
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# write() to finish. This thread is started after the SIGALRM is
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# received (forcing a first EINTR in write()).
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read_results = []
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write_finished = False
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error = None
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def _read():
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try:
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while not write_finished:
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while r in select.select([r], [], [], 1.0)[0]:
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s = os.read(r, 1024)
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read_results.append(s)
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except BaseException as exc:
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nonlocal error
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error = exc
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t = threading.Thread(target=_read)
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t.daemon = True
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def alarm1(sig, frame):
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signal.signal(signal.SIGALRM, alarm2)
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signal.alarm(1)
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def alarm2(sig, frame):
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t.start()
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large_data = item * N
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signal.signal(signal.SIGALRM, alarm1)
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try:
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wio = self.io.open(w, **fdopen_kwargs)
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signal.alarm(1)
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# Expected behaviour:
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# - first raw write() is partial (because of the limited pipe buffer
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# and the first alarm)
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# - second raw write() returns EINTR (because of the second alarm)
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# - subsequent write()s are successful (either partial or complete)
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written = wio.write(large_data)
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self.assertEqual(N, written)
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wio.flush()
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write_finished = True
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t.join()
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self.assertIsNone(error)
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self.assertEqual(N, sum(len(x) for x in read_results))
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finally:
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signal.alarm(0)
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write_finished = True
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os.close(w)
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os.close(r)
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# This is deliberate. If we didn't close the file descriptor
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# before closing wio, wio would try to flush its internal
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# buffer, and could block (in case of failure).
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try:
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wio.close()
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except OSError as e:
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if e.errno != errno.EBADF:
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raise
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@requires_alarm
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@support.requires_resource('walltime')
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def test_interrupted_write_retry_buffered(self):
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self.check_interrupted_write_retry(b"x", mode="wb")
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@requires_alarm
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@support.requires_resource('walltime')
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def test_interrupted_write_retry_text(self):
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self.check_interrupted_write_retry("x", mode="w", encoding="latin1")
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class CSignalsTest(SignalsTest, CTestCase):
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pass
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class PySignalsTest(SignalsTest, PyTestCase):
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pass
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# Handling reentrancy issues would slow down _pyio even more, so the
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# tests are disabled.
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test_reentrant_write_buffered = None
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test_reentrant_write_text = None
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