Python test.support.PIPE_MAX_SIZE Examples

def test_communicate_pipe_buf(self):
        # communicate() with writes larger than pipe_buf
        # This test will probably deadlock rather than fail, if
        # communicate() does not work properly.
        x, y = os.pipe()
        os.close(x)
        os.close(y)
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(sys.stdin.read(47));'
                              'sys.stderr.write("x" * %d);'
                              'sys.stdout.write(sys.stdin.read())' %
                              support.PIPE_MAX_SIZE],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        self.addCleanup(p.stdin.close)
        string_to_write = b"a" * support.PIPE_MAX_SIZE
        (stdout, stderr) = p.communicate(string_to_write)
        self.assertEqual(stdout, string_to_write) 

def test_communicate_pipe_buf(self):
        # communicate() with writes larger than pipe_buf
        # This test will probably deadlock rather than fail, if
        # communicate() does not work properly.
        x, y = os.pipe()
        os.close(x)
        os.close(y)
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(sys.stdin.read(47));'
                              'sys.stderr.write("x" * %d);'
                              'sys.stdout.write(sys.stdin.read())' %
                              support.PIPE_MAX_SIZE],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        self.addCleanup(p.stdin.close)
        string_to_write = b"a" * support.PIPE_MAX_SIZE
        (stdout, stderr) = p.communicate(string_to_write)
        self.assertEqual(stdout, string_to_write) 

def test_communicate_pipe_buf(self):
        # communicate() with writes larger than pipe_buf
        # This test will probably deadlock rather than fail, if
        # communicate() does not work properly.
        x, y = os.pipe()
        os.close(x)
        os.close(y)
        p = subprocess.Popen([sys.executable, "-c",
                              'import sys,os;'
                              'sys.stdout.write(sys.stdin.read(47));'
                              'sys.stderr.write("x" * %d);'
                              'sys.stdout.write(sys.stdin.read())' %
                              support.PIPE_MAX_SIZE],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        self.addCleanup(p.stdout.close)
        self.addCleanup(p.stderr.close)
        self.addCleanup(p.stdin.close)
        string_to_write = b"a" * support.PIPE_MAX_SIZE
        (stdout, stderr) = p.communicate(string_to_write)
        self.assertEqual(stdout, string_to_write) 

def test_broken_pipe_cleanup(self):
        """Broken pipe error should not prevent wait() (Issue 21619)"""
        proc = subprocess.Popen([sys.executable, '-c', 'pass'],
                                stdin=subprocess.PIPE,
                                bufsize=support.PIPE_MAX_SIZE*2)
        proc = proc.__enter__()
        # Prepare to send enough data to overflow any OS pipe buffering and
        # guarantee a broken pipe error. Data is held in BufferedWriter
        # buffer until closed.
        proc.stdin.write(b'x' * support.PIPE_MAX_SIZE)
        self.assertIsNone(proc.returncode)
        # EPIPE expected under POSIX; EINVAL under Windows
        self.assertRaises(OSError, proc.__exit__, None, None, None)
        self.assertEqual(proc.returncode, 0)
        self.assertTrue(proc.stdin.closed) 

def prepare_broken_pipe_test(self):
        # buffer large enough to feed the whole pipe buffer
        large_data = b'x' * support.PIPE_MAX_SIZE

        # the program ends before the stdin can be feeded
        create = asyncio.create_subprocess_exec(
                             sys.executable, '-c', 'pass',
                             stdin=subprocess.PIPE,
                             loop=self.loop)
        proc = self.loop.run_until_complete(create)
        return (proc, large_data) 

def test_write(self):
        rd, wr = os.pipe()
        self.addCleanup(os.close, wr)
        # rd closed explicitly by parent

        # we must write enough data for the write() to block
        data = b"x" * support.PIPE_MAX_SIZE

        code = '\n'.join((
            'import io, os, sys, time',
            '',
            'rd = int(sys.argv[1])',
            'sleep_time = %r' % self.sleep_time,
            'data = b"x" * %s' % support.PIPE_MAX_SIZE,
            'data_len = len(data)',
            '',
            '# let the parent block on write()',
            'time.sleep(sleep_time)',
            '',
            'read_data = io.BytesIO()',
            'while len(read_data.getvalue()) < data_len:',
            '    chunk = os.read(rd, 2 * data_len)',
            '    read_data.write(chunk)',
            '',
            'value = read_data.getvalue()',
            'if value != data:',
            '    raise Exception("read error: %s vs %s bytes"',
            '                    % (len(value), data_len))',
        ))

        proc = self.subprocess(code, str(rd), pass_fds=[rd])
        with kill_on_error(proc):
            os.close(rd)
            written = 0
            while written < len(data):
                written += os.write(wr, memoryview(data)[written:])
            self.assertEqual(proc.wait(), 0) 

def test_broken_pipe_cleanup(self):
        """Broken pipe error should not prevent wait() (Issue 21619)"""
        proc = subprocess.Popen([sys.executable, '-c', 'pass'],
                                stdin=subprocess.PIPE,
                                bufsize=support.PIPE_MAX_SIZE*2)
        proc = proc.__enter__()
        # Prepare to send enough data to overflow any OS pipe buffering and
        # guarantee a broken pipe error. Data is held in BufferedWriter
        # buffer until closed.
        proc.stdin.write(b'x' * support.PIPE_MAX_SIZE)
        self.assertIsNone(proc.returncode)
        # EPIPE expected under POSIX; EINVAL under Windows
        self.assertRaises(OSError, proc.__exit__, None, None, None)
        self.assertEqual(proc.returncode, 0)
        self.assertTrue(proc.stdin.closed) 

def prepare_broken_pipe_test(self):
        # buffer large enough to feed the whole pipe buffer
        large_data = b'x' * support.PIPE_MAX_SIZE

        # the program ends before the stdin can be feeded
        create = asyncio.create_subprocess_exec(
                             sys.executable, '-c', 'pass',
                             stdin=subprocess.PIPE,
                             loop=self.loop)
        proc = self.loop.run_until_complete(create)
        return (proc, large_data) 

def test_write(self):
        rd, wr = os.pipe()
        self.addCleanup(os.close, wr)
        # rd closed explicitly by parent

        # we must write enough data for the write() to block
        data = b"x" * support.PIPE_MAX_SIZE

        code = '\n'.join((
            'import io, os, sys, time',
            '',
            'rd = int(sys.argv[1])',
            'sleep_time = %r' % self.sleep_time,
            'data = b"x" * %s' % support.PIPE_MAX_SIZE,
            'data_len = len(data)',
            '',
            '# let the parent block on write()',
            'time.sleep(sleep_time)',
            '',
            'read_data = io.BytesIO()',
            'while len(read_data.getvalue()) < data_len:',
            '    chunk = os.read(rd, 2 * data_len)',
            '    read_data.write(chunk)',
            '',
            'value = read_data.getvalue()',
            'if value != data:',
            '    raise Exception("read error: %s vs %s bytes"',
            '                    % (len(value), data_len))',
        ))

        proc = self.subprocess(code, str(rd), pass_fds=[rd])
        with kill_on_error(proc):
            os.close(rd)
            written = 0
            while written < len(data):
                written += os.write(wr, memoryview(data)[written:])
            self.assertEqual(proc.wait(), 0) 

def prepare_broken_pipe_test(self):
        # buffer large enough to feed the whole pipe buffer
        large_data = b'x' * support.PIPE_MAX_SIZE

        # the program ends before the stdin can be feeded
        create = asyncio.create_subprocess_exec(
                             sys.executable, '-c', 'pass',
                             stdin=subprocess.PIPE,
                             loop=self.loop)
        proc = self.loop.run_until_complete(create)
        return (proc, large_data) 

def prepare_broken_pipe_test(self):
        # buffer large enough to feed the whole pipe buffer
        large_data = b'x' * support.PIPE_MAX_SIZE

        # the program ends before the stdin can be feeded
        create = asyncio.create_subprocess_exec(
                             sys.executable, '-c', 'pass',
                             stdin=subprocess.PIPE,
                             loop=self.loop)
        proc = self.loop.run_until_complete(create)
        return (proc, large_data) 

def test_broken_pipe_cleanup(self):
        """Broken pipe error should not prevent wait() (Issue 21619)"""
        proc = subprocess.Popen([sys.executable, '-c', 'pass'],
                                stdin=subprocess.PIPE,
                                bufsize=support.PIPE_MAX_SIZE*2)
        proc = proc.__enter__()
        # Prepare to send enough data to overflow any OS pipe buffering and
        # guarantee a broken pipe error. Data is held in BufferedWriter
        # buffer until closed.
        proc.stdin.write(b'x' * support.PIPE_MAX_SIZE)
        self.assertIsNone(proc.returncode)
        # EPIPE expected under POSIX; EINVAL under Windows
        self.assertRaises(OSError, proc.__exit__, None, None, None)
        self.assertEqual(proc.returncode, 0)
        self.assertTrue(proc.stdin.closed) 

def prepare_broken_pipe_test(self):
        # buffer large enough to feed the whole pipe buffer
        large_data = b'x' * support.PIPE_MAX_SIZE

        # the program ends before the stdin can be feeded
        create = asyncio.create_subprocess_exec(
                             sys.executable, '-c', 'pass',
                             stdin=subprocess.PIPE,
                             loop=self.loop)
        proc = self.loop.run_until_complete(create)
        return (proc, large_data) 

def test_write(self):
        rd, wr = os.pipe()
        self.addCleanup(os.close, wr)
        # rd closed explicitly by parent

        # we must write enough data for the write() to block
        data = b"x" * support.PIPE_MAX_SIZE

        code = '\n'.join((
            'import io, os, sys, time',
            '',
            'rd = int(sys.argv[1])',
            'sleep_time = %r' % self.sleep_time,
            'data = b"x" * %s' % support.PIPE_MAX_SIZE,
            'data_len = len(data)',
            '',
            '# let the parent block on write()',
            'time.sleep(sleep_time)',
            '',
            'read_data = io.BytesIO()',
            'while len(read_data.getvalue()) < data_len:',
            '    chunk = os.read(rd, 2 * data_len)',
            '    read_data.write(chunk)',
            '',
            'value = read_data.getvalue()',
            'if value != data:',
            '    raise Exception("read error: %s vs %s bytes"',
            '                    % (len(value), data_len))',
        ))

        proc = self.subprocess(code, str(rd), pass_fds=[rd])
        with kill_on_error(proc):
            os.close(rd)
            written = 0
            while written < len(data):
                written += os.write(wr, memoryview(data)[written:])
            self.assertEqual(proc.wait(), 0) 

def check_interrupted_write(self, item, bytes, **fdopen_kwargs):
        """Check that a partial write, when it gets interrupted, properly
        invokes the signal handler, and bubbles up the exception raised
        in the latter."""
        read_results = []
        def _read():
            if hasattr(signal, 'pthread_sigmask'):
                signal.pthread_sigmask(signal.SIG_BLOCK, [signal.SIGALRM])
            s = os.read(r, 1)
            read_results.append(s)
        t = threading.Thread(target=_read)
        t.daemon = True
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        large_data = item * (support.PIPE_MAX_SIZE // len(item) + 1)
        try:
            wio = self.io.open(w, **fdopen_kwargs)
            t.start()
            # Fill the pipe enough that the write will be blocking.
            # It will be interrupted by the timer armed above.  Since the
            # other thread has read one byte, the low-level write will
            # return with a successful (partial) result rather than an EINTR.
            # The buffered IO layer must check for pending signal
            # handlers, which in this case will invoke alarm_interrupt().
            signal.alarm(1)
            try:
                self.assertRaises(ZeroDivisionError, wio.write, large_data)
            finally:
                signal.alarm(0)
                t.join()
            # We got one byte, get another one and check that it isn't a
            # repeat of the first one.
            read_results.append(os.read(r, 1))
            self.assertEqual(read_results, [bytes[0:1], bytes[1:2]])
        finally:
            os.close(w)
            os.close(r)
            # This is deliberate. If we didn't close the file descriptor
            # before closing wio, wio would try to flush its internal
            # buffer, and block again.
            try:
                wio.close()
            except OSError as e:
                if e.errno != errno.EBADF:
                    raise 

def check_interrupted_write(self, item, bytes, **fdopen_kwargs):
        """Check that a partial write, when it gets interrupted, properly
        invokes the signal handler, and bubbles up the exception raised
        in the latter."""
        read_results = []
        def _read():
            if hasattr(signal, 'pthread_sigmask'):
                signal.pthread_sigmask(signal.SIG_BLOCK, [signal.SIGALRM])
            s = os.read(r, 1)
            read_results.append(s)
        t = threading.Thread(target=_read)
        t.daemon = True
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        large_data = item * (support.PIPE_MAX_SIZE // len(item) + 1)
        try:
            wio = self.io.open(w, **fdopen_kwargs)
            t.start()
            # Fill the pipe enough that the write will be blocking.
            # It will be interrupted by the timer armed above.  Since the
            # other thread has read one byte, the low-level write will
            # return with a successful (partial) result rather than an EINTR.
            # The buffered IO layer must check for pending signal
            # handlers, which in this case will invoke alarm_interrupt().
            signal.alarm(1)
            try:
                self.assertRaises(ZeroDivisionError, wio.write, large_data)
            finally:
                signal.alarm(0)
                t.join()
            # We got one byte, get another one and check that it isn't a
            # repeat of the first one.
            read_results.append(os.read(r, 1))
            self.assertEqual(read_results, [bytes[0:1], bytes[1:2]])
        finally:
            os.close(w)
            os.close(r)
            # This is deliberate. If we didn't close the file descriptor
            # before closing wio, wio would try to flush its internal
            # buffer, and block again.
            try:
                wio.close()
            except OSError as e:
                if e.errno != errno.EBADF:
                    raise 

def check_interrupted_write_retry(self, item, **fdopen_kwargs):
        """Check that a buffered write, when it gets interrupted (either
        returning a partial result or EINTR), properly invokes the signal
        handler and retries if the latter returned successfully."""
        select = support.import_module("select")
        # A quantity that exceeds the buffer size of an anonymous pipe's
        # write end.
        N = support.PIPE_MAX_SIZE
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        # We need a separate thread to read from the pipe and allow the
        # write() to finish.  This thread is started after the SIGALRM is
        # received (forcing a first EINTR in write()).
        read_results = []
        write_finished = False
        error = None
        def _read():
            try:
                while not write_finished:
                    while r in select.select([r], [], [], 1.0)[0]:
                        s = os.read(r, 1024)
                        read_results.append(s)
            except BaseException as exc:
                nonlocal error
                error = exc
        t = threading.Thread(target=_read)
        t.daemon = True
        def alarm1(sig, frame):
            signal.signal(signal.SIGALRM, alarm2)
            signal.alarm(1)
        def alarm2(sig, frame):
            t.start()
        signal.signal(signal.SIGALRM, alarm1)
        try:
            wio = self.io.open(w, **fdopen_kwargs)
            signal.alarm(1)
            # Expected behaviour:
            # - first raw write() is partial (because of the limited pipe buffer
            #   and the first alarm)
            # - second raw write() returns EINTR (because of the second alarm)
            # - subsequent write()s are successful (either partial or complete)
            self.assertEqual(N, wio.write(item * N))
            wio.flush()
            write_finished = True
            t.join()

            self.assertIsNone(error)
            self.assertEqual(N, sum(len(x) for x in read_results))
        finally:
            write_finished = True
            os.close(w)
            os.close(r)
            # This is deliberate. If we didn't close the file descriptor
            # before closing wio, wio would try to flush its internal
            # buffer, and could block (in case of failure).
            try:
                wio.close()
            except OSError as e:
                if e.errno != errno.EBADF:
                    raise 

def check_interrupted_write(self, item, bytes, **fdopen_kwargs):
        """Check that a partial write, when it gets interrupted, properly
        invokes the signal handler, and bubbles up the exception raised
        in the latter."""
        read_results = []
        def _read():
            if hasattr(signal, 'pthread_sigmask'):
                signal.pthread_sigmask(signal.SIG_BLOCK, [signal.SIGALRM])
            s = os.read(r, 1)
            read_results.append(s)
        t = threading.Thread(target=_read)
        t.daemon = True
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        try:
            wio = self.io.open(w, **fdopen_kwargs)
            t.start()
            # Fill the pipe enough that the write will be blocking.
            # It will be interrupted by the timer armed above.  Since the
            # other thread has read one byte, the low-level write will
            # return with a successful (partial) result rather than an EINTR.
            # The buffered IO layer must check for pending signal
            # handlers, which in this case will invoke alarm_interrupt().
            signal.alarm(1)
            try:
                with self.assertRaises(ZeroDivisionError):
                    wio.write(item * (support.PIPE_MAX_SIZE // len(item) + 1))
            finally:
                signal.alarm(0)
                t.join()
            # We got one byte, get another one and check that it isn't a
            # repeat of the first one.
            read_results.append(os.read(r, 1))
            self.assertEqual(read_results, [bytes[0:1], bytes[1:2]])
        finally:
            os.close(w)
            os.close(r)
            # This is deliberate. If we didn't close the file descriptor
            # before closing wio, wio would try to flush its internal
            # buffer, and block again.
            try:
                wio.close()
            except OSError as e:
                if e.errno != errno.EBADF:
                    raise 

def check_interrupted_write(self, item, bytes, **fdopen_kwargs):
        """Check that a partial write, when it gets interrupted, properly
        invokes the signal handler, and bubbles up the exception raised
        in the latter."""
        read_results = []
        def _read():
            s = os.read(r, 1)
            read_results.append(s)

        t = threading.Thread(target=_read)
        t.daemon = True
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        large_data = item * (support.PIPE_MAX_SIZE // len(item) + 1)
        try:
            wio = self.io.open(w, **fdopen_kwargs)
            if hasattr(signal, 'pthread_sigmask'):
                # create the thread with SIGALRM signal blocked
                signal.pthread_sigmask(signal.SIG_BLOCK, [signal.SIGALRM])
                t.start()
                signal.pthread_sigmask(signal.SIG_UNBLOCK, [signal.SIGALRM])
            else:
                t.start()

            # Fill the pipe enough that the write will be blocking.
            # It will be interrupted by the timer armed above.  Since the
            # other thread has read one byte, the low-level write will
            # return with a successful (partial) result rather than an EINTR.
            # The buffered IO layer must check for pending signal
            # handlers, which in this case will invoke alarm_interrupt().
            signal.alarm(1)
            try:
                self.assertRaises(ZeroDivisionError, wio.write, large_data)
            finally:
                signal.alarm(0)
                t.join()
            # We got one byte, get another one and check that it isn't a
            # repeat of the first one.
            read_results.append(os.read(r, 1))
            self.assertEqual(read_results, [bytes[0:1], bytes[1:2]])
        finally:
            os.close(w)
            os.close(r)
            # This is deliberate. If we didn't close the file descriptor
            # before closing wio, wio would try to flush its internal
            # buffer, and block again.
            try:
                wio.close()
            except OSError as e:
                if e.errno != errno.EBADF:
                    raise