summaryrefslogtreecommitdiffstats
path: root/Lib/test/test_signal.py
blob: f64bd4c99ad6442486d0c6c69fbfb26640dc9010 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
import unittest
from test import support
from contextlib import closing
import gc
import pickle
import select
import signal
import subprocess
import traceback
import sys, os, time, errno

if sys.platform in ('os2', 'riscos'):
    raise unittest.SkipTest("Can't test signal on %s" % sys.platform)


class HandlerBCalled(Exception):
    pass


def exit_subprocess():
    """Use os._exit(0) to exit the current subprocess.

    Otherwise, the test catches the SystemExit and continues executing
    in parallel with the original test, so you wind up with an
    exponential number of tests running concurrently.
    """
    os._exit(0)


def ignoring_eintr(__func, *args, **kwargs):
    try:
        return __func(*args, **kwargs)
    except EnvironmentError as e:
        if e.errno != errno.EINTR:
            raise
        return None


@unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
class InterProcessSignalTests(unittest.TestCase):
    MAX_DURATION = 20   # Entire test should last at most 20 sec.

    def setUp(self):
        self.using_gc = gc.isenabled()
        gc.disable()

    def tearDown(self):
        if self.using_gc:
            gc.enable()

    def format_frame(self, frame, limit=None):
        return ''.join(traceback.format_stack(frame, limit=limit))

    def handlerA(self, signum, frame):
        self.a_called = True
        if support.verbose:
            print("handlerA invoked from signal %s at:\n%s" % (
                signum, self.format_frame(frame, limit=1)))

    def handlerB(self, signum, frame):
        self.b_called = True
        if support.verbose:
            print ("handlerB invoked from signal %s at:\n%s" % (
                signum, self.format_frame(frame, limit=1)))
        raise HandlerBCalled(signum, self.format_frame(frame))

    def wait(self, child):
        """Wait for child to finish, ignoring EINTR."""
        while True:
            try:
                child.wait()
                return
            except OSError as e:
                if e.errno != errno.EINTR:
                    raise

    def run_test(self):
        # Install handlers. This function runs in a sub-process, so we
        # don't worry about re-setting the default handlers.
        signal.signal(signal.SIGHUP, self.handlerA)
        signal.signal(signal.SIGUSR1, self.handlerB)
        signal.signal(signal.SIGUSR2, signal.SIG_IGN)
        signal.signal(signal.SIGALRM, signal.default_int_handler)

        # Variables the signals will modify:
        self.a_called = False
        self.b_called = False

        # Let the sub-processes know who to send signals to.
        pid = os.getpid()
        if support.verbose:
            print("test runner's pid is", pid)

        child = ignoring_eintr(subprocess.Popen, ['kill', '-HUP', str(pid)])
        if child:
            self.wait(child)
            if not self.a_called:
                time.sleep(1)  # Give the signal time to be delivered.
        self.assertTrue(self.a_called)
        self.assertFalse(self.b_called)
        self.a_called = False

        # Make sure the signal isn't delivered while the previous
        # Popen object is being destroyed, because __del__ swallows
        # exceptions.
        del child
        try:
            child = subprocess.Popen(['kill', '-USR1', str(pid)])
            # This wait should be interrupted by the signal's exception.
            self.wait(child)
            time.sleep(1)  # Give the signal time to be delivered.
            self.fail('HandlerBCalled exception not thrown')
        except HandlerBCalled:
            self.assertTrue(self.b_called)
            self.assertFalse(self.a_called)
            if support.verbose:
                print("HandlerBCalled exception caught")

        child = ignoring_eintr(subprocess.Popen, ['kill', '-USR2', str(pid)])
        if child:
            self.wait(child)  # Nothing should happen.

        try:
            signal.alarm(1)
            # The race condition in pause doesn't matter in this case,
            # since alarm is going to raise a KeyboardException, which
            # will skip the call.
            signal.pause()
            # But if another signal arrives before the alarm, pause
            # may return early.
            time.sleep(1)
        except KeyboardInterrupt:
            if support.verbose:
                print("KeyboardInterrupt (the alarm() went off)")
        except:
            self.fail("Some other exception woke us from pause: %s" %
                      traceback.format_exc())
        else:
            self.fail("pause returned of its own accord, and the signal"
                      " didn't arrive after another second.")

    # Issue 3864, unknown if this affects earlier versions of freebsd also
    @unittest.skipIf(sys.platform=='freebsd6',
        'inter process signals not reliable (do not mix well with threading) '
        'on freebsd6')
    def test_main(self):
        # This function spawns a child process to insulate the main
        # test-running process from all the signals. It then
        # communicates with that child process over a pipe and
        # re-raises information about any exceptions the child
        # throws. The real work happens in self.run_test().
        os_done_r, os_done_w = os.pipe()
        with closing(os.fdopen(os_done_r, 'rb')) as done_r, \
             closing(os.fdopen(os_done_w, 'wb')) as done_w:
            child = os.fork()
            if child == 0:
                # In the child process; run the test and report results
                # through the pipe.
                try:
                    done_r.close()
                    # Have to close done_w again here because
                    # exit_subprocess() will skip the enclosing with block.
                    with closing(done_w):
                        try:
                            self.run_test()
                        except:
                            pickle.dump(traceback.format_exc(), done_w)
                        else:
                            pickle.dump(None, done_w)
                except:
                    print('Uh oh, raised from pickle.')
                    traceback.print_exc()
                finally:
                    exit_subprocess()

            done_w.close()
            # Block for up to MAX_DURATION seconds for the test to finish.
            r, w, x = select.select([done_r], [], [], self.MAX_DURATION)
            if done_r in r:
                tb = pickle.load(done_r)
                if tb:
                    self.fail(tb)
            else:
                os.kill(child, signal.SIGKILL)
                self.fail('Test deadlocked after %d seconds.' %
                          self.MAX_DURATION)


@unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
class BasicSignalTests(unittest.TestCase):
    def trivial_signal_handler(self, *args):
        pass

    def test_out_of_range_signal_number_raises_error(self):
        self.assertRaises(ValueError, signal.getsignal, 4242)

        self.assertRaises(ValueError, signal.signal, 4242,
                          self.trivial_signal_handler)

    def test_setting_signal_handler_to_none_raises_error(self):
        self.assertRaises(TypeError, signal.signal,
                          signal.SIGUSR1, None)

    def test_getsignal(self):
        hup = signal.signal(signal.SIGHUP, self.trivial_signal_handler)
        self.assertEqual(signal.getsignal(signal.SIGHUP),
                         self.trivial_signal_handler)
        signal.signal(signal.SIGHUP, hup)
        self.assertEqual(signal.getsignal(signal.SIGHUP), hup)


@unittest.skipUnless(sys.platform == "win32", "Windows specific")
class WindowsSignalTests(unittest.TestCase):
    def test_issue9324(self):
        # Updated for issue #10003, adding SIGBREAK
        handler = lambda x, y: None
        for sig in (signal.SIGABRT, signal.SIGBREAK, signal.SIGFPE,
                    signal.SIGILL, signal.SIGINT, signal.SIGSEGV,
                    signal.SIGTERM):
            # Set and then reset a handler for signals that work on windows
            signal.signal(sig, signal.signal(sig, handler))

        with self.assertRaises(ValueError):
            signal.signal(-1, handler)

        with self.assertRaises(ValueError):
            signal.signal(7, handler)


@unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
class WakeupSignalTests(unittest.TestCase):
    TIMEOUT_FULL = 10
    TIMEOUT_HALF = 5

    def test_wakeup_fd_early(self):
        import select

        signal.alarm(1)
        before_time = time.time()
        # We attempt to get a signal during the sleep,
        # before select is called
        time.sleep(self.TIMEOUT_FULL)
        mid_time = time.time()
        self.assertTrue(mid_time - before_time < self.TIMEOUT_HALF)
        select.select([self.read], [], [], self.TIMEOUT_FULL)
        after_time = time.time()
        self.assertTrue(after_time - mid_time < self.TIMEOUT_HALF)

    def test_wakeup_fd_during(self):
        import select

        signal.alarm(1)
        before_time = time.time()
        # We attempt to get a signal during the select call
        self.assertRaises(select.error, select.select,
            [self.read], [], [], self.TIMEOUT_FULL)
        after_time = time.time()
        self.assertTrue(after_time - before_time < self.TIMEOUT_HALF)

    def setUp(self):
        import fcntl

        self.alrm = signal.signal(signal.SIGALRM, lambda x,y:None)
        self.read, self.write = os.pipe()
        flags = fcntl.fcntl(self.write, fcntl.F_GETFL, 0)
        flags = flags | os.O_NONBLOCK
        fcntl.fcntl(self.write, fcntl.F_SETFL, flags)
        self.old_wakeup = signal.set_wakeup_fd(self.write)

    def tearDown(self):
        signal.set_wakeup_fd(self.old_wakeup)
        os.close(self.read)
        os.close(self.write)
        signal.signal(signal.SIGALRM, self.alrm)

@unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
class SiginterruptTest(unittest.TestCase):

    def setUp(self):
        """Install a no-op signal handler that can be set to allow
        interrupts or not, and arrange for the original signal handler to be
        re-installed when the test is finished.
        """
        self.signum = signal.SIGUSR1
        oldhandler = signal.signal(self.signum, lambda x,y: None)
        self.addCleanup(signal.signal, self.signum, oldhandler)

    def readpipe_interrupted(self):
        """Perform a read during which a signal will arrive.  Return True if the
        read is interrupted by the signal and raises an exception.  Return False
        if it returns normally.
        """
        # Create a pipe that can be used for the read.  Also clean it up
        # when the test is over, since nothing else will (but see below for
        # the write end).
        r, w = os.pipe()
        self.addCleanup(os.close, r)

        # Create another process which can send a signal to this one to try
        # to interrupt the read.
        ppid = os.getpid()
        pid = os.fork()

        if pid == 0:
            # Child code: sleep to give the parent enough time to enter the
            # read() call (there's a race here, but it's really tricky to
            # eliminate it); then signal the parent process.  Also, sleep
            # again to make it likely that the signal is delivered to the
            # parent process before the child exits.  If the child exits
            # first, the write end of the pipe will be closed and the test
            # is invalid.
            try:
                time.sleep(0.2)
                os.kill(ppid, self.signum)
                time.sleep(0.2)
            finally:
                # No matter what, just exit as fast as possible now.
                exit_subprocess()
        else:
            # Parent code.
            # Make sure the child is eventually reaped, else it'll be a
            # zombie for the rest of the test suite run.
            self.addCleanup(os.waitpid, pid, 0)

            # Close the write end of the pipe.  The child has a copy, so
            # it's not really closed until the child exits.  We need it to
            # close when the child exits so that in the non-interrupt case
            # the read eventually completes, otherwise we could just close
            # it *after* the test.
            os.close(w)

            # Try the read and report whether it is interrupted or not to
            # the caller.
            try:
                d = os.read(r, 1)
                return False
            except OSError as err:
                if err.errno != errno.EINTR:
                    raise
                return True

    def test_without_siginterrupt(self):
        """If a signal handler is installed and siginterrupt is not called
        at all, when that signal arrives, it interrupts a syscall that's in
        progress.
        """
        i = self.readpipe_interrupted()
        self.assertTrue(i)
        # Arrival of the signal shouldn't have changed anything.
        i = self.readpipe_interrupted()
        self.assertTrue(i)

    def test_siginterrupt_on(self):
        """If a signal handler is installed and siginterrupt is called with
        a true value for the second argument, when that signal arrives, it
        interrupts a syscall that's in progress.
        """
        signal.siginterrupt(self.signum, 1)
        i = self.readpipe_interrupted()
        self.assertTrue(i)
        # Arrival of the signal shouldn't have changed anything.
        i = self.readpipe_interrupted()
        self.assertTrue(i)

    def test_siginterrupt_off(self):
        """If a signal handler is installed and siginterrupt is called with
        a false value for the second argument, when that signal arrives, it
        does not interrupt a syscall that's in progress.
        """
        signal.siginterrupt(self.signum, 0)
        i = self.readpipe_interrupted()
        self.assertFalse(i)
        # Arrival of the signal shouldn't have changed anything.
        i = self.readpipe_interrupted()
        self.assertFalse(i)


@unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
class ItimerTest(unittest.TestCase):
    def setUp(self):
        self.hndl_called = False
        self.hndl_count = 0
        self.itimer = None
        self.old_alarm = signal.signal(signal.SIGALRM, self.sig_alrm)

    def tearDown(self):
        signal.signal(signal.SIGALRM, self.old_alarm)
        if self.itimer is not None: # test_itimer_exc doesn't change this attr
            # just ensure that itimer is stopped
            signal.setitimer(self.itimer, 0)

    def sig_alrm(self, *args):
        self.hndl_called = True
        if support.verbose:
            print("SIGALRM handler invoked", args)

    def sig_vtalrm(self, *args):
        self.hndl_called = True

        if self.hndl_count > 3:
            # it shouldn't be here, because it should have been disabled.
            raise signal.ItimerError("setitimer didn't disable ITIMER_VIRTUAL "
                "timer.")
        elif self.hndl_count == 3:
            # disable ITIMER_VIRTUAL, this function shouldn't be called anymore
            signal.setitimer(signal.ITIMER_VIRTUAL, 0)
            if support.verbose:
                print("last SIGVTALRM handler call")

        self.hndl_count += 1

        if support.verbose:
            print("SIGVTALRM handler invoked", args)

    def sig_prof(self, *args):
        self.hndl_called = True
        signal.setitimer(signal.ITIMER_PROF, 0)

        if support.verbose:
            print("SIGPROF handler invoked", args)

    def test_itimer_exc(self):
        # XXX I'm assuming -1 is an invalid itimer, but maybe some platform
        # defines it ?
        self.assertRaises(signal.ItimerError, signal.setitimer, -1, 0)
        # Negative times are treated as zero on some platforms.
        if 0:
            self.assertRaises(signal.ItimerError,
                              signal.setitimer, signal.ITIMER_REAL, -1)

    def test_itimer_real(self):
        self.itimer = signal.ITIMER_REAL
        signal.setitimer(self.itimer, 1.0)
        if support.verbose:
            print("\ncall pause()...")
        signal.pause()

        self.assertEqual(self.hndl_called, True)

    # Issue 3864, unknown if this affects earlier versions of freebsd also
    @unittest.skipIf(sys.platform in ('freebsd6', 'netbsd5'),
        'itimer not reliable (does not mix well with threading) on some BSDs.')
    def test_itimer_virtual(self):
        self.itimer = signal.ITIMER_VIRTUAL
        signal.signal(signal.SIGVTALRM, self.sig_vtalrm)
        signal.setitimer(self.itimer, 0.3, 0.2)

        start_time = time.time()
        while time.time() - start_time < 60.0:
            # use up some virtual time by doing real work
            _ = pow(12345, 67890, 10000019)
            if signal.getitimer(self.itimer) == (0.0, 0.0):
                break # sig_vtalrm handler stopped this itimer
        else: # Issue 8424
            self.skipTest("timeout: likely cause: machine too slow or load too "
                          "high")

        # virtual itimer should be (0.0, 0.0) now
        self.assertEqual(signal.getitimer(self.itimer), (0.0, 0.0))
        # and the handler should have been called
        self.assertEqual(self.hndl_called, True)

    # Issue 3864, unknown if this affects earlier versions of freebsd also
    @unittest.skipIf(sys.platform=='freebsd6',
        'itimer not reliable (does not mix well with threading) on freebsd6')
    def test_itimer_prof(self):
        self.itimer = signal.ITIMER_PROF
        signal.signal(signal.SIGPROF, self.sig_prof)
        signal.setitimer(self.itimer, 0.2, 0.2)

        start_time = time.time()
        while time.time() - start_time < 60.0:
            # do some work
            _ = pow(12345, 67890, 10000019)
            if signal.getitimer(self.itimer) == (0.0, 0.0):
                break # sig_prof handler stopped this itimer
        else: # Issue 8424
            self.skipTest("timeout: likely cause: machine too slow or load too "
                          "high")

        # profiling itimer should be (0.0, 0.0) now
        self.assertEqual(signal.getitimer(self.itimer), (0.0, 0.0))
        # and the handler should have been called
        self.assertEqual(self.hndl_called, True)

def test_main():
    try:
        support.run_unittest(BasicSignalTests, InterProcessSignalTests,
                             WakeupSignalTests, SiginterruptTest,
                             ItimerTest, WindowsSignalTests)
    finally:
        support.reap_children()


if __name__ == "__main__":
    test_main()