Lib/test/test_signal.py

   1 import unittest
   2 from test import test_support
   3 from contextlib import closing
   4 import gc
   5 import pickle
   6 import select
   7 import signal
   8 import subprocess
   9 import traceback
  10 import sys, os, time, errno
  11
  12 if sys.platform[:3] in ('win', 'os2') or sys.platform == 'riscos':
  13     raise unittest.SkipTest("Can't test signal on %s" % \
  14                                    sys.platform)
  15
  16
  17 class HandlerBCalled(Exception):
  18     pass
  19
  20
  21 def exit_subprocess():
  22     """Use os._exit(0) to exit the current subprocess.
  23
  24     Otherwise, the test catches the SystemExit and continues executing
  25     in parallel with the original test, so you wind up with an
  26     exponential number of tests running concurrently.
  27     """
  28     os._exit(0)
  29
  30
  31 def ignoring_eintr(__func, *args, **kwargs):
  32     try:
  33         return __func(*args, **kwargs)
  34     except EnvironmentError as e:
  35         if e.errno != errno.EINTR:
  36             raise
  37         return None
  38
  39
  40 class InterProcessSignalTests(unittest.TestCase):
  41     MAX_DURATION = 20   # Entire test should last at most 20 sec.
  42
  43     def setUp(self):
  44         self.using_gc = gc.isenabled()
  45         gc.disable()
  46
  47     def tearDown(self):
  48         if self.using_gc:
  49             gc.enable()
  50
  51     def format_frame(self, frame, limit=None):
  52         return ''.join(traceback.format_stack(frame, limit=limit))
  53
  54     def handlerA(self, signum, frame):
  55         self.a_called = True
  56         if test_support.verbose:
  57             print "handlerA invoked from signal %s at:\n%s" % (
  58                 signum, self.format_frame(frame, limit=1))
  59
  60     def handlerB(self, signum, frame):
  61         self.b_called = True
  62         if test_support.verbose:
  63             print "handlerB invoked from signal %s at:\n%s" % (
  64                 signum, self.format_frame(frame, limit=1))
  65         raise HandlerBCalled(signum, self.format_frame(frame))
  66
  67     def wait(self, child):
  68         """Wait for child to finish, ignoring EINTR."""
  69         while True:
  70             try:
  71                 child.wait()
  72                 return
  73             except OSError as e:
  74                 if e.errno != errno.EINTR:
  75                     raise
  76
  77     def run_test(self):
  78         # Install handlers. This function runs in a sub-process, so we
  79         # don't worry about re-setting the default handlers.
  80         signal.signal(signal.SIGHUP, self.handlerA)
  81         signal.signal(signal.SIGUSR1, self.handlerB)
  82         signal.signal(signal.SIGUSR2, signal.SIG_IGN)
  83         signal.signal(signal.SIGALRM, signal.default_int_handler)
  84
  85         # Variables the signals will modify:
  86         self.a_called = False
  87         self.b_called = False
  88
  89         # Let the sub-processes know who to send signals to.
  90         pid = os.getpid()
  91         if test_support.verbose:
  92             print "test runner's pid is", pid
  93
  94         child = ignoring_eintr(subprocess.Popen, ['kill', '-HUP', str(pid)])
  95         if child:
  96             self.wait(child)
  97             if not self.a_called:
  98                 time.sleep(1)  # Give the signal time to be delivered.
  99         self.assertTrue(self.a_called)
 100         self.assertFalse(self.b_called)
 101         self.a_called = False
 102
 103         # Make sure the signal isn't delivered while the previous
 104         # Popen object is being destroyed, because __del__ swallows
 105         # exceptions.
 106         del child
 107         try:
 108             child = subprocess.Popen(['kill', '-USR1', str(pid)])
 109             # This wait should be interrupted by the signal's exception.
 110             self.wait(child)
 111             time.sleep(1)  # Give the signal time to be delivered.
 112             self.fail('HandlerBCalled exception not thrown')
 113         except HandlerBCalled:
 114             self.assertTrue(self.b_called)
 115             self.assertFalse(self.a_called)
 116             if test_support.verbose:
 117                 print "HandlerBCalled exception caught"
 118
 119         child = ignoring_eintr(subprocess.Popen, ['kill', '-USR2', str(pid)])
 120         if child:
 121             self.wait(child)  # Nothing should happen.
 122
 123         try:
 124             signal.alarm(1)
 125             # The race condition in pause doesn't matter in this case,
 126             # since alarm is going to raise a KeyboardException, which
 127             # will skip the call.
 128             signal.pause()
 129             # But if another signal arrives before the alarm, pause
 130             # may return early.
 131             time.sleep(1)
 132         except KeyboardInterrupt:
 133             if test_support.verbose:
 134                 print "KeyboardInterrupt (the alarm() went off)"
 135         except:
 136             self.fail("Some other exception woke us from pause: %s" %
 137                       traceback.format_exc())
 138         else:
 139             self.fail("pause returned of its own accord, and the signal"
 140                       " didn't arrive after another second.")
 141
 142     def test_main(self):
 143         # This function spawns a child process to insulate the main
 144         # test-running process from all the signals. It then
 145         # communicates with that child process over a pipe and
 146         # re-raises information about any exceptions the child
 147         # throws. The real work happens in self.run_test().
 148         os_done_r, os_done_w = os.pipe()
 149         with closing(os.fdopen(os_done_r)) as done_r, \
 150              closing(os.fdopen(os_done_w, 'w')) as done_w:
 151             child = os.fork()
 152             if child == 0:
 153                 # In the child process; run the test and report results
 154                 # through the pipe.
 155                 try:
 156                     done_r.close()
 157                     # Have to close done_w again here because
 158                     # exit_subprocess() will skip the enclosing with block.
 159                     with closing(done_w):
 160                         try:
 161                             self.run_test()
 162                         except:
 163                             pickle.dump(traceback.format_exc(), done_w)
 164                         else:
 165                             pickle.dump(None, done_w)
 166                 except:
 167                     print 'Uh oh, raised from pickle.'
 168                     traceback.print_exc()
 169                 finally:
 170                     exit_subprocess()
 171
 172             done_w.close()
 173             # Block for up to MAX_DURATION seconds for the test to finish.
 174             r, w, x = select.select([done_r], [], [], self.MAX_DURATION)
 175             if done_r in r:
 176                 tb = pickle.load(done_r)
 177                 if tb:
 178                     self.fail(tb)
 179             else:
 180                 os.kill(child, signal.SIGKILL)
 181                 self.fail('Test deadlocked after %d seconds.' %
 182                           self.MAX_DURATION)
 183
 184
 185 class BasicSignalTests(unittest.TestCase):
 186     def trivial_signal_handler(self, *args):
 187         pass
 188
 189     def test_out_of_range_signal_number_raises_error(self):
 190         self.assertRaises(ValueError, signal.getsignal, 4242)
 191
 192         self.assertRaises(ValueError, signal.signal, 4242,
 193                           self.trivial_signal_handler)
 194
 195     def test_setting_signal_handler_to_none_raises_error(self):
 196         self.assertRaises(TypeError, signal.signal,
 197                           signal.SIGUSR1, None)
 198
 199     def test_getsignal(self):
 200         hup = signal.signal(signal.SIGHUP, self.trivial_signal_handler)
 201         self.assertEquals(signal.getsignal(signal.SIGHUP),
 202                           self.trivial_signal_handler)
 203         signal.signal(signal.SIGHUP, hup)
 204         self.assertEquals(signal.getsignal(signal.SIGHUP), hup)
 205
 206
 207 class WakeupSignalTests(unittest.TestCase):
 208     TIMEOUT_FULL = 10
 209     TIMEOUT_HALF = 5
 210
 211     def test_wakeup_fd_early(self):
 212         import select
 213
 214         signal.alarm(1)
 215         before_time = time.time()
 216         # We attempt to get a signal during the sleep,
 217         # before select is called
 218         time.sleep(self.TIMEOUT_FULL)
 219         mid_time = time.time()
 220         self.assertTrue(mid_time - before_time < self.TIMEOUT_HALF)
 221         select.select([self.read], [], [], self.TIMEOUT_FULL)
 222         after_time = time.time()
 223         self.assertTrue(after_time - mid_time < self.TIMEOUT_HALF)
 224
 225     def test_wakeup_fd_during(self):
 226         import select
 227
 228         signal.alarm(1)
 229         before_time = time.time()
 230         # We attempt to get a signal during the select call
 231         self.assertRaises(select.error, select.select,
 232             [self.read], [], [], self.TIMEOUT_FULL)
 233         after_time = time.time()
 234         self.assertTrue(after_time - before_time < self.TIMEOUT_HALF)
 235
 236     def setUp(self):
 237         import fcntl
 238
 239         self.alrm = signal.signal(signal.SIGALRM, lambda x,y:None)
 240         self.read, self.write = os.pipe()
 241         flags = fcntl.fcntl(self.write, fcntl.F_GETFL, 0)
 242         flags = flags | os.O_NONBLOCK
 243         fcntl.fcntl(self.write, fcntl.F_SETFL, flags)
 244         self.old_wakeup = signal.set_wakeup_fd(self.write)
 245
 246     def tearDown(self):
 247         signal.set_wakeup_fd(self.old_wakeup)
 248         os.close(self.read)
 249         os.close(self.write)
 250         signal.signal(signal.SIGALRM, self.alrm)
 251
 252 class SiginterruptTest(unittest.TestCase):
 253     signum = signal.SIGUSR1
 254     def readpipe_interrupted(self, cb):
 255         r, w = os.pipe()
 256         ppid = os.getpid()
 257         pid = os.fork()
 258
 259         oldhandler = signal.signal(self.signum, lambda x,y: None)
 260         cb()
 261         if pid==0:
 262             # child code: sleep, kill, sleep. and then exit,
 263             # which closes the pipe from which the parent process reads
 264             try:
 265                 time.sleep(0.2)
 266                 os.kill(ppid, self.signum)
 267                 time.sleep(0.2)
 268             finally:
 269                 exit_subprocess()
 270
 271         try:
 272             os.close(w)
 273
 274             try:
 275                 d=os.read(r, 1)
 276                 return False
 277             except OSError, err:
 278                 if err.errno != errno.EINTR:
 279                     raise
 280                 return True
 281         finally:
 282             signal.signal(self.signum, oldhandler)
 283             os.waitpid(pid, 0)
 284
 285     def test_without_siginterrupt(self):
 286         i=self.readpipe_interrupted(lambda: None)
 287         self.assertEquals(i, True)
 288
 289     def test_siginterrupt_on(self):
 290         i=self.readpipe_interrupted(lambda: signal.siginterrupt(self.signum, 1))
 291         self.assertEquals(i, True)
 292
 293     def test_siginterrupt_off(self):
 294         i=self.readpipe_interrupted(lambda: signal.siginterrupt(self.signum, 0))
 295         self.assertEquals(i, False)
 296
 297 class ItimerTest(unittest.TestCase):
 298     def setUp(self):
 299         self.hndl_called = False
 300         self.hndl_count = 0
 301         self.itimer = None
 302         self.old_alarm = signal.signal(signal.SIGALRM, self.sig_alrm)
 303
 304     def tearDown(self):
 305         signal.signal(signal.SIGALRM, self.old_alarm)
 306         if self.itimer is not None: # test_itimer_exc doesn't change this attr
 307             # just ensure that itimer is stopped
 308             signal.setitimer(self.itimer, 0)
 309
 310     def sig_alrm(self, *args):
 311         self.hndl_called = True
 312         if test_support.verbose:
 313             print("SIGALRM handler invoked", args)
 314
 315     def sig_vtalrm(self, *args):
 316         self.hndl_called = True
 317
 318         if self.hndl_count > 3:
 319             # it shouldn't be here, because it should have been disabled.
 320             raise signal.ItimerError("setitimer didn't disable ITIMER_VIRTUAL "
 321                 "timer.")
 322         elif self.hndl_count == 3:
 323             # disable ITIMER_VIRTUAL, this function shouldn't be called anymore
 324             signal.setitimer(signal.ITIMER_VIRTUAL, 0)
 325             if test_support.verbose:
 326                 print("last SIGVTALRM handler call")
 327
 328         self.hndl_count += 1
 329
 330         if test_support.verbose:
 331             print("SIGVTALRM handler invoked", args)
 332
 333     def sig_prof(self, *args):
 334         self.hndl_called = True
 335         signal.setitimer(signal.ITIMER_PROF, 0)
 336
 337         if test_support.verbose:
 338             print("SIGPROF handler invoked", args)
 339
 340     def test_itimer_exc(self):
 341         # XXX I'm assuming -1 is an invalid itimer, but maybe some platform
 342         # defines it ?
 343         self.assertRaises(signal.ItimerError, signal.setitimer, -1, 0)
 344         # Negative times are treated as zero on some platforms.
 345         if 0:
 346             self.assertRaises(signal.ItimerError,
 347                               signal.setitimer, signal.ITIMER_REAL, -1)
 348
 349     def test_itimer_real(self):
 350         self.itimer = signal.ITIMER_REAL
 351         signal.setitimer(self.itimer, 1.0)
 352         if test_support.verbose:
 353             print("\ncall pause()...")
 354         signal.pause()
 355
 356         self.assertEqual(self.hndl_called, True)
 357
 358     def test_itimer_virtual(self):
 359         self.itimer = signal.ITIMER_VIRTUAL
 360         signal.signal(signal.SIGVTALRM, self.sig_vtalrm)
 361         signal.setitimer(self.itimer, 0.3, 0.2)
 362
 363         for i in xrange(100000000):
 364             # use up some virtual time by doing real work
 365             _ = pow(12345, 67890, 10000019)
 366             if signal.getitimer(self.itimer) == (0.0, 0.0):
 367                 break # sig_vtalrm handler stopped this itimer
 368
 369         # virtual itimer should be (0.0, 0.0) now
 370         self.assertEquals(signal.getitimer(self.itimer), (0.0, 0.0))
 371         # and the handler should have been called
 372         self.assertEquals(self.hndl_called, True)
 373
 374     def test_itimer_prof(self):
 375         self.itimer = signal.ITIMER_PROF
 376         signal.signal(signal.SIGPROF, self.sig_prof)
 377         signal.setitimer(self.itimer, 0.2, 0.2)
 378
 379         for i in xrange(100000000):
 380             if signal.getitimer(self.itimer) == (0.0, 0.0):
 381                 break # sig_prof handler stopped this itimer
 382
 383         # profiling itimer should be (0.0, 0.0) now
 384         self.assertEquals(signal.getitimer(self.itimer), (0.0, 0.0))
 385         # and the handler should have been called
 386         self.assertEqual(self.hndl_called, True)
 387
 388 def test_main():
 389     test_support.run_unittest(BasicSignalTests, InterProcessSignalTests,
 390         WakeupSignalTests, SiginterruptTest, ItimerTest)
 391
 392
 393 if __name__ == "__main__":
 394     test_main()