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import unittest
from test import test_support
import signal
import os, sys, time
class HandlerBCalled(Exception):
pass
class InterProcessSignalTests(unittest.TestCase):
MAX_DURATION = 20 # Entire test should last at most 20 sec.
# Set up a child to send signals to us (the parent) after waiting
# long enough to receive the alarm. It seems we miss the alarm
# for some reason. This will hopefully stop the hangs on
# Tru64/Alpha. Alas, it doesn't. Tru64 appears to miss all the
# signals at times, or seemingly random subsets of them, and
# nothing done in force_test_exit so far has actually helped.
def spawn_force_test_exit_process(self, parent_pid):
# Sigh, both imports seem necessary to avoid errors.
import os
fork_pid = os.fork()
if fork_pid:
# In parent.
return fork_pid
# In child.
import os, time
try:
# Wait 5 seconds longer than the expected alarm to give enough
# time for the normal sequence of events to occur. This is
# just a stop-gap to try to prevent the test from hanging.
time.sleep(self.MAX_DURATION + 5)
print(" child should not have to kill parent",
file=sys.__stdout__)
for signame in "SIGHUP", "SIGUSR1", "SIGUSR2", "SIGALRM":
os.kill(parent_pid, getattr(signal, signame))
print(" child sent", signame, "to",
parent_pid, file=sys.__stdout__)
time.sleep(1)
finally:
os._exit(0)
def handlerA(self, *args):
self.a_called = True
if test_support.verbose:
print("handlerA invoked", args)
def handlerB(self, *args):
self.b_called = True
if test_support.verbose:
print("handlerB invoked", args)
raise HandlerBCalled(*args)
def test_main(self):
self.assertEquals(signal.getsignal(signal.SIGHUP), self.handlerA)
self.assertEquals(signal.getsignal(signal.SIGUSR1), self.handlerB)
self.assertEquals(signal.getsignal(signal.SIGUSR2), signal.SIG_IGN)
self.assertEquals(signal.getsignal(signal.SIGALRM),
signal.default_int_handler)
# Launch an external script to send us signals.
# We expect the external script to:
# send HUP, which invokes handlerA to set a_called
# send USR1, which invokes handlerB to set b_called and raise
# HandlerBCalled
# send USR2, which is ignored
#
# Then we expect the alarm to go off, and its handler raises
# KeyboardInterrupt, finally getting us out of the loop.
if test_support.verbose:
verboseflag = '-x'
else:
verboseflag = '+x'
pid = self.pid
if test_support.verbose:
print("test runner's pid is", pid)
# Shell script that will send us asynchronous signals
script = """
(
set %(verboseflag)s
sleep 2
kill -HUP %(pid)d
sleep 2
kill -USR1 %(pid)d
sleep 2
kill -USR2 %(pid)d
) &
""" % vars()
signal.alarm(self.MAX_DURATION)
handler_b_exception_raised = False
os.system(script)
try:
if test_support.verbose:
print("starting pause() loop...")
while 1:
try:
if test_support.verbose:
print("call pause()...")
signal.pause()
if test_support.verbose:
print("pause() returned")
except HandlerBCalled:
handler_b_exception_raised = True
if test_support.verbose:
print("HandlerBCalled exception caught")
except KeyboardInterrupt:
if test_support.verbose:
print("KeyboardInterrupt (the alarm() went off)")
self.assert_(self.a_called)
self.assert_(self.b_called)
self.assert_(handler_b_exception_raised)
def setUp(self):
# Install handlers.
self.hup = signal.signal(signal.SIGHUP, self.handlerA)
self.usr1 = signal.signal(signal.SIGUSR1, self.handlerB)
self.usr2 = signal.signal(signal.SIGUSR2, signal.SIG_IGN)
self.alrm = signal.signal(signal.SIGALRM,
signal.default_int_handler)
self.a_called = False
self.b_called = False
self.pid = os.getpid()
self.fork_pid = self.spawn_force_test_exit_process(self.pid)
def tearDown(self):
# Forcibly kill the child we created to ping us if there was a
# test error.
try:
# Make sure we don't kill ourself if there was a fork
# error.
if self.fork_pid > 0:
os.kill(self.fork_pid, signal.SIGKILL)
except:
# If the child killed us, it has probably exited. Killing
# a non-existent process will raise an error which we
# don't care about.
pass
# Restore handlers.
signal.alarm(0) # cancel alarm in case we died early
signal.signal(signal.SIGHUP, self.hup)
signal.signal(signal.SIGUSR1, self.usr1)
signal.signal(signal.SIGUSR2, self.usr2)
signal.signal(signal.SIGALRM, self.alrm)
class BasicSignalTests(unittest.TestCase):
def test_out_of_range_signal_number_raises_error(self):
self.assertRaises(ValueError, signal.getsignal, 4242)
def trivial_signal_handler(*args):
pass
self.assertRaises(ValueError, signal.signal, 4242,
trivial_signal_handler)
def test_setting_signal_handler_to_none_raises_error(self):
self.assertRaises(TypeError, signal.signal,
signal.SIGUSR1, None)
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.assert_(mid_time - before_time < self.TIMEOUT_HALF)
select.select([self.read], [], [], self.TIMEOUT_FULL)
after_time = time.time()
self.assert_(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.assert_(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)
def test_main():
if sys.platform[:3] in ('win', 'os2'):
raise test_support.TestSkipped("Can't test signal on %s" % \
sys.platform)
test_support.run_unittest(BasicSignalTests, InterProcessSignalTests,
WakeupSignalTests)
if __name__ == "__main__":
test_main()
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