def fd_event_handler(self, signal_fd, eventmask):
"""Callback called by dispatcher when any signal is received on
signalfd Reads signal info from fd and calls applicable signal handler.
:return:
"""
del eventmask
siginfo = signalfd_siginfo()
if self.sfd_stream is None:
try:
self.sfd_stream = os.fdopen(signal_fd, 'rb', 0)
except IOError, ex:
self.logger.error("Failed to open signal fd - %s",
os.strerror(ex.errno))
self._cleanup()
return
def main():
# Block signals so that they aren't handled
# according to their default dispositions
mask = sigset_t()
fdsi = signalfd_siginfo()
sigemptyset(mask)
sigaddset(mask, SIGINT)
sigaddset(mask, SIGQUIT)
sigprocmask(SIG_BLOCK, mask, None)
# Get a signalfd descriptor
sfd = signalfd(-1, mask, SFD_CLOEXEC)
# Get a epoll descriptor
epollfd = epoll_create1(EPOLL_CLOEXEC)
ev = epoll_event()
ev.events = EPOLLIN
ev.data.fd = sfd
epoll_ctl(epollfd, EPOLL_CTL_ADD, sfd, byref(ev))
MAX_EVENTS = 10
events = (epoll_event * MAX_EVENTS)()
with fdopen(sfd, 'rb', 0) as sfd_stream:
while True:
nfds = epoll_wait(
epollfd, cast(byref(events), POINTER(epoll_event)),
MAX_EVENTS, -1)
for event_id in range(nfds):
if events[event_id].data.fd == sfd:
# Read the next delivered signal
sfd_stream.readinto(fdsi)
if fdsi.ssi_signo == SIGINT:
print("Got SIGINT")
elif fdsi.ssi_signo == SIGQUIT:
print("Got SIGQUIT")
return
else:
print("Read unexpected signal")
else:
raise Exception("unexpected fd?")
close(sfd)
close(epollfd)
def main():
# Block signals so that they aren't handled
# according to their default dispositions
mask = sigset_t()
fdsi = signalfd_siginfo()
sigemptyset(mask)
sigaddset(mask, SIGINT)
sigaddset(mask, SIGQUIT)
sigprocmask(SIG_BLOCK, mask, None)
# Get a signalfd descriptor
sfd = signalfd(-1, mask, 0)
with fdopen(sfd, 'rb', 0) as sfd_stream:
while True:
# Read the next delivered signal
sfd_stream.readinto(fdsi)
if fdsi.ssi_signo == SIGINT:
print("Got SIGINT")
elif fdsi.ssi_signo == SIGQUIT:
print("Got SIGQUIT")
return
else:
print("Read unexpected signal")
def main():
# Block signals so that they aren't handled
# according to their default dispositions
mask = sigset_t()
fdsi = signalfd_siginfo()
sigemptyset(mask)
sigaddset(mask, SIGINT)
sigaddset(mask, SIGQUIT)
sigaddset(mask, SIGCHLD)
sigaddset(mask, SIGPIPE)
print("Blocking signals")
sigprocmask(SIG_BLOCK, mask, None)
# Get a signalfd descriptor
sfd = signalfd(-1, mask, SFD_CLOEXEC | SFD_NONBLOCK)
print("Got signalfd", sfd)
# Get a epoll descriptor
ep = epoll()
print("Got epollfd", ep.fileno())
print("Adding signalfd fd {} to epoll".format(sfd))
ep.register(sfd, EPOLLIN)
# Get two pair of pipes, one for stdout and one for stderr
stdout_pair = (c_int * 2)()
pipe2(byref(stdout_pair), O_CLOEXEC | O_NONBLOCK)
print("Got stdout pipe pair", stdout_pair[0], stdout_pair[1])
print("Adding pipe fd {} to epoll".format(stdout_pair[0]))
ep.register(stdout_pair[0], EPOLLIN)
stderr_pair = (c_int * 2)()
pipe2(byref(stderr_pair), O_CLOEXEC | O_NONBLOCK)
print("Got stderr pipe pair", stderr_pair[0], stderr_pair[1])
print("Adding pipe fd {} to epoll".format(stdout_pair[0]))
ep.register(stderr_pair[0], EPOLLIN)
prog = argv[1:]
if not prog:
prog = ['echo', 'usage: demo.py PROG [ARGS]']
print("Going to start program:", prog)
# Fork :-)
pid = fork()
if pid == 0: # Child.
# NOTE: we are not closing any of the pipe ends. Why? Because they are
# all O_CLOEXEC and will thus not live across the execlp call down
# below.
dup3(stdout_pair[1], 1, 0)
dup3(stderr_pair[1], 2, 0)
execlp(prog[0], *prog)
return -1
else:
close(stdout_pair[1])
close(stderr_pair[1])
with fdopen(sfd, 'rb', 0) as sfd_stream:
waiting_for = set(['stdout', 'stderr', 'proc'])
while waiting_for:
print("Waiting for events...", ' '.join(waiting_for), flush=True)
event_list = ep.poll(maxevents=10)
print("epoll_wait() read {} events".format(len(event_list)))
for fd, events in event_list:
print("[event]")
event_bits = []
if events & EPOLLIN == EPOLLIN:
event_bits.append('EPOLLIN')
if events & EPOLLOUT == EPOLLOUT:
event_bits.append('EPOLLOUT')
if events & EPOLLRDHUP == EPOLLRDHUP:
event_bits.append('EPOLLRDHUP')
if events & EPOLLPRI == EPOLLPRI:
event_bits.append('EPOLLPRI')
if events & EPOLLERR == EPOLLERR:
event_bits.append('EPOLLERR')
if events & EPOLLHUP == EPOLLHUP:
event_bits.append('EPOLLHUP')
if fd == sfd:
fd_name = 'signalfd()'
elif fd == stdout_pair[0]:
fd_name = 'stdout pipe2()'
elif fd == stderr_pair[0]:
fd_name = 'stderr pipe2()'
else:
fd_name = "???"
print(" events: {} ({})".format(
events, ' | '.join(event_bits)))
print(" fd: {} ({})".format(fd, fd_name))
if fd == sfd:
print("signalfd() descriptor ready")
if events & EPOLLIN:
print("Reading data from signalfd()...")
# Read the next delivered signal
sfd_stream.readinto(fdsi)
if fdsi.ssi_signo == SIGINT:
print("Got SIGINT")
elif fdsi.ssi_signo == SIGQUIT:
print("Got SIGQUIT")
raise SystemExit("exiting prematurly")
elif fdsi.ssi_signo == SIGCHLD:
print("Got SIGCHLD")
waitid_result = waitid(
P_PID, pid,
WNOHANG |
WEXITED | WSTOPPED | WCONTINUED |
WUNTRACED)
if waitid_result is None:
print("child not ready")
else:
print("child event")
print("si_pid:", waitid_result.si_pid)
print("si_uid:", waitid_result.si_uid)
print("si_signo:", waitid_result.si_signo)
assert waitid_result.si_signo == SIGCHLD
print("si_status:", waitid_result.si_status)
print("si_code:", waitid_result.si_code)
if waitid_result.si_code == CLD_EXITED:
# assert WIFEXITED(waitid_result.si_status)
print("child exited normally")
print("exit code:",
WEXITSTATUS(waitid_result.si_status))
waiting_for.remove('proc')
if 'stdout' in waiting_for:
ep.unregister(stdout_pair[0])
close(stdout_pair[0])
waiting_for.remove('stdout')
if 'stderr' in waiting_for:
ep.unregister(stderr_pair[0])
close(stderr_pair[0])
waiting_for.remove('stderr')
elif waitid_result.si_code == CLD_KILLED:
assert WIFSIGNALED(waitid_result.si_status)
print("child was killed by signal")
print("death signal:",
waitid_result.si_status)
waiting_for.remove('proc')
elif waitid_result.si_code == CLD_DUMPED:
assert WIFSIGNALED(waitid_result.si_status)
print("core:",
WCOREDUMP(waitid_result.si_status))
elif waitid_result.si_code == CLD_STOPPED:
print("child was stopped")
print("stop signal:",
waitid_result.si_status)
elif waitid_result.si_code == CLD_TRAPPED:
print("child was trapped")
# TODO: we could explore trap stuff here
elif waitid_result.si_code == CLD_CONTINUED:
print("child was continued")
else:
raise SystemExit(
"Unknown CLD_ code: {}".format(
waitid_result.si_code))
elif fdsi.ssi_signo == SIGPIPE:
print("Got SIGPIPE")
else:
print("Read unexpected signal: {}".format(
fdsi.ssi_signo))
elif fd == stdout_pair[0]:
print("pipe() (stdout) descriptor ready")
if events & EPOLLIN:
print("Reading data from stdout...")
data = read(stdout_pair[0], PIPE_BUF)
print("Read {} bytes from stdout".format(len(data)))
print(data)
if events & EPOLLHUP:
print("Removing stdout pipe from epoll")
ep.unregister(stdout_pair[0])
print("Closing stdout pipe")
close(stdout_pair[0])
waiting_for.remove('stdout')
elif fd == stderr_pair[0]:
print("pipe() (stderr) descriptor ready")
if events & EPOLLIN:
print("Reading data from stdout...")
data = read(stderr_pair[0], PIPE_BUF)
print("Read {} bytes from stderr".format(len(data)))
print(data)
if events & EPOLLHUP:
print("Removing stderr pipe from epoll")
ep.unregister(stderr_pair[0])
print("Closing stderr pipe")
close(stderr_pair[0])
waiting_for.remove('stderr')
else:
# FIXME: we are still getting weird activation events on fd
# 0 (stdin) with events == 0 (nothing). I cannot explain
# this yet.
print("Unexpected descriptor ready:", fd)
assert not waiting_for
print("Closing", ep)
ep.close()
print("Unblocking signals")
sigprocmask(SIG_UNBLOCK, mask, None)
print("Exiting normally")
