c++ - I want to know which a signal is arrived when system call() is interrupted -

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my application has 2 threads. each threads recevive data server via each sockets. threads wait return epoll_wait(). epoll_wait() returns -1 , errno eintr. eintr means system call() interrupted signal. added process eintr. not know signal arrived , why signal arrived. wonder it.

method 1.

i created thread. 

sigset_t smaskofsignal;                                                sigset_t soldmaskofsignal;                                             sigfillset(&smaskofsignal);                                            sigprocmask(sig_unblock, &smaskofsignal, &soldmaskofsignal)  while(1) {                                                                                             sigwait(&smaskofsignal, &sarrivedsignal);                                                  fprintf(stdout, "%d(%s) signal caught\n", sarrivedsignal, strsignal(sarrivedsignal)); }

i not catch signal when epoll_wait() interrupted.

method 2

when execute application in strace tool, epoll_wait() never interrupted.

my problem reproduced in gdb tool. need helps....

you can try implement own signal handler. if application gets interrupted signal again, own signal-handler called , can see, kind of signal has been raised.

void signal_callback_handler(int signum) {   printf("caught signal %d\n",signum);   exit(signum); // terminate application }  int main() {   // register signal handler signals want handle   signal(sigint, signal_callback_handler);   signal(sigabrt, signal_callback_handler);   signal(sigsegv, signal_callback_handler);   // .. , more, if want }

not handy-method, should (hopefully) enable find out, signal has been raised. take here see different signals, can handled (note: not signals can handled in own signal-handler(!)).


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