c - Why I can't receive SIGPOLL signal from ioctl function? -


i got strange problem can't solve. code.

#include <stdio.h> #include <stropts.h> #include <signal.h> #include <sys/types.h>  void handle_signal(int s) {     char c = getchar();     printf("got char '%c'\n");     if(c == 'q')     {         exit(0);     } }  int main(int argc, char** argv) {     sigset(sigpoll, handle_signal);     ioctl(0, i_setsig, s_rdnorm);     printf("type q exit");     while(1);     return 0; }

when run program, type character in terminal did not work!!! can not receive sigpoll signal. have can give me advice? way, operating system ubuntu 12.04.

on linux needs set o_async flag , f_setown property on file descriptor sigio signal (a synonym of sigpoll). , signal handler can call async-signal safe functions:

#include <stdio.h> #include <signal.h> #include <unistd.h> #include <stdlib.h> #include <fcntl.h> #include <ctype.h>  void handle_signal(int) { // can use async-signal safe functions here.     char msg[] = "got char c\n";     char* c = msg + (sizeof msg - 3);     if(1 != read(stdin_fileno, c, 1) || !isprint(*c))         return;     write(stdout_fileno, msg, sizeof msg - 1);     if(*c == 'q')         exit(exit_success); }  int main() {     printf("type q exit\n");      signal(sigio, handle_signal);     fcntl(stdin_fileno, f_setfl, o_async | fcntl(stdin_fileno, f_getfl));     fcntl(stdin_fileno, f_setown, getpid());      sigset_t mask;     sigemptyset(&mask);     for(;;)         sigsuspend(&mask);      return exit_success; }

you may have @ f_setsig allows receiving signal of choosing , information signal handler.


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