tellwait.c (1366B)
1 #include <signal.h> 2 #include "ourhdr.h" 3 4 static volatile sig_atomic_t sigflag; 5 /* set nonzero by signal handler */ 6 static sigset_t newmask, oldmask, zeromask; 7 8 static void 9 sig_usr(int signo) /* one signal handler for SIGUSR1 and SIGUSR2 */ 10 { 11 sigflag = 1; 12 return; 13 } 14 15 void 16 TELL_WAIT() 17 { 18 if (signal(SIGUSR1, sig_usr) == SIG_ERR) 19 err_sys("signal(SIGINT) error"); 20 if (signal(SIGUSR2, sig_usr) == SIG_ERR) 21 err_sys("signal(SIGQUIT) error"); 22 23 sigemptyset(&zeromask); 24 25 sigemptyset(&newmask); 26 sigaddset(&newmask, SIGUSR1); 27 sigaddset(&newmask, SIGUSR2); 28 /* block SIGUSR1 and SIGUSR2, and save current signal mask */ 29 if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0) 30 err_sys("SIG_BLOCK error"); 31 } 32 33 void 34 TELL_PARENT(pid_t pid) 35 { 36 kill(pid, SIGUSR2); /* tell parent we're done */ 37 } 38 39 void 40 WAIT_PARENT(void) 41 { 42 while (sigflag == 0) 43 sigsuspend(&zeromask); /* and wait for parent */ 44 45 sigflag = 0; 46 /* reset signal mask to original value */ 47 if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0) 48 err_sys("SIG_SETMASK error"); 49 } 50 void 51 TELL_CHILD(pid_t pid) 52 { 53 kill(pid, SIGUSR1); /* tell child we're done */ 54 } 55 56 void 57 WAIT_CHILD(void) 58 { 59 while (sigflag == 0) 60 sigsuspend(&zeromask); /* and wait for child */ 61 62 sigflag = 0; 63 /* reset signal mask to original value */ 64 if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0) 65 err_sys("SIG_SETMASK error"); 66 }