tellwait.c

#include "apue.h"</p><p>static volatile sig_atomic_t sigflag; /* set nonzero by sig handler */<br />static sigset_t newmask, oldmask, zeromask;</p><p>static void<br />sig_usr(int signo)/* one signal handler for SIGUSR1 and SIGUSR2 */<br />{<br />sigflag = 1;<br />}</p><p>void<br />TELL_WAIT(void)<br />{<br />if (signal(SIGUSR1, sig_usr) == SIG_ERR)<br />err_sys("signal(SIGUSR1) error");<br />if (signal(SIGUSR2, sig_usr) == SIG_ERR)<br />err_sys("signal(SIGUSR2) error");<br />sigemptyset(&zeromask);<br />sigemptyset(&newmask);<br />sigaddset(&newmask, SIGUSR1);<br />sigaddset(&newmask, SIGUSR2);</p><p>/*<br /> * Block SIGUSR1 and SIGUSR2, and save current signal mask.<br /> */<br />if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)<br />err_sys("SIG_BLOCK error");<br />}</p><p>void<br />TELL_PARENT(pid_t pid)<br />{<br />kill(pid, SIGUSR2);/* tell parent we're done */<br />}</p><p>void<br />WAIT_PARENT(void)<br />{<br />while (sigflag == 0)<br />sigsuspend(&zeromask);/* and wait for parent */<br />sigflag = 0;</p><p>/*<br /> * Reset signal mask to original value.<br /> */<br />if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)<br />err_sys("SIG_SETMASK error");<br />}</p><p>void<br />TELL_CHILD(pid_t pid)<br />{<br />kill(pid, SIGUSR1);/* tell child we're done */<br />}</p><p>void<br />WAIT_CHILD(void)<br />{<br />while (sigflag == 0)<br />sigsuspend(&zeromask);/* and wait for child */<br />sigflag = 0;</p><p>/*<br /> * Reset signal mask to original value.<br /> */<br />if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)<br />err_sys("SIG_SETMASK error");<br />}<br />