Tellwait. c

# Include "apue. H "</P> <p> static volatile sig_atomic_t sigflag;/* Set nonzero by sig handler */<br/> static sigset_t newmask, oldmask, and 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/>