tellwait.c

unix环境高级编程的源代码

#include    <signal.h>
#include    "ourhdr.h"

static volatile sig_atomic_t    sigflag;
                                /* set nonzero by signal handler */
static sigset_t            newmask, oldmask, zeromask;

static void
sig_usr(int signo)    /* one signal handler for SIGUSR1 and SIGUSR2 */
{
    sigflag = 1;
    return;
}

void
TELL_WAIT()
{
    if (signal(SIGUSR1, sig_usr) == SIG_ERR)
        err_sys("signal(SIGINT) error");
    if (signal(SIGUSR2, sig_usr) == SIG_ERR)
        err_sys("signal(SIGQUIT) error");

    sigemptyset(&zeromask);

    sigemptyset(&newmask);
    sigaddset(&newmask, SIGUSR1);
    sigaddset(&newmask, SIGUSR2);
        /* block SIGUSR1 and SIGUSR2, and save current signal mask */
    if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
        err_sys("SIG_BLOCK error");
}

void
TELL_PARENT(pid_t pid)
{
    kill(pid, SIGUSR2);        /* tell parent we're done */
}

void
WAIT_PARENT(void)
{
    while (sigflag == 0)
        sigsuspend(&zeromask);    /* and wait for parent */

    sigflag = 0;
            /* reset signal mask to original value */
    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        err_sys("SIG_SETMASK error");
}
void
TELL_CHILD(pid_t pid)
{
    kill(pid, SIGUSR1);            /* tell child we're done */
}

void
WAIT_CHILD(void)
{
    while (sigflag == 0)
        sigsuspend(&zeromask);    /* and wait for child */

    sigflag = 0;
            /* reset signal mask to original value */
    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        err_sys("SIG_SETMASK error");
}