sleep2.c

UNIX编程高级环境（第二版）的信号部分的程序源码

#include    <setjmp.h>
#include    <signal.h>
#include    <unistd.h>

static jmp_buf    env_alrm;

static void
sig_alrm(int signo)
{
    longjmp(env_alrm, 1);
}

unsigned int
sleep2(unsigned int nsecs)
{
    if (signal(SIGALRM, sig_alrm) == SIG_ERR)
        return(nsecs);
    if (setjmp(env_alrm) == 0) {
        alarm(nsecs);        /* start the timer */
        pause();            /* next caught signal wakes us up */
    }
    return( alarm(0) );        /* turn off timer, return unslept time */
}