Linux模拟实现sleep函数

#include<stdio.h>
#include<unistd.h>
#include<signal.h>
void handler(int signo)//由于程序在睡眠期间什么也不做所以自定义处理函数不执行任何操作
{
}
int mysleep(int time)
{
 sigset_t set;
 sigemptyset(&set);
 struct sigaction act;
 struct sigaction oact;
 act.sa_handler = handler;//自定义处理函数
 act.sa_mask = set;
 act.sa_flags = 0; 
 sigaction(SIGALRM,&act,&oact);//捕捉闹钟信号自定义处理动作
 alarm(time);//time秒后给进程发送信号
 pause();//挂起进程
 int _time = alarm(0);//如果程序被提前唤醒取消闹钟
 sigaction(SIGALRM,&oact,NULL);//恢复捕捉信号的原始状态
 return _time;
}
int main()
{
 while(1)
 {
 printf("hello yingying\n");
 mysleep(2);
 }
 return 0;
}

#include<stdio.h>
#include<unistd.h>
#include<signal.h>
void handler(int signo)
{
}
int mysleep(int time)
{
 sigset_t set,oset,susmask;
 sigemptyset(&set);
 sigaddset(&set,SIGALRM);
 sigprocmask(SIG_BLOCK,&set,&oset);
 struct sigaction act;
 struct sigaction oact;
 act.sa_handler = handler;
 act.sa_mask = set;
 act.sa_flags = 0; 
 sigaction(SIGALRM,&act,&oact);
 alarm(time);
 susmask = oset;
 sigdelset(&susmask,SIGALRM);
 sigsuspend(&susmask);
 int _time = alarm(0);
 sigaction(SIGALRM,&oact,NULL);
 sigprocmask(SIG_BLOCK,&oset,NULL);
 return _time;
}
int main()
{
 while(1)
 {
 printf("hello yingying\n");
 mysleep(2);
 }
 return 0;
}