使用信号SIGALRM 为 connect 设置超时

 1 #include"apue.h"
 2 typedef void Sigfunc(int);
 3 //void (*signal(int signo,void (*func)(int)))(int);
 4 static void connect_alarm(int);
 5 int connect_timeout(int sockfd,(SA*)pserveraddr,socklen_t len,int sec)
 6 {
 7     signal(SIGALRM,connect_alarm);
 8     int res;
 9     Sigfunc * sigfunc=alarm(sec); //sigfunc restore old sig function
10     if((res=connect(sockfd,pserveraddr,len))<0)
11     {
12         if(errno==EINTR)
13         {
14             fprintf(stderr,"time out!\n");
15             errno=ETIMEOUT;
16             close(fd);
17             return n;    //-1 connection error;
18         }
19     }
20     else
21     {
22         alarm(0);
23         signal(SIGALRM,sigfunc);    //restore old sigfunction
24         return n;    // 0 connection success!
25     }
26 
27 }

static void connect_alarm(int)
{
    return ;
}