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connect_timeo.c
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connect_timeo.c
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/* include connect_timeo */
#include "unp.h"
static void connect_alarm(int);
int
connect_timeo(int sockfd, const SA *saptr, socklen_t salen, int nsec)
{
Sigfunc *sigfunc;
int n;
sigfunc = Signal(SIGALRM, connect_alarm);
//把本进程的报警时钟设置成由调用者指定的秒数
//如果此前已经给本进程设置过报警时钟,那么alarm的返回值是这个报警时钟的当前剩余秒数
//否则,alarm的返回值为0
if (alarm(nsec) != 0)
err_msg("connect_timeo: alarm was already set");
//当被捕获的信号为SIGALRM时,signal函数不设置SA_RESTART标准,因此connect不会重新被调用
if ( (n = connect(sockfd, saptr, salen)) < 0) {
close(sockfd);
//如果connect被中断,即返回EINTR错误,就把errno值改设为ETIMEDOUT
if (errno == EINTR)
errno = ETIMEDOUT;
}
//关闭进程的报警时钟
alarm(0); /* turn off the alarm */
//恢复原来的信号处理函数
Signal(SIGALRM, sigfunc); /* restore previous signal handler */
return(n);
}
static void
connect_alarm(int signo)
{
return; /* just interrupt the connect() */
}
/* end connect_timeo */
void
Connect_timeo(int fd, const SA *sa, socklen_t salen, int sec)
{
if (connect_timeo(fd, sa, salen, sec) < 0)
err_sys("connect_timeo error");
}