msgsnd && msgrcv被信号中断

    linux系统消息队列使用时，会与信号冲突。msgsnd/msgrcv以block方式发送/接收消息时，会因为进程收到了信号而中断。此时msgsnd/msgrcv将返回-1，errno被设置为EINTR(-4)。且即使在插入信号时设置了SA_RESTART,也无效。

此时我们只好用如下方式来重启消息队列：

 

while(TRUE)
        {
                err = msgrcv(msgid, buf, sizeof(buf), 0);
                if (-1 == err){
                        if (EINTR == errno){
                                continue;
                        }
                        perror("msgrcv");
                        break;
                }

                /* deal message */
                deal_msg(...);
        }


 

 

 

附：插入信号时，设置SA_RESTART方式：

 

void handler(int signo)
{
        printf("i got the signal %d\n",signo);
}

int main()
{
        struct sigaction action;
        sigset_t set;
        printf("waiting for signal\n");
        
        action.sa_handler=handler;
        sigemptyset(&action.sa_mask);
        action.sa_flags|=SA_RESTART;
        sigaction(SIGALRM,&action,NULL);

        /* do sth with block way */
        do_block_thing();
}