Thread: What would I use in place of select()

I'm modifying some code so that there is a timer on in. When the system has select(), I can just place a timer on select. However, what are some alternatives in the noselect case? Here is a code snippet to give you some idea,

Code:

/*Here is the section that has a timer*/
#ifndef NOSELECT
     /* Set up the input file set for the select call */
     FD_ZERO(&input_set);
     FD_SET(0,&input_set);
     FD_SET(rst,&input_set);
     struct timeval tv;

     tv.tv_sec = atoi(opt[OPT_IDLEOUT].str)*60;
     tv.tv_usec = 0;
 #endif


 /*What are some ideas that I could do this case?*/
 #ifdef NOSELECT
         /* Copy text while I can -- otherwise go to input mode */
         if (output())
         { /*}*/
             /* Wait four seconds for a command */
             alarm(4);
             if (!setjump(jenv,1))
             {
                 read(0,&ch,1);  /* Alarm busts us out of here */
                 alarm(0);
                 docmd(ch);
                 lastaction= time((time_t *)0);
             }
 #else

 /* Wait for input in file or from user */
         iset= input_set;
         select(rst+1, &iset, NULL, NULL, &tv);/* process typed command from user */
        if (FD_ISSET(0,&iset))
        {
            read(0,&ch,1);
            docmd(ch);
            lastaction= time((time_t *)0);
        }

        /* process new text in file */
        if (FD_ISSET(rst,&iset))
        {
            while (!output())
                ;
#endif /*NOSELECT*/

Why wouldn't a system have at least select(), or epoll(), or kpoll(), or some means of selecting an active socket? I can't think of any system that doesn't provide some means of async I/O.

So? Is there some debilitating shortcoming in this?