Re: How to to kill a c program at the exit of my gui?

From: Melissa Schrumpf (reverse-comDOTyahooATm_schrumpf_at_bogus.address)
Date: 05/13/04 

Date: Thu, 13 May 2004 08:30:40 -0400

Hao Xu wrote:

> I think that at the exit of the TclTk gui, the $fd breaks, and there
> is EOF of stdin, isn't it? So I want the recv program to know this
> signal, and use the corresponding signal handler to kill itself.

> My question is:
> Is this feasible? If the answer is yes, then how to do this?

Yes, this is feasible, but checking for a broken file descriptor is something
the running program must do, not tcl.

You have three options that I can think of, off the top of my head. On unix,
you can:

    fd_set rset;
    struct timeval t;
    FD_ZERO(&rset);
    FD_SET(STDIN_FILENO, &rset);
    t.tv_sec = 0;
    t.tv_usec = 1;
    while(1) {
        if ((select(STDIN_FILENO+1), &rset, NULL, NULL, &t)>0) {break;}
        // ...
    }

On Windows, you can:

   while(!_kbhit()) {
      if (ferror(stdout) || ferror(stdin) ||
         feof(stdout) || feof(stdin)) {break;}
      // ...
   }

On either platform, you could wait until you expect no more user input (your
normal I/O is complete), then spawn a thread, and have that thread do a
blocking read (getc()) on stdin, then check for ferror or feof on stdin when
getc completes. 

-- 
MKS

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