On Sat, Sep 22, 2007 at 06:07:14PM +0200, Michael Kerrisk wrote:
On 9/22/07, Bernd Eckenfels <[EMAIL PROTECTED]> wrote:
In article <[EMAIL PROTECTED]> you wrote:
>  1. This design stretches the POSIX timers API in strange
>     ways.

Maybe it is possible to reimplement the POSIX API in usermode using the
kernel's FD implementation?

It's a clever idea...  Without thinking on it too long, I'm not sure
whether or not there might be some details which would make this
difficult.

It seems to be a dangerous idea. It has the potential of breaking userspace applications that rely on POSIX timers not creating fd's.

Image code like this:

        /* Close stdin, stdout, stderr */
        close(0);
        close(1);
        close(2);

        /* Oh, a timer would be nice */
        timer_create(x, y, z);

        /* Create new stdin, stdout, stderr */
        fd = open("/dev/null", flags);
        dup(fd);
        dup(fd);

Unless timer_create does some magic to avoid using the lowest available fd, this would suddenly break as the timerfd would be fd 0.

--
David Härdeman
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