Re: kernel/2182: virtual interval timers always one-shot

[Theo de Raadt <deraadt@cvs.openbsd.org>]

The following reply was made to PR kernel/2182; it has been noted by GNATS.

From: Theo de Raadt <deraadt@cvs.openbsd.org>
To: cb@mit.edu
Cc: gnats@openbsd.org
Subject: Re: kernel/2182: virtual interval timers always one-shot 
Date: Sat, 17 Nov 2001 17:44:37 -0700

 Seems to work fine from what I see.  Would have helped if you had
 included a test program which fails, because mine seems to work.
 
 Your comment about kern_time.c not even using it_interval is wrong
 too, as grep will show.
 
 Perhaps you did not read this paragraph:
 
      If it_value is non-zero, it indicates the time to the next timer expira-
      tion.  If it_interval is non-zero, it specifies a value to be used in
      reloading it_value when the timer expires.  Setting it_value to 0 dis-
      ables a timer.  Setting it_interval to 0 causes a timer to be disabled
      after its next expiration (assuming it_value is non-zero).
 
 There does seem to be something strange with very small values of
 it_interval, in particular, when the time is < 10000 usec.
 
 ---
 
 #include <sys/types.h>
 #include <sys/signal.h>
 #include <sys/time.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
 
 void
 timer(int sigval)
 {
 	int save_errno = errno;
 
 	write(STDOUT_FILENO, ".", 1);
 	errno = save_errno;
 }
 
 main()
 {
 	struct itimerval tvi;
 	struct sigaction sa;
 
 	tvi.it_interval.tv_sec = 1;
 	tvi.it_interval.tv_usec = 0;
 	tvi.it_value.tv_sec = 1;
 	tvi.it_value.tv_usec = 0;
 
 	memset(&sa, 0, sizeof sa);
 	sigemptyset(&sa);
 	sa.sa_handler = timer;
 	sa.sa_flags = SA_RESTART;
 	sigaction(SIGVTALRM, &sa, NULL);
 
 	setitimer(ITIMER_VIRTUAL, &tvi, NULL);
 
 	while (1)
 		;
 }