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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/mach/hurd/setitimer.c
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initial import
Diffstat (limited to 'sysdeps/mach/hurd/setitimer.c')
-rw-r--r--sysdeps/mach/hurd/setitimer.c332
1 files changed, 332 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/setitimer.c b/sysdeps/mach/hurd/setitimer.c
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+++ b/sysdeps/mach/hurd/setitimer.c
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+/* Copyright (C) 1994, 1995 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <ansidecl.h>
+#include <stddef.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <hurd.h>
+#include <hurd/signal.h>
+#include <hurd/msg_request.h>
+#include <mach/message.h>
+
+/* XXX Temporary cheezoid implementation of ITIMER_REAL/SIGALRM. */
+
+spin_lock_t _hurd_itimer_lock = SPIN_LOCK_INITIALIZER;
+struct itimerval _hurd_itimerval; /* Current state of the timer. */
+mach_port_t _hurd_itimer_port; /* Port the timer thread blocks on. */
+thread_t _hurd_itimer_thread; /* Thread waiting for timeout. */
+int _hurd_itimer_thread_suspended; /* Nonzero if that thread is suspended. */
+vm_address_t _hurd_itimer_thread_stack_base; /* Base of its stack. */
+vm_address_t _hurd_itimer_thread_stack_size; /* Size of its stack. */
+struct timeval _hurd_itimer_started; /* Time the thread started waiting. */
+
+static inline void
+subtract_timeval (struct timeval *from, const struct timeval *subtract)
+{
+ from->tv_usec -= subtract->tv_usec;
+ from->tv_sec -= subtract->tv_sec;
+ while (from->tv_usec < 0)
+ {
+ --from->tv_sec;
+ from->tv_usec += 1000000;
+ }
+}
+
+/* Function run by the itimer thread.
+ This code must be very careful not ever to require a MiG reply port. */
+
+static void
+timer_thread (void)
+{
+ while (1)
+ {
+ error_t err;
+ /* The only message we ever expect to receive is the reply from the
+ signal thread to a sig_post call we did. We never examine the
+ contents. */
+ struct
+ {
+ mach_msg_header_t header;
+ error_t return_code;
+ } msg;
+
+ /* Wait for a message on a port that noone sends to. The purpose is
+ the receive timeout. Notice interrupts so that if we are
+ thread_abort'd, we will loop around and fetch new values from
+ _hurd_itimerval. */
+ err = __mach_msg (&msg.header,
+ MACH_RCV_MSG|MACH_RCV_TIMEOUT|MACH_RCV_INTERRUPT,
+ 0, 0, _hurd_itimer_port,
+ _hurd_itimerval.it_value.tv_sec * 1000 +
+ _hurd_itimerval.it_value.tv_usec / 1000,
+ MACH_PORT_NULL);
+ switch (err)
+ {
+ case MACH_RCV_TIMED_OUT:
+ /* We got the expected timeout. Send a message to the signal
+ thread to tell it to post a SIGALRM signal. We use
+ _hurd_itimer_port as the reply port just so we will block until
+ the signal thread has frobnicated things to reload the itimer or
+ has terminated this thread. */
+ __msg_sig_post_request (_hurd_msgport,
+ _hurd_itimer_port,
+ MACH_MSG_TYPE_MAKE_SEND_ONCE,
+ SIGALRM, __mach_task_self ());
+ break;
+
+ case MACH_RCV_INTERRUPTED:
+ /* We were thread_abort'd. This is to tell us that
+ _hurd_itimerval has changed and we need to reexamine it
+ and start waiting with the new timeout value. */
+ break;
+
+ case MACH_MSG_SUCCESS:
+ /* We got the reply message from the sig_post_request above.
+ Ignore it and reexamine the timer value. */
+ __mach_msg_destroy (&msg.header); /* Just in case. */
+ break;
+
+ default:
+ /* Unexpected lossage. Oh well, keep trying. */
+ break;
+ }
+ }
+}
+
+/* Forward declaration. */
+static sighandler_t preempt_sigalrm (thread_t thread, int signo,
+ long int sigcode, int sigerror);
+
+/* Called before any normal SIGALRM signal is delivered.
+ Reload the itimer, or disable the itimer. */
+
+static int
+setitimer_locked (const struct itimerval *new, struct itimerval *old,
+ void *crit)
+{
+ struct itimerval newval = *new;
+ struct timeval now, remaining, elapsed;
+ struct timeval old_interval;
+ error_t err;
+
+ inline void kill_itimer_thread (void)
+ {
+ __thread_terminate (_hurd_itimer_thread);
+ __vm_deallocate (__mach_task_self (),
+ _hurd_itimer_thread_stack_base,
+ _hurd_itimer_thread_stack_size);
+ _hurd_itimer_thread = MACH_PORT_NULL;
+ }
+
+ if ((newval.it_value.tv_sec | newval.it_value.tv_usec) != 0)
+ {
+ /* Make sure the itimer thread is set up. */
+
+ if (_hurd_signal_preempt[SIGALRM] == NULL)
+ {
+ static struct hurd_signal_preempt preempt =
+ { preempt_sigalrm, 0, 0, NULL };
+ _hurd_signal_preempt[SIGALRM] = &preempt;
+ }
+
+ if (_hurd_itimer_port == MACH_PORT_NULL)
+ {
+ /* Allocate a receive right that the itimer thread will
+ block waiting for a message on. */
+ if (err = __mach_port_allocate (__mach_task_self (),
+ MACH_PORT_RIGHT_RECEIVE,
+ &_hurd_itimer_port))
+ goto out;
+ }
+
+ if (_hurd_itimer_thread == MACH_PORT_NULL)
+ {
+ /* Start up the itimer thread running `timer_thread' (below). */
+ if (err = __thread_create (__mach_task_self (),
+ &_hurd_itimer_thread))
+ return __hurd_fail (err);
+ _hurd_itimer_thread_stack_base = 0; /* Anywhere. */
+ _hurd_itimer_thread_stack_size = __vm_page_size; /* Small stack. */
+ if (err = __mach_setup_thread (__mach_task_self (),
+ _hurd_itimer_thread,
+ &timer_thread,
+ &_hurd_itimer_thread_stack_base,
+ &_hurd_itimer_thread_stack_size))
+ {
+ __thread_terminate (_hurd_itimer_thread);
+ _hurd_itimer_thread = MACH_PORT_NULL;
+ goto out;
+ }
+ _hurd_itimer_thread_suspended = 1;
+ }
+ }
+
+ if ((newval.it_value.tv_sec | newval.it_value.tv_usec) != 0 || old != NULL)
+ {
+ /* Calculate how much time is remaining for the pending alarm. */
+ if (__gettimeofday (&now, NULL) < 0)
+ {
+ __spin_unlock (&_hurd_itimer_lock);
+ _hurd_critical_section_unlock (crit);
+ return -1;
+ }
+ elapsed = now;
+ subtract_timeval (&elapsed, &_hurd_itimer_started);
+ remaining = _hurd_itimerval.it_value;
+ if (timercmp (&remaining, &elapsed, <))
+ {
+ /* Hmm. The timer should have just gone off, but has not been reset.
+ This is a possible timing glitch. The alarm will signal soon. */
+ /* XXX wrong */
+ remaining.tv_sec = 0;
+ remaining.tv_usec = 0;
+ }
+ else
+ subtract_timeval (&remaining, &elapsed);
+
+ /* Remember the old reload interval before changing it. */
+ old_interval = _hurd_itimerval.it_interval;
+
+ /* Record the starting time that the timer interval relates to. */
+ _hurd_itimer_started = now;
+ }
+
+ /* Load the new itimer value. */
+ _hurd_itimerval = newval;
+
+ if ((newval.it_value.tv_sec | newval.it_value.tv_usec) == 0)
+ {
+ /* Disable the itimer. */
+ if (_hurd_itimer_thread && !_hurd_itimer_thread_suspended)
+ {
+ /* Suspend the itimer thread so it does nothing. Then abort its
+ kernel context so that when the thread is resumed, mach_msg
+ will return to timer_thread (below) and it will fetch new
+ values from _hurd_itimerval. */
+ if ((err = __thread_suspend (_hurd_itimer_thread)) ||
+ (err = __thread_abort (_hurd_itimer_thread)))
+ /* If we can't save it for later, nuke it. */
+ kill_itimer_thread ();
+ else
+ _hurd_itimer_thread_suspended = 1;
+ }
+ }
+ /* See if the timeout changed. If so, we must alert the itimer thread. */
+ else if (remaining.tv_sec != new->it_value.tv_sec ||
+ remaining.tv_usec != new->it_value.tv_usec)
+ {
+ /* The timeout value is changing. Tell the itimer thread to
+ reexamine it and start counting down. If the itimer thread is
+ marked as suspended, either we just created it, or it was
+ suspended and thread_abort'd last time the itimer was disabled;
+ either way it will wake up and start waiting for the new timeout
+ value when we resume it. If it is not suspended, the itimer
+ thread is waiting to deliver a pending alarm that we will override
+ (since it would come later than the new alarm being set);
+ thread_abort will make mach_msg return MACH_RCV_INTERRUPTED, so it
+ will loop around and use the new timeout value. */
+ if (err = (_hurd_itimer_thread_suspended
+ ? __thread_resume : __thread_abort) (_hurd_itimer_thread))
+ {
+ kill_itimer_thread ();
+ goto out;
+ }
+ _hurd_itimer_thread_suspended = 0;
+ }
+
+ __spin_unlock (&_hurd_itimer_lock);
+ _hurd_critical_section_unlock (crit);
+
+ if (old != NULL)
+ {
+ old->it_value = remaining;
+ old->it_interval = old_interval;
+ }
+ return 0;
+
+ out:
+ __spin_unlock (&_hurd_itimer_lock);
+ _hurd_critical_section_unlock (crit);
+ return __hurd_fail (err);
+}
+
+/* Set the timer WHICH to *NEW. If OLD is not NULL,
+ set *OLD to the old value of timer WHICH.
+ Returns 0 on success, -1 on errors. */
+int
+DEFUN(__setitimer, (which, new, old),
+ enum __itimer_which which AND
+ struct itimerval *new AND struct itimerval *old)
+{
+ void *crit;
+
+ switch (which)
+ {
+ default:
+ return __hurd_fail (EINVAL);
+
+ case ITIMER_VIRTUAL:
+ case ITIMER_PROF:
+ return __hurd_fail (ENOSYS);
+
+ case ITIMER_REAL:
+ break;
+ }
+
+ crit = _hurd_critical_section_lock ();
+ __spin_lock (&_hurd_itimer_lock);
+ return setitimer_locked (new, old, crit);
+}
+
+static sighandler_t
+preempt_sigalrm (thread_t thread, int signo, long int sigcode, int sigerror)
+{
+ struct itimerval it;
+
+ if (thread != _hurd_sigthread || signo != SIGALRM || sigcode != 0)
+ /* Too much monkey business. */
+ return SIG_DFL;
+
+ /* Either reload or disable the itimer. */
+ __spin_lock (&_hurd_itimer_lock);
+ it = _hurd_itimerval;
+ it.it_value = it.it_interval;
+ setitimer_locked (&it, NULL, NULL);
+
+ /* Continue with normal delivery of SIGALRM. */
+ return SIG_DFL;
+}
+
+static void
+fork_itimer (void)
+{
+ /* We must restart the itimer in the child. */
+
+ struct itimerval it;
+
+ __spin_lock (&_hurd_itimer_lock);
+ _hurd_itimer_thread = MACH_PORT_NULL;
+ it = _hurd_itimerval;
+ it.it_value = it.it_interval;
+
+ setitimer_locked (&it, NULL, NULL);
+}
+text_set_element (_hurd_fork_child_hook, fork_itimer);
+
+weak_alias (__setitimer, setitimer)