387 lines
12 KiB
C
387 lines
12 KiB
C
/* Copyright (C) 1994-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stddef.h>
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#include <errno.h>
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#include <sys/time.h>
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#include <time.h>
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#include <hurd.h>
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#include <hurd/signal.h>
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#include <hurd/sigpreempt.h>
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#include <hurd/msg_request.h>
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#include <mach.h>
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#include <mach/message.h>
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/* XXX Temporary cheezoid implementation of ITIMER_REAL/SIGALRM. */
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spin_lock_t _hurd_itimer_lock = SPIN_LOCK_INITIALIZER;
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struct itimerval _hurd_itimerval; /* Current state of the timer. */
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mach_port_t _hurd_itimer_port; /* Port the timer thread blocks on. */
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thread_t _hurd_itimer_thread; /* Thread waiting for timeout. */
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int _hurd_itimer_thread_suspended; /* Nonzero if that thread is suspended. */
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vm_address_t _hurd_itimer_thread_stack_base; /* Base of its stack. */
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vm_size_t _hurd_itimer_thread_stack_size; /* Size of its stack. */
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struct timeval _hurd_itimer_started; /* Time the thread started waiting. */
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static void
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quantize_timeval (struct timeval *tv)
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{
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static time_t quantum = -1;
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if (quantum == -1)
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quantum = 1000000 / __getclktck ();
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tv->tv_usec = ((tv->tv_usec + (quantum - 1)) / quantum) * quantum;
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if (tv->tv_usec >= 1000000)
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{
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++tv->tv_sec;
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tv->tv_usec -= 1000000;
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}
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}
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static inline void
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subtract_timeval (struct timeval *from, const struct timeval *subtract)
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{
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from->tv_usec -= subtract->tv_usec;
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from->tv_sec -= subtract->tv_sec;
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while (from->tv_usec < 0)
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{
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--from->tv_sec;
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from->tv_usec += 1000000;
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}
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}
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/* Function run by the itimer thread.
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This code must be very careful not ever to require a MiG reply port. */
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static void
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timer_thread (void)
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{
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while (1)
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{
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error_t err;
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/* The only message we ever expect to receive is the reply from the
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signal thread to a sig_post call we did. We never examine the
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contents. */
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struct
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{
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mach_msg_header_t header;
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mach_msg_type_t return_code_type;
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error_t return_code;
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} msg;
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/* Wait for a message on a port that noone sends to. The purpose is
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the receive timeout. Notice interrupts so that if we are
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thread_abort'd, we will loop around and fetch new values from
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_hurd_itimerval. */
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err = __mach_msg (&msg.header,
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MACH_RCV_MSG|MACH_RCV_TIMEOUT|MACH_RCV_INTERRUPT,
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0, sizeof(msg), _hurd_itimer_port,
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_hurd_itimerval.it_value.tv_sec * 1000
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+ _hurd_itimerval.it_value.tv_usec / 1000,
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MACH_PORT_NULL);
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switch (err)
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{
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case MACH_RCV_TIMED_OUT:
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/* We got the expected timeout. Send a message to the signal
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thread to tell it to post a SIGALRM signal. We use
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_hurd_itimer_port as the reply port just so we will block until
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the signal thread has frobnicated things to reload the itimer or
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has terminated this thread. */
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__msg_sig_post_request (_hurd_msgport,
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_hurd_itimer_port,
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MACH_MSG_TYPE_MAKE_SEND_ONCE,
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SIGALRM, SI_TIMER, __mach_task_self ());
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break;
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case MACH_RCV_INTERRUPTED:
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/* We were thread_abort'd. This is to tell us that
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_hurd_itimerval has changed and we need to reexamine it
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and start waiting with the new timeout value. */
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break;
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case MACH_MSG_SUCCESS:
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/* We got the reply message from the sig_post_request above.
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Ignore it and reexamine the timer value. */
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__mach_msg_destroy (&msg.header); /* Just in case. */
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break;
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default:
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/* Unexpected lossage. Oh well, keep trying. */
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break;
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}
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}
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}
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/* Forward declaration. */
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static int setitimer_locked (const struct itimerval *new,
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struct itimerval *old, void *crit,
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int hurd_siglocked);
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static sighandler_t
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restart_itimer (struct hurd_signal_preemptor *preemptor,
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struct hurd_sigstate *ss,
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int *signo, struct hurd_signal_detail *detail)
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{
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/* This function gets called in the signal thread
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each time a SIGALRM is arriving (even if blocked). */
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struct itimerval it;
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/* Either reload or disable the itimer. */
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__spin_lock (&_hurd_itimer_lock);
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it.it_value = it.it_interval = _hurd_itimerval.it_interval;
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setitimer_locked (&it, NULL, NULL, 1);
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/* Continue with normal delivery (or hold, etc.) of SIGALRM. */
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return SIG_ERR;
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}
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/* Called before any normal SIGALRM signal is delivered.
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Reload the itimer, or disable the itimer. */
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static int
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setitimer_locked (const struct itimerval *new, struct itimerval *old,
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void *crit, int hurd_siglocked)
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{
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struct itimerval newval;
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struct timeval now, remaining, elapsed;
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struct timeval old_interval;
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error_t err;
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inline void kill_itimer_thread (void)
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{
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__thread_terminate (_hurd_itimer_thread);
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__vm_deallocate (__mach_task_self (),
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_hurd_itimer_thread_stack_base,
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_hurd_itimer_thread_stack_size);
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_hurd_itimer_thread = MACH_PORT_NULL;
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}
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if (!new)
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{
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/* Just return the current value in OLD without changing anything.
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This is what BSD does, even though it's not documented. */
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if (old)
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*old = _hurd_itimerval;
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spin_unlock (&_hurd_itimer_lock);
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_hurd_critical_section_unlock (crit);
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return 0;
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}
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newval = *new;
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quantize_timeval (&newval.it_interval);
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quantize_timeval (&newval.it_value);
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if ((newval.it_value.tv_sec | newval.it_value.tv_usec) != 0)
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{
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/* Make sure the itimer thread is set up. */
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/* Set up a signal preemptor global for all threads to
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run `restart_itimer' each time a SIGALRM would arrive. */
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static struct hurd_signal_preemptor preemptor =
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{
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__sigmask (SIGALRM), SI_TIMER, SI_TIMER,
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&restart_itimer,
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};
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if (!hurd_siglocked)
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__mutex_lock (&_hurd_siglock);
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if (! preemptor.next && _hurdsig_preemptors != &preemptor)
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{
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preemptor.next = _hurdsig_preemptors;
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_hurdsig_preemptors = &preemptor;
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_hurdsig_preempted_set |= preemptor.signals;
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}
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if (!hurd_siglocked)
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__mutex_unlock (&_hurd_siglock);
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if (_hurd_itimer_port == MACH_PORT_NULL)
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{
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/* Allocate a receive right that the itimer thread will
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block waiting for a message on. */
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if (err = __mach_port_allocate (__mach_task_self (),
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MACH_PORT_RIGHT_RECEIVE,
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&_hurd_itimer_port))
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goto out;
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}
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if (_hurd_itimer_thread == MACH_PORT_NULL)
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{
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/* Start up the itimer thread running `timer_thread' (below). */
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if (err = __thread_create (__mach_task_self (),
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&_hurd_itimer_thread))
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goto out;
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_hurd_itimer_thread_stack_base = 0; /* Anywhere. */
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_hurd_itimer_thread_stack_size = __vm_page_size; /* Small stack. */
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if ((err = __mach_setup_thread (__mach_task_self (),
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_hurd_itimer_thread,
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&timer_thread,
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&_hurd_itimer_thread_stack_base,
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&_hurd_itimer_thread_stack_size))
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|| (err = __mach_setup_tls(_hurd_itimer_thread)))
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{
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__thread_terminate (_hurd_itimer_thread);
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_hurd_itimer_thread = MACH_PORT_NULL;
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goto out;
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}
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_hurd_itimer_thread_suspended = 1;
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}
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}
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if ((newval.it_value.tv_sec | newval.it_value.tv_usec) != 0 || old != NULL)
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{
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/* Calculate how much time is remaining for the pending alarm. */
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{
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time_value_t tv;
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__host_get_time (__mach_host_self (), &tv);
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now.tv_sec = tv.seconds;
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now.tv_usec = tv.microseconds;
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}
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elapsed = now;
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subtract_timeval (&elapsed, &_hurd_itimer_started);
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remaining = _hurd_itimerval.it_value;
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if (timercmp (&remaining, &elapsed, <))
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{
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/* Hmm. The timer should have just gone off, but has not been reset.
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This is a possible timing glitch. The alarm will signal soon. */
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/* XXX wrong */
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remaining.tv_sec = 0;
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remaining.tv_usec = 0;
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}
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else
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subtract_timeval (&remaining, &elapsed);
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/* Remember the old reload interval before changing it. */
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old_interval = _hurd_itimerval.it_interval;
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/* Record the starting time that the timer interval relates to. */
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_hurd_itimer_started = now;
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}
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/* Load the new itimer value. */
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_hurd_itimerval = newval;
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if ((newval.it_value.tv_sec | newval.it_value.tv_usec) == 0)
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{
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/* Disable the itimer. */
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if (_hurd_itimer_thread && !_hurd_itimer_thread_suspended)
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{
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/* Suspend the itimer thread so it does nothing. Then abort its
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kernel context so that when the thread is resumed, mach_msg
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will return to timer_thread (below) and it will fetch new
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values from _hurd_itimerval. */
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if ((err = __thread_suspend (_hurd_itimer_thread))
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|| (err = __thread_abort (_hurd_itimer_thread)))
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/* If we can't save it for later, nuke it. */
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kill_itimer_thread ();
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else
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_hurd_itimer_thread_suspended = 1;
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}
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}
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/* See if the timeout changed. If so, we must alert the itimer thread. */
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else if (remaining.tv_sec != newval.it_value.tv_sec
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|| remaining.tv_usec != newval.it_value.tv_usec)
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{
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/* The timeout value is changing. Tell the itimer thread to
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reexamine it and start counting down. If the itimer thread is
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marked as suspended, either we just created it, or it was
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suspended and thread_abort'd last time the itimer was disabled;
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either way it will wake up and start waiting for the new timeout
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value when we resume it. If it is not suspended, the itimer
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thread is waiting to deliver a pending alarm that we will override
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(since it would come later than the new alarm being set);
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thread_abort will make mach_msg return MACH_RCV_INTERRUPTED, so it
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will loop around and use the new timeout value. */
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if (err = (_hurd_itimer_thread_suspended
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? __thread_resume : __thread_abort) (_hurd_itimer_thread))
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{
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kill_itimer_thread ();
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goto out;
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}
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_hurd_itimer_thread_suspended = 0;
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}
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__spin_unlock (&_hurd_itimer_lock);
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_hurd_critical_section_unlock (crit);
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if (old != NULL)
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{
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old->it_value = remaining;
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old->it_interval = old_interval;
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}
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return 0;
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out:
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__spin_unlock (&_hurd_itimer_lock);
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_hurd_critical_section_unlock (crit);
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return __hurd_fail (err);
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}
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/* Set the timer WHICH to *NEW. If OLD is not NULL,
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set *OLD to the old value of timer WHICH.
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Returns 0 on success, -1 on errors. */
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int
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__setitimer (enum __itimer_which which, const struct itimerval *new,
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struct itimerval *old)
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{
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void *crit;
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int ret;
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switch (which)
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{
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default:
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return __hurd_fail (EINVAL);
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case ITIMER_VIRTUAL:
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case ITIMER_PROF:
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return __hurd_fail (ENOSYS);
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case ITIMER_REAL:
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break;
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}
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retry:
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crit = _hurd_critical_section_lock ();
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__spin_lock (&_hurd_itimer_lock);
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ret = setitimer_locked (new, old, crit, 0);
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if (ret == -1 && errno == EINTR)
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/* Got a signal while inside an RPC of the critical section, retry again */
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goto retry;
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return ret;
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}
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static void
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fork_itimer (void)
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{
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/* We must restart the itimer in the child. */
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struct itimerval it;
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__spin_lock (&_hurd_itimer_lock);
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_hurd_itimer_thread = MACH_PORT_NULL;
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it = _hurd_itimerval;
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it.it_value = it.it_interval;
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setitimer_locked (&it, NULL, NULL, 0);
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(void) &fork_itimer; /* Avoid gcc optimizing out the function. */
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}
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text_set_element (_hurd_fork_child_hook, fork_itimer);
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weak_alias (__setitimer, setitimer)
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