| /* Copyright (C) 1994-2014 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 Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <stddef.h> |
| #include <errno.h> |
| #include <sys/time.h> |
| #include <time.h> |
| #include <hurd.h> |
| #include <hurd/signal.h> |
| #include <hurd/sigpreempt.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 void |
| quantize_timeval (struct timeval *tv) |
| { |
| static time_t quantum = -1; |
| |
| if (quantum == -1) |
| quantum = 1000000 / __getclktck (); |
| |
| tv->tv_usec = ((tv->tv_usec + (quantum - 1)) / quantum) * quantum; |
| if (tv->tv_usec >= 1000000) |
| { |
| ++tv->tv_sec; |
| tv->tv_usec -= 1000000; |
| } |
| } |
| |
| 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, 0, __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 int setitimer_locked (const struct itimerval *new, |
| struct itimerval *old, void *crit); |
| |
| static sighandler_t |
| restart_itimer (struct hurd_signal_preemptor *preemptor, |
| struct hurd_sigstate *ss, |
| int *signo, struct hurd_signal_detail *detail) |
| { |
| /* This function gets called in the signal thread |
| each time a SIGALRM is arriving (even if blocked). */ |
| struct itimerval it; |
| |
| /* Either reload or disable the itimer. */ |
| __spin_lock (&_hurd_itimer_lock); |
| it.it_value = it.it_interval = _hurd_itimerval.it_interval; |
| setitimer_locked (&it, NULL, NULL); |
| |
| /* Continue with normal delivery (or hold, etc.) of SIGALRM. */ |
| return SIG_ERR; |
| } |
| |
| |
| /* 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; |
| 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 (!new) |
| { |
| /* Just return the current value in OLD without changing anything. |
| This is what BSD does, even though it's not documented. */ |
| if (old) |
| *old = _hurd_itimerval; |
| spin_unlock (&_hurd_itimer_lock); |
| _hurd_critical_section_unlock (crit); |
| return 0; |
| } |
| |
| newval = *new; |
| quantize_timeval (&newval.it_interval); |
| quantize_timeval (&newval.it_value); |
| if ((newval.it_value.tv_sec | newval.it_value.tv_usec) != 0) |
| { |
| /* Make sure the itimer thread is set up. */ |
| |
| /* Set up a signal preemptor global for all threads to |
| run `restart_itimer' each time a SIGALRM would arrive. */ |
| static struct hurd_signal_preemptor preemptor = |
| { |
| __sigmask (SIGALRM), 0, 0, |
| &restart_itimer, |
| }; |
| __mutex_lock (&_hurd_siglock); |
| if (! preemptor.next && _hurdsig_preemptors != &preemptor) |
| { |
| preemptor.next = _hurdsig_preemptors; |
| _hurdsig_preemptors = &preemptor; |
| } |
| __mutex_unlock (&_hurd_siglock); |
| |
| 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)) |
| goto out; |
| _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 != newval.it_value.tv_sec || |
| remaining.tv_usec != newval.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 |
| __setitimer (enum __itimer_which which, const struct itimerval *new, |
| 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 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); |
| |
| (void) &fork_itimer; /* Avoid gcc optimizing out the function. */ |
| } |
| text_set_element (_hurd_fork_child_hook, fork_itimer); |
| |
| weak_alias (__setitimer, setitimer) |