diff options
Diffstat (limited to 'REORG.TODO/sysdeps/mach/hurd/setitimer.c')
| -rw-r--r-- | REORG.TODO/sysdeps/mach/hurd/setitimer.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/mach/hurd/setitimer.c b/REORG.TODO/sysdeps/mach/hurd/setitimer.c new file mode 100644 index 0000000000..a5ab55405b --- /dev/null +++ b/REORG.TODO/sysdeps/mach/hurd/setitimer.c @@ -0,0 +1,372 @@ +/* Copyright (C) 1994-2017 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_size_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) |