OpenBSD-4.6/lib/libpthread/uthread/uthread_sig.c
/* $OpenBSD: uthread_sig.c,v 1.24 2007/05/18 19:28:50 kurt Exp $ */
/*
* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: uthread_sig.c,v 1.20 1999/09/29 15:18:39 marcel Exp $
*/
#include <string.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"
/* Initialize signal handling facility: */
void
_thread_sig_init(void)
{
int i;
/* Clear local state */
for (i = 1; i < NSIG; i++) {
_SPINLOCK_INIT(&_thread_sigq[i - 1].lock);
_thread_sigq[i - 1].pending = 0;
}
}
/*
* This is the only installed signal handler. In addition to handling
* thread kernel signals it is installed in place of application handlers
* and dispatches signals appropriately.
*/
void
_thread_sig_handler(int sig, siginfo_t *info, struct sigcontext * scp)
{
struct pthread *curthread = _get_curthread();
int dispatch;
char c;
if (sig == _SCHED_SIGNAL) {
/* Update the scheduling clock: */
gettimeofday((struct timeval *)&_sched_tod, NULL);
_sched_ticks++;
/* only process signal when scheduler isn't running */
if (_thread_kern_in_sched == 0) {
if (curthread->sig_defer_count > 0) {
/*
* The scheduler interrupt has come when
* the currently running thread has deferred
* thread signals.
*/
curthread->yield_on_sig_undefer = 1;
} else {
/* Schedule the next thread. */
_thread_kern_sched(scp);
/*
* The scheduler currently returns here instead
* of calling sigreturn due to a sparc sigreturn
* bug. We should also return. That brings
* us back to the sigtramp code which will
* sigreturn to the context stored on the
* current stack (which is the same as scp,
* above). The code originally did this:
*
* PANIC("Returned to signal function "
* "from scheduler");
*/
return;
}
}
} else {
/*
* save the info for this signal in a per signal queue of depth
* one. Per a POSIX suggestion, only the info for the first
* of multiple activations of the same signal is kept.
*/
_SPINLOCK(&_thread_sigq[sig - 1].lock);
if (_thread_sigq[sig - 1].pending == 0) {
sigaddset(&_process_sigpending, sig);
_thread_sigq[sig - 1].pending++;
memcpy(&_thread_sigq[sig - 1].siginfo, info,
sizeof *info);
}
_SPINUNLOCK(&_thread_sigq[sig - 1].lock);
if ((_queue_signals != 0) ||
((_thread_kern_in_sched == 0) &&
(curthread->sig_defer_count > 0))) {
/*
* The kernel has been interrupted while the scheduler
* is accessing the scheduling queues or there is a
* currently running thread that has deferred signals.
*
* Cast the signal number to a character variable
* and Write the signal number to the kernel pipe so
* that it will be ready to read when this signal
* handler returns.
*/
c = (char)sig;
_thread_sys_write(_thread_kern_pipe[1], &c, 1);
_sigq_check_reqd = 1;
} else {
_queue_signals = 1;
dispatch = _thread_sig_handle(sig, scp);
_queue_signals = 0;
if (dispatch)
_dispatch_signals(scp);
}
}
}
/*
* Clear the pending flag for the given signal on all threads
* if per process, or only for the given thread if non null
* and the signal doesn't exist in _process_sigpending.
*/
void
_thread_clear_pending(int sig, pthread_t thread)
{
pthread_t pthread;
_thread_sigq[sig - 1].pending = 0;
if (sigismember(&_process_sigpending, sig)) {
sigdelset(&_process_sigpending, sig);
TAILQ_FOREACH(pthread, &_thread_list, tle) {
sigdelset(&pthread->sigpend, sig);
}
} else if (thread)
sigdelset(&thread->sigpend, sig);
}
/*
* Process the given signal. Returns 1 if the signal may be dispatched,
* otherwise 0. Signals MUST be defered when this function is called.
*/
/* ARGSUSED */
int
_thread_sig_handle(int sig, struct sigcontext * scp)
{
struct pthread *curthread = _get_curthread();
int i;
pthread_t pthread, pthread_next;
if (sig == SIGINFO)
_thread_dump_info(); /* Dump thread information */
else if (sig == _SCHED_SIGNAL)
; /* This shouldn't ever occur (should this panic?). */
else {
if (sig == SIGCHLD) {
/*
* Go through the file list and set all files
* to non-blocking again in case the child
* set some of them to block. Sigh.
*/
for (i = 0; i < _thread_max_fdtsize; i++)
if (_thread_fd_table[i] != NULL &&
_thread_fd_table[i]->status_flags != NULL)
_thread_sys_fcntl(i, F_SETFL,
_thread_fd_table[i]->status_flags->flags |
O_NONBLOCK);
}
/*
* If the handler is SIG_IGN the signal never happened.
* remove it from the pending list and return.
*/
if (_thread_sigact[sig - 1].sa_handler == SIG_IGN) {
_thread_clear_pending(sig, curthread);
return 0;
}
/*
* POSIX says that pending SIGCONT signals are discarded
* when one of these signals occurs and vice versa.
*/
if (sig == SIGSTOP || sig == SIGTSTP || sig == SIGTTIN ||
sig == SIGTTOU)
_thread_clear_pending(SIGCONT, curthread);
if (sig == SIGCONT) {
_thread_clear_pending(SIGSTOP, curthread);
_thread_clear_pending(SIGTSTP, curthread);
_thread_clear_pending(SIGTTIN, curthread);
_thread_clear_pending(SIGTTOU, curthread);
}
/*
* Enter a loop to process each thread in the waiting
* list that is sigwait-ing on a signal. Since POSIX
* doesn't specify which thread will get the signal
* if there are multiple waiters, we'll give it to the
* first one we find.
*/
for (pthread = TAILQ_FIRST(&_waitingq);
pthread != NULL; pthread = pthread_next) {
/*
* Grab the next thread before possibly destroying
* the link entry.
*/
pthread_next = TAILQ_NEXT(pthread, pqe);
if ((pthread->state == PS_SIGWAIT) &&
sigismember(pthread->data.sigwait, sig)) {
/*
* found a sigwaiter. Mark its state as
* running, save the signal that will be
* returned, and mark the signal as no
* longer pending.
*/
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
pthread->signo = sig;
_thread_clear_pending(sig, pthread);
return 0;
}
}
/*
* mark the signal as pending for each thread
* and give the thread a chance to update
* its state.
*/
TAILQ_FOREACH(pthread, &_thread_list, tle) {
/* Current thread inside critical region? */
if (curthread->sig_defer_count > 0)
pthread->sig_defer_count++;
_thread_signal(pthread,sig);
if (curthread->sig_defer_count > 0)
pthread->sig_defer_count--;
}
return 1;
}
return 0;
}
/* Perform thread specific actions in response to a signal: */
void
_thread_signal(pthread_t pthread, int sig)
{
/* Flag the signal as pending. It may be dispatched later. */
sigaddset(&pthread->sigpend,sig);
/* skip this thread if signal is masked */
if (sigismember(&pthread->sigmask, sig))
return;
/* Process according to thread state: */
switch (pthread->state) {
/*
* States which do not change when a signal is trapped:
*/
case PS_COND_WAIT:
case PS_DEAD:
case PS_FDLR_WAIT:
case PS_FDLW_WAIT:
case PS_FILE_WAIT:
case PS_JOIN:
case PS_MUTEX_WAIT:
case PS_RUNNING:
case PS_SIGTHREAD:
case PS_SIGWAIT:
case PS_SUSPENDED:
case PS_SPINBLOCK:
case PS_DEADLOCK:
case PS_STATE_MAX: /* only here to quell a compiler warning */
/* Nothing to do here. */
break;
/*
* The wait state is a special case due to the handling of
* SIGCHLD signals.
*/
case PS_WAIT_WAIT:
/*
* Check for signals other than the death of a child
* process:
*/
if (sig != SIGCHLD)
/* Flag the operation as interrupted: */
pthread->interrupted = 1;
/* Change the state of the thread to run: */
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
/* Return the signal number: */
pthread->signo = sig;
break;
/*
* States that are interrupted by the occurrence of a signal
* other than the scheduling alarm:
*/
case PS_FDR_WAIT:
case PS_FDW_WAIT:
case PS_POLL_WAIT:
case PS_SLEEP_WAIT:
case PS_SELECT_WAIT:
if (sig != SIGCHLD ||
_thread_sigact[sig - 1].sa_handler != SIG_DFL) {
/* Flag the operation as interrupted: */
pthread->interrupted = 1;
if (pthread->flags & PTHREAD_FLAGS_IN_WORKQ)
PTHREAD_WORKQ_REMOVE(pthread);
/* Change the state of the thread to run: */
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
/* Return the signal number: */
pthread->signo = sig;
}
break;
case PS_SIGSUSPEND:
/*
* Only wake up the thread if the signal is unblocked
* and there is a handler installed for the signal.
*/
if (_thread_sigact[sig - 1].sa_handler != SIG_DFL) {
/* Change the state of the thread to run: */
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
/* Return the signal number: */
pthread->signo = sig;
}
break;
}
}
/*
* Dispatch a signal to the current thread after setting up the
* appropriate signal mask.
*/
void
_dispatch_signal(int sig, struct sigcontext * scp)
{
struct pthread *curthread = _get_curthread();
sigset_t set;
sigset_t oset;
struct sigaction act;
void (*action)(int, siginfo_t *, void *);
/* save off the action and set the signal mask */
action = _thread_sigact[sig - 1].sa_sigaction;
set = _thread_sigact[sig - 1].sa_mask;
if ((_thread_sigact[sig-1].sa_flags & SA_NODEFER) == 0)
sigaddset(&set, sig);
oset = curthread->sigmask;
curthread->sigmask |= set;
/* clear custom handler if SA_RESETHAND set. */
if (_thread_sigact[sig - 1].sa_flags & SA_RESETHAND) {
act.sa_handler = SIG_DFL;
act.sa_flags = 0;
sigemptyset(&act.sa_mask);
sigaction(sig, &act, NULL);
}
/*
* clear the pending flag, deliver the signal, then reset the
* signal mask
*/
_thread_clear_pending(sig, curthread);
(*action)(sig, &_thread_sigq[sig - 1].siginfo, scp);
curthread->sigmask = oset;
}
/*
* possibly dispatch a signal to the current thread.
*/
void
_dispatch_signals(struct sigcontext * scp)
{
struct pthread *curthread = _get_curthread();
int i;
/*
* Check if there are pending signals for the running
* thread that aren't blocked:
*/
if ((curthread->sigpend & ~curthread->sigmask) != 0)
/* Look for all possible pending signals: */
for (i = 1; i < NSIG; i++)
/*
* Check that a custom handler is installed
* and if the signal is not blocked:
*/
if (_thread_sigact[i - 1].sa_handler != SIG_DFL &&
_thread_sigact[i - 1].sa_handler != SIG_IGN &&
sigismember(&curthread->sigpend,i) &&
!sigismember(&curthread->sigmask,i))
/* dispatch */
_dispatch_signal(i, scp);
}
#endif