8d048bba15
handler. Thread-to-thread signals (pthread_signal) are treated differently than process signals; a pthread_signal can wakeup a blocked thread if a signal handler is not installed for that signal. Found by: ACE tests
599 lines
16 KiB
C
599 lines
16 KiB
C
/*
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* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/signalvar.h>
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#include <signal.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <errno.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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/* Prototypes: */
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static void _thread_sig_check_state(pthread_t pthread, int sig);
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/* Static variables: */
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static spinlock_t signal_lock = _SPINLOCK_INITIALIZER;
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static unsigned int pending_sigs[NSIG];
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static unsigned int handled_sigs[NSIG];
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static int volatile check_pending = 0;
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/* Initialize signal handling facility: */
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void
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_thread_sig_init(void)
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{
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int i;
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/* Clear pending and handled signal counts: */
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for (i = 1; i < NSIG; i++) {
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pending_sigs[i - 1] = 0;
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handled_sigs[i - 1] = 0;
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}
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/* Clear the lock: */
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signal_lock.access_lock = 0;
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/* Clear the process pending signals: */
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sigemptyset(&_process_sigpending);
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}
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void
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_thread_sig_handler(int sig, int code, ucontext_t * scp)
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{
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pthread_t pthread;
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int i;
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char c;
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/* Check if an interval timer signal: */
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if (sig == _SCHED_SIGNAL) {
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if (_thread_kern_in_sched != 0) {
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/*
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* The scheduler is already running; ignore this
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* signal.
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*/
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}
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/*
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* Check if the scheduler interrupt has come when
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* the currently running thread has deferred thread
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* signals.
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*/
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else if (_thread_run->sig_defer_count > 0)
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_thread_run->yield_on_sig_undefer = 1;
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else {
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/*
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* Schedule the next thread. This function is not
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* expected to return because it will do a longjmp
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* instead.
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*/
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_thread_kern_sched(scp);
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/*
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* This point should not be reached, so abort the
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* process:
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*/
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PANIC("Returned to signal function from scheduler");
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}
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}
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/*
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* Check if the kernel has been interrupted while the scheduler
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* is accessing the scheduling queues or if there is a currently
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* running thread that has deferred signals.
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*/
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else if ((_queue_signals != 0) || ((_thread_kern_in_sched == 0) &&
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(_thread_run->sig_defer_count > 0))) {
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/* Cast the signal number to a character variable: */
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c = sig;
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/*
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* Write the signal number to the kernel pipe so that it will
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* be ready to read when this signal handler returns.
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*/
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_thread_sys_write(_thread_kern_pipe[1], &c, 1);
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/* Indicate that there are queued signals in the pipe. */
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_sigq_check_reqd = 1;
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}
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else {
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if (_atomic_lock(&signal_lock.access_lock)) {
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/* There is another signal handler running: */
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pending_sigs[sig - 1]++;
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check_pending = 1;
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}
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else {
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/* It's safe to handle the signal now. */
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pthread = _thread_sig_handle(sig, scp);
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/* Reset the pending and handled count back to 0: */
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pending_sigs[sig - 1] = 0;
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handled_sigs[sig - 1] = 0;
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if (pthread == NULL)
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signal_lock.access_lock = 0;
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else {
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sigaddset(&pthread->sigmask, sig);
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signal_lock.access_lock = 0;
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_thread_sig_deliver(pthread, sig);
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sigdelset(&pthread->sigmask, sig);
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}
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}
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/* Enter a loop to process pending signals: */
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while ((check_pending != 0) &&
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(_atomic_lock(&signal_lock.access_lock) == 0)) {
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check_pending = 0;
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for (i = 1; i < NSIG; i++) {
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if (pending_sigs[i - 1] > handled_sigs[i - 1]) {
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pending_sigs[i - 1] = handled_sigs[i - 1];
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pthread = _thread_sig_handle(i, scp);
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if (pthread != NULL) {
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sigaddset(&pthread->sigmask, i);
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signal_lock.access_lock = 0;
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_thread_sig_deliver(pthread, i);
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sigdelset(&pthread->sigmask, i);
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if (_atomic_lock(&signal_lock.access_lock)) {
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check_pending = 1;
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return;
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}
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}
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}
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}
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signal_lock.access_lock = 0;
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}
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}
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}
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pthread_t
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_thread_sig_handle(int sig, ucontext_t * scp)
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{
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int i, handler_installed;
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pthread_t pthread, pthread_next;
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pthread_t suspended_thread, signaled_thread;
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/* Check if the signal requires a dump of thread information: */
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if (sig == SIGINFO)
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/* Dump thread information to file: */
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_thread_dump_info();
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/* Check if an interval timer signal: */
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else if (sig == _SCHED_SIGNAL) {
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/*
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* This shouldn't ever occur (should this panic?).
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*/
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} else {
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/* Check if a child has terminated: */
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if (sig == SIGCHLD) {
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/*
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* Go through the file list and set all files
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* to non-blocking again in case the child
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* set some of them to block. Sigh.
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*/
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for (i = 0; i < _thread_dtablesize; i++) {
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/* Check if this file is used: */
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if (_thread_fd_table[i] != NULL) {
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/*
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* Set the file descriptor to
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* non-blocking:
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*/
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_thread_sys_fcntl(i, F_SETFL,
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_thread_fd_table[i]->flags |
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O_NONBLOCK);
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}
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}
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/*
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* Enter a loop to wake up all threads waiting
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* for a process to complete:
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*/
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for (pthread = TAILQ_FIRST(&_waitingq);
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pthread != NULL; pthread = pthread_next) {
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/*
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* Grab the next thread before possibly
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* destroying the link entry:
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*/
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pthread_next = TAILQ_NEXT(pthread, pqe);
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/*
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* If this thread is waiting for a child
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* process to complete, wake it up:
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*/
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if (pthread->state == PS_WAIT_WAIT) {
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/* Make the thread runnable: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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/* Return the signal number: */
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pthread->signo = sig;
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}
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}
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}
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/*
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* POSIX says that pending SIGCONT signals are
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* discarded when one of these signals occurs.
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*/
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if (sig == SIGTSTP || sig == SIGTTIN || sig == SIGTTOU) {
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/*
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* Enter a loop to discard pending SIGCONT
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* signals:
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*/
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TAILQ_FOREACH(pthread, &_thread_list, tle) {
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sigdelset(&pthread->sigpend,SIGCONT);
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}
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}
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/*
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* Enter a loop to look for threads that have the signal
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* unmasked. POSIX specifies that a thread in a sigwait
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* will get the signal over any other threads. Second
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* preference will be threads in in a sigsuspend. If
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* none of the above, then the signal is delivered to the
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* first thread we find. Note that if a custom handler
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* is not installed, the signal only affects threads in
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* sigwait.
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*/
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suspended_thread = NULL;
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signaled_thread = NULL;
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if ((_thread_sigact[sig - 1].sa_handler == SIG_IGN) ||
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(_thread_sigact[sig - 1].sa_handler == SIG_DFL))
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handler_installed = 0;
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else
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handler_installed = 1;
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for (pthread = TAILQ_FIRST(&_waitingq);
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pthread != NULL; pthread = pthread_next) {
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/*
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* Grab the next thread before possibly destroying
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* the link entry.
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*/
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pthread_next = TAILQ_NEXT(pthread, pqe);
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if ((pthread->state == PS_SIGWAIT) &&
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sigismember(pthread->data.sigwait, sig)) {
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/* Change the state of the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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/* Return the signal number: */
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pthread->signo = sig;
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/*
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* POSIX doesn't doesn't specify which thread
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* will get the signal if there are multiple
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* waiters, so we give it to the first thread
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* we find.
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*
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* Do not attempt to deliver this signal
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* to other threads.
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*/
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return (NULL);
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}
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else if ((handler_installed != 0) &&
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!sigismember(&pthread->sigmask, sig)) {
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if (pthread->state == PS_SIGSUSPEND) {
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if (suspended_thread == NULL)
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suspended_thread = pthread;
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} else if (signaled_thread == NULL)
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signaled_thread = pthread;
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}
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}
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/*
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* Only perform wakeups and signal delivery if there is a
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* custom handler installed:
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*/
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if (handler_installed != 0) {
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/*
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* If we didn't find a thread in the waiting queue,
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* check the all threads queue:
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*/
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if (suspended_thread == NULL &&
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signaled_thread == NULL) {
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/*
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* Enter a loop to look for other threads
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* capable of receiving the signal:
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*/
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TAILQ_FOREACH(pthread, &_thread_list, tle) {
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if (!sigismember(&pthread->sigmask,
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sig)) {
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signaled_thread = pthread;
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break;
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}
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}
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}
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if (suspended_thread == NULL &&
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signaled_thread == NULL)
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/*
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* Add it to the set of signals pending
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* on the process:
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*/
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sigaddset(&_process_sigpending, sig);
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else {
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/*
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* We only deliver the signal to one thread;
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* give preference to the suspended thread:
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*/
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if (suspended_thread != NULL)
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pthread = suspended_thread;
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else
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pthread = signaled_thread;
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/*
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* Perform any state changes due to signal
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* arrival:
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*/
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_thread_sig_check_state(pthread, sig);
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return (pthread);
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}
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}
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}
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/* Returns nothing. */
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return (NULL);
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}
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/* Perform thread specific actions in response to a signal: */
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static void
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_thread_sig_check_state(pthread_t pthread, int sig)
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{
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/*
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* Process according to thread state:
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*/
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switch (pthread->state) {
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/*
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* States which do not change when a signal is trapped:
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*/
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case PS_COND_WAIT:
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case PS_DEAD:
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case PS_DEADLOCK:
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case PS_FILE_WAIT:
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case PS_JOIN:
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case PS_MUTEX_WAIT:
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case PS_RUNNING:
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case PS_STATE_MAX:
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case PS_SIGTHREAD:
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case PS_SPINBLOCK:
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case PS_SUSPENDED:
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/* Increment the pending signal count. */
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sigaddset(&pthread->sigpend,sig);
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break;
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case PS_SIGWAIT:
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/* Wake up the thread if the signal is blocked. */
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if (sigismember(pthread->data.sigwait, sig)) {
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/* Change the state of the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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/* Return the signal number: */
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pthread->signo = sig;
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} else
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/* Increment the pending signal count. */
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sigaddset(&pthread->sigpend,sig);
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break;
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/*
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* The wait state is a special case due to the handling of
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* SIGCHLD signals.
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*/
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case PS_WAIT_WAIT:
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/*
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* Check for signals other than the death of a child
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* process:
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*/
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if (sig != SIGCHLD)
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/* Flag the operation as interrupted: */
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pthread->interrupted = 1;
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/* Change the state of the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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/* Return the signal number: */
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pthread->signo = sig;
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break;
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/*
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* States that are interrupted by the occurrence of a signal
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* other than the scheduling alarm:
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*/
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case PS_FDLR_WAIT:
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case PS_FDLW_WAIT:
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case PS_FDR_WAIT:
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case PS_FDW_WAIT:
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case PS_POLL_WAIT:
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case PS_SLEEP_WAIT:
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case PS_SELECT_WAIT:
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if ((_thread_sigact[sig - 1].sa_flags & SA_RESTART) == 0) {
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/* Flag the operation as interrupted: */
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pthread->interrupted = 1;
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if (pthread->flags & PTHREAD_FLAGS_IN_WORKQ)
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PTHREAD_WORKQ_REMOVE(pthread);
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/* Change the state of the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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/* Return the signal number: */
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pthread->signo = sig;
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}
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break;
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case PS_SIGSUSPEND:
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/*
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* Only wake up the thread if there is a handler installed
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* for the signal.
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*/
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if (_thread_sigact[sig - 1].sa_handler != SIG_DFL) {
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/* Change the state of the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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/* Return the signal number: */
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pthread->signo = sig;
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}
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break;
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}
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}
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/* Send a signal to a specific thread (ala pthread_kill): */
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void
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_thread_sig_send(pthread_t pthread, int sig)
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{
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/*
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* Check that the signal is not being ignored:
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*/
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if (_thread_sigact[sig - 1].sa_handler != SIG_IGN) {
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if (pthread->state == PS_SIGWAIT &&
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sigismember(pthread->data.sigwait, sig)) {
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/* Change the state of the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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/* Return the signal number: */
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pthread->signo = sig;
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} else if (pthread->state != PS_SIGWAIT &&
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!sigismember(&pthread->sigmask, sig)) {
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/* Perform any state changes due to signal arrival: */
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_thread_sig_check_state(pthread, sig);
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/* Call the installed signal handler: */
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_thread_sig_deliver(pthread, sig);
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}
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else {
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/* Increment the pending signal count. */
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sigaddset(&pthread->sigpend,sig);
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}
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}
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}
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/* Dispatch pending signals to the running thread: */
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void
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_dispatch_signals()
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{
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sigset_t sigset;
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int i;
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/*
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* Check if there are pending signals for the running
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* thread or process that aren't blocked:
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*/
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sigset = _thread_run->sigpend;
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SIGSETOR(sigset, _process_sigpending);
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SIGSETNAND(sigset, _thread_run->sigmask);
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if (SIGNOTEMPTY(sigset)) {
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/*
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* Enter a loop to calculate deliverable pending signals
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* before actually delivering them. The pending signals
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* must be removed from the pending signal sets before
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* calling the signal handler because the handler may
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* call library routines that again check for and deliver
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* pending signals.
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*/
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for (i = 1; i < NSIG; i++) {
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/*
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* Check that a custom handler is installed
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* and if the signal is not blocked:
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*/
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if (_thread_sigact[i - 1].sa_handler != SIG_DFL &&
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_thread_sigact[i - 1].sa_handler != SIG_IGN &&
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sigismember(&sigset, i)) {
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if (sigismember(&_thread_run->sigpend,i))
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/* Clear the thread pending signal: */
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sigdelset(&_thread_run->sigpend,i);
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else
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/* Clear the process pending signal: */
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sigdelset(&_process_sigpending,i);
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}
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else
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/* Remove the signal if it can't be handled: */
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sigdelset(&sigset, i);
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}
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/* Now deliver the signals: */
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for (i = 1; i < NSIG; i++) {
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if (sigismember(&sigset, i))
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/* Deliver the signal to the running thread: */
|
|
_thread_sig_deliver(_thread_run, i);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Deliver a signal to a thread: */
|
|
void
|
|
_thread_sig_deliver(pthread_t pthread, int sig)
|
|
{
|
|
sigset_t mask;
|
|
pthread_t pthread_saved;
|
|
|
|
/*
|
|
* Check that a custom handler is installed
|
|
* and if the signal is not blocked:
|
|
*/
|
|
if (_thread_sigact[sig - 1].sa_handler != SIG_DFL &&
|
|
_thread_sigact[sig - 1].sa_handler != SIG_IGN) {
|
|
/* Save the current thread: */
|
|
pthread_saved = _thread_run;
|
|
|
|
/* Save the threads signal mask: */
|
|
mask = pthread->sigmask;
|
|
|
|
/*
|
|
* Add the current signal and signal handler
|
|
* mask to the threads current signal mask:
|
|
*/
|
|
SIGSETOR(pthread->sigmask, _thread_sigact[sig - 1].sa_mask);
|
|
sigaddset(&pthread->sigmask, sig);
|
|
|
|
/* Current thread inside critical region? */
|
|
if (_thread_run->sig_defer_count > 0)
|
|
pthread->sig_defer_count++;
|
|
|
|
_thread_run = pthread;
|
|
|
|
/*
|
|
* Dispatch the signal via the custom signal
|
|
* handler:
|
|
*/
|
|
(*(_thread_sigact[sig - 1].sa_handler))(sig);
|
|
|
|
_thread_run = pthread_saved;
|
|
|
|
/* Current thread inside critical region? */
|
|
if (_thread_run->sig_defer_count > 0)
|
|
pthread->sig_defer_count--;
|
|
|
|
/* Restore the threads signal mask: */
|
|
pthread->sigmask = mask;
|
|
}
|
|
}
|
|
#endif
|