367 lines
9.5 KiB
C
367 lines
9.5 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 REGENTS 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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*/
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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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/* Static variables: */
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static int volatile yield_on_unlock_dead = 0;
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static int volatile yield_on_unlock_thread = 0;
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static spinlock_t thread_dead_lock = _SPINLOCK_INITIALIZER;
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static spinlock_t thread_link_list_lock = _SPINLOCK_INITIALIZER;
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/* Lock the thread list: */
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void
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_lock_thread_list()
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{
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/* Lock the thread list: */
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_SPINLOCK(&thread_link_list_lock);
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}
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/* Lock the dead thread list: */
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void
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_lock_dead_thread_list()
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{
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/* Lock the dead thread list: */
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_SPINLOCK(&thread_dead_lock);
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}
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/* Lock the thread list: */
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void
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_unlock_thread_list()
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{
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/* Unlock the thread list: */
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_SPINUNLOCK(&thread_link_list_lock);
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/*
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* Check if a scheduler interrupt occurred while the thread
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* list was locked:
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*/
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if (yield_on_unlock_thread) {
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/* Reset the interrupt flag: */
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yield_on_unlock_thread = 0;
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/* This thread has overstayed it's welcome: */
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sched_yield();
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}
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}
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/* Lock the dead thread list: */
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void
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_unlock_dead_thread_list()
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{
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/* Unlock the dead thread list: */
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_SPINUNLOCK(&thread_dead_lock);
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/*
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* Check if a scheduler interrupt occurred while the dead
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* thread list was locked:
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*/
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if (yield_on_unlock_dead) {
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/* Reset the interrupt flag: */
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yield_on_unlock_dead = 0;
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/* This thread has overstayed it's welcome: */
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sched_yield();
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}
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}
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void
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_thread_sig_handler(int sig, int code, struct sigcontext * scp)
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{
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char c;
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int i;
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int dispatch = 0;
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pthread_t pthread;
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/*
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* Check if the pthread kernel has unblocked signals (or is about to)
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* and was on its way into a _select when the current
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* signal interrupted it:
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*/
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if (_thread_kern_in_select) {
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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. This
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* means that the _select call will complete
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* immediately.
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*/
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_thread_sys_write(_thread_kern_pipe[1], &c, 1);
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}
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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 == SIGVTALRM) {
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/* Check if the scheduler interrupt has come at an
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* unfortunate time which one of the threads is
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* modifying the thread list:
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*/
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if (thread_link_list_lock.access_lock)
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/*
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* Set a flag so that the thread that has
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* the lock yields when it unlocks the
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* thread list:
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*/
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yield_on_unlock_thread = 1;
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/* Check if the scheduler interrupt has come at an
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* unfortunate time which one of the threads is
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* modifying the dead thread list:
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*/
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if (thread_dead_lock.access_lock)
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/*
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* Set a flag so that the thread that has
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* the lock yields when it unlocks the
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* dead thread list:
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*/
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yield_on_unlock_dead = 1;
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/*
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* Check if the kernel has not been interrupted while
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* executing scheduler code:
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*/
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else if (!_thread_kern_in_sched) {
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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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} 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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/*
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* POSIX says that pending SIGCONT signals are
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* discarded when one of there 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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for (pthread = _thread_link_list;
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pthread != NULL;
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pthread = pthread->nxt)
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sigdelset(&pthread->sigpend,SIGCONT);
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}
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/*
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* Enter a loop to process each thread in the linked
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* list that is sigwait-ing on a signal. Since POSIX
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* doesn't specify which thread will get the signal
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* if there are multiple waiters, we'll give it to the
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* first one we find.
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*/
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for (pthread = _thread_link_list; pthread != NULL;
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pthread = pthread->nxt) {
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if ((pthread->state == PS_SIGWAIT) &&
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sigismember(&pthread->sigmask, 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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* Do not attempt to deliver this signal
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* to other threads.
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*/
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return;
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}
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}
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/* Check if the signal is not being ignored: */
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if (_thread_sigact[sig - 1].sa_handler != SIG_IGN)
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/*
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* Enter a loop to process each thread in the linked
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* list:
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*/
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for (pthread = _thread_link_list; pthread != NULL;
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pthread = pthread->nxt)
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_thread_signal(pthread,sig);
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/* Dispatch pending signals to the running thread: */
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_dispatch_signals();
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}
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/* Returns nothing. */
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return;
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}
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/* Perform thread specific actions in response to a signal: */
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void
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_thread_signal(pthread_t pthread, int sig)
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{
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pthread_t saved;
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struct sigaction act;
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/*
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* Flag the signal as pending. It will be dispatched later.
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*/
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sigaddset(&pthread->sigpend,sig);
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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_FDLR_WAIT:
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case PS_FDLW_WAIT:
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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_SIGWAIT:
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case PS_SUSPENDED:
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/* Nothing to do here. */
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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_FDR_WAIT:
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case PS_FDW_WAIT:
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case PS_SLEEP_WAIT:
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case PS_SELECT_WAIT:
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if (sig != SIGCHLD ||
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_thread_sigact[sig - 1].sa_handler != SIG_DFL) {
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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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}
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break;
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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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int i;
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/*
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* Check if there are pending signals for the running
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* thread that aren't blocked:
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*/
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if ((_thread_run->sigpend & ~_thread_run->sigmask) != 0)
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/* Look for all possible pending signals: */
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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(&_thread_run->sigpend,i) &&
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!sigismember(&_thread_run->sigmask,i)) {
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/* Clear the pending signal: */
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sigdelset(&_thread_run->sigpend,i);
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/*
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* Dispatch the signal via the custom signal
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* handler:
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*/
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(*(_thread_sigact[i - 1].sa_handler))(i);
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}
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}
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#endif
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