freebsd-dev/lib/libpthread/thread/thr_sigaction.c
Daniel Eischen b5a8a15c2f Don't needlessly poll file descriptors when there are no
file descriptors needing to be polled (Doh!).  Reported
by Dan Nelson <dnelson@emsphone.com>.

Don't install and start the scheduling timer until the
first thread is created.  This prevents the overhead of
having a periodic scheduling signal in a single threaded
program.  Reported by Dan Nelson <dnelson@emsphone.com>.

Allow builtin longjmps out of application installed
signal handlers without the need perform any post-handler
cleanup:

  o Change signal handling to save the threads interrupted
    context on the stack.  The threads current context is
    now always stored in the same place (in the pthread).
    If and when a signal handler returns, the interrupted
    context is copied back to the storage area in the pthread.

  o Before calling invoking a signal handler for a thread,
    back the thread out of any internal waiting queues
    (mutex, CV, join, etc) to which it belongs.

Rework uthread_info.c a bit to make it easier to change
the format of a thread dump.

Use an alternal signal stack for the thread library's
signal handler.  This allows us to fiddle with the main
threads stack without fear of it being in use.

Reviewed by:	jasone
2000-11-09 05:08:26 +00:00

112 lines
3.7 KiB
C

/*
* 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.
*
* $FreeBSD$
*/
#include <signal.h>
#include <errno.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"
int
_sigaction(int sig, const struct sigaction * act, struct sigaction * oact)
{
int ret = 0;
struct sigaction gact;
/* Check if the signal number is out of range: */
if (sig < 1 || sig > NSIG) {
/* Return an invalid argument: */
errno = EINVAL;
ret = -1;
} else {
/*
* Check if the existing signal action structure contents are
* to be returned:
*/
if (oact != NULL) {
/* Return the existing signal action contents: */
oact->sa_handler = _thread_sigact[sig - 1].sa_handler;
oact->sa_mask = _thread_sigact[sig - 1].sa_mask;
oact->sa_flags = _thread_sigact[sig - 1].sa_flags;
}
/* Check if a signal action was supplied: */
if (act != NULL) {
/* Set the new signal handler: */
_thread_sigact[sig - 1].sa_mask = act->sa_mask;
_thread_sigact[sig - 1].sa_flags = act->sa_flags;
_thread_sigact[sig - 1].sa_handler = act->sa_handler;
}
/*
* Check if the kernel needs to be advised of a change
* in signal action:
*/
if (act != NULL && sig != _SCHED_SIGNAL && sig != SIGCHLD &&
sig != SIGINFO) {
/*
* Ensure the signal handler cannot be interrupted
* by other signals. Always request the POSIX signal
* handler arguments.
*/
sigfillset(&gact.sa_mask);
gact.sa_flags = SA_SIGINFO | SA_ONSTACK;
/*
* Check if the signal handler is being set to
* the default or ignore handlers:
*/
if (act->sa_handler == SIG_DFL ||
act->sa_handler == SIG_IGN)
/* Specify the built in handler: */
gact.sa_handler = act->sa_handler;
else
/*
* Specify the thread kernel signal
* handler:
*/
gact.sa_handler = (void (*) ()) _thread_sig_handler;
/* Change the signal action in the kernel: */
if (_thread_sys_sigaction(sig,&gact,NULL) != 0)
ret = -1;
}
}
/* Return the completion status: */
return (ret);
}
__strong_reference(_sigaction, sigaction);
#endif