293 lines
9.0 KiB
C
293 lines
9.0 KiB
C
/************************************************************
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* sig_timedwait.c
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*
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* Copyright (C) 2007 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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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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*
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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
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name Gregory Nutt nor the names of its contributors may be
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* 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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************************************************************/
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/************************************************************
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* Included Files
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************************************************************/
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#include <sys/types.h>
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#include <string.h>
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#include <signal.h>
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#include <time.h>
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#include <wdog.h>
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#include <assert.h>
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#include <debug.h>
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#include <sched.h>
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#include <nuttx/arch.h>
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#include "os_internal.h"
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#include "sig_internal.h"
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#include "clock_internal.h"
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/************************************************************
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* Definitions
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************************************************************/
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/************************************************************
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* Private Type Declarations
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************************************************************/
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/************************************************************
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* Global Variables
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************************************************************/
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/************************************************************
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* Private Variables
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************************************************************/
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/************************************************************
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* Private Functionss
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************************************************************/
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/************************************************************
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* Function: sig_timeout
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*
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* Description:
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* A timeout elapsed while waiting for signals to be queued.
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************************************************************/
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static void sig_timeout(int argc, uint32 itcb, ...)
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{
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/* On many small machines, pointers are encoded and cannot
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* be simply cast from uint32 to _TCB*. The following
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* union works around this (see wdogparm_t). This odd
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* logic could be conditioned on CONFIG_CAN_CAST_POINTERS,
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* but it is not too bad in any case.
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*/
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union
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{
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FAR _TCB *wtcb;
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uint32 itcb;
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} u;
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u.itcb = itcb;
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if (!u.wtcb)
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{
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PANIC(OSERR_TIMEOUTNOTCB);
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}
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/* There may be a race condition -- make sure the task is
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* still waiting for a signal
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*/
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if (u.wtcb->task_state == TSTATE_WAIT_SIG)
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{
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u.wtcb->sigunbinfo.si_signo = ERROR;
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u.wtcb->sigunbinfo.si_code = SI_TIMEOUT;
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u.wtcb->sigunbinfo.si_value.sival_int = 0;
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up_unblock_task(u.wtcb);
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}
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}
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/************************************************************
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* Public Functions
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************************************************************/
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/************************************************************
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* Function: sigtimedwait
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*
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* Description:
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* This function selects the pending signal set specified
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* by the argument set. If multiple signals are pending
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* in set, it will remove and return the lowest numbered
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* one. If no signals in set are pending at the time of
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* the call, the calling process will be suspended until
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* one of the signals in set becomes pending, OR until
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* the process is interrupted by an unblocked signal, OR
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* until the time interval specified by timeout (if any),
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* has expired. If timeout is NULL, then the timeout
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* interval is forever.
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*
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* If the info argument is non-NULL, the selected signal
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* number is stored in the si_signo member and the cause
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* of the signal is store in the si_code emember. The
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* content of si_value is only meaningful if the signal was
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* generated by sigqueue().
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*
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* The following values for si_code are defined in signal.h:
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* SI_QUEUE - Signal sent from sigqueue
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* SI_MESGQ - Signal generated by arrival of a message on an
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* empty message queue
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* SI_NOWAIT - Signal already pending -- don't know how sent
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* SI_TIMEOUT - No Signal, restarted by timeout
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*
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* Parameters:
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* set - The pending signal set.
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* info - The returned value
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* timeout - The amount of time to wait
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*
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* Return Value:
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* Signal number that cause the wait to be terminated, otherwise
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* -1 (ERROR) is returned.
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*
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* Assumptions:
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*
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************************************************************/
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int sigtimedwait(const sigset_t *set, struct siginfo *info,
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const struct timespec *timeout)
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{
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FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
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sigset_t intersection;
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FAR sigpendq_t *sigpend;
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WDOG_ID wdog;
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irqstate_t saved_state;
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sint32 waitticks;
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int ret = ERROR;
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sched_lock(); /* Not necessary */
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/* Several operations must be performed below: We must determine if any
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* signal is pending and, if not, wait for the signal. Since signals can
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* be posted from the interrupt level, there is a race condition that
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* can only be eliminated by disabling interrupts!
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*/
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saved_state = irqsave();
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/* Check if there is a pending signal corresponding to one of the
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* signals in the pending signal set argument.
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*/
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intersection = *set & sig_pendingset(rtcb);
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if (intersection != NULL_SIGNAL_SET)
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{
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/* One or more of the signals in intersections is sufficient to cause
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* us to not wait. Pick the lowest numbered signal and mark it not
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* pending.
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*/
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sigpend = sig_removependingsignal(rtcb, sig_lowest(&intersection));
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if (!sigpend)
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{
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PANIC(OSERR_NOPENDINGSIGNAL);
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}
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/* Return the signal info to the caller if so requested */
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if (info)
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{
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memcpy(info, &sigpend->info, sizeof(struct siginfo));
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}
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/* Then dispose of the pending signal structure properly */
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sig_releasependingsignal(sigpend);
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irqrestore(saved_state);
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/* The return value is the number of the signal that awakened us */
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ret = info->si_signo;
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}
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/* We will have to wait for a signal to be posted to this task. */
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else
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{
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/* Save the set of pending signals to wait for */
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rtcb->sigwaitmask = *set;
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/* Check if we should wait for the timeout */
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if (timeout)
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{
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/* Convert the timespec to milliseconds */
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waitticks = MSEC2TICK(timeout->tv_sec * MSEC_PER_SEC
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+ timeout->tv_nsec / NSEC_PER_MSEC);
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/* Create a watchdog */
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wdog = wd_create();
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if (wdog)
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{
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/* This little of nonsense is necessary for some
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* processors where sizeof(pointer) < sizeof(uint32).
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* see wdog.h.
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*/
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wdparm_t wdparm;
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wdparm.pvarg = (void*)rtcb;
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/* Start the watchdog */
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wd_start(wdog, waitticks, (wdentry_t)sig_timeout,
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1, wdparm.dwarg);
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/* Now wait for either the signal or the watchdog */
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up_block_task(rtcb, TSTATE_WAIT_SIG);
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/* We no longer need the watchdog */
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wd_delete(wdog);
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}
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}
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/* No timeout, just wait */
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else
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{
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/* And wait until one of the unblocked signals is posted */
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up_block_task(rtcb, TSTATE_WAIT_SIG);
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}
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/* We are running again, clear the sigwaitmask */
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rtcb->sigwaitmask = NULL_SIGNAL_SET;
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/* When we awaken, the cause will be in the TCB. Return the signal
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* info to the caller if so requested
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*/
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if (info)
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{
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memcpy(info, &rtcb->sigunbinfo, sizeof(struct siginfo));
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}
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irqrestore(saved_state);
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/* The return value is the number of the signal that awakened us */
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ret = info->si_signo;
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}
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sched_unlock();
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return ret;
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}
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