/**************************************************************************** * sched/sig_timedwait.c * * Copyright (C) 2007-2009, 2012 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 * COPYRIGHT OWNER 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include #include "os_internal.h" #include "sig_internal.h" #include "clock_internal.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* This is a special value of si_signo that means that it was the timeout * that awakened the wait... not the receipt of a signal. */ #define SIG_WAIT_TIMEOUT 0xff /**************************************************************************** * Private Type Declarations ****************************************************************************/ /**************************************************************************** * Global Variables ****************************************************************************/ /**************************************************************************** * Private Variables ****************************************************************************/ /**************************************************************************** * Private Functionss ****************************************************************************/ /**************************************************************************** * Function: sig_timeout * * Description: * A timeout elapsed while waiting for signals to be queued. * ****************************************************************************/ static void sig_timeout(int argc, uint32_t itcb) { /* On many small machines, pointers are encoded and cannot be simply cast * from uint32_t to _TCB*. The following union works around this * (see wdogparm_t). This odd logic could be conditioned on * CONFIG_CAN_CAST_POINTERS, but it is not too bad in any case. */ union { FAR _TCB *wtcb; uint32_t itcb; } u; u.itcb = itcb; if (!u.wtcb) { PANIC(OSERR_TIMEOUTNOTCB); } /* There may be a race condition -- make sure the task is * still waiting for a signal */ if (u.wtcb->task_state == TSTATE_WAIT_SIG) { u.wtcb->sigunbinfo.si_signo = SIG_WAIT_TIMEOUT; u.wtcb->sigunbinfo.si_code = SI_TIMER; u.wtcb->sigunbinfo.si_value.sival_int = 0; up_unblock_task(u.wtcb); } } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Function: sigtimedwait * * Description: * This function selects the pending signal set specified by the argument * set. If multiple signals are pending in set, it will remove and return * the lowest numbered one. If no signals in set are pending at the time * of the call, the calling process will be suspended until one of the * signals in set becomes pending, OR until the process is interrupted by * an unblocked signal, OR until the time interval specified by timeout * (if any), has expired. If timeout is NULL, then the timeout interval * is forever. * * If the info argument is non-NULL, the selected signal number is stored * in the si_signo member and the cause of the signal is store in the * si_code emember. The content of si_value is only meaningful if the * signal was generated by sigqueue(). * * The following values for si_code are defined in signal.h: * SI_USER - Signal sent from kill, raise, or abort * SI_QUEUE - Signal sent from sigqueue * SI_TIMER - Signal is result of timer expiration * SI_ASYNCIO - Signal is the result of asynch IO completion * SI_MESGQ - Signal generated by arrival of a message on an * empty message queue. * * Parameters: * set - The pending signal set. * info - The returned value * timeout - The amount of time to wait * * Return Value: * Signal number that cause the wait to be terminated, otherwise -1 (ERROR) * is returned with errno set to either: * * EAGAIN - No signal specified by set was generated within the specified * timeout period. * EINTR - The wait was interrupted by an unblocked, caught signal. * * Assumptions: * ****************************************************************************/ int sigtimedwait(FAR const sigset_t *set, FAR struct siginfo *info, FAR const struct timespec *timeout) { FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head; sigset_t intersection; FAR sigpendq_t *sigpend; WDOG_ID wdog; irqstate_t saved_state; int32_t waitticks; int ret = ERROR; sched_lock(); /* Not necessary */ /* Several operations must be performed below: We must determine if any * signal is pending and, if not, wait for the signal. Since signals can * be posted from the interrupt level, there is a race condition that * can only be eliminated by disabling interrupts! */ saved_state = irqsave(); /* Check if there is a pending signal corresponding to one of the * signals in the pending signal set argument. */ intersection = *set & sig_pendingset(rtcb); if (intersection != NULL_SIGNAL_SET) { /* One or more of the signals in intersections is sufficient to cause * us to not wait. Pick the lowest numbered signal and mark it not * pending. */ sigpend = sig_removependingsignal(rtcb, sig_lowest(&intersection)); if (!sigpend) { PANIC(OSERR_NOPENDINGSIGNAL); } /* Return the signal info to the caller if so requested */ if (info) { memcpy(info, &sigpend->info, sizeof(struct siginfo)); } /* Then dispose of the pending signal structure properly */ sig_releasependingsignal(sigpend); irqrestore(saved_state); /* The return value is the number of the signal that awakened us */ ret = info->si_signo; } /* We will have to wait for a signal to be posted to this task. */ else { /* Save the set of pending signals to wait for */ rtcb->sigwaitmask = *set; /* Check if we should wait for the timeout */ if (timeout) { /* Convert the timespec to milliseconds */ waitticks = MSEC2TICK(timeout->tv_sec * MSEC_PER_SEC + timeout->tv_nsec / NSEC_PER_MSEC); /* Create a watchdog */ wdog = wd_create(); if (wdog) { /* This little of nonsense is necessary for some * processors where sizeof(pointer) < sizeof(uint32_t). * see wdog.h. */ wdparm_t wdparm; wdparm.pvarg = (FAR void*)rtcb; /* Start the watchdog */ wd_start(wdog, waitticks, (wdentry_t)sig_timeout, 1, wdparm.dwarg); /* Now wait for either the signal or the watchdog */ up_block_task(rtcb, TSTATE_WAIT_SIG); /* We no longer need the watchdog */ wd_delete(wdog); } } /* No timeout, just wait */ else { /* And wait until one of the unblocked signals is posted */ up_block_task(rtcb, TSTATE_WAIT_SIG); } /* We are running again, clear the sigwaitmask */ rtcb->sigwaitmask = NULL_SIGNAL_SET; /* When we awaken, the cause will be in the TCB. Get the signal number * or timeout) that awakened us. */ if (GOOD_SIGNO(rtcb->sigunbinfo.si_signo)) { /* We were awakened by a signal... but is it one of the signals that * we were waiting for? */ if (sigismember(set, rtcb->sigunbinfo.si_signo)) { /* Yes.. the return value is the number of the signal that * awakened us. */ ret = rtcb->sigunbinfo.si_signo; } else { /* No... then set EINTR and report an error */ set_errno(EINTR); ret = ERROR; } } else { /* Otherwise, we must have been awakened by the timeout. Set EGAIN * and return an error. */ DEBUGASSERT(rtcb->sigunbinfo.si_signo == SIG_WAIT_TIMEOUT); set_errno(EAGAIN); ret = ERROR; } /* Return the signal info to the caller if so requested */ if (info) { memcpy(info, &rtcb->sigunbinfo, sizeof(struct siginfo)); } irqrestore(saved_state); } sched_unlock(); return ret; }