270 lines
8.8 KiB
C
270 lines
8.8 KiB
C
/****************************************************************************
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* sched/sig_action.c
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*
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* Copyright (C) 2007, 2008 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 NuttX 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 <signal.h>
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#include <queue.h>
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#include <sched.h>
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#include "os_internal.h"
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#include "sig_internal.h"
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/****************************************************************************
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* Definitions
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****************************************************************************/
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#define COPY_SIGACTION(t,f) \
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{ (t)->sa_sigaction = (f)->sa_sigaction; \
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(t)->sa_mask = (f)->sa_mask; \
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(t)->sa_flags = (f)->sa_flags; }
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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 Functions
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****************************************************************************/
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/****************************************************************************
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* Function: sig_allocateaction
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*
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* Description:
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* Allocate a new element for a sigaction queue
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*
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****************************************************************************/
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static FAR sigactq_t *sig_allocateaction(void)
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{
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FAR sigactq_t *sigact;
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/* Try to get the signal action structure from the free list */
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sigact = (FAR sigactq_t*)sq_remfirst(&g_sigfreeaction);
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/* Check if we got one. */
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if (!sigact)
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{
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/* Add another block of signal actions to the list */
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sig_allocateactionblock();
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/* And try again */
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sigact = (FAR sigactq_t*)sq_remfirst(&g_sigfreeaction);
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if (!sigact)
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{
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PANIC(OSERR_OUTOFMEMORY);
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}
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}
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return sigact;
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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: sigaction
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*
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* Description:
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* This function allows the calling process to examine and/or specify the
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* action to be associated with a specific signal.
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*
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* The structure sigaction, used to describe an action to be taken, is
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* defined to include the following members:
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*
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* - sa_u.sa_handler: Pointer to a signal-catching function
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* - sa_u.sa_sigaction: Alternative form of the signal-catching function
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* - sa_mask: An additional set of signals to be blocked during execution
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* of a signal catching function
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* - sa_flags. Special flags to affect the behavior of a signal.
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*
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* If the argument 'act' is not NULL, it points to a structure specifying
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* the action to be associated with the specified signal. If the argument
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* 'oact' is not NULL, the action previously associated with the signal
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* is stored in the location pointed to by the argument 'oact.'
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*
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* When a signal is caught by a signal-catching function installed by
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* sigaction() function, a new signal mask is calculated and installed for
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* the duration of the signal-catching function. This mask is formed by
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* taking the union of the current signal mask and the value of the
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* sa_mask for the signal being delivered and then including the signal
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* being delivered. If and when the user's signal handler returns, the
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* original signal mask is restored.
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*
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* Once an action is installed for a specific signal, it remains installed
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* until another action is explicitly requested by another call to sigaction().
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*
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* Parameters:
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* sig - Signal of interest
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* act - Location of new handler
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* oact - Location to store only handler
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*
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* Return Value:
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* 0 (OK), or -1 (ERROR) if the signal number is invalid.
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* (errno is not set)
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*
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* Assumptions:
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*
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* POSIX Compatibility:
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* - Special values of sa_handler in the struct sigaction
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* act input not handled (SIG_DFL, SIG_IGN).
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* - All sa_flags in struct sigaction of act input are
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* ignored (all treated like SA_SIGINFO).
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*
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****************************************************************************/
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int sigaction(int signo, FAR const struct sigaction *act, FAR struct sigaction *oact)
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{
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FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
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FAR sigactq_t *sigact;
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int ret = ERROR; /* Assume failure */
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/* Since sigactions can only be installed from the running thread of
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* execution, no special precautions should be necessary.
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*/
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/* Verify the signal */
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if (GOOD_SIGNO(signo))
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{
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ret = OK; /* Assume success */
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/* Find the signal in the sigactionq */
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sigact = sig_findaction(rtcb, signo);
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/* Return the old sigaction value if so requested */
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if (oact)
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{
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if (sigact)
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{
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COPY_SIGACTION(oact, &sigact->act);
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}
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else
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{
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/* There isn't an old value */
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oact->sa_u._sa_handler = NULL;
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oact->sa_mask = NULL_SIGNAL_SET;
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oact->sa_flags = 0;
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}
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}
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/* If no sigaction was found, but one is needed, then
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* allocate one.
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*/
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if (!sigact && act && act->sa_u._sa_handler)
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{
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sigact = sig_allocateaction();
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/* An error has occurred if we could not allocate the sigaction */
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if (!sigact)
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{
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ret = ERROR;
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}
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else
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{
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/* Put the signal number in the queue entry */
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sigact->signo = (ubyte)signo;
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/* Add the new sigaction to sigactionq */
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sq_addlast((FAR sq_entry_t*)sigact, &rtcb->sigactionq);
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}
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}
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/* Set the new sigaction if so requested */
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if ((sigact) && (act))
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{
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/* Check if it is a request to install a new handler */
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if (act->sa_u._sa_handler)
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{
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COPY_SIGACTION(&sigact->act, act);
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}
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/* No.. It is a request to remove the old handler */
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else
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{
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/* Remove the old sigaction from sigactionq */
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sq_rem((FAR sq_entry_t*)sigact, &rtcb->sigactionq);
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/* And deallocate it */
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sig_releaseaction(sigact);
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}
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}
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}
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return ret;
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}
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/****************************************************************************
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* Function: sig_releaseaction
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*
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* Description:
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* Deallocate a sigaction Q entry
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*
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****************************************************************************/
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void sig_releaseaction(FAR sigactq_t *sigact)
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{
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/* Just put it back on the free list */
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sq_addlast((FAR sq_entry_t*)sigact, &g_sigfreeaction);
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}
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