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- /****************************************************************************
- * sched/signal/sig_action.c
- *
- * Copyright (C) 2007-2009, 2013, 2016-2018 Gregory Nutt. All rights
- * reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * 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 <nuttx/config.h>
- #include <stdint.h>
- #include <stdbool.h>
- #include <signal.h>
- #include <queue.h>
- #include <sched.h>
- #include <errno.h>
- #include <nuttx/irq.h>
- #include "sched/sched.h"
- #include "group/group.h"
- #include "signal/signal.h"
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: nxsig_alloc_action
- *
- * Description:
- * Allocate a new element for a sigaction queue
- *
- ****************************************************************************/
- static FAR sigactq_t *nxsig_alloc_action(void)
- {
- FAR sigactq_t *sigact;
- /* Try to get the signal action structure from the free list */
- sigact = (FAR sigactq_t *)sq_remfirst(&g_sigfreeaction);
- /* Check if we got one. */
- if (!sigact)
- {
- /* Add another block of signal actions to the list */
- nxsig_alloc_actionblock();
- /* And try again */
- sigact = (FAR sigactq_t *)sq_remfirst(&g_sigfreeaction);
- DEBUGASSERT(sigact);
- }
- return sigact;
- }
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: nxsig_action and sigaction
- *
- * Description:
- * This function allows the calling process to examine and/or specify the
- * action to be associated with a specific signal.
- *
- * The structure sigaction, used to describe an action to be taken, is
- * defined to include the following members:
- *
- * - sa_u.sa_handler: Pointer to a signal-catching function
- * - sa_u.sa_sigaction: Alternative form of the signal-catching function
- * - sa_mask: An additional set of signals to be blocked during execution
- * of a signal catching function
- * - sa_flags. Special flags to affect the behavior of a signal.
- *
- * If the argument 'act' is not NULL, it points to a structure specifying
- * the action to be associated with the specified signal. If the argument
- * 'oact' is not NULL, the action previously associated with the signal
- * is stored in the location pointed to by the argument 'oact.'
- *
- * When a signal is caught by a signal-catching function installed by
- * sigaction() function, a new signal mask is calculated and installed for
- * the duration of the signal-catching function. This mask is formed by
- * taking the union of the current signal mask and the value of the
- * sa_mask for the signal being delivered and then including the signal
- * being delivered. If and when the user's signal handler returns, the
- * original signal mask is restored.
- *
- * Once an action is installed for a specific signal, it remains installed
- * until another action is explicitly requested by another call to
- * sigaction().
- *
- * nxsig_action() is an internal version of sigaction that adds an
- * additional parameter, force, that is used to set default signal actions
- * (which may not normally be settable). nxsig_action() does not alter the
- * errno variable.
- *
- * Input Parameters:
- * sig - Signal of interest
- * act - Location of new handler
- * oact - Location to store only handler
- * force - Force setup of the signal handler, even if it cannot normally
- * be caught or ignored (nxsig_action only)
- *
- * Returned Value:
- * nxsig_action:
- * Zero (OK) is returned on success; a negated errno value is returned
- * on failure
- * sigaction:
- * Zero (OK) is returned on success; -1 (ERROR) is returned on any
- * failure if the signal number is invalid with the errno set appropriately
- *
- * Assumptions:
- *
- * POSIX Compatibility:
- * - If CONFIG_SIG_DEFAULT is not defined, then there are no default actions
- * so the special value SIG_DFL is treated like SIG_IGN.
- * - All sa_flags in struct sigaction of act input are ignored (all
- * treated like SA_SIGINFO). The one exception is if CONFIG_SCHED_CHILD_STATUS
- * is defined; then SA_NOCLDWAIT is supported but only for SIGCHLD
- *
- ****************************************************************************/
- int nxsig_action(int signo, FAR const struct sigaction *act,
- FAR struct sigaction *oact, bool force)
- {
- FAR struct tcb_s *rtcb = this_task();
- FAR struct task_group_s *group;
- FAR sigactq_t *sigact;
- _sa_handler_t handler;
- /* Since sigactions can only be installed from the running thread of
- * execution, no special precautions should be necessary.
- */
- DEBUGASSERT(rtcb != NULL && rtcb->group != NULL);
- group = rtcb->group;
- /* Verify the signal number */
- if (!GOOD_SIGNO(signo))
- {
- return -EINVAL;
- }
- #ifdef CONFIG_SIG_DEFAULT
- /* Check if the user is trying to catch or ignore a signal that cannot be
- * caught or ignored.
- */
- if (act != NULL && !force && act->sa_handler != SIG_DFL &&
- !nxsig_iscatchable(signo))
- {
- return -EINVAL;
- }
- #endif
- /* Find the signal in the signal action queue */
- sigact = nxsig_find_action(group, signo);
- /* Return the old sigaction value if so requested */
- if (oact != NULL)
- {
- #ifdef CONFIG_SIG_DEFAULT
- if (nxsig_isdefault(rtcb, signo))
- {
- /* Return SIG_DFL if the default signal is attached */
- oact->sa_handler = SIG_DFL;
- oact->sa_mask = NULL_SIGNAL_SET;
- oact->sa_flags = SA_SIGINFO;
- }
- else
- #endif
- if (sigact)
- {
- /* Return the old signal action */
- oact->sa_handler = sigact->act.sa_handler;
- oact->sa_mask = sigact->act.sa_mask;
- oact->sa_flags = sigact->act.sa_flags;
- }
- else
- {
- /* There isn't an old value */
- oact->sa_handler = NULL;
- oact->sa_mask = NULL_SIGNAL_SET;
- oact->sa_flags = 0;
- }
- }
- /* If the argument act is a null pointer, signal handling is unchanged;
- * thus, the call can be used to inquire about the current handling of
- * a given signal.
- */
- if (act == NULL)
- {
- return OK;
- }
- #if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS)
- /* Handle a special case. Retention of child status can be suppressed
- * if signo == SIGCHLD and sa_flags == SA_NOCLDWAIT.
- *
- * POSIX.1 leaves it unspecified whether a SIGCHLD signal is generated
- * when a child process terminates. In NuttX, a SIGCHLD signal is
- * generated in this case; but in some other implementations, it may not
- * be.
- */
- if (signo == SIGCHLD && (act->sa_flags & SA_NOCLDWAIT) != 0)
- {
- irqstate_t flags;
- /* We do require a critical section to muck with the TCB values that
- * can be modified by the child thread.
- */
- flags = enter_critical_section();
- /* Mark that status should be not be retained */
- rtcb->group->tg_flags |= GROUP_FLAG_NOCLDWAIT;
- /* Free all pending exit status */
- group_removechildren(rtcb->group);
- leave_critical_section(flags);
- }
- #endif
- handler = act->sa_handler;
- #ifdef CONFIG_SIG_DEFAULT
- /* If the caller is setting the handler to SIG_DFL, then we need to
- * replace this with the correct, internal default signal action handler.
- */
- if (handler == SIG_DFL)
- {
- /* nxsig_default() may returned SIG_IGN */
- handler = nxsig_default(rtcb, signo, true);
- }
- else
- {
- /* We will be replacing the default action (or ignoring it) */
- (void)nxsig_default(rtcb, signo, false);
- }
- #endif
- /* Handle the case where no sigaction is supplied (SIG_IGN) */
- if (handler == SIG_IGN)
- {
- /* Do we still have a sigaction container from the previous setting? */
- if (sigact)
- {
- /* Yes.. Remove it from signal action queue */
- sq_rem((FAR sq_entry_t *)sigact, &group->tg_sigactionq);
- /* And deallocate it */
- nxsig_release_action(sigact);
- }
- }
- /* A sigaction has been supplied */
- else
- {
- /* Do we still have a sigaction container from the previous setting?
- * If so, then re-use for the new signal action.
- */
- if (sigact == NULL)
- {
- /* No.. Then we need to allocate one for the new action. */
- sigact = nxsig_alloc_action();
- /* An error has occurred if we could not allocate the sigaction */
- if (!sigact)
- {
- return -ENOMEM;
- }
- /* Put the signal number in the queue entry */
- sigact->signo = (uint8_t)signo;
- /* Add the new sigaction to signal action queue */
- sq_addlast((FAR sq_entry_t *)sigact, &group->tg_sigactionq);
- }
- /* Set the new sigaction */
- sigact->act.sa_handler = handler;
- sigact->act.sa_mask = act->sa_mask;
- sigact->act.sa_flags = act->sa_flags;
- }
- return OK;
- }
- int sigaction(int signo, FAR const struct sigaction *act,
- FAR struct sigaction *oact)
- {
- int ret;
- /* nxsig_action() does all of the work */
- ret = nxsig_action(signo, act, oact, false);
- if (ret < 0)
- {
- set_errno(-ret);
- return ERROR;
- }
- return OK;
- }
- /****************************************************************************
- * Name: nxsig_release_action
- *
- * Description:
- * Deallocate a sigaction Q entry
- *
- ****************************************************************************/
- void nxsig_release_action(FAR sigactq_t *sigact)
- {
- /* Just put it back on the free list */
- sq_addlast((FAR sq_entry_t *)sigact, &g_sigfreeaction);
- }
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