227 lines
8.0 KiB
C
227 lines
8.0 KiB
C
/****************************************************************************
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* sched/signal/sig_deliver.c
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*
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* Copyright (C) 2007, 2008, 2012-2013, 2016, 2019 Gregory Nutt. All
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* rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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 <nuttx/config.h>
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#include <sys/types.h>
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#include <signal.h>
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#include <unistd.h>
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#include <sched.h>
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#include <string.h>
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#include <debug.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include "signal/signal.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsig_deliver
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*
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* Description:
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* This function is called on the thread of execution of the signal
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* receiving task. It processes all queued signals then returns.
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*
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****************************************************************************/
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void nxsig_deliver(FAR struct tcb_s *stcb)
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{
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FAR sigq_t *sigq;
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sigset_t savesigprocmask;
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sigset_t newsigprocmask;
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sigset_t altsigprocmask;
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irqstate_t flags;
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int saved_errno;
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/* Loop while there are signals to be delivered */
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for (; ; )
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{
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/* Test if this task is already handling a signal (we don't permit
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* nested signals on the same thread).
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*/
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flags = enter_critical_section();
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if ((stcb->flags & TCB_FLAG_SIGNAL_ACTION) != 0)
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{
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/* Yes.. then we must wait for the signal handler to return */
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leave_critical_section(flags);
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break;
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}
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/* Remove the signal structure from the head of the sigpendactionq. */
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sigq = (FAR sigq_t *)sq_remfirst(&stcb->sigpendactionq);
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if (sigq == NULL)
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{
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/* All queued signal actions have been dispatched */
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leave_critical_section(flags);
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break;
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}
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/* Indicate that a signal is being delivered */
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stcb->flags |= TCB_FLAG_SIGNAL_ACTION;
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sinfo("Deliver signal %d to PID %d\n",
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sigq->info.si_signo, stcb->pid);
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/* Add the signal structure to the sigpostedq. NOTE: Since signals
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* are processed one at a time, there should never be more than one
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* signal in the sigpostedq
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*/
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sq_addlast((FAR sq_entry_t *)sigq, &(stcb->sigpostedq));
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/* Save the thread errno. When we finished dispatching the
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* signal actions and resume the task, the errno value must
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* be unchanged by the operation of the signal handling. In
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* particular, the EINTR indication that says that the task
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* was reawakened by a signal must be retained.
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*/
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saved_errno = stcb->pterrno;
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/* Save a copy of the old sigprocmask and install the new
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* (temporary) sigprocmask. The new sigprocmask is the union
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* of the current sigprocmask and the sa_mask for the signal being
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* delivered plus the signal being delivered.
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*/
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savesigprocmask = stcb->sigprocmask;
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newsigprocmask = savesigprocmask | sigq->mask |
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SIGNO2SET(sigq->info.si_signo);
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stcb->sigprocmask = newsigprocmask;
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#if defined(CONFIG_BUILD_PROTECTED) || defined(CONFIG_BUILD_KERNEL)
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/* In the kernel build this has to be handled differently if we are
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* dispatching to a signal handler in a user-space task or thread; we
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* have to switch to user-mode before calling the task.
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*/
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#ifdef CONFIG_SIG_DEFAULT
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/* The default signal action handlers, however always reside in the
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* kernel address space, regardless of configuration.
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*/
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if (nxsig_isdefault(stcb, sigq->info.si_signo))
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{
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/* Leave the critical section before calling the handler */
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leave_critical_section(flags);
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(*sigq->action.sighandler)(sigq->info.si_signo, &sigq->info,
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NULL);
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}
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else
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#endif
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if ((stcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_KERNEL)
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{
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siginfo_t info;
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/* The sigq_t pointed to by sigq resides in kernel space. So we
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* cannot pass a reference to sigq->info to the user application.
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* Instead, we will copy the siginfo_t structure onto the stack.
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* We are currently executing on the stack of the user thread
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* (albeit temporarily in kernel mode), so the copy of the
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* siginfo_t structure will be accessible by the user thread.
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*/
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memcpy(&info, &sigq->info, sizeof(siginfo_t));
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/* Leave the critical section before calling the handler */
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leave_critical_section(flags);
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up_signal_dispatch(sigq->action.sighandler, sigq->info.si_signo,
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&info, NULL);
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}
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else
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#endif
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{
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/* The kernel thread signal handler is much simpler. */
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leave_critical_section(flags);
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(*sigq->action.sighandler)(sigq->info.si_signo, &sigq->info,
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NULL);
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}
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/* Indicate that a signal has been delivered */
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flags = enter_critical_section();
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stcb->flags &= ~TCB_FLAG_SIGNAL_ACTION;
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/* Restore the original errno value and sigprocmask. */
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stcb->pterrno = saved_errno;
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/* What if the signal handler changed the sigprocmask? Try to retain
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* any such changes here.
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*
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* REVISIT: This logic is imperfect. It will fail to detect bits set
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* in the current sigprocmask that were already set by newsigprocmask.
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*/
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altsigprocmask = stcb->sigprocmask ^ newsigprocmask;
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stcb->sigprocmask = (stcb->sigprocmask & altsigprocmask) |
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(savesigprocmask & ~altsigprocmask);
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/* Remove the signal structure from the sigpostedq */
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sq_rem((FAR sq_entry_t *)sigq, &(stcb->sigpostedq));
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leave_critical_section(flags);
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/* Now, handle the (rare?) case where (a) a blocked signal was
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* received while the signal handling executed but (b) restoring the
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* original sigprocmask will unblock the signal.
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*/
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nxsig_unmask_pendingsignal();
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/* Then deallocate the signal structure */
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nxsig_release_pendingsigaction(sigq);
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}
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}
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