215 lines
7.1 KiB
C
215 lines
7.1 KiB
C
/****************************************************************************
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* sched/signal/sig_deliver.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <nuttx/signal.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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/* Save the errno. This must be preserved throughout the signal handling
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* so that the user code final gets the correct errno value (probably
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* EINTR).
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*/
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int saved_errno = get_errno();
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int16_t saved_errcode = stcb->errcode;
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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 tmpset1;
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sigset_t tmpset2;
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irqstate_t flags;
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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 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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sigorset(&newsigprocmask, &savesigprocmask, &sigq->mask);
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nxsig_addset(&newsigprocmask, sigq->info.si_signo);
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stcb->sigprocmask = newsigprocmask;
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#ifndef CONFIG_BUILD_FLAT
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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 sigprocmask.
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*
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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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nxsig_xorset(&tmpset1, &stcb->sigprocmask, &newsigprocmask);
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sigandset(&tmpset2, &stcb->sigprocmask, &tmpset1);
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nxsig_nandset(&tmpset1, &savesigprocmask, &tmpset1);
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sigorset(&stcb->sigprocmask, &tmpset1, &tmpset2);
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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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/* Restore the saved errno value */
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set_errno(saved_errno);
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stcb->errcode = saved_errcode;
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}
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