403 lines
11 KiB
C
403 lines
11 KiB
C
/****************************************************************************
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* fs/vfs/fs_signalfd.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 <stdio.h>
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#include <poll.h>
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <debug.h>
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#include <nuttx/mutex.h>
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#include <nuttx/signal.h>
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#include <sys/signalfd.h>
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#include "inode/inode.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/* This structure describes the internal state of the driver */
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struct signalfd_priv_s
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{
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sigset_t sigmask; /* The set of signals caller wishes */
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mutex_t mutex; /* Enforces device exclusive access */
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uint8_t crefs; /* References counts on signalfd (max: 255) */
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FAR struct pollfd *fds[CONFIG_SIGNAL_FD_NPOLLWAITERS];
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static int signalfd_file_open(FAR struct file *filep);
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static int signalfd_file_close(FAR struct file *filep);
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static ssize_t signalfd_file_read(FAR struct file *filep,
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FAR char *buffer, size_t len);
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static int signalfd_file_poll(FAR struct file *filep,
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FAR struct pollfd *fds, bool setup);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_signalfd_fileops =
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{
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signalfd_file_open, /* open */
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signalfd_file_close, /* close */
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signalfd_file_read, /* read */
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NULL, /* write */
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NULL, /* seek */
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NULL, /* ioctl */
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NULL, /* truncate */
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NULL, /* mmap */
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signalfd_file_poll /* poll */
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};
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static struct inode g_signalfd_inode =
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{
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NULL, /* i_parent */
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NULL, /* i_peer */
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NULL, /* i_child */
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1, /* i_crefs */
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FSNODEFLAG_TYPE_DRIVER, /* i_flags */
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{
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&g_signalfd_fileops /* u */
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}
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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static void signalfd_action(int signo, FAR siginfo_t *info,
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FAR void *ucontext)
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{
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FAR struct signalfd_priv_s *dev = info->si_user;
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if (sigismember(&dev->sigmask, signo) > 0)
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{
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poll_notify(dev->fds, CONFIG_SIGNAL_FD_NPOLLWAITERS, POLLIN);
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}
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}
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static int signalfd_file_open(FAR struct file *filep)
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{
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FAR struct signalfd_priv_s *dev = filep->f_priv;
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int ret;
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nxmutex_lock(&dev->mutex);
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if (dev->crefs >= 255)
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{
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ret = -EMFILE;
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}
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else
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{
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dev->crefs += 1;
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ret = OK;
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}
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nxmutex_unlock(&dev->mutex);
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return ret;
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}
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static int signalfd_file_close(FAR struct file *filep)
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{
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FAR struct signalfd_priv_s *dev = filep->f_priv;
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int signo;
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nxmutex_lock(&dev->mutex);
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if (dev->crefs > 1)
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{
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dev->crefs--;
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nxmutex_unlock(&dev->mutex);
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return OK;
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}
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for (signo = MIN_SIGNO; signo <= MAX_SIGNO; signo++)
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{
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if (nxsig_ismember(&dev->sigmask, signo))
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{
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signal(signo, SIG_DFL);
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}
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}
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nxmutex_unlock(&dev->mutex);
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nxmutex_destroy(&dev->mutex);
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kmm_free(dev);
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return OK;
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}
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static ssize_t signalfd_file_read(FAR struct file *filep,
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FAR char *buffer, size_t len)
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{
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FAR struct signalfd_priv_s *dev = filep->f_priv;
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FAR struct signalfd_siginfo *siginfo;
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struct siginfo info;
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sigset_t pendmask;
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ssize_t ret;
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int count;
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count = len / sizeof(struct signalfd_siginfo);
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if (buffer == NULL || count == 0)
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{
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return -EINVAL;
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}
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pendmask = nxsig_pendingset(NULL) & dev->sigmask;
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if (pendmask == 0)
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{
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if (filep->f_oflags & O_NONBLOCK)
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{
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return -EAGAIN;
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}
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else
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{
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pendmask = dev->sigmask;
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}
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}
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siginfo = (FAR struct signalfd_siginfo *)buffer;
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do
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{
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ret = nxsig_waitinfo(&pendmask, &info);
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if (ret < 0)
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{
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goto errout;
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}
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memset(siginfo, 0, sizeof(*siginfo));
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siginfo->ssi_signo = info.si_signo;
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siginfo->ssi_errno = info.si_errno;
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siginfo->ssi_code = info.si_code;
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#ifdef CONFIG_SCHED_HAVE_PARENT
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siginfo->ssi_pid = info.si_pid;
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siginfo->ssi_status = info.si_status;
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#endif
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siginfo->ssi_int = info.si_value.sival_int;
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siginfo->ssi_ptr = (uint64_t)(uintptr_t)info.si_value.sival_ptr;
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siginfo++;
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pendmask = nxsig_pendingset(NULL) & dev->sigmask;
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}
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while (--count != 0 && pendmask != 0);
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errout:
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len = (FAR char *)siginfo - buffer;
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return len > 0 ? len : ret;
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}
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static int signalfd_file_poll(FAR struct file *filep,
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FAR struct pollfd *fds, bool setup)
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{
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FAR struct signalfd_priv_s *dev = filep->f_priv;
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int ret = 0;
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int i;
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nxmutex_lock(&dev->mutex);
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if (!setup)
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{
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/* This is a request to tear down the poll. */
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FAR struct pollfd **slot = (FAR struct pollfd **)fds->priv;
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/* Remove all memory of the poll setup */
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*slot = NULL;
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fds->priv = NULL;
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goto out;
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}
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/* This is a request to set up the poll. Find an available
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* slot for the poll structure reference
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*/
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for (i = 0; i < CONFIG_SIGNAL_FD_NPOLLWAITERS; i++)
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{
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/* Find an available slot */
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if (!dev->fds[i])
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{
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/* Bind the poll structure and this slot */
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dev->fds[i] = fds;
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fds->priv = &dev->fds[i];
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break;
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}
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}
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if (i >= CONFIG_SIGNAL_FD_NPOLLWAITERS)
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{
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ret = -EBUSY;
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goto out;
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}
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/* Notify the POLLIN event if the counter is not zero */
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if ((nxsig_pendingset(NULL) & dev->sigmask) != 0)
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{
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poll_notify(dev->fds, CONFIG_SIGNAL_FD_NPOLLWAITERS, POLLIN);
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}
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out:
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nxmutex_unlock(&dev->mutex);
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return ret;
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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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* Name: signalfd
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*
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* Description:
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* signalfd() creates a file descriptor that can be used to accept signals
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* targeted at the caller.
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*
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* The mask argument specifies the set of signals that the caller wishes
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* to accept via the file descriptor. This argument is a signal set whose
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* contents can be initialized using the macros described in sigsetops.
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* Normally, the set of signals to be received via the file descriptor
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* should be blocked using sigprocmask, to prevent the signals being
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* handled according to their default dispositions. It is not possible
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* to receive SIGKILL or SIGSTOP signals via a signalfd file descriptor.
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* these signals are silently ignored if specified in mask.
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*
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* If the fd argument is -1, then the call creates a new file descriptor
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* and associates the signal set specified in mask with that file
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* descriptor. If fd is not -1, then it must specify a valid existing
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* signalfd file descriptor, and mask is used to replace the signal
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* set associated with that file descriptor.
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*
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* The following values may be bitwise ORed in flags to change the
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* behavior of signalfd():
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*
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* SFD_NONBLOCK Set the O_NONBLOCK file status flag on the open file
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* description referred to by the new file descriptor.
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* Using this flag saves extra calls to fcntl to achieve
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* the same result.
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*
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* SFD_CLOEXEC Set the close-on-exec (FD_CLOEXEC) flag on the new file
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* descriptor. See the description of the O_CLOEXEC flag
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* in open for reasons why this may be useful.
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*
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* Returned Value:
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* On success, signalfd() returns a signalfd file descriptor; this is
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* either a new file descriptor (if fd was -1), or fd if fd was a valid
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* signalfd file descriptor. On error, -1 is returned and errno is set
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* to indicate the error.
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*
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****************************************************************************/
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int signalfd(int fd, FAR const sigset_t *mask, int flags)
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{
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FAR struct signalfd_priv_s *dev;
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struct sigaction act;
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int ret = EINVAL;
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int signo;
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if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
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{
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goto errout;
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}
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if (fd == -1)
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{
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dev = kmm_zalloc(sizeof(*dev));
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if (dev == NULL)
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{
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ret = ENOMEM;
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goto errout;
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}
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nxmutex_init(&dev->mutex);
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fd = file_allocate(&g_signalfd_inode, O_RDOK | flags,
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0, dev, 0, true);
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if (fd < 0)
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{
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ret = -fd;
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goto errout_with_dev;
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}
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}
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else
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{
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FAR struct file *filep;
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if (fs_getfilep(fd, &filep) < 0)
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{
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ret = EBADF;
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goto errout;
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}
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if (filep->f_inode->u.i_ops != &g_signalfd_fileops)
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{
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goto errout;
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}
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dev = filep->f_priv;
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for (signo = MIN_SIGNO; signo <= MAX_SIGNO; signo++)
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{
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if (nxsig_ismember(&dev->sigmask, signo))
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{
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signal(signo, SIG_DFL);
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}
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}
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}
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dev->sigmask = *mask;
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nxsig_delset(&dev->sigmask, SIGKILL);
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nxsig_delset(&dev->sigmask, SIGSTOP);
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act.sa_sigaction = signalfd_action;
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act.sa_flags = SA_KERNELHAND | SA_SIGINFO;
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act.sa_user = dev;
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for (signo = MIN_SIGNO; signo <= MAX_SIGNO; signo++)
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{
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if (nxsig_ismember(&dev->sigmask, signo))
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{
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nxsig_action(signo, &act, NULL, false);
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}
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}
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return fd;
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errout_with_dev:
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nxmutex_destroy(&dev->mutex);
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kmm_free(dev);
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errout:
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set_errno(ret);
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return ERROR;
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}
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