402 lines
12 KiB
C
402 lines
12 KiB
C
/****************************************************************************
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* fs/vfs/fs_poll.c
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*
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* Copyright (C) 2008-2009, 2012-2016 Gregory Nutt. All 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 <stdbool.h>
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#include <poll.h>
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#include <time.h>
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#include <semaphore.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/clock.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/net/net.h>
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#include <nuttx/semaphore.h>
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#include <arch/irq.h>
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#include "inode/inode.h"
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#ifndef CONFIG_DISABLE_POLL
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define poll_semgive(sem) sem_post(sem)
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: poll_semtake
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****************************************************************************/
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static int poll_semtake(FAR sem_t *sem)
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{
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/* Take the semaphore (perhaps waiting) */
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if (sem_wait(sem) < 0)
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{
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int err = get_errno();
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/* The only case that an error should occur here is if the wait were
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* awakened by a signal.
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*/
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DEBUGASSERT(err == EINTR);
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return -err;
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}
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return OK;
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}
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/****************************************************************************
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* Name: poll_fdsetup
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*
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* Description:
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* Configure (or unconfigure) one file/socket descriptor for the poll
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* operation. If fds and sem are non-null, then the poll is being setup.
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* if fds and sem are NULL, then the poll is being torn down.
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*
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****************************************************************************/
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#if CONFIG_NFILE_DESCRIPTORS > 0
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static int poll_fdsetup(int fd, FAR struct pollfd *fds, bool setup)
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{
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/* Check for a valid file descriptor */
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if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
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{
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/* Perform the socket ioctl */
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#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
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if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS+CONFIG_NSOCKET_DESCRIPTORS))
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{
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return net_poll(fd, fds, setup);
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}
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else
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#endif
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{
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return -EBADF;
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}
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}
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return file_poll(fd, fds, setup);
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}
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#endif
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/****************************************************************************
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* Name: poll_setup
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*
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* Description:
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* Setup the poll operation for each descriptor in the list.
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*
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****************************************************************************/
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#if CONFIG_NFILE_DESCRIPTORS > 0
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static inline int poll_setup(FAR struct pollfd *fds, nfds_t nfds, sem_t *sem)
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{
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unsigned int i;
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unsigned int j;
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int ret;
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/* Process each descriptor in the list */
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for (i = 0; i < nfds; i++)
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{
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/* Setup the poll descriptor */
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fds[i].sem = sem;
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fds[i].revents = 0;
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fds[i].priv = NULL;
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/* Check for invalid descriptors. "If the value of fd is less than 0,
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* events shall be ignored, and revents shall be set to 0 in that entry
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* on return from poll()."
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*
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* NOTE: There is a potential problem here. If there is only one fd
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* and if it is negative, then poll will hang. From my reading of the
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* spec, that appears to be the correct behavior.
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*/
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if (fds[i].fd >= 0)
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{
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/* Set up the poll on this valid file descriptor */
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ret = poll_fdsetup(fds[i].fd, &fds[i], true);
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if (ret < 0)
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{
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/* Setup failed for fds[i]. We now need to teardown previously
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* setup fds[0 .. (i - 1)] to release allocated resources and
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* to prevent memory corruption by access to freed/released 'fds'
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* and 'sem'.
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*/
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for (j = 0; j < i; j++)
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{
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(void)poll_fdsetup(fds[j].fd, &fds[j], false);
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}
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/* Indicate an error on the file descriptor */
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fds[i].revents |= POLLERR;
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return ret;
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}
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}
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}
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return OK;
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}
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#endif
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/****************************************************************************
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* Name: poll_teardown
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*
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* Description:
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* Teardown the poll operation for each descriptor in the list and return
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* the count of non-zero poll events.
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*
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****************************************************************************/
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#if CONFIG_NFILE_DESCRIPTORS > 0
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static inline int poll_teardown(FAR struct pollfd *fds, nfds_t nfds, int *count,
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int ret)
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{
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unsigned int i;
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int status;
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/* Process each descriptor in the list */
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*count = 0;
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for (i = 0; i < nfds; i++)
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{
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/* Ignore negative descriptors */
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if (fds[i].fd >= 0)
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{
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/* Teardown the poll */
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status = poll_fdsetup(fds[i].fd, &fds[i], false);
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if (status < 0)
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{
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ret = status;
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}
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}
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/* Check if any events were posted */
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if (fds[i].revents != 0)
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{
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(*count)++;
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}
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/* Un-initialize the poll structure */
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fds[i].sem = NULL;
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}
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return ret;
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}
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Function: file_poll
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*
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* Description:
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* The standard poll() operation redirects operations on file descriptors
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* to this function.
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*
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* Input Parameters:
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* fd - The file descriptor of interest
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* fds - The structure describing the events to be monitored, OR NULL if
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* this is a request to stop monitoring events.
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* setup - true: Setup up the poll; false: Teardown the poll
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*
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* Returned Value:
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* 0: Success; Negated errno on failure
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*
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****************************************************************************/
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#if CONFIG_NFILE_DESCRIPTORS > 0
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int file_poll(int fd, FAR struct pollfd *fds, bool setup)
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{
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FAR struct file *filep;
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FAR struct inode *inode;
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int ret = -ENOSYS;
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/* Get the file pointer corresponding to this file descriptor */
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filep = fs_getfilep(fd);
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if (!filep)
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{
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/* The errno value has already been set */
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return -get_errno();
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}
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/* Is a driver registered? Does it support the poll method?
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* If not, return -ENOSYS
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*/
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inode = filep->f_inode;
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if (inode && inode->u.i_ops && inode->u.i_ops->poll)
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{
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/* Yes, then setup the poll */
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ret = (int)inode->u.i_ops->poll(filep, fds, setup);
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}
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return ret;
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}
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#endif
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/****************************************************************************
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* Name: poll
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*
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* Description:
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* poll() waits for one of a set of file descriptors to become ready to
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* perform I/O. If none of the events requested (and no error) has
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* occurred for any of the file descriptors, then poll() blocks until
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* one of the events occurs.
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*
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* Inputs:
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* fds - List of structures describing file descriptors to be monitored
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* nfds - The number of entries in the list
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* timeout - Specifies an upper limit on the time for which poll() will
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* block in milliseconds. A negative value of timeout means an infinite
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* timeout.
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*
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* Return:
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* On success, the number of structures that have non-zero revents fields.
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* A value of 0 indicates that the call timed out and no file descriptors
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* were ready. On error, -1 is returned, and errno is set appropriately:
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*
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* EBADF - An invalid file descriptor was given in one of the sets.
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* EFAULT - The fds address is invalid
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* EINTR - A signal occurred before any requested event.
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* EINVAL - The nfds value exceeds a system limit.
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* ENOMEM - There was no space to allocate internal data structures.
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* ENOSYS - One or more of the drivers supporting the file descriptor
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* does not support the poll method.
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*
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****************************************************************************/
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int poll(FAR struct pollfd *fds, nfds_t nfds, int timeout)
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{
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sem_t sem;
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int count = 0;
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int err;
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int ret;
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sem_init(&sem, 0, 0);
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ret = poll_setup(fds, nfds, &sem);
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if (ret >= 0)
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{
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if (timeout == 0)
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{
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/* Poll returns immediately whether we have a poll event or not. */
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ret = OK;
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}
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else if (timeout > 0)
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{
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/* Either wait for either a poll event(s), for a signal to occur,
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* or for the specified timeout to elapse with no event.
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*
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* NOTE: If a poll event is pending (i.e., the semaphore has already
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* been incremented), sem_tickwait() will not wait, but will return
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* immediately.
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*/
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ret = sem_tickwait(&sem, clock_systimer(), MSEC2TICK(timeout));
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if (ret < 0)
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{
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if (ret == -ETIMEDOUT)
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{
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/* Return zero (OK) in the event of a timeout */
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ret = OK;
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}
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/* EINTR is the only other error expected in normal operation */
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}
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}
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else
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{
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/* Wait for the poll event or signal with no timeout */
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ret = poll_semtake(&sem);
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}
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/* Teardown the poll operation and get the count of events. Zero will be
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* returned in the case of a timeout.
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*
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* Preserve ret, if negative, since it holds the result of the wait.
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*/
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err = poll_teardown(fds, nfds, &count, ret);
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if (err < 0 && ret >= 0)
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{
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ret = err;
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}
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}
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sem_destroy(&sem);
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/* Check for errors */
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if (ret < 0)
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{
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set_errno(-ret);
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return ERROR;
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}
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return count;
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}
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#endif /* CONFIG_DISABLE_POLL */
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