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/****************************************************************************
* drivers/dev_null.c
*
* Copyright (C) 2007, 2008, 2013 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 <sys/types.h>
#include <stdbool.h>
#include <string.h>
#include <poll.h>
#include <errno.h>
#include <nuttx/fs/fs.h>
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static ssize_t devnull_read(FAR struct file *, FAR char *, size_t);
static ssize_t devnull_write(FAR struct file *, FAR const char *, size_t);
#ifndef CONFIG_DISABLE_POLL
static int devnull_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup);
#endif
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations devnull_fops =
{
0, /* open */
0, /* close */
devnull_read, /* read */
devnull_write, /* write */
0, /* seek */
0 /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, devnull_poll /* poll */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: devnull_read
****************************************************************************/
static ssize_t devnull_read(FAR struct file *filep, FAR char *buffer, size_t len)
{
return 0; /* Return EOF */
}
/****************************************************************************
* Name: devnull_write
****************************************************************************/
static ssize_t devnull_write(FAR struct file *filep, FAR const char *buffer, size_t len)
{
return len; /* Say that everything was written */
}
/****************************************************************************
* Name: devnull_poll
****************************************************************************/
#ifndef CONFIG_DISABLE_POLL
static int devnull_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup)
{
if (setup)
{
fds->revents |= (fds->events & (POLLIN|POLLOUT));
if (fds->revents != 0)
{
sem_post(fds->sem);
}
}
return OK;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: devnull_register
*
* Description:
* Register /dev/null
*
****************************************************************************/
void devnull_register(void)
{
(void)register_driver("/dev/null", &devnull_fops, 0666, NULL);
}
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