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- /****************************************************************************
- * drivers/dev_zero.c
- *
- * Copyright (C) 2008-2009, 2012-2013, 2016 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>
- #include <nuttx/drivers/drivers.h>
- /****************************************************************************
- * Private Function Prototypes
- ****************************************************************************/
- static ssize_t devzero_read(FAR struct file *filep, FAR char *buffer,
- size_t buflen);
- static ssize_t devzero_write(FAR struct file *filep, FAR const char *buffer,
- size_t buflen);
- #ifndef CONFIG_DISABLE_POLL
- static int devzero_poll(FAR struct file *filep, FAR struct pollfd *fds,
- bool setup);
- #endif
- /****************************************************************************
- * Private Data
- ****************************************************************************/
- static const struct file_operations devzero_fops =
- {
- NULL, /* open */
- NULL, /* close */
- devzero_read, /* read */
- devzero_write, /* write */
- NULL, /* seek */
- NULL /* ioctl */
- #ifndef CONFIG_DISABLE_POLL
- , devzero_poll /* poll */
- #endif
- #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
- , NULL /* unlink */
- #endif
- };
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: devzero_read
- ****************************************************************************/
- static ssize_t devzero_read(FAR struct file *filep, FAR char *buffer,
- size_t len)
- {
- memset(buffer, 0, len);
- return len;
- }
- /****************************************************************************
- * Name: devzero_write
- ****************************************************************************/
- static ssize_t devzero_write(FAR struct file *filep, FAR const char *buffer,
- size_t len)
- {
- return len;
- }
- /****************************************************************************
- * Name: devzero_poll
- ****************************************************************************/
- #ifndef CONFIG_DISABLE_POLL
- static int devzero_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: devzero_register
- *
- * Description:
- * Register /dev/zero
- *
- ****************************************************************************/
- void devzero_register(void)
- {
- (void)register_driver("/dev/zero", &devzero_fops, 0666, NULL);
- }
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