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- /****************************************************************************
- * drivers/dev_null.c
- *
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership. The
- * ASF licenses this file to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance with the
- * License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
- * under the License.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <sys/types.h>
- #include <stdbool.h>
- #include <string.h>
- #include <poll.h>
- #include <errno.h>
- #include <nuttx/semaphore.h>
- #include <nuttx/fs/fs.h>
- #include <nuttx/drivers/drivers.h>
- /****************************************************************************
- * Private Function Prototypes
- ****************************************************************************/
- static ssize_t devnull_read(FAR struct file *filep, FAR char *buffer,
- size_t buflen);
- static ssize_t devnull_write(FAR struct file *filep, FAR const char *buffer,
- size_t buflen);
- static int devnull_poll(FAR struct file *filep, FAR struct pollfd *fds,
- bool setup);
- /****************************************************************************
- * Private Data
- ****************************************************************************/
- static const struct file_operations devnull_fops =
- {
- NULL, /* open */
- NULL, /* close */
- devnull_read, /* read */
- devnull_write, /* write */
- NULL, /* seek */
- NULL, /* ioctl */
- devnull_poll /* poll */
- #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
- , NULL /* unlink */
- #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
- ****************************************************************************/
- 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)
- {
- nxsem_post(fds->sem);
- }
- }
- return OK;
- }
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: devnull_register
- *
- * Description:
- * Register /dev/null
- *
- ****************************************************************************/
- void devnull_register(void)
- {
- register_driver("/dev/null", &devnull_fops, 0666, NULL);
- }
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