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