6a3c2aded6
* Simplify EINTR/ECANCEL error handling 1. Add semaphore uninterruptible wait function 2 .Replace semaphore wait loop with a single uninterruptible wait 3. Replace all sem_xxx to nxsem_xxx * Unify the void cast usage 1. Remove void cast for function because many place ignore the returned value witout cast 2. Replace void cast for variable with UNUSED macro
141 lines
4.9 KiB
C
141 lines
4.9 KiB
C
/****************************************************************************
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* drivers/dev_zero.c
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*
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* Copyright (C) 2008-2009, 2012-2013, 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 <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 devzero_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t devzero_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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static int devzero_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 devzero_fops =
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{
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NULL, /* open */
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NULL, /* close */
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devzero_read, /* read */
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devzero_write, /* write */
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NULL, /* seek */
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NULL, /* ioctl */
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devzero_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: devzero_read
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****************************************************************************/
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static ssize_t devzero_read(FAR struct file *filep, FAR char *buffer,
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size_t len)
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{
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memset(buffer, 0, len);
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return len;
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}
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/****************************************************************************
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* Name: devzero_write
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****************************************************************************/
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static ssize_t devzero_write(FAR struct file *filep, FAR const char *buffer,
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size_t len)
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{
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return len;
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}
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/****************************************************************************
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* Name: devzero_poll
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****************************************************************************/
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static int devzero_poll(FAR struct file *filep, FAR struct pollfd *fds,
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bool setup)
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{
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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: devzero_register
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*
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* Description:
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* Register /dev/zero
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*
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****************************************************************************/
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void devzero_register(void)
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{
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register_driver("/dev/zero", &devzero_fops, 0666, NULL);
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}
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