119 lines
4.0 KiB
C
119 lines
4.0 KiB
C
/****************************************************************************
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* drivers/pipes/fifo.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 <sys/stat.h>
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#include <stdint.h>
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#include <errno.h>
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#include <nuttx/fs/fs.h>
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#include "pipe_common.h"
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#if CONFIG_DEV_FIFO_SIZE > 0
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_fifo_fops =
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{
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pipecommon_open, /* open */
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pipecommon_close, /* close */
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pipecommon_read, /* read */
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pipecommon_write, /* write */
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NULL, /* seek */
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pipecommon_ioctl, /* ioctl */
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NULL, /* mmap */
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NULL, /* truncate */
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pipecommon_poll /* poll */
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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, pipecommon_unlink /* unlink */
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#endif
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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: nx_mkfifo
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*
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* Description:
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* nx_mkfifo() makes a FIFO device driver file with name 'pathname.' Unlike
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* Linux, a NuttX FIFO is not a special file type but simply a device
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* driver instance. 'mode' specifies the FIFO's permissions.
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*
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* Once the FIFO has been created by nx_mkfifo(), any thread can open it
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* for reading or writing, in the same way as an ordinary file. However, it
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* must have been opened from both reading and writing before input or
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* output can be performed. This FIFO implementation will block all
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* attempts to open a FIFO read-only until at least one thread has opened
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* the FIFO for writing.
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*
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* If all threads that write to the FIFO have closed, subsequent calls to
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* read() on the FIFO will return 0 (end-of-file).
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*
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* NOTE: nx_mkfifo is a special, non-standard, NuttX-only interface. Since
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* the NuttX FIFOs are based in in-memory, circular buffers, the ability
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* to control the size of those buffers is critical for system tuning.
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*
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* Input Parameters:
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* pathname - The full path to the FIFO instance to attach to or to create
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* (if not already created).
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* mode - Ignored for now
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* bufsize - The size of the in-memory, circular buffer in bytes.
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*
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* Returned Value:
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* 0 is returned on success; a negated errno value is returned on a
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* failure.
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*
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****************************************************************************/
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int nx_mkfifo(FAR const char *pathname, mode_t mode, size_t bufsize)
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{
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FAR struct pipe_dev_s *dev;
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int ret;
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/* Allocate and initialize a new device structure instance */
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dev = pipecommon_allocdev(bufsize);
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if (!dev)
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{
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return -ENOMEM;
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}
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ret = register_pipedriver(pathname, &g_fifo_fops, mode, (FAR void *)dev);
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if (ret != 0)
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{
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pipecommon_freedev(dev);
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}
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return ret;
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}
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#endif /* CONFIG_DEV_FIFO_SIZE > 0 */
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