/****************************************************************************
* drivers/pipe.c
*
* Copyright (C) 2008 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Compilation Switches
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <nuttx/fs.h>
#include <stdio.h>
#include <unistd.h>
#include <semaphore.h>
#include <fcntl.h>
#include <errno.h>
#include "pipe_common.h"
#if CONFIG_DEV_PIPE_SIZE > 0
/****************************************************************************
* Definitions
****************************************************************************/
#define MAX_PIPES 32
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int pipe_close(FAR struct file *filep);
/****************************************************************************
* Private Data
****************************************************************************/
static struct file_operations pipe_fops =
{
pipecommon_open, /* open */
pipe_close, /* close */
pipecommon_read, /* read */
pipecommon_write, /* write */
0, /* seek */
0 /* ioctl */
};
static sem_t g_pipesem = { 1 };
static uint32 g_pipeset = 0;
static uint32 g_pipecreated = 0;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: pipe_allocate
****************************************************************************/
static inline int pipe_allocate(void)
{
int pipeno;
int ret = -ENFILE;
for (pipeno = 0; pipeno < MAX_PIPES; pipeno++)
{
if ((g_pipeset & (1 << pipeno)) == 0)
{
g_pipeset |= (1 << pipeno);
ret = pipeno;
break;
}
}
return ret;
}
/****************************************************************************
* Name: pipe_free
****************************************************************************/
static inline void pipe_free(int pipeno)
{
int ret = sem_wait(&g_pipesem);
if (ret == 0)
{
g_pipeset &= ~(1 << pipeno);
(void)sem_post(&g_pipesem);
}
}
/****************************************************************************
* Name: pipe_close
****************************************************************************/
static int pipe_close(FAR struct file *filep)
{
struct inode *inode = filep->f_inode;
struct pipe_dev_s *dev = inode->i_private;
int ret;
/* Some sanity checking */
#if CONFIG_DEBUG
if (!dev)
{
return -EBADF;
}
#endif
/* Perform common close operations */
ret = pipecommon_close(filep);
if (ret == 0 && dev->d_refs == 0)
{
/* Release the pipe when there are no further open references to it. */
pipe_free(dev->d_pipeno);
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pipe
*
* Description:
* pipe() creates a pair of file descriptors, pointing to a pipe inode, and
* places them in the array pointed to by 'filedes'. filedes[0] is for reading,
* filedes[1] is for writing.
*
* Inputs:
* filedes[2] - The user provided array in which to catch the pipe file
* descriptors
*
* Return:
* 0 is returned on success; otherwise, -1 is returned with errno set
* appropriately.
*
****************************************************************************/
int pipe(int filedes[2])
{
struct pipe_dev_s *dev = NULL;
char devname[16];
int pipeno;
int err;
int ret;
/* Get exclusive access to the pipe allocation data */
ret = sem_wait(&g_pipesem);
if (ret < 0)
{
/* sem_wait() will have already set errno */
return ERROR;
}
/* Allocate a minor number for the pipe device */
pipeno = pipe_allocate();
if (pipeno < 0)
{
(void)sem_post(&g_pipesem);
err = -pipeno;
goto errout;
}
/* Create a pathname to the pipe device */
sprintf(devname, "/dev/pipe%d", pipeno);
/* Check if the pipe device has already been created */
if ((g_pipecreated & (1 << pipeno)) == 0)
{
/* No.. Allocate and initialize a new device structure instance */
dev = pipecommon_allocdev();
if (!dev)
{
(void)sem_post(&g_pipesem);
err = ENOMEM;
goto errout_with_pipe;
}
dev->d_pipeno = pipeno;
/* Register the pipe device */
ret = register_driver(devname, &pipe_fops, 0666, (void*)dev);
if (ret != 0)
{
(void)sem_post(&g_pipesem);
err = -ret;
goto errout_with_dev;
}
/* Remember that we created this device */
g_pipecreated |= (1 << pipeno);
}
(void)sem_post(&g_pipesem);
/* Get a write file descriptor */
filedes[1] = open(devname, O_WRONLY);
if (filedes[1] < 0)
{
err = -filedes[1];
goto errout_with_driver;
}
/* Get a read file descriptor */
filedes[0] = open(devname, O_RDONLY);
if (filedes[0] < 0)
{
err = -filedes[0];
goto errout_with_wrfd;
}
return OK;
errout_with_wrfd:
close(filedes[1]);
errout_with_driver:
unregister_driver(devname);
errout_with_dev:
pipecommon_freedev(dev);
errout_with_pipe:
pipe_free(pipeno);
errout:
errno = err;
return ERROR;
}
#endif /* CONFIG_DEV_PIPE_SIZE > 0 */
