diff options
Diffstat (limited to 'nuttx/drivers/pipes/pipe.c')
| -rw-r--r-- | nuttx/drivers/pipes/pipe.c | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/nuttx/drivers/pipes/pipe.c b/nuttx/drivers/pipes/pipe.c new file mode 100644 index 000000000..95049b354 --- /dev/null +++ b/nuttx/drivers/pipes/pipe.c @@ -0,0 +1,282 @@ +/**************************************************************************** + * drivers/pipes/pipe.c + * + * Copyright (C) 2008-2009 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 const struct file_operations pipe_fops = +{ + pipecommon_open, /* open */ + pipe_close, /* close */ + pipecommon_read, /* read */ + pipecommon_write, /* write */ + 0, /* seek */ + 0 /* ioctl */ +#ifndef CONFIG_DISABLE_POLL + , pipecommon_poll /* poll */ +#endif +}; + +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 */ |