drivers/pipes/pipe.c

/****************************************************************************
 * drivers/pipes/pipe.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/
#include "pipe_common.h"
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <semaphore.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include "fs/driver.h"
#include "los_init.h"

#if CONFIG_DEV_PIPE_SIZE > 0

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#define MAX_PIPES 32

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

static int pipe_close(struct file *filep);
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
int pipe_unlink(struct Vnode *priv);
#endif

/****************************************************************************
 * Private Data
 ****************************************************************************/

static ssize_t pipe_map(struct file* filep, LosVmMapRegion *region)
{
  PRINTK("%s %d, mmap is not support\n", __FUNCTION__, __LINE__);
  return 0;
}

static const struct file_operations_vfs pipe_fops =
{
  .open = pipecommon_open,      /* open */
  .close = pipe_close,          /* close */
  .read = pipecommon_read,      /* read */
  .write = pipecommon_write,    /* write */
  .seek = NULL,                 /* seek */
  .ioctl = NULL,                /* ioctl */
  .mmap = pipe_map,             /* mmap */
  .poll = pipecommon_poll,      /* poll */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
  .unlink = pipe_unlink,        /* unlink */
#endif
};

static sem_t  g_pipesem       = {NULL};
static uint32_t g_pipeset     = 0;
static uint32_t 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;

  ret = sem_wait(&g_pipesem);
  if (ret == OK)
    {
      g_pipeset &= ~(1 << pipeno);
      (void)sem_post(&g_pipesem);
    }
}

/****************************************************************************
 * Name: pipe_close
 ****************************************************************************/

static int pipe_close(struct file *filep)
{
  struct Vnode *vnode    = filep->f_vnode;
  struct pipe_dev_s *dev = (struct pipe_dev_s *)((struct drv_data *)vnode->data)->priv;
  int ret;

  if (dev == NULL)
    {
      return -EINVAL;
    }

  /* Perform common close operations */

  ret = pipecommon_close(filep);
  if (ret == 0 && vnode->useCount <= 1)
    {
      /* Release the pipe when there are no further open references to it. */

      pipe_free(dev->d_pipeno);
    }

  return ret;
}

/****************************************************************************
 * Name: pipe_unlink
 ****************************************************************************/

#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
 int pipe_unlink(struct Vnode *vnode)
{
  struct pipe_dev_s *dev = ((struct drv_data *)vnode->data)->priv;
  uint8_t pipeno = 0;
  int ret;

  if (dev != NULL)
    {
        pipeno = dev->d_pipeno;
    }
  /* Perform common close operations */
  ret = pipecommon_unlink(vnode);
  if (ret == 0)
    {
      (void)sem_wait(&g_pipesem);
      g_pipecreated &= ~(1 << pipeno);
      (void)sem_post(&g_pipesem);
      /* Release the pipe when there are no further open references to it. */
      pipe_free(pipeno);
    }
  return ret;
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: pipe2
 *
 * Description:
 *   pipe() creates a pair of file descriptors, pointing to a pipe vnode,
 *   and  places them in the array pointed to by 'fd'. fd[0] is for reading,
 *   fd[1] is for writing.
 *
 *   NOTE: mkfifo2 is a special, non-standard, NuttX-only interface.  Since
 *   the NuttX FIFOs are based in in-memory, circular buffers, the ability
 *   to control the size of those buffers is critical for system tuning.
 *
 * Input Parameters:
 *   fd[2] - The user provided array in which to catch the pipe file
 *   descriptors
 *   bufsize - The size of the in-memory, circular buffer in bytes.
 *
 * Returned Value:
 *   0 is returned on success; otherwise, -1 is returned with errno set
 *   appropriately.
 *
 ****************************************************************************/

static void UpdateDev(struct pipe_dev_s *dev)
{
  int ret;
  struct Vnode *vnode = NULL;
  struct pipe_dev_s *olddev = NULL;
  struct drv_data *data = NULL;

  VnodeHold();
  ret = VnodeLookup(dev->name, &vnode, 0);
  if (ret != 0)
    {
      VnodeDrop();
      PRINT_ERR("[%s,%d] failed. err: %d\n", __FUNCTION__, __LINE__, ret);
      return;
    }
  data = (struct drv_data *)vnode->data;
  olddev = (struct pipe_dev_s *)data->priv;
  if (olddev != NULL)
    {
      if (olddev->d_buffer != NULL)
        {
          free(olddev->d_buffer);
          olddev->d_buffer = NULL;
        }
      pipecommon_freedev(olddev);
    }
  data->priv = dev;
  VnodeDrop();
  return;
}

int pipe(int fd[2])
{
  struct pipe_dev_s *dev = NULL;
  char devname[16];
  int pipeno;
  int errcode;
  int ret;
  struct file *filep = NULL;
  size_t bufsize = 1024;

  /* Get exclusive access to the pipe allocation data */

  ret = sem_wait(&g_pipesem);
  if (ret < 0)
    {
      errcode = -ret;
      goto errout;
    }

  /* Allocate a minor number for the pipe device */

  pipeno = pipe_allocate();
  if (pipeno < 0)
    {
      (void)sem_post(&g_pipesem);
      errcode = -pipeno;
      goto errout;
    }

  /* Create a pathname to the pipe device */

  snprintf_s(devname, sizeof(devname), sizeof(devname) - 1, "/dev/pipe%d", pipeno);

  /* No.. Allocate and initialize a new device structure instance */

  dev = pipecommon_allocdev(bufsize, devname);
  if (!dev)
    {
      (void)sem_post(&g_pipesem);
      errcode = ENOMEM;
      goto errout_with_pipe;
    }

  dev->d_pipeno = pipeno;

  /* Check if the pipe device has already been created */

  if ((g_pipecreated & (1 << pipeno)) == 0)
    {
      /* Register the pipe device */

      ret = register_driver(devname, &pipe_fops, 0660, (void *)dev);
      if (ret != 0)
        {
          (void)sem_post(&g_pipesem);
          errcode = -ret;
          goto errout_with_dev;
        }

      /* Remember that we created this device */

       g_pipecreated |= (1 << pipeno);
    }
  else
    {
       UpdateDev(dev);
    }
  (void)sem_post(&g_pipesem);

  /* Get a write file descriptor */

  fd[1] = open(devname, O_WRONLY);
  if (fd[1] < 0)
    {
      errcode = -fd[1];
      goto errout_with_driver;
    }

  /* Get a read file descriptor */

  fd[0] = open(devname, O_RDONLY);
  if (fd[0] < 0)
    {
      errcode = -fd[0];
      goto errout_with_wrfd;
    }

  ret = fs_getfilep(fd[0], &filep);
  filep->ops = &pipe_fops;

  ret = fs_getfilep(fd[1], &filep);
  filep->ops = &pipe_fops;

  return OK;

errout_with_wrfd:
  close(fd[1]);

errout_with_driver:
  unregister_driver(devname);
  (void)sem_wait(&g_pipesem);
  g_pipecreated &= ~(1 << pipeno);
  (void)sem_post(&g_pipesem);

errout_with_dev:
  if (dev)
    {
      pipecommon_freedev(dev);
    }

errout_with_pipe:
  pipe_free(pipeno);

errout:
  set_errno(errcode);
  return VFS_ERROR;
}

int pipe_init(void)
{
    int ret = sem_init(&g_pipesem, 0, 1);
    if (ret != 0) {
        dprintf("pipe_init failed!\n");
    }
    return ret;
}

LOS_MODULE_INIT(pipe_init, LOS_INIT_LEVEL_KMOD_EXTENDED);

#endif /* CONFIG_DEV_PIPE_SIZE > 0 */