nuttx/fs/vfs/fs_statfs.c

/****************************************************************************
 * fs/vfs/fs_statfs.c
 *
 *   Copyright (C) 2007-2009, 2012, 2017 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/statfs.h>
#include <string.h>
#include <limits.h>
#include <sched.h>
#include <errno.h>

#include "inode/inode.h"

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: statpseudo
 ****************************************************************************/

static int statpseudofs(FAR struct inode *inode, FAR struct statfs *buf)
{
  memset(buf, 0, sizeof(struct statfs));
  buf->f_type    = PROC_SUPER_MAGIC;
  buf->f_namelen = NAME_MAX;
  return OK;
}

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

/****************************************************************************
 * Name: statfs
 *
 * Return: Zero on success; -1 on failure with errno set:
 *
 *   EACCES  Search permission is denied for one of the directories in the
 *           path prefix of path.
 *   EFAULT  Bad address.
 *   ENOENT  A component of the path path does not exist, or the path is an
 *           empty string.
 *   ENOMEM  Out of memory
 *   ENOTDIR A component of the path is not a directory.
 *   ENOSYS  The file system does not support this call.
 *
 ****************************************************************************/

int statfs(FAR const char *path, FAR struct statfs *buf)
{
  struct inode_search_s desc;
  FAR struct inode *inode;
  int ret = OK;

  /* Sanity checks */

  if (path == NULL  || buf == NULL)
    {
      ret = EFAULT;
      goto errout;
    }

  if (*path == '\0')
    {
      ret = ENOENT;
      goto errout;
    }

  /* Check for the fake root directory (which has no inode) */

  if (strcmp(path, "/") == 0)
    {
      return statpseudofs(NULL, buf);
    }

  /* Get an inode for this file */

  SETUP_SEARCH(&desc, path, false);

  ret = inode_find(&desc);
  if (ret < 0)
    {
      /* This name does not refer to a psudeo-inode and there is no
       * mountpoint that includes in this path.
       */

      ret = -ret;
      goto errout_with_search;
    }

  /* Get the search results */

  inode = desc.node;
  DEBUGASSERT(inode != NULL);

  /* The way we handle the statfs depends on the type of inode that we
   * are dealing with.
   */

#ifndef CONFIG_DISABLE_MOUNTPOINT
  if (INODE_IS_MOUNTPT(inode))
    {
      /* The node is a file system mointpoint. Verify that the mountpoint
       * supports the statfs() method
       */

      if (inode->u.i_mops && inode->u.i_mops->statfs)
        {
          /* Perform the statfs() operation */

          ret = inode->u.i_mops->statfs(inode, buf);
        }
    }
  else
#endif
    {
      /* The node is part of the root pseudo file system */

      ret = statpseudofs(inode, buf);
    }

  /* Check if the statfs operation was successful */

  if (ret < 0)
    {
      ret = -ret;
      goto errout_with_inode;
    }

  /* Successfully statfs'ed the file */

  inode_release(inode);
  RELEASE_SEARCH(&desc);
  return OK;

/* Failure conditions always set the errno appropriately */

errout_with_inode:
  inode_release(inode);

errout_with_search:
  RELEASE_SEARCH(&desc);

errout:
  set_errno(ret);
  return ERROR;
}