/************************************************************
 * fs_opendir.c
 *
 *   Copyright (C) 2007 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 Gregory Nutt 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/types.h>
#include <stdlib.h>
#include <dirent.h>
#include <errno.h>
#include <nuttx/fs.h>
#include "fs_internal.h"

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

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

/************************************************************
 * Name: opendir
 *
 * Description:
 *   The  opendir() function opens a directory stream
 *   corresponding to the directory name, and returns a
 *   pointer to the directory stream. The stream is
 *   positioned at the first entry in the directory.
 *
 * Inputs:
 *   path -- the directory to open
 *
 * Return:
 *   The opendir() function returns a pointer to the
 *   directory stream.  On error, NULL is returned, and
 *   errno is set appropriately.
 *
 *   EACCES  - Permission denied.
 *   EMFILE  - Too many file descriptors in use by process.
 *   ENFILE  - Too many files are currently open in the
 *             system.
 *   ENOENT  - Directory does not exist, or name is an empty
 *             string.
 *   ENOMEM  - Insufficient memory to complete the operation.
 *   ENOTDIR - 'path' is not a directory.
 *
 ************************************************************/

#if CONFIG_NFILE_DESCRIPTORS > 0

FAR DIR *opendir(const char *path)
{
  FAR struct inode *inode;
  FAR struct internal_dir_s *dir;

  /* Get an inode corresponding to the path.  On successful
   * return, we will hold on reference count on the inode.
   */

  inode = inode_finddir(path);
  if (!inode)
    {
      /* 'path' is not a directory.*/

      *get_errno_ptr() = ENOTDIR;
      return NULL;
    }

  /* Allocate a type DIR -- which is little more than an inode
   * container.
   */

  dir = (FAR struct internal_dir_s *)zalloc(sizeof(struct internal_dir_s));
  if (!dir)
    {
      /* Insufficient memory to complete the operation.*/

      *get_errno_ptr() = ENOMEM;
      inode_release(inode);
      return NULL;
    }

  /* Populate the DIR structure and return it to the caller */

  dir->root = inode;   /* Save where we started in case we rewind */
  inode_addref(inode); /* Now we have two references on inode */
  dir->next = inode;   /* This is the next node to use for readdir() */
  return ((DIR*)dir);
}

#endif /* CONFIG_NFILE_DESCRIPTORS */