/****************************************************************************
 * fs/vfs/fs_getfilep.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 <nuttx/config.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <unistd.h>
#include <fcntl.h>
#include <sched.h>
#include <errno.h>

#include "inode/inode.h"

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

/****************************************************************************
 * Name: fs_getfilep
 *
 * Description:
 *   Given a file descriptor, return the corresponding instance of struct
 *   file.  NOTE that this function will currently fail if it is provided
 *   with a socket descriptor.
 *
 * Input Parameters:
 *   fd    - The file descriptor
 *   filep - The location to return the struct file instance
 *
 * Returned Value:
 *   Zero (OK) is returned on success; a negated errno value is returned on
 *   any failure.
 *
 ****************************************************************************/

int fs_getfilep(int fd, FAR struct file **filep)
{
  FAR struct filelist *list;

  DEBUGASSERT(filep != NULL);
  *filep = (FAR struct file *)NULL;

  if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
    {
      return -EBADF;
    }

  /* The descriptor is in a valid range to file descriptor... Get the
   * thread-specific file list.
   */

  list = nxsched_get_files();

  /* The file list can be NULL under two cases:  (1) One is an obscure
   * cornercase:  When memory management debug output is enabled.  Then
   * there may be attempts to write to stdout from malloc before the group
   * data has been allocated.  The other other is (2) if this is a kernel
   * thread.  Kernel threads have no allocated file descriptors.
   */

  if (list == NULL)
    {
      return -EAGAIN;
    }

  /* And return the file pointer from the list */

  *filep = &list->fl_files[fd];
  return OK;
}