text: /****************************************************************************
   * fs/fs_filedup.c
   *
   *   Copyright (C) 2007-2009, 2011-2012 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 <sched.h>
  #include <errno.h>
  
  #include <nuttx/fs/fs.h>
  
  #include "fs_internal.h"
  
  #if CONFIG_NFILE_DESCRIPTORS > 0
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  #define DUP_ISOPEN(fd, list) \
    ((unsigned int)fd < CONFIG_NFILE_DESCRIPTORS && \
     list->fl_files[fd].f_inode != NULL)
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Global Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: file_dup OR dup
   *
   * Description:
   *   Clone a file descriptor 'fd' to an arbitray descriptor number (any value
   *   greater than or equal to 'minfd'). If socket descriptors are
   *   implemented, then this is called by dup() for the case of file
   *   descriptors.  If socket descriptors are not implemented, then this
   *   function IS dup().
   *
   ****************************************************************************/
  
  int file_dup(int fildes, int minfd)
  {
    FAR struct filelist *list;
    int fildes2;
  
    /* Get the thread-specific file list */
  
    list = sched_getfiles();
    if (!list)
      {
        set_errno(EMFILE);
        return ERROR;
      }
  
    /* Verify that fildes is a valid, open file descriptor */
  
    if (!DUP_ISOPEN(fildes, list))
      {
        set_errno(EBADF);
        return ERROR;
      }
  
    /* Increment the reference count on the contained inode */
  
    inode_addref(list->fl_files[fildes].f_inode);
  
    /* Then allocate a new file descriptor for the inode */
  
    fildes2 = files_allocate(list->fl_files[fildes].f_inode,
                             list->fl_files[fildes].f_oflags,
                             list->fl_files[fildes].f_pos,
                             minfd);
    if (fildes2 < 0)
      {
        set_errno(EMFILE);
        inode_release(list->fl_files[fildes].f_inode);
        return ERROR;
      }
  
    return fildes2;
  }
  
  #endif /* CONFIG_NFILE_DESCRIPTORS > 0 */
  
  