text: /******************************************************************************
  *                                                                             *
  * License Agreement                                                           *
  *                                                                             *
  * Copyright (c) 2004 Altera Corporation, San Jose, California, USA.           *
  * All rights reserved.                                                        *
  *                                                                             *
  * Permission is hereby granted, free of charge, to any person obtaining a     *
  * copy of this software and associated documentation files (the "Software"),  *
  * to deal in the Software without restriction, including without limitation   *
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,    *
  * and/or sell copies of the Software, and to permit persons to whom the       *
  * Software is furnished to do so, subject to the following conditions:        *
  *                                                                             *
  * The above copyright notice and this permission notice shall be included in  *
  * all copies or substantial portions of the Software.                         *
  *                                                                             *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  *
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    *
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      *
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     *
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         *
  * DEALINGS IN THE SOFTWARE.                                                   *
  *                                                                             *
  * This agreement shall be governed in all respects by the laws of the State   *
  * of California and by the laws of the United States of America.              *
  *                                                                             *
  * Altera does not recommend, suggest or require that this reference design    *
  * file be used in conjunction or combination with any other product.          *
  ******************************************************************************/
  
  #include <unistd.h>
  
  #include "sys/alt_errno.h"
  #include "sys/alt_warning.h"
  #include "priv/alt_file.h"
  #include "os/alt_syscall.h"
  
  #ifdef ALT_USE_DIRECT_DRIVERS
  
  int ALT_CLOSE (int fildes)
  {
    /* Generate a link time warning, should this function ever be called. */
    
    ALT_STUB_WARNING(close);
    
    /* Indicate an error */
    
    ALT_ERRNO = ENOSYS;
    return -1;
  }
  
  #else /* !ALT_USE_DIRECT_DRIVERS */
  
  /*
   * close() is called by an application to release a file descriptor. If the
   * associated file system/device has a close() callback function registered 
   * then this called. The file descriptor is then marked as free.
   *
   * ALT_CLOSE is mapped onto the close() system call in alt_syscall.h
   */
   
  int ALT_CLOSE (int fildes)
  {
    alt_fd* fd;
    int     rval;
  
    /*
     * A common error case is that when the file descriptor was created, the call
     * to open() failed resulting in a negative file descriptor. This is trapped
     * below so that we don't try and process an invalid file descriptor.
     */
  
    fd = (fildes < 0) ? NULL : &alt_fd_list[fildes];
  
    if (fd)
    {
      /*
       * If the associated file system/device has a close function, call it so 
       * that any necessary cleanup code can run.
       */
  
      rval = (fd->dev->close) ? fd->dev->close(fd) : 0;
  
      /* Free the file descriptor structure and return. */
  
      alt_release_fd (fildes);
      if (rval < 0)
      {
        ALT_ERRNO = -rval;
        return -1;
      }
      return 0;
    }
    else
    {
      ALT_ERRNO = EBADFD;
      return -1;
    }
  }
  
  #endif /* ALT_USE_DIRECT_DRIVERS */
  