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/*

 *  unmount() - Unmount a File System

 *

 *  This routine is not defined in the POSIX 1003.1b standard but

 *  in some form is supported on most UNIX and POSIX systems.  This

 *  routine is necessary to mount instantiations of a file system

 *  into the file system name space.

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  $Id: unmount.c,v 1.2 2001-09-27 12:01:15 chris Exp $

 */

#include <sys/types.h>

#include <sys/stat.h>

#include <chain.h>

#include <fcntl.h>

#include <unistd.h>

#include <errno.h>

#include <stdlib.h>

#include <string.h>

#include <assert.h>

#include "imfs.h"

#include "libio_.h"

/*

 *  Data structures and routines private to mount/unmount pair.

 */

extern Chain_Control                    rtems_filesystem_mount_table_control;

extern rtems_filesystem_location_info_t rtems_filesystem_current;

int search_mt_for_mount_point(

  rtems_filesystem_location_info_t *location_of_mount_point

);

int file_systems_below_this_mountpoint(

  const char                            *mount_path,

  rtems_filesystem_location_info_t      *temp_loc,

  rtems_filesystem_mount_table_entry_t  *temp_mt_entry

);

/*

 *  unmount

 *

 *  This routine will attempt to unmount the file system that has been

 *  is mounted a mount_path.  If the operation is successful, 0 will

 *  be returned to the calling routine.  Otherwise, 1 will be returned.

 */

int unmount(

  const char *mount_path

)

{

  int                                   status;

  rtems_filesystem_location_info_t      temp_loc;

  rtems_filesystem_mount_table_entry_t  temp_mt_entry;

  /*

   *  Are there any file systems below the mount_path specified

   */

  status = file_systems_below_this_mountpoint(

    mount_path,

    &temp_loc,

    &temp_mt_entry

  );

  if ( status != 0 )

    return -1;

  /*

   *  Is the current node reference pointing to a node in the file system

   *  we are attempting to unmount ?

   */

  if ( rtems_filesystem_current.mt_entry == temp_loc.mt_entry ) {

    rtems_filesystem_freenode( &temp_loc );

    set_errno_and_return_minus_one( EBUSY );

  }

  /*

   *  Run the file descriptor table to determine if there are any file

   *  descriptors that are currently active and reference nodes in the

   *  file system that we are trying to unmount

   */

  if ( rtems_libio_is_open_files_in_fs( temp_loc.mt_entry ) == 1 ) {

    rtems_filesystem_freenode( &temp_loc );

    set_errno_and_return_minus_one( EBUSY );

  }

  /*

   * Allow the file system being mounted on to do its cleanup.

   * XXX - Did I change these correctly ??? It looks like either I did

   * XXX   this backwards or the IMFS_unmount and IMFS_fsumount are swapped.

   * XXX   Add to the mt_point_node unmount to set the mt_entry back to null

   * XXX   I will step off in space when evaluating past the end of the node.

   */

  if ((temp_mt_entry.mt_point_node.ops->unmount )( temp_loc.mt_entry ) != 0 ) {

    rtems_filesystem_freenode( &temp_loc );

    return -1;

  }

  /*

   * Run the unmount function for the subordinate file system.

   */

  if ((temp_mt_entry.mt_fs_root.ops->fsunmount_me )( temp_loc.mt_entry ) != 0){

    rtems_filesystem_freenode( &temp_loc );

    return -1;

  }

  /*

   *  Extract the mount table entry from the chain

   */

  Chain_Extract( ( Chain_Node * ) temp_loc.mt_entry );

  /*

   *  Free the memory associated with the extracted mount table entry.

   */

  rtems_filesystem_freenode( &temp_loc.mt_entry->mt_point_node );

  free( temp_loc.mt_entry );

  rtems_filesystem_freenode( &temp_loc );

  return 0;

}

/*

 *  file_systems_below_this_mountpoint

 *

 *  This routine will run through the entries that currently exist in the

 *  mount table chain. For each entry in the mount table chain it will

 *  compare the mount tables mt_fs_root to the new_fs_root_node. If any of the

 *  mount table file system root nodes matches the new file system root node

 *  this indicates that we are trying to mount a file system that has already

 *  been mounted. This is not a permitted operation. temp_loc is set to

 *  the root node of the file system being unmounted.

 */

int file_systems_below_this_mountpoint(

  const char                            *mount_path,

  rtems_filesystem_location_info_t      *temp_loc,

  rtems_filesystem_mount_table_entry_t  *temp_mt_entry

)

{

  Chain_Node                           *the_node;

  rtems_filesystem_mount_table_entry_t *the_mount_entry;

  rtems_filesystem_mount_table_entry_t *current_fs_mt_entry;

  /*

   *  Is the mount_path even a valid node name in the existing tree?

   */

  if ( rtems_filesystem_evaluate_path( mount_path, 0x0, temp_loc, TRUE ) )

    return -1;

  /*

   *  Look for the node defined in temp_loc as a mount point in the

   *  mount table chain.

   */

  for ( the_node = rtems_filesystem_mount_table_control.first;

        !Chain_Is_tail( &rtems_filesystem_mount_table_control, the_node );

        the_node = the_node->next ) {

     the_mount_entry = ( rtems_filesystem_mount_table_entry_t * )the_node;

     if  (the_mount_entry->mt_point_node.node_access  ==

          temp_loc->node_access ) {

        current_fs_mt_entry = the_mount_entry;

        *temp_loc = current_fs_mt_entry->mt_fs_root;

        goto after_real_mount_point_found;

     }

  }

  set_errno_and_return_minus_one( EACCES );

after_real_mount_point_found:

  for ( the_node = rtems_filesystem_mount_table_control.first;

        !Chain_Is_tail( &rtems_filesystem_mount_table_control, the_node );

        the_node = the_node->next ) {

     the_mount_entry = (  rtems_filesystem_mount_table_entry_t * )the_node;

     /*

      *  Exclude the current file systems mount table entry from the test

      */

     if ( current_fs_mt_entry != the_mount_entry ) {

       if ( the_mount_entry->mt_point_node.mt_entry  == current_fs_mt_entry ) {

          /*

           *  There is at least one fs below the fs on the mount_path.

           */

          set_errno_and_return_minus_one( EBUSY );

       }

     }

  }

  *temp_mt_entry = *current_fs_mt_entry;

  return 0;

}