Added base version of file system infrastructure. This includes a major

overhaul of the RTEMS system call interface.  This base file system is
the "In-Memory File System" aka IMFS.

The design and implementation was done by the following people:

  + Joel Sherrill (joel@OARcorp.com)
  + Jennifer Averett (jennifer@OARcorp.com)
  + Steve "Mr Mount" Salitasc (salitasc@OARcorp.com)
  + Kerwin Wade (wade@OARcorp.com)

PROBLEMS
========
  + It is VERY likely that merging this will break the UNIX port.  This
    can/will be fixed.

  + There is likely some reentrancy/mutual exclusion needed.

  + Eventually, there should be a "mini-IMFS" description table to
    eliminate links, symlinks, etc to save memory.  All you need to
    have "classic RTEMS" functionality is technically directories
    and device IO.  All the rest could be left out to save memory.

1 files changed, 214 insertions, 0 deletions

diff --git a/c/src/exec/libcsupport/src/unmount.c b/c/src/exec/libcsupport/src/unmount.c
new file mode 100644
index 0000000000..f50e63ff42
--- /dev/null
+++ b/c/src/exec/libcsupport/src/unmount.c
@@ -0,0 +1,214 @@
+/*
+ *  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) 1989-1998.
+ *  On-Line Applications Research Corporation (OAR).
+ *  Copyright assigned to U.S. Government, 1994.
+ *
+ *  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.
+ *
+ *  $Id$
+ */
+
+#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;
+  int                                   result;
+
+  /*
+   *  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 )
+    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 )
+    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 swaped.
+   * 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 )
+     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 )
+     return -1;
+
+  /*
+   * Allow the file system to clean up.
+   */
+
+  result = (*temp_loc.ops->fsunmount_me)( temp_loc.mt_entry );
+
+  /*
+   *  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.
+   */
+
+  free( temp_loc.mt_entry );
+
+  return result;
+
+}
+
+
+/*
+ *  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;
+}