From daf1622eddf251d0cdb7a3d755af89930bbeadbd Mon Sep 17 00:00:00 2001
From: Joel Sherrill <joel.sherrill@OARcorp.com>
Date: Mon, 11 Oct 1999 13:50:13 +0000
Subject: New files.

---
 doc/filesystem/imfs.t | 1875 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 1875 insertions(+)
 create mode 100644 doc/filesystem/imfs.t

(limited to 'doc/filesystem/imfs.t')

diff --git a/doc/filesystem/imfs.t b/doc/filesystem/imfs.t
new file mode 100644
index 0000000000..0127261d5d
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+++ b/doc/filesystem/imfs.t
@@ -0,0 +1,1875 @@
+
+@chapter In-Memory File System 
+
+This chapter describes the In-Memory File System.
+
+@section OPS Table Functions
+
+OPS table functions are defined in a rtems_filesystem_operations_table
+structure.  It defines functions that are specific to a given file system.
+One table exists for each file system that is supported in the RTEMS
+configuration. The structure definition appears below and is followed by
+general developmental information on each of the functions contained in this
+function management structure.
+
+@example
+typedef struct @{
+  rtems_filesystem_evalpath_t        evalpath;
+  rtems_filesystem_evalmake_t        evalformake;
+  rtems_filesystem_link_t            link;
+  rtems_filesystem_unlink_t          unlink;
+  rtems_filesystem_node_type_t       node_type;
+  rtems_filesystem_mknod_t           mknod;
+  rtems_filesystem_rmnod_t           rmnod;
+  rtems_filesystem_chown_t           chown;
+  rtems_filesystem_freenode_t        freenod;
+  rtems_filesystem_mount_t           mount;
+  rtems_filesystem_fsmount_me_t      fsmount_me;
+  rtems_filesystem_unmount_t         unmount;
+  rtems_filesystem_fsunmount_me_t    fsunmount_me;
+  rtems_filesystem_utime_t           utime;
+  rtems_filesystem_evaluate_link_t   eval_link;
+  rtems_filesystem_symlink_t         symlink;
+@} rtems_filesystem_operations_table;
+@end example
+
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection evalpath()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection evalformake()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection link()
+
+@subheading Slot Function:
+
+link
+
+@subheading Arguments:
+
+
+@example
+rtems_filesystem_location_info_t    *to_loc,      /* IN */
+rtems_filesystem_location_info_t    *parent_loc,  /* IN */
+const char                          *token        /* IN */
+@end example
+
+@subheading File:
+
+imfs_link.c
+
+@subheading Development Comments:
+
+
+This routine is used in the IMFS file system to create a hard-link.
+
+It will first examine the st_nlink count of the node that we are trying to.
+If the link count exceeds LINK_MAX an error will be returned.
+
+The name of the link will be normalized to remove extraneous separators from
+the end of the name.
+
+IMFS_create_node will be used to create a file system node that will have the
+following characteristics:
+
+@itemize @bullet
+
+@item parent that was determined in the link() function in file link.c
+
+@item Type will be set to IMFS_HARD_LINK
+
+@item name will be set to the normalized name
+
+@item mode of the hard-link will be set to the mode of the target node
+
+@end itemize
+
+If there was trouble allocating memory for the new node an error will be
+returned.
+
+The st_nlink count of the target node will be incremented to reflect the new
+link.
+
+The time fields of the link will be set to reflect the creation time of the
+hard-link.
+
+
+@c @c @c
+
+@page
+
+@subsection unlink()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection node_type()
+
+@subheading Slot Function:
+
+IMFS_node_type()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t    *pathloc        /* IN */
+@end example
+
+@subheading File:
+
+imfs_ntype.c
+
+@subheading Development Comments:
+
+This routine will locate the IMFS_jnode_t structure that holds ownership
+information for the selected node in the file system.
+
+This structure is pointed to by pathloc->node_access.
+
+The IMFS_jnode_t type element indicates one of the node types listed below:
+
+@itemize @bullet
+
+@item RTEMS_FILESYSTEM_DIRECTORY
+
+@item RTEMS_FILESYSTEM_DEVICE
+
+@item RTEMS_FILESYSTEM_HARD_LINK
+
+@item RTEMS_FILESYSTEM_MEMORY_FILE
+
+@end itemize
+
+@c
+@c
+@c
+
+@page
+
+@subsection mknod()
+
+@subheading Slot Function:
+
+IMFS_mknod()
+
+@subheading Arguments:
+
+@example
+const char                          *token,        /* IN */
+mode_t                               mode,         /* IN */
+dev_t                                dev,          /* IN */
+rtems_filesystem_location_info_t    *pathloc       /* IN/OUT */
+@end example
+
+@subheading File:
+
+imfs_mknod.c
+
+@subheading Development Comments:
+
+This routine will examine the mode argument to determine is we are trying to
+create a directory, regular file and a device node. The creation of other
+node types is not permitted and will cause an assert.
+
+Memory space will be allocated for a -jnode- and the node will be set up
+according to the nodal type that was specified. The IMFS_create_node()
+function performs the allocation and setup of the node.
+
+The only problem that is currently reported is the lack of memory when we
+attempt to allocate space for the -jnode- (ENOMEN).
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection rmnod()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection chown()
+
+@subheading Slot Function:
+
+IMFS_chown()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t    *pathloc        /* IN */
+uid_t                                owner          /* IN */
+gid_t                                group          /* IN */
+@end example
+
+@subheading File:
+
+imfs_chown.c
+
+@subheading Development Comments:
+
+This routine will locate the IMFS_jnode_t structure that holds ownership
+information for the selected node in the file system.
+
+This structure is pointed to by pathloc->node_access.
+
+The st_uid and st_gid fields of the node are then modified. Since this is a
+memory based file system, no further action is required to alter the
+ownership of the IMFS_jnode_t structure.
+
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection freenod()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX 
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection mount()
+
+@subheading Slot Function:
+
+IMFS_mount()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_mount_table_entry_t   *mt_entry
+@end example
+
+@subheading File:
+
+imfs_mount.c
+
+@subheading Development Comments:
+
+This routine provides the file system specific processing required to mount a
+file system for the system that contains the mount point. It will determine
+if the point that we are trying to mount onto is a node of IMFS_DIRECTORY
+type.
+
+If it is the node's info element is altered so that the info.directory.mt_fs
+element points to the mount table chain entry that is associated with the
+mounted file system at this point. The info.directory.mt_fs element can be
+examined to determine if a file system is mounted at a directory. If it is
+NULL, the directory does not serve as a mount point. A non-NULL entry
+indicates that the directory does serve as a mount point and the value of
+info.directory.mt_fs can be used to locate the mount table chain entry that
+describes the file system mounted at this point.
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection fsmount_me()
+
+@subheading Slot Function:
+
+IMFS_initialize()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_mount_table_entry_t   *mt_entry    
+@end example
+
+@subheading File:
+
+imfs_init.c
+
+@subheading Development Comments:
+
+This function is provided with a file system to take care of the internal
+file system management details associated with mounting that file system
+under the RTEMS environment.
+
+It is not responsible for the mounting details associated the file system
+containing the mount point.
+
+The rtems_filesystem_mount_table_entry_t structure contains the key elements
+below:
+
+rtems_filesystem_location_info_t         *mt_point_node,
+
+This structure contains information about the mount point. This 
+allows us to find the ops-table and the handling functions 
+associated with the file system containing the mount point.
+
+rtems_filesystem_location_info_t         *fs_root_node,
+
+This structure contains information about the root node in the file 
+system to be mounted. It allows us to find the ops-table and the 
+handling functions associated with the file system to be mounted.
+
+rtems_filesystem_options_t                 options,
+
+Read only or read/write access
+
+void                                         *fs_info,
+
+This points to an allocated block of memory the will be used to 
+hold any file system specific information of a global nature. This 
+allocated region if important because it allows us to mount the 
+same file system type more than once under the RTEMS system. 
+Each instance of the mounted file system has its own set of global 
+management information that is separate from the global 
+management information associated with the other instances of the 
+mounted file system type.
+
+rtems_filesystem_limits_and_options_t    pathconf_info,
+
+The table contains the following set of values associated with the 
+mounted file system:
+
+@itemize @bullet
+
+@item link_max
+
+@item max_canon
+
+@item max_input
+
+@item name_max
+
+@item path_max
+
+@item pipe_buf
+
+@item posix_async_io
+
+@item posix_chown_restrictions
+
+@item posix_no_trunc
+
+@item posix_prio_io
+
+@item posix_sync_io
+
+@item posix_vdisable
+
+@end itemize
+
+These values are accessed with the pathconf() and the fpathconf ()  
+functions.
+
+const char                                   *dev
+
+The is intended to contain a string that identifies the device that contains
+the file system information. The file systems that are currently implemented
+are memory based and don't require a device specification.
+
+If the mt_point_node.node_access is NULL then we are mounting the base file 
+system.
+
+The routine will create a directory node for the root of the IMFS file
+system.
+
+The node will have read, write and execute permissions for owner, group and
+others.
+
+The node's name will be a null string.
+
+A file system information structure(fs_info) will be allocated and
+initialized for the IMFS file system. The fs_info pointer in the mount table
+entry will be set to point the file system information structure.
+
+The pathconf_info element of the mount table will be set to the appropriate
+table of path configuration constants ( IMFS_LIMITS_AND_OPTIONS ).
+
+The fs_root_node structure will be filled in with the following:
+
+@itemize @bullet
+
+@item pointer to the allocated root node of the file system
+
+@item directory handlers for a directory node under the IMFS file system
+
+@item OPS table functions for the IMFS
+
+@end itemize
+
+A 0 will be returned to the calling routine if the process succeeded,
+otherwise a 1 will be returned.
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection unmount()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX 
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection fsunmount_me()
+
+@subheading Slot Function:
+
+imfs_fsunmount_me()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_mount_table_entry_t   *mt_entry    
+@end example
+
+@subheading File:
+
+imfs_fsunmount_me.c
+
+@subheading Development Comments:
+
+XXX 
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection utime()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX 
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection eval_link()
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+@page
+@section Handler Table Functions for Regular Files
+
+Handler table functions are defined in a rtems_filesystem_file_handlers_r
+structure. It defines functions that are specific to a node type in a given
+file system. One table exists for each of the file system's node types. The
+structure definition appears below. It is followed by general developmental
+information on each of the functions associated with regular files contained
+in this function management structure.
+
+@example
+typedef struct @{
+    rtems_filesystem_open_t           open;
+    rtems_filesystem_close_t          close;
+    rtems_filesystem_read_t           read;
+    rtems_filesystem_write_t          write;
+    rtems_filesystem_ioctl_t          ioctl;
+    rtems_filesystem_lseek_t          lseek;
+    rtems_filesystem_fstat_t          fstat;
+    rtems_filesystem_fchmod_t         fchmod;
+    rtems_filesystem_ftruncate_t      ftruncate;
+    rtems_filesystem_fpathconf_t      fpathconf;
+    rtems_filesystem_fsync_t          fsync;
+    rtems_filesystem_fdatasync_t      fdatasync;
+@} rtems_filesystem_file_handlers_r;
+@end example
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection open() for Regular File
+
+@subheading Slot Function:
+
+memfile_open()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t   *iop,
+const char      *pathname,
+unsigned32       flag,
+unsigned32       mode
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Development Comments:
+
+Currently this function is a shell. No meaningful processing is performed and
+a success code is always returned.
+
+@c
+@c
+@c
+
+@page
+
+@subsection close() for Regular File
+
+@subheading Slot Function:
+
+memfile_close()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Development Comments:
+
+This routine is a dummy for regular files under the base file system. It
+performs a capture of the IMFS_jnode_t pointer from the file control block
+and then immediately returns a success status.
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection read() for Regular File
+
+@subheading Slot Function:
+
+memfile_read()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop,
+void              *buffer,
+unsigned32         count
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Development Comments:
+
+This routine will determine the -jnode- that is associated with this file.
+
+It will then call IMFS_memfile_read() with the -jnode-, file position index,
+buffer and transfer count as arguments.
+
+IMFS_memfile_read() will do the following:
+
+@itemize @bullet
+
+@item Verify that the -jnode- is associated with a memory file
+
+@item Verify that the destination of the read is valid
+
+@item Adjust the length of the read if it is too long
+
+@item Acquire data from the memory blocks associated with the file
+
+@item Update the access time for the data in the file
+
+@end itemize
+
+@c
+@c
+@c
+
+@page
+
+@subsection write() for Regular File
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+
+@page
+
+@subsection ioctl() for Regular File
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop,
+unsigned32       command,
+void              *buffer
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Development Comments:
+
+The current code is a placeholder for future development. The routine returns
+a successful completion status.
+
+@c
+@c
+@c
+
+@page
+
+@subsection lseek() for Regular File
+
+@subheading Slot Function:
+
+Memfile_lseek()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop,
+off_t              offset,
+int                whence
+@end example
+
+@subheading File:
+
+memfile.c
+
+@subheading Development Comments:
+
+This routine make sure that the memory based file is sufficiently large to
+allow for the new file position index.
+
+The IMFS_memfile_extend() function is used to evaluate the current size of
+the memory file and allocate additional memory blocks if required by the new
+file position index. A success code is always returned from this routine.
+
+@c
+@c
+@c
+
+@page
+
+@subsection fstat() for Regular File
+
+@subheading Slot Function:
+
+IMFS_stat()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t   *loc,
+struct stat                        *buf
+@end example
+
+@subheading File:
+
+imfs_stat.c
+
+@subheading Development Comments:
+
+This routine actually performs status processing for both devices and regular
+files.
+
+The IMFS_jnode_t structure is referenced to determine the type of node under
+the file system.
+
+If the node is associated with a device, node information is extracted and
+transformed to set the st_dev element of the stat structure.
+
+If the node is a regular file, the size of the regular file is extracted from
+the node.
+
+This routine rejects other node types.
+
+The following information is extracted from the node and placed in the stat
+structure:
+
+@itemize @bullet
+
+@item st_mode
+
+@item st_nlink
+
+@item st_ino
+
+@item st_uid
+
+@item st_gid
+
+@item st_atime
+
+@item st_mtime
+
+@item st_ctime
+
+@end itemize
+
+@c
+@c
+@c
+
+@page
+
+@subsection fchmod() for Regular File
+
+@subheading Slot Function:
+
+IMFS_fchmod()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop
+mode_t              mode
+@end example
+
+@subheading File:
+
+imfs_fchmod.c
+
+@subheading Development Comments:
+
+This routine will obtain the pointer to the IMFS_jnode_t structure from the
+information currently in the file control block.
+
+Based on configuration the routine will acquire the user ID from a call to
+getuid()  or from the IMFS_jnode_t structure.
+
+It then checks to see if we have the ownership rights to alter the mode of
+the file.  If the caller does not, an error code is returned.
+
+An additional test is performed to verify that the caller is not trying to
+alter the nature of the node. If the caller is attempting to alter more than
+the permissions associated with user group and other, an error is returned.
+
+If all the preconditions are met, the user, group and other fields are set
+based on the mode calling parameter.
+
+@c
+@c
+@c
+
+@page
+
+@subsection ftruncate() for Regular File
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+
+@page
+
+@subsection fpathconf() for Regular File
+
+@subheading Slot Function:
+
+NULL
+
+@subheading Arguments:
+
+Not Implemented
+
+@subheading File:
+
+Not Implemented
+
+@subheading Development Comments:
+
+Not Implemented
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection fsync() for Regular File
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection fdatasync() for Regular File
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+@page
+@section Handler Table Functions for Directories
+
+Handler table functions are defined in a rtems_filesystem_file_handlers_r
+structure. It defines functions that are specific to a node type in a given
+file system. One table exists for each of the file system's node types. The
+structure definition appears below. It is followed by general developmental
+information on each of the functions associated with directories contained in
+this function management structure.
+
+@example
+typedef struct @{
+    rtems_filesystem_open_t           open;
+    rtems_filesystem_close_t          close;
+    rtems_filesystem_read_t           read;
+    rtems_filesystem_write_t          write;
+    rtems_filesystem_ioctl_t          ioctl;
+    rtems_filesystem_lseek_t          lseek;
+    rtems_filesystem_fstat_t          fstat;
+    rtems_filesystem_fchmod_t         fchmod;
+    rtems_filesystem_ftruncate_t      ftruncate;
+    rtems_filesystem_fpathconf_t      fpathconf;
+    rtems_filesystem_fsync_t          fsync;
+    rtems_filesystem_fdatasync_t      fdatasync;
+@} rtems_filesystem_file_handlers_r;
+@end example
+
+
+@c
+@c
+@c
+
+@page
+
+@section open() for Directories
+
+@subheading Slot Function:
+
+imfs_dir_open()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t  *iop,
+const char     *pathname,
+unsigned32      flag,
+unsigned32      mode
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading Development Comments:
+
+This routine will look into the file control block to find the -jnode- that
+is associated with the directory.
+
+The routine will verify that the node is a directory. If its not a directory
+an error code will be returned.
+
+If it is a directory, the offset in the file control block will be set to 0.
+This allows us to start reading at the beginning of the directory.
+
+@c
+@c
+@c
+
+@page
+
+@section close() for Directories
+
+@subheading Slot Function:
+
+imfs_dir_close()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading Development Comments:
+
+This routine is a dummy for directories under the base file system. It
+immediately returns a success status.
+
+@c
+@c
+@c
+
+@page
+
+@section read() for Directories
+
+@subheading Slot Function:
+
+imfs_dir_read
+
+@subheading Arguments:
+
+@example
+rtems_libio_t  *iop,
+void           *buffer,
+unsigned32      count
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading Development Comments:
+
+This routine will read a fixed number of directory entries from the current
+directory offset. The number of directory bytes read will be returned from
+this routine.
+
+
+@c
+@c
+@c
+
+@page
+
+@section write() for Directories
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+
+@page
+
+@section ioctl() for Directories
+
+@subheading Slot Function:
+
+ioctl
+
+@subheading Arguments:
+
+
+@subheading File:
+
+Not supported
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+
+@page
+
+@section lseek() for Directories
+
+@subheading Slot Function:
+
+imfs_dir_lseek()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t      *iop,
+off_t               offset,
+int                 whence
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading Development Comments:
+
+This routine alters the offset in the file control block.
+
+No test is performed on the number of children under the current open
+directory.  The imfs_dir_read() function protects against reads beyond the
+current size to the directory by returning a 0 bytes transfered to the
+calling programs whenever the file position index exceeds the last entry in
+the open directory.
+
+@c
+@c
+@c
+
+@page
+
+@section fstat() for Directories
+
+@subheading Slot Function:
+
+imfs_dir_fstat()
+
+@subheading Arguments:
+
+
+@example
+rtems_filesystem_location_info_t   *loc,
+struct stat                        *buf
+@end example
+
+@subheading File:
+
+imfs_directory.c
+
+@subheading Development Comments:
+
+The node access information in the rtems_filesystem_location_info_t structure
+is used to locate the appropriate IMFS_jnode_t structure. The following
+information is taken from the IMFS_jnode_t structure and placed in the stat
+structure:
+
+@itemize @bullet
+@item st_ino
+@item st_mode
+@item st_nlink
+@item st_uid
+@item st_gid
+@item st_atime
+@item st_mtime
+@item st_ctime
+@end itemize
+
+The st_size field is obtained by running through the chain of directory
+entries and summing the sizes of the dirent structures associated with each
+of the children of the directory.
+
+@c
+@c
+@c
+
+@page
+
+@section fchmod() for Directories
+
+@subheading Slot Function:
+
+IMFS_fchmod()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop
+mode_t             mode
+@end example
+
+@subheading File:
+
+imfs_fchmod.c
+
+@subheading Development Comments:
+
+This routine will obtain the pointer to the IMFS_jnode_t structure from the
+information currently in the file control block.
+
+Based on configuration the routine will acquire the user ID from a call to
+getuid()  or from the IMFS_jnode_t structure.
+
+It then checks to see if we have the ownership rights to alter the mode of
+the file.  If the caller does not, an error code is returned.
+
+An additional test is performed to verify that the caller is not trying to
+alter the nature of the node. If the caller is attempting to alter more than
+the permissions associated with user group and other, an error is returned.
+
+If all the preconditions are met, the user, group and other fields are set
+based on the mode calling parameter.
+
+@c
+@c
+@c
+
+@page
+
+@section ftruncate() for Directories
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+
+@page
+
+@section fpathconf() for Directories
+
+@subheading Slot Function:
+
+fpathconf
+
+@subheading Arguments:
+
+Not Implemented
+
+@subheading File:
+
+Not Implemented
+
+@subheading Development Comments:
+
+Not Implemented
+
+
+@c
+@c
+@c
+
+@page
+
+@section fsync() for Directories
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@c
+@c
+@c
+
+@page
+
+@section fdatasync() for Directories
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@section Handler Table Functions for Devices
+
+Handler table functions are defined in a rtems_filesystem_file_handlers_r
+structure. It defines functions that are specific to a node type in a given
+file system. One table exists for each of the file system's node types. The
+structure definition appears below. It is followed by general developmental
+information on each of the functions associated with devices contained in
+this function management structure.
+
+@example
+typedef struct @{
+  rtems_filesystem_open_t           open;
+  rtems_filesystem_close_t          close;
+  rtems_filesystem_read_t           read;
+  rtems_filesystem_write_t          write;
+  rtems_filesystem_ioctl_t          ioctl;
+  rtems_filesystem_lseek_t          lseek;
+  rtems_filesystem_fstat_t          fstat;
+  rtems_filesystem_fchmod_t         fchmod;
+  rtems_filesystem_ftruncate_t      ftruncate;
+  rtems_filesystem_fpathconf_t      fpathconf;
+  rtems_filesystem_fsync_t          fsync;
+  rtems_filesystem_fdatasync_t      fdatasync;
+@} rtems_filesystem_file_handlers_r;
+@end example
+
+@c
+@c
+@c
+
+@page
+
+@section open() for Devices
+
+@subheading Slot Function:
+
+device_open()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop,
+const char        *pathname,
+unsigned32         flag,
+unsigned32         mode
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading Development Comments:
+
+This routine will use the file control block to locate the node structure for
+the device.
+
+It will extract the major and minor device numbers from the -jnode-.
+
+The major and minor device numbers will be used to make a rtems_io_open()  
+function call to open the device driver. An argument list is sent to the
+driver that contains the file control block, flags and mode information.
+
+@c
+@c
+@c
+
+@page
+
+@section close() for Devices
+
+@subheading Slot Function:
+
+device_close()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading Development Comments:
+
+This routine extracts the major and minor device driver numbers from the
+IMFS_jnode_t that is referenced in the file control block.
+
+It also forms an argument list that contains the file control block.
+
+A rtems_io_close() function call is made to close the device specified by the
+major and minor device numbers.
+
+
+@c
+@c
+@c
+
+@page
+
+@section read() for Devices
+
+@subheading Slot Function:
+
+device_read()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop,
+void              *buffer,
+unsigned32         count
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading Development Comments:
+
+This routine will extract the major and minor numbers for the device from the -
+jnode- associated with the file descriptor.
+
+A rtems_io_read() call will be made to the device driver associated with the file 
+descriptor. The major and minor device number will be sent as arguments as well 
+as an argument list consisting of:
+
+@itemize @bullet
+@item file control block
+
+@item file position index
+
+@item buffer pointer where the data read is to be placed
+
+@item count indicating the number of bytes that the program wishes to read 
+from the device
+
+@item flags from the file control block
+
+@end itemize
+
+On return from the rtems_io_read() the number of bytes that were actually
+read will be returned to the calling program.
+
+
+@c
+@c
+@c
+
+@page
+
+@section write() for Devices
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+
+@page
+
+@section ioctl() for Devices
+
+@subheading Slot Function:
+
+ioctl
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop,
+unsigned32         command,
+void              *buffer
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading Development Comments:
+
+This handler will obtain status information about a device.
+
+The form of status is device dependent.
+
+The rtems_io_control() function uses the major and minor number of the device
+to obtain the status information.
+
+rtems_io_control() requires an rtems_libio_ioctl_args_t argument list which
+contains the file control block, device specific command and a buffer pointer
+to return the device status information.
+
+The device specific command should indicate the nature of the information
+that is desired from the device.
+
+After the rtems_io_control() is processed, the buffer should contain the
+requested device information.
+
+If the device information is not obtained properly a -1 will be returned to
+the calling program, otherwise the ioctl_return value is returned.
+
+@c
+@c
+@c
+
+@page
+
+@section lseek() for Devices
+
+@subheading Slot Function:
+
+device_lseek()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop,
+off_t              offset,
+int                whence
+@end example
+
+@subheading File:
+
+deviceio.c
+
+@subheading Development Comments:
+
+At the present time this is a placeholder function. It always returns a
+successful status.
+
+@c
+@c
+@c
+
+@page
+
+@section fstat() for Devices
+
+@subheading Slot Function:
+
+IMFS_stat()
+
+@subheading Arguments:
+
+@example
+rtems_filesystem_location_info_t   *loc,
+struct stat                        *buf
+@end example
+
+@subheading File:
+
+imfs_stat.c
+
+@subheading Development Comments:
+
+This routine actually performs status processing for both devices and regular files. 
+
+The IMFS_jnode_t structure is referenced to determine the type of node under the 
+file system. 
+
+If the node is associated with a device, node information is extracted and 
+transformed to set the st_dev element of the stat structure.
+
+If the node is a regular file, the size of the regular file is extracted from the node.
+
+This routine rejects other node types.
+
+The following information is extracted from the node and placed in the stat 
+structure:
+
+@itemize @bullet
+
+@item st_mode
+
+@item st_nlink
+
+@item st_ino
+
+@item st_uid
+
+@item st_gid
+
+@item st_atime
+
+@item st_mtime
+
+@item st_ctime
+
+@end itemize
+
+
+
+@c
+@c
+@c
+
+@page
+
+@section fchmod() for Devices
+
+@subheading Slot Function:
+
+IMFS_fchmod()
+
+@subheading Arguments:
+
+@example
+rtems_libio_t     *iop
+mode_t             mode
+@end example
+
+@subheading File:
+
+imfs_fchmod.c
+
+@subheading Development Comments:
+
+This routine will obtain the pointer to the IMFS_jnode_t structure from the
+information currently in the file control block.
+
+Based on configuration the routine will acquire the user ID from a call to
+getuid()  or from the IMFS_jnode_t structure.
+
+It then checks to see if we have the ownership rights to alter the mode of
+the file.  If the caller does not, an error code is returned.
+
+An additional test is performed to verify that the caller is not trying to
+alter the nature of the node. If the caller is attempting to alter more than
+the permissions associated with user group and other, an error is returned.
+
+If all the preconditions are met, the user, group and other fields are set
+based on the mode calling parameter.
+
+
+@c
+@c
+@c
+
+@page
+
+@section ftruncate() for Devices
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+@c
+@c
+@c
+
+@page
+
+@section fpathconf() for Devices
+
+@subheading Slot Function:
+
+fpathconf
+
+@subheading Arguments:
+
+Not Implemented
+
+@subheading File:
+
+Not Implemented
+
+@subheading Development Comments:
+
+Not Implemented
+
+
+@c
+@c
+@c
+
+@page
+
+@section fsync() for Devices
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
+
+@c
+@c
+@c
+
+@page
+
+@subsection fdatasync() for Devices
+
+Not Implemented
+
+@subheading Slot Function:
+
+XXX
+
+@subheading Arguments:
+
+XXX
+
+@subheading File:
+
+XXX
+
+@subheading Development Comments:
+
+XXX
+
-- 
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