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@c  COPYRIGHT (c) 1988-1998.
@c  On-Line Applications Research Corporation (OAR).
@c  All rights reserved.
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@ifinfo
@node Preface, , Top, Top
@end ifinfo
@unnumbered Preface

The following file system capabilities have been added to the existing
RTEMS system:

@itemize @bullet

@item Mountable file systems

@item Hierarchical file system directory structure

@item POSIX compliant set of routines for the manipulation of files and directories

@item Individual file and directory support for the following:

@enumerate

@item Permissions for read, write and execute

@item User ID

@item Group ID

@item Access time

@item Modification time

@item Creation time

@end enumerate

@item Hard links to files and directories are supported

@item Symbolic links to files and directories are supported

@end itemize

These enhancements have been made to provide the framework for `UNIX like'
file system support. The POSIX file and directory functions have been
implemented to allow a standard method of accessing file, device and
directory information within the file system. The file system concept that
has been implemented allows for expansion and adaptation of the file
system to a variety of existing and future data storage devices. To this
end, file system mount and unmount capabilities have been included in this
RTEMS framework.

This framework slightly alters the manner in which devices are handled
under RTEMS. Devices that are defined under a given RTEMS configuration
will now be registered as files in a mounted file system. Access to these
devices and their associated device handlers will be obtained through the
traditional file system open(), read(), write(), lseek(), fstat() and
ioctl() functions.

A node structure is maintained for each file, device, and directory in the
file system. The node structure is used to manage ownership, access
rights, access time, modification time, and creation time. A union of
structures within the nodal structure provide for manipulation of file
data, device selection, or directory content as required by the nodal
type. Manipulation of these properties is accomplished through the POSIX
set of file and directory functions.