Copyright (C) 2001-2004 Bernhard Wiedemann (mailto:translucency04 at lsmod.de)
translucency is free software; you can redistribute it and/or modify under 
the terms of the GNU GPL version 2, or (at your option) any later version. 
 translucency is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 (use it at your own risk and joy!)
see file COPYING for more details

for usage information see translucency manual page

this module will install tweaked syscall handlers that redirect
each access for files within a given directory to another one while 
failed reads (nonexistent overlay files) will cause fallback 
to the original files thus virtually (logically) merging both directories
(possibly being on different medii with different filesystems each)


alternative names for the thing achieved earlier (mostly at filesystem level):
inheriting (ifs), stacking, translucency (tfs), loopback (lofs), overlay (ovlfs)
some of those actually have (by design) more power than my simple
syscall-redirecting module aproach.
There is even a block-level translucency in the md (software RAID) package
but that will most certainly fail for ISO9660 and other read-only filesystems.

currently translucency is relatively robust within usual patterns 
There are certainly serious buffer overflow conditions not caught
but this stuff is mainly aimed at productivity (allowing write on CD-ROM)
yet not on security. To be sure mount ro things that should not be changed
or chattr -i that_file

latest version should be available at
http://www.informatik.hu-berlin.de/~wiedeman/development/translucency.tgz
or from
http://translucency.sourceforge.net