Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pasteur!ames!coherent!dplatt
From: dplatt@coherent.com (Dave Platt)
Newsgroups: comp.sys.mac.programmer
Subject: Re: help
Message-ID: <23315@coherent.com>
Date: 7 Apr 89 17:40:42 GMT
References: <3369@nunki.usc.edu> <11251@well.UUCP>
Reply-To: dplatt@coherent.com (Dave Platt)
Organization: Coherent Thought Inc., Palo Alto CA
Lines: 37

In article <11251@well.UUCP> svc@well.UUCP (Leonard Rosenthol) writes:
> In article <3369@nunki.usc.edu>, anthonyt@castor.usc.edu (Anthony Tieu) writes:
> > I am writing an init to keep users from writing on to the hard disk.
> > I would like to know how to detect and obtain the last file or folder
> > that was created, so I can delete it. Any comments is welcome..
> > 
> 
> It seems to me that is the DEFINATELY the wrong approch to the problem!
> If I were doing this (which I am not, thank god) I would simply patch
> _Open and _Create so that if a appl tries to open a file it is returned
> ReadOnly and _Create always returns an error so no files are created.
> You might be careful with these as this would mean that NOTHING could
> write to the disk (including the OS, Inits, DA's ,etc.)

Another approach would be to do as Jeff Shulman's "DiskLock" desk
accessory does... set the software-lock bit in the disk's HFS volume
structure.  This has the same effect (from the user's point of view) as
setting the write-protect tab on a floppy disk... the Finder will
display the little padlock icon in the disk and folder windows.  Of
course, a sufficiently-knowledgeable user armed with the right tools
could undo the locking... but the same user could defeat Anthony's
original idea simply by booting from a floppy disk and bypassing the
INIT entirely.

Locking an entire hard-disk will render many of the applications on it
entirely unusable.  Any application that wishes to create a scratch-file
will be unable to run (I'm thinking of MS Word in particular).  Any
application that tries to save the Clipboard to disk will have problems.
The same sort of problems will occur with Anthony's "delete the last
file created" approach, too... and perhaps even more severely.  Imagine
what Word might do if it were to create a temp file, and then (several
seconds later) find that the file had mysteriously disappeared.  Not good...
-- 
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