[comp.unix.wizards] Deletion of Unwritable Files

joe@cit-vax.Caltech.Edu (Joe Beckenbach) (11/19/88)

	I understand exactly how the mechanism of directory permissions
works. What I can't really understand is why a file which is read-only was
originally allowed to be deleted in the first place. I mean, sure, removing 
a link affects the directory inode. BUT IT POTENTIALLY AFFECTS THE FILE!
[Remove the last link, and close the last open(), and bye bye data!]

On other words, why is this particular alteration of a file allowable [deletion]
when less drastic alterations [writing] are specifically disallowed by the
file permissions?

	Or did someone near Day 1 slip up and no-one's had the heart to
correct it? :-|

-- 
Joe Beckenbach	joe@csvax.caltech.edu	Caltech 256-80, Pasadena CA 91125
	rjm-antibody [emeritus] for the CS department

bzs@encore.com (Barry Shein) (11/20/88)

>	Or did someone near Day 1 slip up and no-one's had the heart to
>correct it? :-|
>
>-- 
>Joe Beckenbach	joe@csvax.caltech.edu	Caltech 256-80, Pasadena CA 91125

No, no one has slipped up, you just don't understand the file system
design or you're inventing your own and declaring it to be the one
true way. Referents and contents are separate concepts and you are
free to protect either independantly. This new-fangled directory
sticky bit thing has been added which more or less addresses your
concerns. It's a reasonably clever idea I guess tho there have always
been other solutions (eg. a setuid program which adds files in a
controlled manner, mail systems have always done this.)

The primary problem with operating systems are people who can only
think of one way to do something and declare the O/S deficient because
it doesn't accommodate their limited view rather than perhaps
adjusting to its original design.

Unix is currently collapsing under this weight and has now ceased to
be a technical object, it's a political object, anyone with power to
modify it to suit their (often misguided) whims does, they just need
to know how to scream loudly enough, rational consideration is passe'.

Ah well, it was fun while it lasted...

	-Barry Shein, ||Encore||