From: Aidan Kehoe (kehoea at domain parhasard.net)
Date: Sat 20 Jul 2002 - 20:24:50 IST
Ar an 20u la de mi 7, scriobh kevin lyda :
> actaully i think soft links were invented because you can't hard link
> directories.
But you could hard link directories, back when soft links were
being invented, AFAIK.
> apparently some systems limited soft links to the same device but
> gave up after a while.
Why?
> sadly, i can't find a link that supports that...
>
> > classic Berkeley hackery (cf. gethostbyname, h_errno, and the
> > resultant problems implementing mt-safe interfaces); they do what they
> > were intended for, but break fairly easily, in this case when the
>
> soft-links are like one way hyperlinks (ala the www). the target does
> not inform those that target it when it moves or gets deleted.
A better way of doing it would be a) have global unique filesystem
identifiers for every FS created (such that the chance of two of them
clashing is miniscule; 64 bits creatively used would do it, I'd say),
and b) implement the target info for the soft link as a {FSID, inode}
pair; the OS can work out if the thing linked to is now on a different
mount point, or has been moved. (HFS fans, is that what's done? Or are
aliases implemented differently?)
> and in fairness to berkeley, their socket api is very portably across
> network protocols. i've seen appletalk code written with the socket api.
> and ipv6 code is written with the socket api. the few things that
> return static buffers or are not protocol independant are truly annoying,
> but they did get a lot of that right.
Yeah. Berkeley made Unix into the world-beater it was in the eighties;
FFS, quotas (well, some guy in Australia, but it was released with
BSD), multiple network protocols, multiple terminal support and more,
and they deserve recognition for it. That doesn't mean what they did
was perfect; some of it wasn't *that* well designed, but it was there,
and it was free from restrictive licences. :-) .
-- I'm not a pheasant plucker / I'm a pheasant plucker's son. I'm just a'plucking pheasants / 'Til the pheasant plucker comes.
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