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Plasma Active Three releasedPlasma Active Three releasedPosted Oct 16, 2012 17:20 UTC (Tue) by viro (subscriber, #7872)In reply to: Plasma Active Three released by efraim Parent article: Plasma Active Three released
"Entirely independent way" meaning...? Implementing fs-related parts of v7 API is trivial, especially when you essentially don't care about races (and I wouldn't bet a dime on safety of fs syscalls from what-was-it-called... their "stay in background, get woken up on interrupts" kludge... TSR? At most I'd expect them to disable interrupts in what they deemed to be critical areas; most likely would've missed a bunch of races, at that).
So no, I don't think they bothered to nick actual v7 source. But that definitely had been a (trivial) reimplementation of existing interface.
It's about a man-month of work to implement and such reimplementations had been done quite a few times. Including initial debugging, enough to make it mostly usable, if not quite safe. In their case I'd expect the most PITA to have come from making it play nice with the preexisting pile of garbage (FCB syscalls).
If your point was that hierarchical filesystems had turned out to be useful enough for a lot of systems to reimplement them - sure, that's true, but what the hell does that have to do with independent anything? If we are talking about bitty-box parodies on OS, might as well bring Amiga - at least there it really seems that influence might have been not entirely from Unix (I don't know the TRIPOS history well enough to tell, but at least in that case a direct influence from Multics is plausible).
Since late 60s it had been fairly common. And it's simple enough to describe and implement by such description, at least in the basic forms[1]. More to the point, a lot of software depends on having that available, so not implementing a hierarchical fs means serious self-inflicted PITA in porting and redesigning user interfaces. The tricky part is maintaining a sane directory tree layout, but "let's not bother with that" is a lousy answer - all attempts so far seem to have been sucky. FWIW, I'm very sceptical about the tags-based approaches - the problem is real, but I don't think it's solvable that way...
[1] Once you have to deal with the UCB bad trips (cross-directory renames, handling of dangling symlinks, etc.) the things get more hairy, of course, but that's a separate story.
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Plasma Active Three released Posted Oct 16, 2012 19:37 UTC (Tue) by anselm (subscriber, #2796) [Link] Even the Apple II had a hierarchical file system with an OS that was not an obvious Unix knockoff. It is reasonable to say that in the early 1980s, hierarchical file systems were simply an idea whose time had come.
Plasma Active Three released Posted Oct 16, 2012 21:01 UTC (Tue) by dgm (subscriber, #49227) [Link]
> It is reasonable to say that in the early 1980s, hierarchical file systems were simply an idea whose time had come.
I would be, if you replaced the date with mid to late 60s.
Plasma Active Three released Posted Oct 16, 2012 21:06 UTC (Tue) by rmini (subscriber, #4991) [Link]
Interestingly enough, MS was a v7 licensee before MS-DOS was around (Xenix). As an historical aside, MS-DOS handled protecting its non-reentrant APIs by setting a flag in memory that TSRs were supposed to check (with interrupts disabled) before making any DOS calls.
Plasma Active Three released Posted Oct 21, 2012 23:06 UTC (Sun) by efraim (subscriber, #65977) [Link]
My original point is: the "original reimplementation" thing just means that the creators of those system found the feature useful enough to implement it.
If those systems were UNIX-derived, it would not say much - after all they'd inherit the implementation together with source code or at least API design.
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