Re: Syscall table AKA hijacking syscalls

[Libor Vanek <libor@conet.cz>]

Jörn Engel wrote:
> On Fri, 2 January 2004 19:58:48 +0100, Libor Vanek wrote:
> 
>>On Fri, Jan 02, 2004 at 07:04:31PM +0100, Jörn Engel wrote:
>>
>>>On Fri, 2 January 2004 17:59:22 +0100, Libor Vanek wrote:
>>>
>>>>This is also something (but just a bit) different - I don't need "change 
>>>>notification" but "pre-change notification" ;)
>>>
>>>"Vor dem Spiel ist nach dem Spiel" -- Sepp Herberger
>>>
>>>Except for exactly two cases, pre-change and post-change and the same,
>>>just off-by-one.  So you would need a bootup/mount/whenever special
>>>case now, is that a big problem?
>>
>>Probably my english is bad but I don't understand what are you trying to 
>>say (except the german part ;-))
>>A bit more about pre/post-change (if this is what are you trying to say) - 
>>I need allways pre-change because after file is changed I can no longer get 
>>original (pre-change) version of file which I need for snapshot.
> If you take a snapshot on every change within your scope, it doesn't
> really matter whether you do it before or after the change.  Before
> change n is just after change n-1.  All you have to do is take another
> snapshot before the first change, that is the special case.

But this special case in fact means to copy all the data, if wanted to do it 100% working ;-) And I suggest that it wont' go through my exam ;)

> Actually, with userspace notification in place, you could even get
> this with just cvs.  Whenever a file is changed, commit.  cvs add on
> creation, etc.  Yes, it sucks, but implementation simplicity has it's
> own beauty and it would only take a few minutes. :)

I've heard about some fs from Microsoft which should have cvs-like behaviour for all the time ("I want this file version from yesterday") - but I haven't had any details (and I suppose performance hit must be big)

-- 

Libor Vanek