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List:       freebsd-hackers
Subject:    Re: mmap #2
From:       Julian Assange <proff () suburbia ! net>
Date:       1996-08-12 18:00:41
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> 
> 
> I think it was the other way around, it was truncating a mmap'd file.
> 
> Specifically, I had problems when the active file shrunk after an rmgroup,
> then I would get weird behaviour.  John said he saw where that could
> potentially be problematic, but I never saw any fixes run by that
> addressed it by name.

Hmm. I only test behavior in the first block. There are a lot of complicated
involvements that can happen when you play with the fd and the mmap at
the same time. A number of mmap implimentations failed to do shared
writes correctly, when "correctly" was defined opening a file, mmaping it,
writing something to the mmaped region, lseek()ing back to offset 0, and
then using read() to fetch data.

-- 
"Of all tyrannies a tyranny sincerely  exercised for the good of its victims  
 may be the most  oppressive.  It may be better to live under  robber barons  
 than  under  omnipotent  moral busybodies,  The robber baron's  cruelty may  
 sometimes sleep,  his cupidity may at some point be satiated; but those who  
 torment us for own good  will torment us  without end,  for they do so with 
 the approval of their own conscience."    -   C.S. Lewis, _God in the Dock_ 
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|Julian Assange RSO   | PO Box 2031 BARKER | Secret Analytic Guy Union        |
|proff@suburbia.net   | VIC 3122 AUSTRALIA | finger for PGP key hash ID =     |
|proff@gnu.ai.mit.edu | FAX +61-3-98199066 | 0619737CCC143F6DEA73E27378933690 |
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