Mandatory File Locking
Mark Haney
mhaney at ercbroadband.org
Fri Nov 21 19:26:28 UTC 2008
test test wrote:
> Hello,
>
>
>
> I need to put a mandatory lock on /dev/fb0 (presently any file) in Linux OS.
> But in actual scenario it will be a device file.
>
>
>
> OS: Ubuntu Hardy Heron 8.04
>
>
>
> Scenario:
>
> 1. Process A is super process (controller).
>
> 2. Process B is normal process.
>
> 3. *Process A and B are non-cooperating process, they simple don't know
> about other process existence and they are not interested in knowing it
> either.(So, advisory locking is out of scope). *
>
> 4. At particular instance Process B is accessing /dev/fb0.
>
> 5. Now, Process A wants access to it.
>
> 6. Process A locks /dev/fb0
>
> 7. It can hold the lock as long it wants & in any case process B cannot
> write anything to it. (It's better if B cannot read the contents also).
>
>
>
> I also changed permissions of directory and lock file.
>
>
>
> I used:
>
> chmod g-x test
>
> chmod g+s test
>
>
http://www.hackinglinuxexposed.com/articles/20030623.html
That was a quick google on file locking in Linux. Are you coding these
processes yourself? I mean there are documented ways of locking files
programmatically in linux as well.
Based on what you posted the file locking should work. Are you saying
it doesn't?
--
Frustra laborant quotquot se calculationibus fatigant pro inventione
quadraturae circuli
Mark Haney
Sr. Systems Administrator
ERC Broadband
(828) 350-2415
Call (866) ERC-7110 for after hours support
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