linux-kernel - Re: 4096 byte limit to /proc/PID/environ ?

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Message-ID: <46D6CBED.4040301@moving-picture.com>
Date:	Thu, 30 Aug 2007 14:53:49 +0100
From:	James Pearson <james-p@...ing-picture.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Guy Streeter <guy.streeter@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: 4096 byte limit to /proc/PID/environ ?

H. Peter Anvin wrote:
> Guy Streeter wrote:
> 
>>On 6/1/06, James Pearson <james-p@...ing-picture.com> wrote:
>>
>>>H. Peter Anvin wrote:
>>>
>>>>I think this is the wrong approach.
>>>>
>>>>Many of these should probably be converted to seq_file, but in the
>>>>particular case of environ, the right approach is to observe the fact
>>>>that reading environ is just like reading /proc/PID/mem, except:
>>>>
>>>> a. the access restrictions are less strict, and
>>>> b. there is a range restriction, which needs to be enforced, and
>>>> c. there is an offset.
>>>>
>>>>Pretty much, take the guts from /proc/PID/mem and generalize it
>>>>slightly, and you have the code that can run either /proc/PID/mem or
>>>>/proc/PID/environ.
>>>
>>>The following patch is based on the /proc/PID/mem code appears to work fine.
>>>
>>
>>This thread has gone stale. The PAGE_SIZE limit still exists. Is this
>>solution acceptable?
>>
> 
> 
> Can we avoid the code duplication?

There isn't that much that is duplicated - and there are also bits of 
the /proc/PID/mem code that are not needed in this case, so I'm not 
really sure if it is worth doing.

I did submit a patch a few months ago - see:

<http://marc.info/?l=linux-kernel&m=117862109623007&w=2>

James Pearson
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