linux-kernel - Re: execve and /proc/PID/environ

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Date:	Tue, 18 Mar 2014 15:42:55 +0000
From:	Paul Jolly <paul@...tcv.org.uk>
To:	linux-kernel@...r.kernel.org
Subject: Re: execve and /proc/PID/environ

After a bit more reading, I have totally ditched my approach in favour
of http://lwn.net/Articles/531114/

Thanks for the great work on the Linux kernel

On 17 March 2014 20:33, Paul Jolly <paul@...tcv.org.uk> wrote:
> Hi - this is my first post here so I hope I'm duly abiding by the
> etiquette outlined in [1]. Indeed I am not subscribed to the list and
> so would be very grateful to be copied on any replies, per ADB's
> comment in [2]
>
> I am trying to build a fuse-based file system that implements a
> version of variant symlinks [3]
>
> Ignoring the expense of such a file system (for now at least), I've
> hit upon an issue that I think relates to [4]
>
> My fuse-based file system works by examining the environment of the
> calling process in order to resolve the 'symlink'. If however that
> process is performing an execve [5] with a filename argument that
> corresponds to a file within my file system, I essentially hit
> deadlock because I can't perform an open [6] on the /proc/PID/environ
> of the calling process.
>
> Perhaps someone can confirm the behaviour I am seeing is as expected?
>
> In this instance (where an execve is in progress), is there any way to
> get the environ of the calling process?
>
> For reference:
>
> $ uname -s -r -v -m -p -i -o
> Linux 3.11.0-18-generic #32-Ubuntu SMP Tue Feb 18 21:11:14 UTC 2014
> x86_64 x86_64 x86_64 GNU/Linux
>
> Many thanks
>
>
> [1] http://www.tux.org/lkml/#s3-1
> [2] http://www.tux.org/lkml/#s3-3
> [3] https://wiki.freebsd.org/200808DevSummit?action=AttachFile&do=get&target=variant-symlinks-for-freebsd.pdf
> [4] https://lkml.org/lkml/2012/3/10/174
> [5] http://man7.org/linux/man-pages/man2/execve.2.html
> [6] http://man7.org/linux/man-pages/man2/open.2.html



-- 
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paul@...tcv.org.uk
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