Re: [PATCH] proc: Add complete process group list

From: KOSAKI Motohiro
Date: Tue Jun 22 2010 - 20:10:33 EST


> If a process is in more than NGROUPS_SMALL (32) groups, it's not possible
> for any other user space process to determine the list of groups it is
> in using /proc/<pid>/status.
>
> Increasing the list of groups listed by /proc/<pid>/status would lead to
> very long lines that file, and possible misbehavior of userspace programs
> that parse /proc/<pid>/status, so instead I have opted to create a new
> file /proc/<pid>/groups, which contains the list of supplementary groups
> for each pid.
>
> The new file /proc/<pid>/groups consists of a single group id per line,
> with each line being 11 characters long. This should be enough space
> for 16bit or 32bit group ids.
>
> This feature might be useful for a server listening on a unix domain pipe
> to determine the list of groups that a client process is in from its pid.
>
> Signed-off-by: Mike McCormack <mikem@xxxxxxxxxx>

Just dumb question.

Why don't you fix /proc/<pid>/status? Can we share your worry? I haven't review your patch
carefully yet. but your groups_proc_show() seems don't have heavy weight lock.

note: I'm not against your plan. it's just curiosity.


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