On Thu, Apr 14, 2016 at 10:34:48AM +0100, Richard W.M. Jones wrote:
> It's not possible to read the process umask without also modifying it,
> which is what umask(2) does. A library cannot read umask safely,
> especially if the main program might be multithreaded.
>
> Add a new status line ("Umask") in /proc/<PID>/status. It contains
> the file mode creation mask (umask) in octal. It is only shown for
> tasks which have task->fs.
>
> For the library this allows me to read the umask from
> /proc/self/status.
>
> This patch is adapted from one originally written by Pierre Carrier:
> https://lkml.org/lkml/2012/5/4/451
Sorry, I meant to add an example of what this looks like:
$ grep Umask /proc/1/status
Umask: 022
$ grep Umask /proc/2/status
Umask: 022
$ grep Umask /proc/self/status
Umask: 022
$ umask 002
$ grep Umask /proc/self/status
Umask: 02
Rich.
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