Re: [patch] Add note about there is no default permission mode in umask man page

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

Hi Kevin!

On 7/23/20 8:39 PM, kevin dankwardt wrote:
> man pages version 5.08
> 
>>From 884004f93893cb01002d886387c78ba58d1aff53 Mon Sep 17 00:00:00 2001
> From: Kevin Dankwardt <kevin.dankwardt@gmail.com>
> Date: Thu, 23 Jul 2020 11:31:55 -0700
> Subject: [PATCH] Add note about there is no default permission mode
> 
> ---
>  man2/umask.2 | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/man2/umask.2 b/man2/umask.2
> index e74e8ef..6bc8ba1 100644
> --- a/man2/umask.2
> +++ b/man2/umask.2
> @@ -138,6 +138,8 @@ Inspecting this field in
>  .IR /proc/self/status
>  allows a process to retrieve its umask without at the same time changing
> it.
>  .PP
> +The Linux kernel has no default permission modes for created files or
> directories and thus the permission modes are non-deterministic for a file
> or directory created with no requested permission modes.
> +.PP
>  The umask setting also affects the permissions assigned to POSIX IPC
> objects
>  .RB ( mq_open (3),
>  .BR sem_open (3),

The umask(2) page seems the wrong place for a note such as this,
since this doesn't really relate to the umask. I assume that what
you really care about here is a call to open(2) that wrongly 
omits mode:

fd = open(path, O_CREAT | O_RDWR);

The open(2) manual page already warns against that, but I have 
reworded the text in that page a little to further emphasize the
point.

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/