XDG_RUNTIME_DIR on a system with no "logins"

[Pekka Paalanen]

On Tue, 17 Dec 2019 19:18:15 +0100 (CET)
Jan Engelhardt <jengelh at inai.de> wrote:

> On Tuesday 2019-12-17 18:55, Guillermo Rodriguez wrote:
> 
> >Hi all,
> >
> >Weston requires XDG_RUNTIME_DIR to exist. The specification for this
> >(https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html)
> >says:
> >
> >===
> >$XDG_RUNTIME_DIR defines the base directory relative to which
> >user-specific non-essential runtime files and other file objects (such
> >as sockets, named pipes, ...) should be stored. The directory MUST be
> >owned by the user, and he MUST be the only one having read and write
> >access to it. Its Unix access mode MUST be 0700.
> >
> >The lifetime of the directory MUST be bound to the user being logged
> >in. It MUST be created when the user first logs in and if the user
> >fully logs out the directory MUST be removed. If the user logs in more
> >than once he should get pointed to the same directory, and it is
> >mandatory that the directory continues to exist from his first login
> >to his last logout on the system, and not removed in between. Files in
> >the directory MUST not survive reboot or a full logout/login cycle.
> >===
> >
> >But how is this done for a system where normally no users "log in",
> >e.g. a fixed-function embedded system with a graphical user interface?  
> 
> Well you simply create the directory before running the program that desires
> said directory. Does not matter if the user identity change is by way of
> a system manager, runuser(8), or login(8)/PAM (as called by xdm/etc.).
> 
> 
> kiosk.service
>  User=npc
>  ExecStart=/home/npc/startx.sh
> 
> startx.sh:
>  export XDG_RUNTIME_DIR=/home/npc/xdg
>  rm -Rf "$XDG_RUNTIME_DIR"
>  mkdir "$XDG_RUNTIME_DIR"
>  weston # or whatever

If you invent XDG_RUNTIME_DIR like this, please also make sure to
adhere to the XDG specification requirements. Specifically, it is a
good idea to use a tmpfs for this. If it is backed by an actual
disk, it may incur unnecessary disk I/O, which in embedded systems
might be really bad.


Thanks,
pq
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/wayland-devel/attachments/20191218/96fa7b6c/attachment.sig>