[bug#63508] [PATCH v4 2/2] gnu: eudev: Have udevadm look in /etc/udev/rules.d. (Closes: #63508)

[Felix Lechner via Guix-patches via <guix-patches@gnu.org>]

Hi Bruno,

On Mon, May 29, 2023 at 1:28 PM Bruno Victal <mirai@makinata.eu> wrote:
>
> Perhaps instead of substituting, can you check if
> #:configure-flags or #:make-flags could be used instead?

Thank you for that suggestion! I did, and I do not believe it is
possible to specify a separate runtime path for udevadm via
./configure at this time.

It would be possible to add a second variable in configure.ac [1] and
use that in the relevant Makefile.am. [2] The change would get picked
up for the runtime search path throughout [3] and for the inotify
watch in udevd. [4]

In that scenario, it would be crucial not to modify the installation
directory that was specified via the variable prefix "udevrules_" in
several Makefiles.am, [5][6][7] which use Automake's "uniform" naming
scheme that leaves off 'dir'. [8]

Unfortunately, for most distros the distinctions are meaningless, and
perhaps even incomprehensible. I estimated the chance of upstream
acceptance as low. After some reflection, it was easier to patch the
runtime path directly in the lone place that matters to Guix. [2,
again]

I also do not see how the second variable needed can be introduced by
invoking 'make' in a different way. Please let me know if you find a
way. Thanks!

Kind regards
Felix

[1] https://github.com/eudev-project/eudev/blob/0a4dae19c1a191c8054fc2b9c2d592e797715a69/configure.ac#L180
[2] https://github.com/eudev-project/eudev/blob/0a4dae19c1a191c8054fc2b9c2d592e797715a69/src/udev/Makefile.am#L10
[3] https://github.com/eudev-project/eudev/blob/2703baf55615b7554fb67c4f1c241f057f8c0a79/src/udev/udev-rules.c#L53
[4] https://github.com/eudev-project/eudev/blob/2703baf55615b7554fb67c4f1c241f057f8c0a79/src/udev/udevd.c#L1306
[5] https://github.com/eudev-project/eudev/blob/2703baf55615b7554fb67c4f1c241f057f8c0a79/rules/Makefile.am#L9
[6] https://github.com/eudev-project/eudev/blob/2703baf55615b7554fb67c4f1c241f057f8c0a79/rules/Makefile.am#L35
[7] https://github.com/eudev-project/eudev/blob/2703baf55615b7554fb67c4f1c241f057f8c0a79/rule_generator/Makefile.am#L12
[8] https://www.gnu.org/software/automake/manual/html_node/Uniform.html