[CMake] Specifying a file owner

[Domen Vrankar]

> Hi,
>
> I was looking at https://www.cmake.org/Bug/view.php?id=3602 "Add
> possibility to change file owner into install macro".

I am also interested in this feature but mostly because of packaging
limitations - implementing this feature would give CPackRPM the
ability to set user and group for every file/directory/link that
generated RPM will contain. This can already be done by a workaround -
providing the file with user and group in
CPACK_RPM_<component>_USER_FILELIST- but extending install command
would be a more elegant solution.

> I believe we should in fact support specifying the file owner, and
> handle the case where that owner does not exist in the same way (from a
> user experience) as we handle platforms that don't support SETUID - i.e.
> do nothing (logging some kind of non-fatal error would be good).

I am usually using install target for installing the entire project
locally for testing and in such cases I prefer to have everything
installed as current user in a subdirectory of my build directory.
I believe that this use case should be solved by providing a new
target - rootless_install - which ignores USER and GROUP setting in
INSTALL commands.

On the other hand when I want to install something permanently on my
system after building the project I would prefer that user and group
settings are applied and in such case I would prefer a fatal error if
user/group permission can not be applied (preferably with CMake
rolling back the changes that it already made on the file system - new
feature?). This could be part of current install target.

> Automatically creating a non-existing user would also be nice but is
> orthogonal and should be handled as a separate feature request rather
> than muddying the waters around this feature discussion.

Not certain if I'd like this feature or not but I agree that it should
be discussed as a separate feature.

There was also a third case provided by Brad:
3.) What if installing into a DESTDIR that exists on a mount point and
the user names should be translated to uids with $(DESTDIR)/etc/passwd
instead of /etc/passwd? How should this be specified?

I've already encountered a situation where I mounted a partition that
had files with users and groups that were present in /etc/passwd but
under different uids and gids so ls -l was showing numbers instead of
names. In such case only root user may create new files since they
will have a different uids and gids so nothing changes... I'd say that
different uids for the same user name is users problem and should be
ignored by CMake.

Regards,
Domen