[Buildroot] [PATCH 19/20] system: make systemd work on a read-only rootfs

[Arnout Vandecappelle]

On 18-07-17 19:25, Yann E. MORIN wrote:
[snip]
> With a line like:
> 
>     C /var/something - - - -
> 
> it will look for /usr/share/factory/something and copy it (recursively
> if it is a directory) to /var/something, but only if it does not already
> exist there.

 So we could just have a line

C /var - - - -

and be done with it?

[snip]
> Note that we treat symlinks a little bit specially, by creating symlinks
> to the factory defaults rather than copying them.

 You forgot to explain why. I guess because a relative symlink that was created
based on the /usr/share/factory location wouldn't work any more.

 However, it is possible that a package creates a relative symlink based on the
/var location. Most symlinks that we create in Buildroot stupidly assume that
all the path components are not symlinks. So a package could for example do

ln -sf ../srv/www $DESTDIR/var/www

This will now create a broken symlink. It's fine as long as it is copied as-is
to /var, but not with your approach...

[snip]
> +define SKELETON_SYSTEMD_ROOT_RO_OR_RW
> +	mkdir -p $(TARGET_DIR)/etc/systemd/tmpfiles.d
> +	mkdir -p $(TARGET_DIR)/usr/share/factory
> +	ln -s usr/share/factory $(TARGET_DIR)/var

 Since other stuff may also want to put things in /usr/share/factory, I think it
should be
	mkdir -p $(TARGET_DIR)/usr/share/factory/var
	ln -s usr/share/factory/var $(TARGET_DIR)/var

 Regards,
 Arnout

[snip]

-- 
Arnout Vandecappelle                          arnout at mind be
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