[Buildroot] [PATCH] Makefile: check rootfs overlays with BR2_ROOTFS_MERGED_USR enabled

[Yann E. MORIN <yann.morin.1998@free.fr>]

Carlos, All,

On 2018-05-05 10:47 -0300, Carlos Santos spake thusly:
> > From: "Yann E. MORIN" <yann.morin.1998@free.fr>
> > To: "Carlos Santos" <casantos@datacom.ind.br>
> > Cc: "buildroot" <buildroot@buildroot.org>
> > Sent: Saturday, May 5, 2018 7:01:00 AM
> > Subject: Re: [Buildroot] [PATCH] Makefile: check rootfs overlays with BR2_ROOTFS_MERGED_USR enabled
> 
> > Carlos, All,
> > 
> > On 2018-05-03 09:19 -0300, Carlos Santos spake thusly:
> >> Since commit 0db34529f48 we use rsync with the --keep-dirlinks option to
> >> prevent overlays from accidentally overwriding /{usr,bin,sbin,lib} links
> >> when BR2_ROOTFS_MERGED_USR option is enabled. Unfortunately this also
> >> prevents replacing a symlink by a directory on purpose (e.g. /var/log,
> >> to persist system logs).
> > 
> > In that case, I suggest your use a post-build script instead.
> 
> That was my first approach.
> 
> > In facct, I think that any modifications that change the layout of the
> > filesystem should be done as a post-build script rather than an overlay.
> > 
> > So, I am pretty much reluctant to see this patch go in.
> 
> This change does not prevent the user from using a post-build but I'd
> prefer to let Buildroot check the correctness of user changes as much
> as possible instead of just prohibiting them.

It's not about prohibiting them.

But I'd prefer we keep things simple in Buildroot, and since there is
already a way to do it, I don't mind that overlays do not provide this
solution. A post-build script is way more versatile when it comes to
changing the layout.

> Overlays are simpler to create and less error prone than scripts. They
> are also self-documented, since a "find" or "tree" command shows the
> resulting structure.

True, but they are less versatile...

Regards,
Yann E. MORIN.

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