Re: [gentoo-dev] collision-protect -> protect-owned ?

[Alexandre Rostovtsev]

On Thu, 2013-01-03 at 00:25 -0500, Rick "Zero_Chaos" Farina wrote:
> On 01/03/2013 12:06 AM, Michał Górny wrote:
> > On Wed, 02 Jan 2013 19:49:02 -0800
> > ""Paweł Hajdan, Jr."" <phajdan.jr@g.o> wrote:
> >
> >> It came up again with <https://bugs.gentoo.org/show_bug.cgi?id=449918>,
> >> and I think it's worth to think about a better fix. I still keep hitting
> >> mysterious collisions with orphaned files from time to time.
> >>
> >> How about switching the developer profile from collision-protect to
> >> protect-owned, and proceeding with enabling protect-owned by default for
> >> all profiles? (not all developers are using the developer profile)
> >
> > Well, it all depends.
> >
> > protect-owned is easy and lazy. You just get errors on package
> > collisions, care about nothing else.
> >
> > collision-protect cares about every collision. It can help you notice
> > that *your* package lefts orphaned files for some reason or writes
> > where it is not supposed to write.
> >
> In the years I ran collision-protect I can say it prevented hundreds of
> merges of linux-firmware (because the kernel also installs firmware) and
> not much else.
>
> Would you be able to share more specific insight on how
> collision-protect helped protect files that need to be protected where
> protect-owned would have been inferior?

It protects files that cannot be owned by any one package, but must still
be protected, for example /usr/share/glib-2.0/schemas/gschemas.compiled

This file contains the compiled database of all your gsettings schemas.
It needs to be updated by running glib-compile-schemas every time you
install or remove a gsettings schemas xml file. Ebuilds for glib-based
stuff have to run glib-compile-schemas in pkg_postinst(), and the
gschemas.compiled must remain outside package manager control.

However, some packages' build systems have "make" or "make install" call
glib-compile-schemas by default. A careless developer who doesn't use
collision-protect *and* doesn't pay attention to protect-owned's warning
messages might accidentally allow his ebuild to compile and install 
/usr/share/glib-2.0/schemas/gschemas.compiled in src_install(), marking
the file as owned by his ebuild. When his ebuild is uninstalled, the
gschemas.compiled file would be removed, breaking the system.