Re: [Ltib] Support for %Post section of .spec file?

[Stuart Hughes]

On Tue, 2008-09-16 at 15:12 -0500, Chip Webb wrote:
> Hi Stuart,
> 
> Thanks again for the quick response. I think we're saying the same
> thing, and I agree that it's not possible with the current version of
> LTIB
> to use a %Post section. The reason is that the build-phase
> source .spec file
> that is under dist/lfs-5.1/mypackage/mypackage.spec can't run the
> %Post section. However, the deploy phase binary .spec file 
> (which is automatically created by ltib) can run the %Post section, if
> it exists. 

No, that's not how it works.  That section you're patching is only for
use with -m scdeploy, which is for single package mode. 


> 
> So the patch I submitted essentially takes the %Post post section
> (if present) from the build-phase .spec file and copies it into the
> automatically created deploy-phase .spec file, so that during
> the deploy phase, RPM runs the %Post scriptlet when doing the deploy.
> 

There is no real deploy phase as you mean it.  -m scdeploy is a mnemonic
to match the real rpm modes -m scbuild -m scinstall.  These let you do
things with rpm without rebuilding everything (and unpacking).  The
deploy phase just does the rpm %install and then actually installs the
rpm on the host in the rootfs are, which is the NFS area for the target
rootfs. 

> Here's an example. It works with the ltib patch I submitted this
> morning.
> The example below (which isn't exactly what I'm doing, but serves
> to illustrate the point) allows multiple packages to edit a file
> called /etc/pkglist.
> > %Post
> > set -x
> > echo "<**** Registering mypackage in [target]/etc/pkglist ****>"
> > cd $RPM_INSTALL_PREFIX/
> > echo mypackage >> etc/pkglist

Which version are you on, I'm surprised that works.  If it's an old one,
then  yes you can do that because it doesn't rely on anything
target-ish.  However it's stuff run by the host.  All you're doing is
taking advantage of the fact the rpm install phase is run as root and
therefore you can do pretty much what you like.  As this is on your host
you can see this is a very bad idea.  LTIB goes to great lengths to make
sure that you can't overwrite host files, this would defeat that.  So
please don't do this.

On later versions of LTIB (current Savannh), you'll see rpms are install
with (for example):

/opt/ltib/usr/bin/rpm --root /home/seh/ltib_bsps/savannah_ltib/rootfs --dbpath 
/var/lib/rpm --prefix / --ignorearch -ivh --force --excludedocs --define 
'_tmppath /tmp/ltib' 
/home/seh/ltib_bsps/savannah_ltib/rpm/RPMS/arm/sysconfig-1.2-1.arm.rpm

The important thing here is that --root <ltib-rootfs> is used.  What
this does is to chroot first to the root directory.  This means that you
can't hose your host filesystem.  However it also means that you would
not be able to run %post, as it would try to start a shell, which unless
the target is the same as the host, will not work.

> 
> I hope that this helps explain what I'm trying to do.
> 

To safely do the same thing (e.g. just modify files), you can either:

1/ use an rc.local
2/ put stuff into a merge directory
3/ have another rpm which places your custom files where you want on the
target system (in the %files section).

Regards, Stuart