[OE-core] Directory Ownership - RFC

[Mark Hatle]

I've spoken to a few people on this..  Revision and comments below in-line...

On 6/6/11 11:31 AM, Mark Hatle wrote:
> I'm starting to work on an enhancement that will allow (binary) packages
> produced from the recipes to clearly own directories.  I'm trying to find a
> simple enough solution that avoids having to change most recipes, while still
> giving the developer and distribution designers flexibility to establish clear
> lines of ownership and system/distribution policy.
> 
> Problem
> -------
> 
> Currently directories are "owned" by whatever packages use them.  This works for
> the most part, but can lead to problems when many different packages use the
> same directory -- such as /bin, /sbin, /etc, /lib, /usr/lib, etc....
> 
> When packaging (at least with RPM), the directory permissions, owners and groups
> are automatically included into the package using the existing FILES_pkg globbing.
> 
> The primary issue is that the first package that creates/uses the directory is
> generally the one that sets the permissions, owner and group.  For many
> directories 0755, root, root is perfectly fine, however other standard
> directories may require specific modes, owners and groups...  (We recently had
> an issue with sudo creating /var and /var/lib as 0700... which caused failures
> in other packages.)
> 
> This causes issues with consistency between recipes as well as potential
> security implications on multi-user systems.
> 
> Proposed solution
> -----------------
> 

Remove the items below

> Add a new "DIRS" variable, similar to the existing "FILES", that will specify
> the directories for a package to own.  By default DIRS = FILES, i.e. DIRS_${PN}
> ?= FILES_${PN}
> 
> The purpose of this is to automatically inherit the files list and walk the
> directories in the same way that existing recipes do it.  Resulting in no change
> to most recipes, but also giving a package a clear way to override the values
> and specify select directories to own.
> 
> A key difference in behavior between the DIRS and FILES methods would be any
> directory specified with a "/" at the end of the name would avoid walking the
> directory.  For example, DIRS = /usr/share/foo  would include "foo" and all of
> the directories under it.  While DIRS = /usr/share/foo/ would simply include
> "foo", and avoid walking the subdirectories.  Q: Is this confusing behavior?
> 
> In addition to the above, a new way to exclude directories from being included
> -- even if in the DIRS list is needed to keep things "simple".

Remove the items above

This is thought to be way too confusing, as DIRS is the same as FILES 99% of the
time.  Instead, the portion below on the EXCLUDEDIRS would be modified to work
like "FILES".  It would attempt to use globbing to walk directories and such.

So if you didn't want all of the directories in say ${mandir}, you would add:

${mandir}/*

to the EXCLUDEDIRS.

This would have the effect of excluding all directories in and under the
${mandir} path.

The only difference in behavior between FILES and EXCLUDEDIRS is that
directories specified w/o globbing at the end would be treated as just THAT
directory.  If there is globbing as the last item (ending with a "*"), then
whatever is found, and those directories contained within will be excluded from
ownership as well.

> This requires adding a new variable that that will contain a list of directories
> that should be ignored when processing the FILES_pkg.  This exclusion list only
> covers the directories themselves, not the files that would normally be found
> inside of them.
> 
> The exclusion variable would be set, by default, to (based on base-files):
> 
> /tmp ${localstatedir}/volatile/lock ${localstatedir}/volatile/tmp
> /home ${prefix}/src ${localstatedir}/local
> /bin /boot /dev ${sysconfdir} ${sysconfdir}/default
> ${sysconfdir}/skel /lib /mnt /proc /home/root /sbin
> ${prefix} ${bindir} ${docdir} /usr/games ${includedir}
> ${libdir} ${sbindir} ${datadir}
> ${datadir}/common-licenses ${datadir}/dict ${infodir}
> ${mandir} ${datadir}/misc ${localstatedir}
> ${localstatedir}/backups ${localstatedir}/lib
> /sys ${localstatedir}/lib/misc ${localstatedir}/spool
> ${localstatedir}/volatile ${localstatedir}/volatile/cache
> ${localstatedir}/volatile/lock/subsys
> ${localstatedir}/volatile/log
> ${localstatedir}/volatile/run
> /mnt /media /media/card /media/cf /media/net /media/ram
> /media/union /media/realroot /media/hdd
> /media/mmc1
> /srv
> ${prefix}/local ${prefix}/local/bin ${prefix}/local/games
> ${prefix}/local/include ${prefix}/local/lib ${prefix}/local/sbin
> ${prefix}/local/share ${prefix}/local/src
> /var/mail
> 
> Assuming the variable is called "EXCLUDEDIRS" (I'm still looking for a good
> variable name), a recipe would be able to override it for the recipe as a whole,
> or for the split packages.  Almost all recipes would not need to ever override
> the value.
> 
> ----
> 
> The net result is any existing package will continue to work.
> 
> A new distribution wide set of directories that regular recipes should not own
> can be created.
> 
> And the few key packages that need to own directories can do so, and be sure
> that they are the exclusive owners.
> 
> Comments, Suggestions?
> 
> --Mark
> 
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