Modifications to INSTALL/DEINSTALL (mk/pkginstall)

["Johnny C. Lam" <jlam%NetBSD.org@localhost>]

I am going to modify the pkgsrc/mk/pkginstall module that generates the
default INSTALL/DEINSTALL scripts for packages in the following ways:

1. Change the scripts so that they can be invoked without modifying the
   package metadata directory (${PKG_DBDIR}/${PKGNAME}).

   Currently, when the INSTALL script is invoked, it does an "UNPACK"
   action which unpacks several scripts into the package metadata
   directory, followed by and invoking each of those scripts to do the
   {PRE,POST}-INSTALL actions.  This "UNPACK" action assumes the metadata
   directory is mutable, which may not be true for other package formats
   than the pkgsrc "pkg" format.

   I propose that the scripts be changed so that they can be invoked
   without the assumption of a mutable metadata directory, yet still
   preserving their "idempotent" property of being able to invoke an
   action multiple times yet only doing the actions once.

   There are two ways to do this change.

   The first is simply to place all of the scripts into ${PREFIX}.  For
   example, we could place all of the +INSTALL, +DEINSTALL, +FONTS, +FILES,
   etc., into ${PREFIX}/share/pkginstall/${PKGNAME} and simply have the
   install and deinstall scripts for the package just invoke the scripts in
   ${PREFIX}.  This requires a secondary change to pkg_add(1) to
   pre-extract that directory to allow for proper PRE-INSTALL checks to
   take place.

   The second is modify the scripts to be just be a single INSTALL and a
   single DEINSTALL script that don't unpack anything.  This doesn't
   require any changes to pkg_add(1) or pkg_delete(1).

   I am planning on doing the second option.

2. Remove direct use of pkg_admin(1) and pkg_info(1) in the scripts.

   I propose abstracting the information requests that require pkg_admin(1)
   and pkg_info(1) into shell functions that can be defined in files under
   mk/pkgformat/${PKG_FORMAT} and are pulled in as additional templates.
   This allows for the scripts to be more generally usable by other package
   formats and tools.

   This is a precursor to my other project to improve the encapsulation of
   pkgformat-specific code into mk/pkgformat.

Comments?

-- Johnny C. Lam