$NetBSD: README,v 1.5 2002/12/26 17:08:56 jlam Exp $

For more general information about the use of buildlink2, see the file
buildlink2.txt in this directory.

 0 buildlink2 Wrapper Script System
 ==================================

The purpose of the buildlink2 wrapper script system is to replace calls to
compiler tool with scripts that tranlate any arguments into their buildlink
equivalents, then invoke the actual compiler tools with the translated
arguments.  The pkgsrc/mk/buildlink2 directory contains bits of the wrapper
script system for the buildlink2 framework.  The wrapper script system is
composed of three parts: the main wrapper script, the "cache", and the
"logic" script.

 0.1 Main wrapper script
 =======================

The main wrapper script for a compiler tool (cc, ld, as, etc.) is
generated from wrapper.sh, except for the libtool wrapper script which is
generated from libtool.sh.  The wrapper scripts share a common set of logic
files that translate arguments into their buildlink equivalents.

 0.2 Cache
 =========

The cache is a giant Bourne shell "case" statement that stores
pre-translated arguments from previous wrapper invocations.  This allows
speedy translation of already-seen arguments without having to run the
utilities needed to perform a translation from scratch.  There are two
caches: the common cache and a wrapper-specific cache.  The common cache
is used by all wrapper scripts.  The wrapper-specific cache is read before
the common cache and contains wrapper-specific argument translation that
shouldn't be used by other wrapper scripts.

 0.3 Logic script
 ================

The logic script contains a large "case" statement that handles the
actual translation of an argument into its buildlink equivalent.  The logic
script also invokes a wrapper-specific logic script which may contain extra
commands that perform further translation of an argument after the main
translation has been performed by the logic script.  Finally, the logic
script may save the translations results into a cache file if requested by
the wrapper script.