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[20060727]
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pkgsrc: the big picture
When we started pkgsrc in 1997, the whole engine was basically one
big Makefile, pkgsrc/mk/bsd.pkg.mk. I've stopped working on
pkgsrc some time ago, but things haven't stopped. Quite on the
contrary, pkgsrc has evolved a big deal, and the single big
Makefile was split into many seperate files. I won't claim to
still have an overview, and each time I look into pkgsrc/mk, I
wonder where to start. Obviously the best way would be starting with
bsd.pkg.mk and reading through everything, but I'll defer that
for the time being. Instead, I tried getting some overview
by looking at the include structure of the files, and with
some shell magic and
dot(1), this was easily done:
% cd /usr/pkgsrc/mk
% ( echo 'digraph pkgsrc {' ; \
grep ^.include * \
| sed \
-e 's,:[^/]*/," -> ",' \
-e 's,:.*<," -> ",' \
-e 's,\.\./\.\./mk/,,' \
-e 's,\.\./mk/,,' \
-e 's,mk/,,' \
-e 's,[>"]$,";,' \
-e 's,^, ",' ; \
echo "}" ) > /tmp/pkgsrc.dot
% dot -Grankdir=LR -Nfontname=Adobe -Tpng /tmp/pkgsrc.dot > /tmp/pkgsrc.png
The
result
shows that bsd.pkg.mk pulls in a lot of files from directories
named after the various stages of the build process (pkgsrc/mk/fetch,
pkgsrc/mk/checksum, ...). This makes identifying which code is
used where easier in the long run.
In the lower half, a lot of "buildlink" files read bsd.prefs.mk to
find out about user preferences and provide defaults for several
applications or subsystems like X11, PAM, Berkeley DB etc.
These buildlink files are aligned with a number of "builtin"
files, which determine if several features are possibly built
into any of the many operating systems that pkgsrc runs on,
or if packages that provide that functionality need to be installed,
in order to, say, have PAM available for a package to use.
Documentation on many of these files is in the form of comments
of the files. There's also some documentation in the pkgsrc
guide in pkgsrc/doc/guide, but I don't know how much that is
in sync with the code. (I think quite some work is needed on
the pkgsrc guide - any takers?)
[Tags: pkgsrc]
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