Painless Perl Ports
with cpan2port
Benny Siegert ‹bsiegert@gmail.com›
The MirOS Project (http://www.mirbsd.org)
FOSDEM 2009

Contents
1. Introduction
Perl, MirPorts
2. Presenting cpan2port
with live demo
3. Implementation notes
4. Conclusion

Perl and CPAN
‣ Comprehensive Perl Archive Network
‣ 15 000 modules by >7000 authors
➡ lots of ports to create
‣ CPAN module and shell
(perl -MCPAN -eshell)
does not know about ports and packages

Ports
‣ mechanism to install 3rd-party software in
BSD operating systems
‣ ports are used to create binary packages
‣ installation “recipe” in a Makefile + metadata
↪What is required to create a port?

# $MirOS: ports/devel/svk/Makefile,v 1.4 2008/10/04 19:46:50 bsiegert Exp $
one-line description
COMMENT= distributed version control system
VERSION= 2.2.0
distribution name, version
DASH_VER= 0
DISTNAME= SVK-v${VERSION}
PKGNAME= svk-${VERSION}-${DASH_VER}
category
CATEGORIES= devel net
HOMEPAGE= http://svk.bestpractical.com/
MASTER_SITES= ${MASTER_SITE_PERL_CPAN:=../by-authors/id/C/CL/CLKAO/}
where to download
RESPONSIBLE= Benny Siegert <bsiegert@gmx.de>
# LGPL
PERMIT_PACKAGE_CDROM= Yes
PERMIT_PACKAGE_FTP= Yes
PERMIT_DISTFILES_CDROM= Yes
PERMIT_DISTFILES_FTP= Yes
B_R_DEPENDS+= ::archivers/p5-PerlIO-via-Bzip2
[...]
dependencies!
CONFIGURE_STYLE= perl
CONFIGURE_ARGS+= --defaultdeps
.include <bsd.port.mk>

Other metadata
‣ DESCR: long description (about 100 words)
‣ PLIST: packing list (automatically created)
‣ distinfo: checksums for distfile
(automatically created)

Introducing cpan2port
‣ Perl script allowing the rapid creation
of Perl module ports
‣ using the CPAN module
‣ creates a stub port which may be refined
and drops you to a shell
‣ only a few more commands needed
in the ideal case

… live demo …
Log::Dispatch module

Implementation notes

How does it work?
‣ CPAN.pm discovers most of the information
needed
‣ finds the distribution name for a module
(e.g. D/DR/DROLSKY/Log-Dispatch-2.22.tar.gz)
‣ for more info, “make“ the module inside cpan

How does it work?
‣ CPAN.pm discovers most of the information
needed
‣ finds the distribution name for a module
(e.g. D/DR/DROLSKY/Log-Dispatch-2.22.tar.gz)
download dir
‣ for more info, “make“ the module inside cpan

How does it work?
‣ CPAN.pm discovers most of the information
needed
‣ finds the distribution name for a module
(e.g. D/DR/DROLSKY/Log-Dispatch-2.22.tar.gz)
DISTNAME
‣ for more info, “make“ the module inside cpan

How does it work?
‣ CPAN.pm discovers most of the information
needed
‣ finds the distribution name for a module
(e.g. D/DR/DROLSKY/Log-Dispatch-2.22.tar.gz)
EXTRACT_SUFX
‣ for more info, “make“ the module inside cpan

Before “make“
Module id = Log::Dispatch
DESCRIPTION Log messages to multiple outputs
CPAN_USERID DROLSKY (Dave Rolsky <autarch@urth.org>)
CPAN_VERSION 2.22
CPAN_FILE D/DR/DROLSKY/Log-Dispatch-2.22.tar.gz
DSLI_STATUS RdpO (released,developer,perl,object-oriented)
INST_FILE (not installed)
Distribution id = D/DR/DROLSKY/Log-Dispatch-2.22.tar.gz
CPAN_USERID DROLSKY (Dave Rolsky <autarch@urth.org>)
CONTAINSMODS Log::Dispatch::File::Locked [...]

After “make“
Distribution id = D/DR/DROLSKY/Log-Dispatch-2.22.tar.gz
CPAN_USERID DROLSKY (Dave Rolsky <autarch@urth.org>)
CALLED_FOR Log::Dispatch
CONTAINSMODS Log::Dispatch::File::Locked [...]
MD5_STATUS OK
archived tar
build_dir /Users/bsiegert/.cpan/build/Log-Dispatch-2.22
localfile /Users/bsiegert/.cpan/sources/authors/id/D/DR/
DROLSKY/Log-Dispatch-2.22.tar.gz
make YES
prereq_pm Test::More Params::Validate File::Temp Module::Build
prereq_pm_detected 1
unwrapped YES
writemakefile YES

Dependencies
‣ prereq_pm is a hash with
module => minversion
‣ expand module to distname
‣ static table of modules in the base system,
with “unsystematic“ names or non-CPAN
‣ rest: glob for /usr/ports/*/p5-NAME
‣ output dependency string in our format

Descriptions
‣ For some modules, cpan knows a one-line
description (COMMENT), not for others
‣ readmes are useless for getting a longer one
‣ parse the manpage, i.e. the POD

POD parsing
‣ “NAME“ section contains one-line comment
‣ Log::Dispatch - Dispatches messages to one or
more outputs
‣ longer description: first few paragraphs from
“DESCRIPTION“ section
‣ up to first control command
‣ plain-text conversion is easy
my $parser = Pod::Text->new(indent => 0, width
=> 72);

finally …
‣ ask user for category, create directory
‣ variable substitution in Makefile template
‣ write DESCR
‣ copy distfile to Distfiles directory
‣ run “make checksum“
‣ drop user to a shell, needs to run regress,
update-plist, install targets

Porting to other systems
‣ right now, cpan2port is available for MirPorts
‣ easily portable
‣ adapt perlmod.Makefile template
‣ change base module list accordingly
‣ adapt dependency output to your syntax

Conclusion

‣ cpan2port does the routine work
in porting Perl modules
‣ available in MirPorts, easy to port
‣ pkgsrc, FreeBSD, OpenBSD people: try it!
‣ Sources available at
http://cvs.mirbsd.de/ports/infrastructure/scripts/cpan2port
http://cvs.mirbsd.de/ports/infrastructure/templates/
perlmod.Makefile

Thank you for your attention!
Questions?