The GNU Autotools

1
The GNU Autotools

• Your very own ./configure

2
Say Hello to the Autotools

• Autoconf, with the power of ./configure!
• Automake, making makefiles suck less!
• Libtool, friend to shared and static library
  alike!

3
The Autotools are Hard!

• No, theyre not!
• Well, maybe a little
• Okay, heres why you should learn them anyway.
• User configurability
• Standards are everybodys friend!
• Portability your code isnt as portable as you
  think!

4
Getting Started

• From scratch A blank Autotools project
• http//lugatgt.org/articles/autotools/autoblank.ta
  r.gz
• Use an IDE (like Anjuta)
• Retrofit an existing project

5
The Initial Process

• Create a few initial stub sources (if you dont
  already have any)
• Create Makefile.am files
• http//lugatgt.org/articles/autotools/amwiz/
• Run autoscan and create configure.ac
• Autoconf Macro Archivehttp//autoconf-archive.cry
  p.to/
• Run autoreconf --install
• Run ./configure!

6
Automake

• Makefile.am ? Makefile.in ? Makefile
• Basically, a Makefile with special variable
  declarations
• Primaries What is being produced
• bin_PROGRAMS, lib_LTLIBRARIES, etc.
• Secondaries How to produce it
• _CFLAGS, _SOURCES, _LIBADD, etc.

7
Autoconf

• Run autoscan to produce configure.scan
• Detects source file types
• Detects toolchain dependencies
• Merge configure.scan into configure.ac
• Add AM_INIT_AUTOMAKE to add Automake support
• Add AC_PROG_LIBTOOL to add Libtool support

8
Developing, developing, developing

• Whenever configure.ac or Makefile.am changes,
  re-run autoreconf
• autoreconf --make is useful here
• Generated Makefile is often smart enough to do it
  for you
• Standard make targets generated by Automake
• User all (default), install, clean
• Developer dist, check, distcheck

9
Debugging

• Libtool hides linking issues
• Automatically relinks on install
• Oops Libtool gets in the way
• Your binary may not be a binary!
• Use libtool gdb instead of gdb

10
Source control What to check in

• General rule Only check in files that you have
  created
• Only configure.ac and Makefile.am
• Set ignores for the generated files
• Add to note to HACKING about what versions of
  Autoconf, Automake, and Libtool you used

11
What about portability?

• The other reason to use Autoconf
• General strategy
• Study the config.h generated by ./configure
• For every define
• Can we work around the issue?
• Is the tested feature an absolute requirement?
• Autoconf is not a magic bullet!
• Its up to YOU to decide how to react

12
Beyond ./configure

• make check Unit tests with DejaGNU
• Custom configure.ac tests
• Tests are written in GNU M4
• Use AC_ARG_ENABLE to allow the user to customize
  your package with --enable-feature
• Fine-tuning
• Different flavors of clean

13
Theres much more to say

• But this presentation is too small to contain it.
• http//lugatgt.org/articles/autotools/
• Autoconf Macro Archivehttp//autoconf-archive.cr
  yp.to/
• GNU Autoconf, Automake, and Libtool by Gary
  Vaughan, et al.http//sourceware.org/autobook/(f
  ree download!)