The GNU Autotools

1. The GNU Autotools Your very own ./configure Michael Imamura / LUG@GT

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! Michael Imamura / LUG@GT

3. The Autotools are Hard! • No, they’re not! • Well, maybe a little… • Okay, here’s why you should learn them anyway. • User configurability • Standards are everybody’s friend! • Portability – your code isn’t as portable as you think! Michael Imamura / LUG@GT

4. Getting Started • From scratch: A blank Autotools project • http://lugatgt.org/articles/autotools/autoblank.tar.gz • Use an IDE (like Anjuta) • Retrofit an existing project Michael Imamura / LUG@GT

5. The Initial Process • Create a few initial stub sources (if you don’t already have any) • Create Makefile.am files • http://lugatgt.org/articles/autotools/amwiz/ • Run autoscan and create configure.ac • Autoconf Macro Archivehttp://autoconf-archive.cryp.to/ • Run autoreconf --install • Run ./configure! Michael Imamura / LUG@GT

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. Michael Imamura / LUG@GT

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 Michael Imamura / LUG@GT

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 Michael Imamura / LUG@GT

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” Michael Imamura / LUG@GT

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 Michael Imamura / LUG@GT

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! • It’s up to YOU to decide how to react Michael Imamura / LUG@GT

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” Michael Imamura / LUG@GT

13. There’s much more to say… • But this presentation is too small to contain it. • http://lugatgt.org/articles/autotools/ • Autoconf Macro Archive:http://autoconf-archive.cryp.to/ • “GNU Autoconf, Automake, and Libtool” by Gary Vaughan, et al.http://sourceware.org/autobook/(free download!) Michael Imamura / LUG@GT