Determining Dependencies of Autotools-based Packages

Finding what’s needed
Things to exclude

Finding what’s needed

A sensible starting point when hunting for dependencies is:

./configure --help

Pay attention to the various --{enable,disable}-foo and --with{,out}-foo options in the output, as they often correspond with dependencies.

Dependencies in configure.ac/configure.in are usually specified using one of the following macros:

AC_CHECK_LIB
PKG_CHECK_MODULES
GTK_DOC_CHECK (annoyingly, gtk-doc has its very own macro)

For extra thoroughness, check the following macros (but usually the results are redundant with the above checks):

AC_CHECK_HEADERS

For even more thoroughness, build the package then check which shared libs are used by its ELF binaries:

readelf -d /usr/bin/foo | grep NEEDED
readelf -d /usr/lib64/libfoo.so | grep NEEDED

There are some caveats for the readelf approach:

It misses dependencies pulled in by the dlopen() call
Libtool may add extra links culled from a binary’s true dependencies, and though these are also reported as NEEDED, they shouldn’t be considered dependencies

troll.rb is a convenient readelf wrapper which lists dependencies of ELF binaries on a per-package basis. It can be obtained with:

git clone git://git.exherbo.org/~ingmar/troll

Usage:

troll.rb dev-libs/libusb

Results are given like so:

libc.so.6
libusb-0.1.so.4
libstdc++.so.6
libm.so.6
libgcc_s.so.1
librt.so.1
libpthread.so.0
libc.so.6

Things to exclude

Generally, anything that’s part of a basic Unixy system, or that’s part of the basic C toolchain, should not be listed in DEPENDENCIES, as they are already present on a functional Exherbo system.

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