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GNU Autoconf Scripting Snippets

Thursday, January 13, 2005 by digitalpeer

Face it, you're constantly searching for autoconf macros or how to do things when you've got your source written and you're ready to get it built with the GNU auto tools. I do the same thing. So, here's a bunch of configure.ac or configure.in snippets I've seen or written for your viewing pleasure.

Generate variables with the build, host, and target identifiers.

AC_CANONICAL_BUILD
AC_CANONICAL_HOST
AC_CANONICAL_TARGET

An if,else statement.

if test "x${with_gnome}" = xyes
then 
    GNOME_PACKAGES="gtk+-2.0 libgnome-2.0 libgnomeui-2.0 pango"
elif test "x${with_gtk}" = xyes
then
    GNOME_PACKAGES="gtk+-2.0"
else
    GNOME_PACKAGES=""
fi

A for loop over a list of words.

for pkg in $GNOME_PACKAGES
do
    AC_MSG_CHECKING([version of $pkg])
    if gnomevers=`pkg-config --modversion $pkg`
    then
        AC_MSG_RESULT($gnomevers)
    else
        AC_MSG_ERROR([$pkg was not found by pkg-config])        
    fi
done

Define a variable for use later in your Makefile.am.

GNOME_CFLAGS=-g
AC_SUBST(GNOME_CFLAGS)

Display a notice during configure.

AC_MSG_NOTICE([Adding gcc options: $CFLAGS])

Try to compile a test code and report the results.

AC_TRY_COMPILE([
#ifdef HAVE_SYS_MMAN_H
#  include <sys/mman.h>
#endif],[
#ifdef HAVE_MMAP
if (mmap (NULL, 0, 0, 0, 0, 0) == MAP_FAILED)
	return 0;
#else
#error mmap unavailable
#endif], ,[
	AC_DEFINE([MAP_FAILED], [(void *)-1L],
	[Define if MAP_FAILED constant not available])
])
AC_MSG_RESULT()