Autotools library and object file output control

makefile gnu autotools autoconf automake
John Bellone picture John Bellone · Jun 19, 2009 · Viewed 7.9k times · Source

My goal is to have all object files built in a .objs directory instead of the root of the Makefile, and to have the binaries (and libraries) copied into the project's bin/ directory. But I have been unable to find any resources to explain how to do this. How would I go about doing this?

Here is my configure.ac and src/Makefile.am - I have similar Makefile.am files for two shared libraries that are referenced. They compile, and after copying them to the bin/ directory work as they should. I'm just looking to automate this process.

configure.ac

AC_PREREQ([2.63])
AC_INIT([gtkworkbook], [0.12], [[email protected]])
AC_CONFIG_SRCDIR([gtkworkbook/cell.c])
AM_INIT_AUTOMAKE([gtkworkbook], [0.12])

# Checks for programs.
AC_PROG_CXX
AC_PROG_CC
AC_PROG_INSTALL
AC_PROG_MAKE_SET
AC_PROG_RANLIB
AC_PROG_LIBTOOL
AC_PROG_CC_C_O

AC_CHECK_LIB([pthread], [pthread_mutex_init], [], [
            echo "pthread library is missing. pthread is required for this program"
            exit -1])

# Checks for header files.
AC_CHECK_HEADERS([arpa/inet.h netdb.h netinet/in.h stdlib.h string.h sys/socket.h unistd.h])

# Checks for typedefs, structures, and compiler characteristics.
AC_HEADER_STDBOOL
AC_C_INLINE
AC_TYPE_SIZE_T

# Checks for library functions.
AC_CHECK_FUNCS([gethostbyname memset socket])

AC_OUTPUT([Makefile
       csv/Makefile
       gtkworkbook/Makefile
       src/Makefile])

src/Makefile.am

AUTOMAKE_OPTIONS= foreign

C_FLAGS= -I/usr/local/include -I/usr/include -I/usr/local/include/gtkextra-2.0 -I$(top_srcdir)/include `pkg-config gtk+-2.0 glib-2.0 --cflags`
L_FLAGS= -L/usr/local/lib -L/usr/lib -L$(top_srcdir)/lib `pkg-config gtk+-2.0 glib-2.0 --libs` -lgtkextra-x11-2.0

bin_PROGRAMS= gtkworkbook
gtkworkbook_SOURCES= application.c config.c main.c parse.c plugin.c
gtkworkbook_CFLAGS= -Wall -lgthread-2.0 -std=c99 $(C_FLAGS)  
gtkworkbook_LFLAGS= -ldl $(L_FLAGS)
gtkworkbook_LDFLAGS= $(L_FLAGS)
gtkworkbook_LDADD= ../gtkworkbook/libgtkworkbook.la ../csv/libcsv.la

lib_LTLIBRARIES= realtime.la
realtime_la_SOURCES= realtime/CsvParser.cpp realtime/Network.cpp realtime/Packet.cpp realtime/plugin_main.cpp \
    realtime/thread_main.cpp realtime/concurrent/Mutex.cpp realtime/concurrent/Semaphore.cpp \
    realtime/concurrent/Thread.cpp realtime/concurrent/ThreadGroup.cpp realtime/concurrent/ThreadPool.cpp \
    realtime/proactor/Dispatcher.cpp realtime/proactor/Event.cpp realtime/proactor/Proactor.cpp \
    realtime/proactor/InputDispatcher.cpp realtime/proactor/Worker.cpp realtime/network/Tcp.cpp
realtime_la_CPPFLAGS= -Wall -Wno-write-strings $(C_FLAGS)
realtime_la_LFLAGS= -lgtkworkbook -lcsv $(L_FLAGS)
realtime_la_LDFLAGS= -module -export-dynamic 
realtime_la_LIBADD= ../gtkworkbook/libgtkworkbook.la ../csv/libcsv.la

So, my question is how to specify the output directories for the compile results of each Makefile (I wish them to be copied to bin/, and for the object files to be in .obj of each project instead of in the root of the Makefile.

Thanks for the help thus far.. this website has been a great resource, and I have learned a lot from the links provided already.

Answer

adl picture adl · Jun 23, 2009

The GNU Build System does not use obj/ directories, so the autotools are not designed to support that.

However I can think of two ways to work around this.

As an installer, you can build any package out of its source directory by typing

mkdir builddir
cd builddir
../path-to-sourcedir/configure
make

Then any output file will be created in the builddir/ directory. This compilation scheme makes it possible to compile source code out stored in a readonly directory (this made more sense back in the years where the FSF was distributing CDs with uncompressed source code), or to compile the same source with differents settings (or even for different architectures).

As a packager, the only way you could force your package to build everything in obj/ is to put your Makefile.am in obj/, and declare all your build rules there. This would mean a obj/Makefile.am looking like:

bin_PROGRAMS = foo bar
foo_SOURCES = ../src/foo/main.c ../src/foo/help.c ../src/foo/list.c
bar_SOURCES = ../src/bar/bar.c

etc. I remember that 10 years ago, POSE, the Palm OS Emulator, was using a setup like the above. I don't recommend it as it's not really maintainable. It's really better to stick with the philosophy of the tools, and use a build systems that work like the other GNU packages.

For an introduction to the GNU Build System, I recommend reading the introduction of the Automake manual: http://www.gnu.org/software/automake/manual/automake.html#GNU-Build-System

Especially the Use-Cases section. If you don't care about these use cases, I think your best course is NOT to use Automake, and build your own Makefiles. Otherwise you will keep trying to force Automake doing something it is not designed for, and you'll quickly hate it.

EDIT 2013-08-26: Note that an Automake project using a subdirectory named using obj/ is not portable to BSD make.

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