using automake for so-library

Ephracis · 10-27-2008, 11:54 AM

I am using autotools to build a shared lib. All the docs on the net use either the .a or the .la extension and both require different commands in the Makefile.am file.

What would a really simple Makefile.am look like for a shared library named "foobar" (where the final binary would be named libfoobar.so)?

Thanks.

ta0kira · 10-27-2008, 07:46 PM

The solution is to not specify; use libtool. Look at info libtool, which should also have some info in info automake. libtool will determine the "best type" of library to use based on the system because some systems don't use dynamic linking. Here's an example from one of my projects:

Code:

STANDARD_INCLUDES=-I/usr/include -I/usr/local/include
ALL_INCLUDES=$(STANDARD_INCLUDES) -I$(srcdir)/../.. -I$(srcdir)/../../include/rservr -I$(srcdir)/../../include -I$(srcdir)/../include
AM_CPPFLAGS=-DENABLE_VIRT_ARRAY_ALL $(ALL_INCLUDES)
AM_CXXFLAGS=-ansi -Wall
AM_CFLAGS=-Wall
STANDARD_LIBS=-L/lib -L/usr/lib -L/usr/local/lib
AM_LDFLAGS=--version-info 1:1:0 $(STANDARD_LIBS)
lib_LTLIBRARIES=librservr-filter.la
librservr_filter_la_SOURCES=filter-main.c api-filter.c api-filter.h
librservr_filter_la_LIBADD=

The .la files are just text files used by libtool at link time. You shouldn't ever have to deal with real extensions.
ta0kira

PS You use the .la file when linking within Makefile.am, e.g. if the library above needed to link to libdependency.(so|a) you would add libdependency.la to *_LIBADD, using a path prefix if it's part of the same project and therefore isn't installed yet. libtool will always give you a static library at installation time and a shared library if possible and if not disabled; therefore, normal linking can still be done with -l outside of automake (or within it, but that would be nonstandard.)

This might be a better example:

Code:

STANDARD_INCLUDES=-I/usr/include -I/usr/local/include
ALL_INCLUDES=$(STANDARD_INCLUDES) -I$(srcdir)/../.. -I$(srcdir)/../../include/rservr -I$(srcdir)/../../include -I$(srcdir)/../include
AM_CPPFLAGS=-DENABLE_VIRT_ARRAY_ALL -DRSERVR_RESTRICT_COMMAND_INTERFACE $(ALL_INCLUDES)
AM_CXXFLAGS=-ansi -Wall
AM_CFLAGS=-Wall
STANDARD_LIBS=-L/lib -L/usr/lib -L/usr/local/lib
AM_LDFLAGS=--version-info 1:1:0 $(STANDARD_LIBS)
lib_LTLIBRARIES=librsvp-rqsrvc.la librsvp-rqsrvc-auto.la
librsvp_rqsrvc_la_SOURCES=api-rqsrvc.cpp plugin-rqsrvc.cpp api-rqsrvc.h plugin-rqsrvc.hpp
librsvp_rqsrvc_la_LIBADD=../../libs/command/librservr-command.la
librsvp_rqsrvc_auto_la_SOURCES=rqsrvc-auto.cpp
librsvp_rqsrvc_auto_la_LIBADD=librsvp-rqsrvc.la ../../libs/client/librservr-client.la

Ephracis · 10-28-2008, 06:17 PM

I am not sure I fully understand what you are saying.

The libraries are part of a project but my goal is to make them independent from the rest of the project, so that they can be packaged and reused with other projects.

Since I am not very familiar with the autotools just yet I am using the summary from http://markuskimius.wikidot.com/prog...ut:autotools:5 as a guide.

I will just lay out all the details here:

cpp files are inside src/ and header files are inside include/

This is configure.ac

Code:

# -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.

AC_PREREQ(2.61)
AC_INIT([avesta], [1.1], XXX)
AM_INIT_AUTOMAKE([avesta], [1.1])
AC_CONFIG_FILES(Makefile)
AC_CONFIG_HEADER([config.h])

# Checks for programs.
AC_PROG_CXX
AC_PROG_CC
AC_PROG_LIBTOOL

# set C++ compiling and linkage
AC_LANG_CPLUSPLUS

# Checks for libraries.

# Checks for header files.
AC_HEADER_STDC
AC_CHECK_HEADERS([inttypes.h limits.h malloc.h memory.h stdlib.h string.h unistd.h wchar.h])

# Checks for typedefs, structures, and compiler characteristics.
AC_HEADER_STDBOOL
AC_C_CONST
AC_C_INLINE
AC_TYPE_INT64_T
AC_C_RESTRICT
AC_TYPE_SIZE_T
AC_STRUCT_TM
AC_TYPE_UINT64_T

# Checks for library functions.
AC_FUNC_MALLOC
AC_FUNC_REALLOC
AC_FUNC_STAT
AC_FUNC_VPRINTF
AC_CHECK_FUNCS([atexit memset mkdir strrchr])

AC_CONFIG_FILES([src/Makefile])
AC_OUTPUT

This is Makefile.am

Code:

SUBDIRS = src

This is src/Makefile.am

Code:

# library to build
lib_LTLIBRARIES = libavesta.la

# the header files
libavesta_la_HEADERS =	../include/avesta_common_base.h \
			../include/avesta_common_config.h \
			../include/avesta_common_debug.h \
			../include/avesta_common.h \
			../include/avesta_common_memory.h \
			../include/avesta_common_neutral.h \
			../include/avesta_common_platform.h \
			../include/avesta_common_types.h \
			../include/avesta_common_utility.h \
			../include/avesta_common_windows.h \
			../include/avesta_endian_from.h \
			../include/avesta_endian.h \
			../include/avesta_endian_sizes.h \
			../include/avesta_endian_swap.h \
			../include/avesta_file.h \
			../include/avesta_file_utility.h \
			../include/avesta.h \
			../include/avesta_hashmap.h \
			../include/avesta_math_consts.h \
			../include/avesta_math.h \
			../include/avesta_math_utility.h \
			../include/avesta_memory_allocator.h \
			../include/avesta_memory.h \
			../include/avesta_memory_reporter.h \
			../include/avesta_memory_tracker.h \
			../include/avesta_memory_utility.h \
			../include/avesta_priorityqueue.h \
			../include/avesta_string.h \
			../include/avesta_string_utility.h \
			../include/_.h
			
# header installation path
libavesta_ladir = $(includedir)/avesta

# the source code
libavesta_la_SOURCES =	$(libavesta_so_headers) \
			avesta_common_debug.cpp \
			avesta_common_memory.cpp \
			avesta_common_utility.cpp \
			avesta_file_utility.cpp \
			avesta_memory_reporter.cpp \
			avesta_memory_tracker.cpp \
			avesta_string_utility.cpp

# libraries needed

# additional include paths needed
INCLUDES = -I$(top_srcdir)/include

This compiles fine but on my Ubuntu system (which I know uses .so-files) all I get is a file called libavesta.la where I would like libavesta.so instead, or even libavesta.so.0.1 or something like that, where installing the libraries would even create the symlinks and everything.

Thanks,

ta0kira · 10-28-2008, 09:06 PM

You have to make install for that to happen; it normally won't happen until then with libtool because it will link them in place.
ta0kira