Using autoconf for a shared library

[Thomas Nyberg]

Hello,

I've been reading the manuals for autoconf/automake and have been unable 
to get a setup working correctly with autoconf. I've written up a toy 
shared library and right now the Makefile has a rule to install the 
library directly to `/usr/local`. All I really want from autoconf is to 
be able to have `--prefix` user-configurable. I figured it was better to 
use autoconf/automake than reinvent the wheel, but I'm totally unable to 
get it working.

Does anyone here know a source for a very simple example of what is 
needed (configure.ac/Makefile.in) to get this type of setup working? 
I've been reading both manuals, but I can't figure it out. Maybe someone 
here can even immediately see how to do this.

I'm attaching an extremely simplified version of a shared library setup. 
I'm also pasting the text of the files in below in case you just want to 
read directly (instead of extracting something from a random person on 
the internet). Basically if you run `make` it compiles a shared library 
for you with publicly exports one function called `public_func`. If you 
run `make test` it will test it by setting the current directory to 
LD_LIBRARY_PATH. You can install it by running `make install` and then 
ldconfig (though I doubt you want to...). This is the repo structure:

.
├── include
│   └── public.h
├── Makefile
├── src
│   ├── private.c
│   ├── private.h
│   └── public.c
└── test.c

Here are the files:

include/public.h
-----------------------------------
int public_func(void);
-----------------------------------

src/public.h
-----------------------------------
#include <private.h>


int public_func(void) {
    return private_func();
}
-----------------------------------

src/private.h
-----------------------------------
int private_func(void);
-----------------------------------

src/private.c
-----------------------------------
#include <private.h>


int private_func(void) {
    return 1;
}
-----------------------------------

test.c
-----------------------------------
#include <public.h>
#include <stdio.h>


int main(void) {
    printf("public value: %d\n", public_func());
    return 0;
}
-----------------------------------

Makefile
-----------------------------------
so = libpublic.so
solinkname = -lpublic

install_target = /usr/local

srcs = $(wildcard src/*.c)
objs = $(patsubst %.c,%.o,$(srcs))

includes = include/public.h
installed_includes = $(addprefix $(install_target)/,$(includes))

cc = gcc
cflags = -c -g -fPIC -Wall -Wextra -Wfatal-errors -pedantic-errors
privateincludedirs = -Isrc
publicincludedirs = -Iinclude
ldflags = -shared -Wl,-soname,$(so)


all: $(so)

$(so): $(objs)
        $(cc) $(ldflags) $(objs) -o $(so)

%.o:%.c
        $(cc) $(cflags) $(privateincludedirs) -c -o $@ $<

clean:
        rm -f *.o src/*.o *.so test

install:
        cp -v $(includes) $(install_target)/include
        cp -v $(so) $(install_target)/lib
-----------------------------------

Thanks for any help!

Cheers,
Thomas

library.tar.bz2
Description: application/bzip