source: vendor/3.5.5/lib/replace/dlfcn.m4

dnl dummies provided by dlfcn.c if not available
save_LIBS="$LIBS"
LIBS=""

libreplace_cv_dlfcn=no
AC_SEARCH_LIBS(dlopen, dl)

AC_CHECK_HEADERS(dlfcn.h)
AC_CHECK_FUNCS([dlopen dlsym dlerror dlclose],[],[libreplace_cv_dlfcn=yes])

libreplace_cv_shl=no
AC_SEARCH_LIBS(shl_load, sl)
AC_CHECK_HEADERS(dl.h)
AC_CHECK_FUNCS([shl_load shl_unload shl_findsym],[],[libreplace_cv_shl=yes])

AC_VERIFY_C_PROTOTYPE([void *dlopen(const char* filename, unsigned int flags)],
        [
        return 0;
        ],[
        AC_DEFINE(DLOPEN_TAKES_UNSIGNED_FLAGS, 1, [Whether dlopen takes unsigned int flags])
        ],[],[
        #include <dlfcn.h>
        ])

if test x"${libreplace_cv_dlfcn}" = x"yes";then
        LIBREPLACEOBJ="${LIBREPLACEOBJ} $libreplacedir/dlfcn.o"
fi

LIBDL="$LIBS"
AC_SUBST(LIBDL)
LIBS="$save_LIBS"