ac_lib_upnp

This macro will check for the existence of libupnp (http://upnp.sourceforge.net/). It does this by checking for the header file upnp.h and the upnp library object file. A --with-libupnp option is supported as well. The following output variables are set with AC_SUBST:

   UPNP_CPPFLAGS
   UPNP_LDFLAGS
   UPNP_LIBS

You can use them like this in Makefile.am:

   AM_CPPFLAGS = $(UPNP_CPPFLAGS)
   AM_LDFLAGS = $(UPNP_LDFLAGS)
   program_LDADD = $(UPNP_LIBS)

Additionally, the C preprocessor symbol HAVE_LIBUPNP will be defined with AC_DEFINE if libupnp is available.

AC_DEFUN([AC_LIB_UPNP], [
  AH_TEMPLATE([HAVE_LIBUPNP], [Define if libupnp is available])
  AC_ARG_WITH(libupnp, [  --with-libupnp=DIR      prefix for upnp library files and headers], [
    if test "$withval" = "no"; then
      ac_upnp_path=
      $2
    elif test "$withval" = "yes"; then
      ac_upnp_path=/usr
    else
      ac_upnp_path="$withval"
    fi
  ],[ac_upnp_path=/usr])
  if test "$ac_upnp_path" != ""; then
    saved_CPPFLAGS="$CPPFLAGS"
    CPPFLAGS="$CPPFLAGS -I$ac_upnp_path/include/upnp"
    AC_CHECK_HEADER([upnp.h], [
      saved_LDFLAGS="$LDFLAGS"
      LDFLAGS="$LDFLAGS -L$ac_upnp_path/lib"
      AC_CHECK_LIB(upnp, UpnpInit, [
        AC_SUBST(UPNP_CPPFLAGS, [-I$ac_upnp_path/include/upnp])
        AC_SUBST(UPNP_LDFLAGS, [-L$ac_upnp_path/lib])
        AC_SUBST(UPNP_LIBS, [-lupnp])
	AC_DEFINE([HAVE_LIBUPNP])
        $1
      ], [
	:
        $2
      ])
      LDFLAGS="$saved_LDFLAGS"
    ], [
      AC_MSG_RESULT([not found])
      $2
    ])
    CPPFLAGS="$saved_CPPFLAGS"
  fi
])