Add socket/nsl check to local m4

diff --git a/m4/ax_lib_socket_nsl.m4 b/m4/ax_lib_socket_nsl.m4
new file mode 100644 (file)
index 0000000..058e975
--- /dev/null
+++ b/m4/ax_lib_socket_nsl.m4
@@ -0,0 +1,40 @@
+# ===========================================================================
+#     http://www.gnu.org/software/autoconf-archive/ax_lib_socket_nsl.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_LIB_SOCKET_NSL
+#
+# DESCRIPTION
+#
+#   This macro figures out what libraries are required on this platform to
+#   link sockets programs.
+#
+#   The common cases are not to need any extra libraries, or to need
+#   -lsocket and -lnsl. We need to avoid linking with libnsl unless we need
+#   it, though, since on some OSes where it isn't necessary it will totally
+#   break networking. Unisys also includes gethostbyname() in libsocket but
+#   needs libnsl for socket().
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Russ Allbery <rra@stanford.edu>
+#   Copyright (c) 2008 Stepan Kasal <kasal@ucw.cz>
+#   Copyright (c) 2008 Warren Young <warren@etr-usa.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 6
+
+AU_ALIAS([LIB_SOCKET_NSL], [AX_LIB_SOCKET_NSL])
+AC_DEFUN([AX_LIB_SOCKET_NSL],
+[
+       AC_SEARCH_LIBS([gethostbyname], [nsl])
+       AC_SEARCH_LIBS([socket], [socket], [], [
+               AC_CHECK_LIB([socket], [socket], [LIBS="-lsocket -lnsl $LIBS"],
+               [], [-lnsl])])
+])