From 57d6c3d36045aab8957ffeb7324728bf17faf8bd Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Mon, 2 Feb 2015 20:31:29 +0100
Subject: [PATCH] configure: Eliminate the hard-coded libnl-3 include path

See also commit 3dde41998625fe0e24119a2e1f4509ba3ba2fd9a.

(cherry picked from commit 852dcd644cfe4cfc7177649eaec163d6221f2be1)

Original commit included modifications to configure script.
Do not keep these modifications, since they caused lots of conflicts, and
configure script is meant to be automatically generated.

Signed-off-by: Julien Floret <julien.floret@6wind.com>

Conflicts:
	configure
---
 aclocal.m4                  |   1 +
 configure.d/config_os_libs2 |  30 ++++++-
 m4/pkg.m4                   | 214 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 243 insertions(+), 2 deletions(-)
 create mode 100644 m4/pkg.m4

diff --git a/aclocal.m4 b/aclocal.m4
index cd80c7486f2f..45e3608ed480 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -22,3 +22,4 @@ m4_include([m4/ltversion.m4])
 m4_include([m4/lt~obsolete.m4])
 m4_include([m4/netsnmp_arg.m4])
 m4_include([m4/netsnmp_search_libs.m4])
+m4_include([m4/pkg.m4])
diff --git a/configure.d/config_os_libs2 b/configure.d/config_os_libs2
index 47491e24ce0a..10bd414b879e 100644
--- a/configure.d/config_os_libs2
+++ b/configure.d/config_os_libs2
@@ -225,11 +225,37 @@ fi
 if test "x$with_nl" != "xno"; then
     case $target_os in
     linux*) # Check for libnl (linux)
+        # The test below verifies whether the libnl-3 package been installed.
+        # This test works as follows:
+        # - If pkg-config was not installed at the time autogen.sh was run,
+        #   the definition of the PKG_CHECK_EXISTS() macro will not be found by
+        #   autogen.sh. Augogen.sh will generate a configure script that prints
+        #   a warning about pkg-config and proceeds as if libnl-3 has not been
+        #   installed.
+        # - If pkg-config was installed at the time autogen.sh was run,
+        #   the generated configure script will try to detect the presence of
+        #   the libnl-3 library by looking up compile and linker flags in the
+        #   file called libnl-3.pc.
+        # - pkg-config settings can be overridden via the configure variables
+        #   LIBNL3_CFLAGS and LIBNL3_LIBS (added by the pkg-config m4 macro's to
+        #   the configure script -- see also ./configure --help).
+        # - The LIBNL3_CFLAGS and LIBNL3_LIBS configure variables can be used
+        #   even if the pkg-config executable is not present on the system on
+        #   which the configure script is run.
+        ifdef(
+          [PKG_CHECK_EXISTS],
+          [PKG_CHECK_EXISTS([libnl-3.0],
+            [PKG_CHECK_MODULES([LIBNL3], [libnl-3.0])])
+          ],
+          AC_MSG_WARN([pkg-config has not been installed or is too old.])
+          AC_MSG_WARN([Detection of libnl-3.0 will be skipped.])
+        )
+
         netsnmp_save_CPPFLAGS="$CPPFLAGS"
-        CPPFLAGS="-I/usr/include/libnl3 $CPPFLAGS"
+        CPPFLAGS="${LIBNL3_CFLAGS} $CPPFLAGS"
         NETSNMP_SEARCH_LIBS(nl_connect, nl-3,
             [AC_CHECK_HEADERS(netlink/netlink.h)
-            EXTERNAL_MIBGROUP_INCLUDES="$EXTERNAL_MIBGROUP_INCLUDES -I/usr/include/libnl3"],
+            EXTERNAL_MIBGROUP_INCLUDES="$EXTERNAL_MIBGROUP_INCLUDES ${LIBNL3_CFLAGS}"],
             [CPPFLAGS="$netsnmp_save_CPPFLAGS"], [], [], [LMIBLIBS])
         if test "x$ac_cv_header_netlink_netlink_h" != xyes; then
             NETSNMP_SEARCH_LIBS(nl_connect, nl, [
diff --git a/m4/pkg.m4 b/m4/pkg.m4
new file mode 100644
index 000000000000..c5b26b52e6cd
--- /dev/null
+++ b/m4/pkg.m4
@@ -0,0 +1,214 @@
+# pkg.m4 - Macros to locate and utilise pkg-config.            -*- Autoconf -*-
+# serial 1 (pkg-config-0.24)
+# 
+# Copyright © 2004 Scott James Remnant <scott@netsplit.com>.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+#
+# As a special exception to the GNU General Public License, if you
+# distribute this file as part of a program that contains a
+# configuration script generated by Autoconf, you may include it under
+# the same distribution terms that you use for the rest of that program.
+
+# PKG_PROG_PKG_CONFIG([MIN-VERSION])
+# ----------------------------------
+AC_DEFUN([PKG_PROG_PKG_CONFIG],
+[m4_pattern_forbid([^_?PKG_[A-Z_]+$])
+m4_pattern_allow([^PKG_CONFIG(_(PATH|LIBDIR|SYSROOT_DIR|ALLOW_SYSTEM_(CFLAGS|LIBS)))?$])
+m4_pattern_allow([^PKG_CONFIG_(DISABLE_UNINSTALLED|TOP_BUILD_DIR|DEBUG_SPEW)$])
+AC_ARG_VAR([PKG_CONFIG], [path to pkg-config utility])
+AC_ARG_VAR([PKG_CONFIG_PATH], [directories to add to pkg-config's search path])
+AC_ARG_VAR([PKG_CONFIG_LIBDIR], [path overriding pkg-config's built-in search path])
+
+if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
+	AC_PATH_TOOL([PKG_CONFIG], [pkg-config])
+fi
+if test -n "$PKG_CONFIG"; then
+	_pkg_min_version=m4_default([$1], [0.9.0])
+	AC_MSG_CHECKING([pkg-config is at least version $_pkg_min_version])
+	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
+		AC_MSG_RESULT([yes])
+	else
+		AC_MSG_RESULT([no])
+		PKG_CONFIG=""
+	fi
+fi[]dnl
+])# PKG_PROG_PKG_CONFIG
+
+# PKG_CHECK_EXISTS(MODULES, [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
+#
+# Check to see whether a particular set of modules exists.  Similar
+# to PKG_CHECK_MODULES(), but does not set variables or print errors.
+#
+# Please remember that m4 expands AC_REQUIRE([PKG_PROG_PKG_CONFIG])
+# only at the first occurence in configure.ac, so if the first place
+# it's called might be skipped (such as if it is within an "if", you
+# have to call PKG_CHECK_EXISTS manually
+# --------------------------------------------------------------
+AC_DEFUN([PKG_CHECK_EXISTS],
+[AC_REQUIRE([PKG_PROG_PKG_CONFIG])dnl
+if test -n "$PKG_CONFIG" && \
+    AC_RUN_LOG([$PKG_CONFIG --exists --print-errors "$1"]); then
+  m4_default([$2], [:])
+m4_ifvaln([$3], [else
+  $3])dnl
+fi])
+
+# _PKG_CONFIG([VARIABLE], [COMMAND], [MODULES])
+# ---------------------------------------------
+m4_define([_PKG_CONFIG],
+[if test -n "$$1"; then
+    pkg_cv_[]$1="$$1"
+ elif test -n "$PKG_CONFIG"; then
+    PKG_CHECK_EXISTS([$3],
+                     [pkg_cv_[]$1=`$PKG_CONFIG --[]$2 "$3" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes ],
+		     [pkg_failed=yes])
+ else
+    pkg_failed=untried
+fi[]dnl
+])# _PKG_CONFIG
+
+# _PKG_SHORT_ERRORS_SUPPORTED
+# -----------------------------
+AC_DEFUN([_PKG_SHORT_ERRORS_SUPPORTED],
+[AC_REQUIRE([PKG_PROG_PKG_CONFIG])
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi[]dnl
+])# _PKG_SHORT_ERRORS_SUPPORTED
+
+
+# PKG_CHECK_MODULES(VARIABLE-PREFIX, MODULES, [ACTION-IF-FOUND],
+# [ACTION-IF-NOT-FOUND])
+#
+#
+# Note that if there is a possibility the first call to
+# PKG_CHECK_MODULES might not happen, you should be sure to include an
+# explicit call to PKG_PROG_PKG_CONFIG in your configure.ac
+#
+#
+# --------------------------------------------------------------
+AC_DEFUN([PKG_CHECK_MODULES],
+[AC_REQUIRE([PKG_PROG_PKG_CONFIG])dnl
+AC_ARG_VAR([$1][_CFLAGS], [C compiler flags for $1, overriding pkg-config])dnl
+AC_ARG_VAR([$1][_LIBS], [linker flags for $1, overriding pkg-config])dnl
+
+pkg_failed=no
+AC_MSG_CHECKING([for $1])
+
+_PKG_CONFIG([$1][_CFLAGS], [cflags], [$2])
+_PKG_CONFIG([$1][_LIBS], [libs], [$2])
+
+m4_define([_PKG_TEXT], [Alternatively, you may set the environment variables $1[]_CFLAGS
+and $1[]_LIBS to avoid the need to call pkg-config.
+See the pkg-config man page for more details.])
+
+if test $pkg_failed = yes; then
+   	AC_MSG_RESULT([no])
+        _PKG_SHORT_ERRORS_SUPPORTED
+        if test $_pkg_short_errors_supported = yes; then
+	        $1[]_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "$2" 2>&1`
+        else 
+	        $1[]_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "$2" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$$1[]_PKG_ERRORS" >&AS_MESSAGE_LOG_FD
+
+	m4_default([$4], [AC_MSG_ERROR(
+[Package requirements ($2) were not met:
+
+$$1_PKG_ERRORS
+
+Consider adjusting the PKG_CONFIG_PATH environment variable if you
+installed software in a non-standard prefix.
+
+_PKG_TEXT])[]dnl
+        ])
+elif test $pkg_failed = untried; then
+     	AC_MSG_RESULT([no])
+	m4_default([$4], [AC_MSG_FAILURE(
+[The pkg-config script could not be found or is too old.  Make sure it
+is in your PATH or set the PKG_CONFIG environment variable to the full
+path to pkg-config.
+
+_PKG_TEXT
+
+To get pkg-config, see <http://pkg-config.freedesktop.org/>.])[]dnl
+        ])
+else
+	$1[]_CFLAGS=$pkg_cv_[]$1[]_CFLAGS
+	$1[]_LIBS=$pkg_cv_[]$1[]_LIBS
+        AC_MSG_RESULT([yes])
+	$3
+fi[]dnl
+])# PKG_CHECK_MODULES
+
+
+# PKG_INSTALLDIR(DIRECTORY)
+# -------------------------
+# Substitutes the variable pkgconfigdir as the location where a module
+# should install pkg-config .pc files. By default the directory is
+# $libdir/pkgconfig, but the default can be changed by passing
+# DIRECTORY. The user can override through the --with-pkgconfigdir
+# parameter.
+AC_DEFUN([PKG_INSTALLDIR],
+[m4_pushdef([pkg_default], [m4_default([$1], ['${libdir}/pkgconfig'])])
+m4_pushdef([pkg_description],
+    [pkg-config installation directory @<:@]pkg_default[@:>@])
+AC_ARG_WITH([pkgconfigdir],
+    [AS_HELP_STRING([--with-pkgconfigdir], pkg_description)],,
+    [with_pkgconfigdir=]pkg_default)
+AC_SUBST([pkgconfigdir], [$with_pkgconfigdir])
+m4_popdef([pkg_default])
+m4_popdef([pkg_description])
+]) dnl PKG_INSTALLDIR
+
+
+# PKG_NOARCH_INSTALLDIR(DIRECTORY)
+# -------------------------
+# Substitutes the variable noarch_pkgconfigdir as the location where a
+# module should install arch-independent pkg-config .pc files. By
+# default the directory is $datadir/pkgconfig, but the default can be
+# changed by passing DIRECTORY. The user can override through the
+# --with-noarch-pkgconfigdir parameter.
+AC_DEFUN([PKG_NOARCH_INSTALLDIR],
+[m4_pushdef([pkg_default], [m4_default([$1], ['${datadir}/pkgconfig'])])
+m4_pushdef([pkg_description],
+    [pkg-config arch-independent installation directory @<:@]pkg_default[@:>@])
+AC_ARG_WITH([noarch-pkgconfigdir],
+    [AS_HELP_STRING([--with-noarch-pkgconfigdir], pkg_description)],,
+    [with_noarch_pkgconfigdir=]pkg_default)
+AC_SUBST([noarch_pkgconfigdir], [$with_noarch_pkgconfigdir])
+m4_popdef([pkg_default])
+m4_popdef([pkg_description])
+]) dnl PKG_NOARCH_INSTALLDIR
+
+
+# PKG_CHECK_VAR(VARIABLE, MODULE, CONFIG-VARIABLE,
+# [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
+# -------------------------------------------
+# Retrieves the value of the pkg-config variable for the given module.
+AC_DEFUN([PKG_CHECK_VAR],
+[AC_REQUIRE([PKG_PROG_PKG_CONFIG])dnl
+AC_ARG_VAR([$1], [value of $3 for $2, overriding pkg-config])dnl
+
+_PKG_CONFIG([$1], [variable="][$3]["], [$2])
+AS_VAR_COPY([$1], [pkg_cv_][$1])
+
+AS_VAR_IF([$1], [""], [$5], [$4])dnl
+])# PKG_CHECK_VAR
-- 
2.1.0

