scripts: check features to generate configuration header

This script looks for types, macros and functions in header files using
compilation options found in the environment (CC, CFLAGS, CPPFLAGS) to
define feature macros in a generated header.

Useful in combination with external headers that do not provide such macros.

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

MAINTAINERS

@@ -45,6 +45,7 @@ F: Makefile
 F: config/
 F: mk/
 F: pkg/
+F: scripts/auto-config-h.sh
 F: scripts/depdirs-rule.sh
 F: scripts/gen-build-mk.sh
 F: scripts/gen-config-h.sh

scripts/auto-config-h.sh

@@ -0,0 +1,136 @@
+#!/bin/sh
+#
+#   BSD LICENSE
+#
+#   Copyright 2014-2015 6WIND S.A.
+#
+#   Redistribution and use in source and binary forms, with or without
+#   modification, are permitted provided that the following conditions
+#   are met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in
+#       the documentation and/or other materials provided with the
+#       distribution.
+#     * Neither the name of 6WIND S.A. nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Crude script to detect whether particular types, macros and functions are
+# defined by trying to compile a file with a given header. Can be used to
+# perform cross-platform checks since the resulting object file is not
+# executed.
+#
+# Set VERBOSE=1 in the environment to display compiler output and errors.
+#
+# CC, CPPFLAGS, CFLAGS, EXTRA_CPPFLAGS and EXTRA_CFLAGS are taken from the
+# environment.
+#
+# AUTO_CONFIG_CFLAGS may append additional CFLAGS without modifying the
+# above variables.
+
+file=${1:?output file name required (config.h)}
+macro=${2:?output macro name required (HAVE_*)}
+include=${3:?include name required (foo.h)}
+type=${4:?object type required (define, enum, type, field, func)}
+name=${5:?define/type/function name required}
+
+: ${CC:=cc}
+
+temp=/tmp/${0##*/}.$$.c
+
+case $type in
+define)
+	code="\
+#ifndef $name
+#error $name not defined
+#endif
+"
+	;;
+enum)
+	code="\
+long test____ = $name;
+"
+	;;
+type)
+	code="\
+$name test____;
+"
+	;;
+field)
+	code="\
+void test____(void)
+{
+	${name%%.*} test_____;
+
+	(void)test_____.${name#*.};
+}
+"
+	;;
+func)
+	code="\
+void (*test____)() = (void (*)())$name;
+"
+	;;
+*)
+	unset error
+	: ${error:?unknown object type \"$type\"}
+	exit
+esac
+
+if [ "${VERBOSE}" = 1 ]
+then
+	err=2
+	out=1
+	eol='
+'
+else
+	exec 3> /dev/null ||
+	exit
+	err=3
+	out=3
+	eol=' '
+fi &&
+printf 'Looking for %s %s in %s.%s' \
+	"${name}" "${type}" "${include}" "${eol}" &&
+printf "\
+#include <%s>
+
+%s
+" "$include" "$code" > "${temp}" &&
+if ${CC} ${CPPFLAGS} ${EXTRA_CPPFLAGS} ${CFLAGS} ${EXTRA_CFLAGS} \
+	${AUTO_CONFIG_CFLAGS} \
+	-c -o /dev/null "${temp}" 1>&${out} 2>&${err}
+then
+	rm -f "${temp}"
+	printf "\
+#ifndef %s
+#define %s 1
+#endif /* %s */
+
+" "${macro}" "${macro}" "${macro}" >> "${file}" &&
+	printf 'Defining %s.\n' "${macro}"
+else
+	rm -f "${temp}"
+	printf "\
+/* %s is not defined. */
+
+" "${macro}" >> "${file}" &&
+	printf 'Not defining %s.\n' "${macro}"
+fi
+
+exit