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 at 6wind.com>
---
 MAINTAINERS              |   1 +
 scripts/auto-config-h.sh | 136 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 137 insertions(+)
 create mode 100755 scripts/auto-config-h.sh

diff --git a/MAINTAINERS b/MAINTAINERS
index 349ad2b..631e8ea 100644
--- a/MAINTAINERS
+++ b/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
diff --git a/scripts/auto-config-h.sh b/scripts/auto-config-h.sh
new file mode 100755
index 0000000..4356d7e
--- /dev/null
+++ b/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
-- 
2.1.0

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