#!/bin/sh

#

# Discover the CFLAGS to use during compilation.

#

# Copyright (C) 2013 Richard Cochran <richardcochran@gmail.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.,

# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

#

# Look for functional prototypes in the C library.

#

user_flags()

{

	# Needed for vasprintf().

	printf " -D_GNU_SOURCE"

	# Get list of directories searched for header files.

	dirs=$(echo "" | ${CROSS_COMPILE}cpp -Wp,-v 2>&1 >/dev/null | grep ^" /")

	# Look for clock_adjtime().

	for d in $dirs; do

		files=$(find $d -type f -name time.h -o -name timex.h)

		for f in $files; do

			if grep -q clock_adjtime $f; then

				printf " -DHAVE_CLOCK_ADJTIME"

				break 2

			fi

		done

	done

	# Look for posix_spawn().

	for d in $dirs; do

		files=$(find $d -type f -name spawn.h)

		for f in $files; do

			if grep -q posix_spawn $f; then

				printf " -DHAVE_POSIX_SPAWN"

				break 2

			fi

		done

	done

}

#

# Find the most appropriate kernel header for the SIOCSHWTSTAMP ioctl.

#

# 1. custom kernel or cross build using KBUILD_OUTPUT

# 2. sanitized headers installed under /lib/modules/`uname -r`/build

# 3. normal build using standard system headers

#

kernel_flags()

{

	prefix=""

	tstamp=/usr/include/linux/net_tstamp.h

	if [ "x$KBUILD_OUTPUT" != "x" ]; then

		# With KBUILD_OUTPUT set, we are building against

		# either a custom kernel or a cross compiled kernel.

		build=${KBUILD_OUTPUT}

	else

		# If the currently running kernel is a custom build

		# with the headers installed, then we should use them.

		build=/lib/modules/`uname -r`/build

	fi

	if [ -f ${build}${tstamp} ]; then

		prefix=${build}

		printf " -I%s/usr/include" $prefix

	fi

	if grep -q HWTSTAMP_TX_ONESTEP_SYNC ${prefix}${tstamp}; then

		printf " -DHAVE_ONESTEP_SYNC"

	fi

	if grep -q HWTSTAMP_TX_ONESTEP_P2P ${prefix}${tstamp}; then

		printf " -DHAVE_ONESTEP_P2P"

	fi

}

flags="$(user_flags)$(kernel_flags)"

echo "$flags"