#!/bin/sh
#-
# Copyright (c) 2013 Dag-Erling Smørgrav
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. 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.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
#
# $FreeBSD$
#

set -e

USERLAND_VERSION="@@REVISION@@-@@BRANCH@@"

: ${ROOT:=}
: ${LOADER_DIR:=$ROOT/boot}
: ${LOADER_CONF_FILES:=$LOADER_DIR/defaults/loader.conf $LOADER_DIR/loader.conf $LOADER_DIR/loader.conf.local}
LOADER_RE1='^\([A-Z_a-z][0-9A-Z_a-z]*=[-./0-9A-Z_a-z]\{1,\}\).*$'
LOADER_RE2='^\([A-Z_a-z][0-9A-Z_a-z]*="[-./0-9A-Z_a-z]\{1,\}"\).*$'
KERNEL_RE='^@@TYPE@@ \([-.0-9A-Za-z]\{1,\}\) .*$'

progname=${0##*/}

#
# Print an error message and exit.
#
error() {
	echo "$progname: $*" >&2
	exit 1
}

#
# Try to get the name of the installed kernel from loader.conf and
# return the full path.  If loader.conf does not exist or we could not
# read it, return the path to the default kernel.
#
kernel_file() {
	eval $(sed -n "s/$LOADER_RE1/\\1;/p; s/$LOADER_RE2/\\1;/p" \
	    $LOADER_CONF_FILES 2>/dev/null)
	echo "$LOADER_DIR/${kernel:-kernel}/${bootfile:-kernel}"
}

#
# Extract the kernel version from the installed kernel.
#
kernel_version() {
	kernfile=$(kernel_file)
	if [ ! -f "$kernfile" -o ! -r "$kernfile" ] ; then
		error "unable to locate kernel"
	fi
	what -qs "$kernfile" | sed -n "s/$KERNEL_RE/\\1/p"
}

#
# Print the version of the currently running kernel.
#
running_version() {
	sysctl -n kern.osrelease
}

#
# Print the hardcoded userland version.
#
userland_version() {
	echo $USERLAND_VERSION
}

#
# Print a usage string and exit.
#
usage() {
	echo "usage: $progname [-kru]" >&2
	exit 1
}

#
# Main program.
#
main() {
	# parse command-line arguments
	while getopts "kru" option ; do
		case $option in
		k)
			opt_k=1
			;;
		r)
			opt_r=1
			;;
		u)
			opt_u=1
			;;
		*)
			usage
			;;
		esac
	done
	if [ $OPTIND -le $# ] ; then
		usage
	fi

	# default is -u
	if [ $((opt_k + opt_r + opt_u)) -eq 0 ] ; then
		opt_u=1
	fi

	# print installed kernel version
	if [ $opt_k ] ; then
		kernel_version
	fi

	# print running kernel version
	if [ $opt_r ] ; then
		running_version
	fi

	# print userland version
	if [ $opt_u ] ; then
		userland_version
	fi
}

main "$@"