#!/usr/bin/env sh
#
# vim: ft=sh
#
# Copyright (c) 2017 Ian Gregory
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# Based on "OpenBSD Memory Plugin for Nagios" - Copyright 2008 - patrick@pahem.deA
#
# This plugin checks the used/free/total # memory of OpenBSD. You can set
# warning and critical integer/precentage(%) values  with -w and -c.
#
# Example usage:
# check_openbsd_mem.sh -w 15% -c 10%
# Will produce following output:
# OK - Free: 503M Used: 504M Total: 1007M | free_mem=503MB;151;100;0;1007
#

PROGNAME=$(basename "$0")
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3

print_usage()
{
    echo "Usage: $PROGNAME [-w <integer value>] [-c <integer value>]"
    echo ""
    echo "Arguments:"
    echo "  -w <integer value>"
    echo "    Generate warning state if free memory under percentage(%) value"
    echo "  -c <integer value>"
    echo "    Generate critical state if free memory under percentage(%) value"
    echo ""
}

while test -n "$1"; do
    case "$1" in
        -w)
            PERCENT_WARN=$2
            shift
            ;;
        -c)
            PERCENT_CRIT=$2
            shift
            ;;
        *)
            echo "Unknown argument: $1"
            print_usage
            exit $STATE_UNKNOWN
            ;;
    esac
    shift
done

FREE_MEM=$(( $(/usr/bin/vmstat | /usr/bin/tail -1 | /usr/bin/awk '{ print $5 }') / 1024 ))
TOTAL_MEM=$(( $(/sbin/sysctl -n hw.physmem) / 1024 / 1024 ))
USED_MEM=$((TOTAL_MEM - FREE_MEM));

# checks -w and -c parameter and transform input
if [ -n "$PERCENT_WARN" ]; then
    if [ "$PERCENT_WARN" -gt 100 ]; then
        echo "Error: Percentage of warning (-w) over 100%."
        exit $STATE_UNKNOWN
    else
        WARN=$((TOTAL_MEM * PERCENT_WARN / 100))
    fi
fi

if [ -n "$PERCENT_CRIT" ]; then
    if [ "$PERCENT_CRIT" -gt 100 ]; then
        echo "Error: Percentage of critical (-c) over 100%."
        exit $STATE_UNKNOWN
    else
        CRIT=$((TOTAL_MEM * PERCENT_CRIT / 100))
    fi
fi

OUTPUT="Free: ${FREE_MEM}M Used: ${USED_MEM}M Total: ${TOTAL_MEM}M | free_mem=${FREE_MEM}MB;$WARN;$CRIT;0;$TOTAL_MEM"

# checks critical parameter if any specified
if [ -n "$CRIT" ]; then
    if [ $FREE_MEM -lt $CRIT ]; then
        echo "CRITICAL - $OUTPUT"
        exit $STATE_CRITICAL
    fi
fi
# checks warning parameter if any specified
if [ -n "$WARN" ];then
    if [ $FREE_MEM -lt $WARN ]; then
        echo "WARNING - $OUTPUT"
        exit $STATE_WARNING
    fi
fi

# output for STATE_OK
echo "OK - $OUTPUT"
exit $STATE_OK