Added check_range shell function to utils.sh.in

plugins-scripts/utils.sh.in

@@ -21,3 +21,88 @@ support() {
 	$ECHO "@SUPPORT@" | sed -e 's/\n/ /g'
 }
 
+
+# check_range takes a value and a range string, returning successfully if an
+# alert should be raised based on the range
+check_range() {
+	local v range yes no err decimal start end cmp match
+	v="$1"
+	range="$2"
+
+	# whether to raise an alert or not
+	yes=0
+	no=1
+	err=2
+
+	# regex to match a decimal number
+	decimal="-?([0-9]+\.?[0-9]*|[0-9]*\.[0-9]+)"
+
+	# compare numbers (including decimals), returning true/false
+	cmp() { awk "BEGIN{ if ($1) exit(0); exit(1)}"; }
+
+	# returns successfully if the string in the first argument matches the
+	# regex in the second
+	match() { echo "$1" | grep -E -q -- "$2"; }
+
+	# make sure value is valid
+	if ! match "$v" "^$decimal$"; then
+		echo "${0##*/}: check_range: invalid value" >&2
+		unset -f cmp match
+		return "$err"
+	fi
+
+	# make sure range is valid
+	if ! match "$range" "^@?(~|$decimal)(:($decimal)?)?$"; then
+		echo "${0##*/}: check_range: invalid range" >&2
+		unset -f cmp match
+		return "$err"
+	fi
+
+	# check for leading @ char, which negates the range
+	if match $range '^@'; then
+		range=${range#@}
+		yes=1
+		no=0
+	fi
+
+	# parse the range string
+	if ! match "$range" ':'; then
+		start=0
+		end="$range"
+	else
+		start="${range%%:*}"
+		end="${range#*:}"
+	fi
+
+	# do the comparison, taking positive ("") and negative infinity ("~")
+	# into account
+	if [ "$start" != "~" ] && [ "$end" != "" ]; then
+		if cmp "$start <= $v" && cmp "$v <= $end"; then
+			unset -f cmp match
+			return "$no"
+		else
+			unset -f cmp match
+			return "$yes"
+		fi
+	elif [ "$start" != "~" ] && [ "$end" = "" ]; then
+		if cmp "$start <= $v"; then
+			unset -f cmp match
+			return "$no"
+		else
+			unset -f cmp match
+			return "$yes"
+		fi
+	elif [ "$start" = "~" ] && [ "$end" != "" ]; then
+		if cmp "$v <= $end"; then
+			unset -f cmp match
+			return "$no"
+		else
+			unset -f cmp match
+			return "$yes"
+		fi
+	else
+		unset -f cmp match
+		return "$no"
+	fi
+}
+