Fix documentation and a possible slice bounds out of range

collector/loadavg_linux.go

@@ -33,7 +33,7 @@ func init() {
 	Factories["loadavg"] = NewLoadavgCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing load average
+// Take a prometheus registry and return a new Collector exposing load average.
 func NewLoadavgCollector() (Collector, error) {
 	return &loadavgCollector{
 		metric: []prometheus.Gauge{
@@ -59,7 +59,7 @@ func NewLoadavgCollector() (Collector, error) {
 func (c *loadavgCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	loads, err := getLoad()
 	if err != nil {
-		return fmt.Errorf("Couldn't get load: %s", err)
+		return fmt.Errorf("couldn't get load: %s", err)
 	}
 	for i, load := range loads {
 		log.Debugf("Set load %d: %f", i, load)
@@ -69,28 +69,32 @@ func (c *loadavgCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	return err
 }
 
-// Read loadavg from /proc
+// Read loadavg from /proc.
 func getLoad() (loads []float64, err error) {
 	data, err := ioutil.ReadFile(procFilePath("loadavg"))
 	if err != nil {
-		return loads, err
+		return nil, err
 	}
 	loads, err = parseLoad(string(data))
 	if err != nil {
-		return loads, err
+		return nil, err
 	}
 	return loads, nil
 }
 
-// Parse /proc loadavg and return 1m, 5m and 15m
+// Parse /proc loadavg and return 1m, 5m and 15m.
 func parseLoad(data string) (loads []float64, err error) {
 	loads = make([]float64, 3)
 	parts := strings.Fields(data)
-	for i, load := range parts[0:3] {
-		loads[i], err = strconv.ParseFloat(load, 64)
-		if err != nil {
-			return loads, fmt.Errorf("Could not parse load '%s': %s", load, err)
+	if len(parts) >= 3 {
+		for i, load := range parts[0:3] {
+			loads[i], err = strconv.ParseFloat(load, 64)
+			if err != nil {
+				return nil, fmt.Errorf("could not parse load '%s': %s", load, err)
+			}
 		}
+	} else {
+		return nil, fmt.Errorf("unexpected content in %s", procFilePath("loadavg"))
 	}
 	return loads, nil
 }