From 2148a7de281fc523413e6439c35bbb99f17a2343 Mon Sep 17 00:00:00 2001
From: Julian Kornberger <jk+github@digineo.de>
Date: Thu, 6 Jul 2017 11:33:20 +0200
Subject: [PATCH] Fix division by zero to calculate memory usage

Closes #41
---
 meshviewer/node.go | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/meshviewer/node.go b/meshviewer/node.go
index 266968f..8abc49f 100644
--- a/meshviewer/node.go
+++ b/meshviewer/node.go
@@ -23,15 +23,15 @@ type Flags struct {
 
 // Statistics a meshviewer spezifisch struct, diffrent from respondd
 type Statistics struct {
-	NodeID      string  `json:"node_id"`
-	Clients     uint32  `json:"clients"`
-	RootFsUsage float64 `json:"rootfs_usage,omitempty"`
-	LoadAverage float64 `json:"loadavg,omitempty"`
-	MemoryUsage float64 `json:"memory_usage,omitempty"`
-	Uptime      float64 `json:"uptime,omitempty"`
-	Idletime    float64 `json:"idletime,omitempty"`
-	GatewayIPv4 string  `json:"gateway,omitempty"`
-	GatewayIPv6 string  `json:"gateway6,omitempty"`
+	NodeID      string   `json:"node_id"`
+	Clients     uint32   `json:"clients"`
+	RootFsUsage float64  `json:"rootfs_usage,omitempty"`
+	LoadAverage float64  `json:"loadavg,omitempty"`
+	MemoryUsage *float64 `json:"memory_usage,omitempty"`
+	Uptime      float64  `json:"uptime,omitempty"`
+	Idletime    float64  `json:"idletime,omitempty"`
+	GatewayIPv4 string   `json:"gateway,omitempty"`
+	GatewayIPv6 string   `json:"gateway6,omitempty"`
 	Processes   struct {
 		Total   uint32 `json:"total"`
 		Running uint32 `json:"running"`
@@ -57,7 +57,11 @@ func NewStatistics(stats *data.Statistics) *Statistics {
 	 * calc is coppied from node statuspage (look discussion:
 	 * https://github.com/FreifunkBremen/yanic/issues/35)
 	 */
-	memoryUsage := 1 - (float64(stats.Memory.Free)+float64(stats.Memory.Buffers)+float64(stats.Memory.Cached))/float64(stats.Memory.Total)
+	var memoryUsage *float64
+	if stats.Memory.Total > 0 {
+		usage := 1 - (float64(stats.Memory.Free)+float64(stats.Memory.Buffers)+float64(stats.Memory.Cached))/float64(stats.Memory.Total)
+		memoryUsage = &usage
+	}
 
 	return &Statistics{
 		NodeID:      stats.NodeID,