From 4ef34fc7f26e728dac90fc3224d57f0189866b37 Mon Sep 17 00:00:00 2001
From: Vsevolod Stakhov <vsevolod@highsecure.ru>
Date: Thu, 22 Mar 2018 13:35:40 +0000
Subject: [PATCH] [Minor] Fix division by zero

---
 src/plugins/lua/bayes_expiry.lua | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/plugins/lua/bayes_expiry.lua b/src/plugins/lua/bayes_expiry.lua
index de848611a6..6ca22bd336 100644
--- a/src/plugins/lua/bayes_expiry.lua
+++ b/src/plugins/lua/bayes_expiry.lua
@@ -183,8 +183,12 @@ local expiry_script = [[
   end
   redis.replicate_commands()
 
-  local mean = sum / nelts
-  local stddev = math.sqrt(sum_squares / nelts - mean * mean)
+  local mean, stddev = 0, 0
+
+  if nelts > 0 then
+    mean = sum / nelts
+    stddev = math.sqrt(sum_squares / nelts - mean * mean)
+  end
 
   for key,token in pairs(tokens) do
     local ham, spam, ttl = token[1], token[2], token[3]
-- 
2.47.3