From 0700886b37806930e83e4707354b6797bd9d55ab Mon Sep 17 00:00:00 2001
From: Alexey Rybalchenko <alexryba@gmail.com>
Date: Mon, 30 Jul 2018 14:24:47 +0200
Subject: [PATCH] guard localtime with a mutex to avoid race

---
 logger/Logger.cxx | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/logger/Logger.cxx b/logger/Logger.cxx
index 113f3ab..d584dcd 100644
--- a/logger/Logger.cxx
+++ b/logger/Logger.cxx
@@ -575,9 +575,12 @@ void Logger::RemoveCustomSink(const string& key)
 Logger& Logger::Log()
 {
     char tsstr[32];
-    if (!strftime(tsstr, sizeof(tsstr), "%H:%M:%S", localtime(&(fMetaData.timestamp))))
     {
-        tsstr[0] = 'u';
+        lock_guard<mutex> lock(fMtx); // localtime is not threadsafe, guard it
+        if (!strftime(tsstr, sizeof(tsstr), "%H:%M:%S", localtime(&(fMetaData.timestamp))))
+        {
+            tsstr[0] = 'u';
+        }
     }
 
     if ((!fColored && LoggingToConsole()) || LoggingToFile())