Core/Thread: Fix race condition converting time values to local time

Replace thread-unsafe localtime() http://www.cplusplus.com/reference/ctime/localtime/ with thread-safe portable ACE_OS::localtime_r() .

Helgrind log:
 Possible data race during read of size 4 at 0x6F183C0 by thread #1
 Locks held: none
  at 0x14E72E3: World::InitDailyQuestResetTime() (World.cpp:2772)
  by 0x14E3A01: World::SetInitialWorldSettings() (World.cpp:1790)
  by 0x101122A: Master::Run() (Master.cpp:164)
  by 0x101740C: main (Main.cpp:142)

 This conflicts with a previous write of size 4 by thread #2
 Locks held: none
  at 0x6C2D3BA: __tzfile_compute (tzfile.c:797)
  by 0x6C2D036: __tz_convert (tzset.c:627)
  by 0x164146C: LogMessage::getTimeStr(long) (Appender.cpp:23)
  by 0x1641550: LogMessage::getTimeStr() (Appender.cpp:31)
  by 0x1641722: Appender::write(LogMessage&) (Appender.cpp:80)
  by 0x1633FCE: Logger::write(LogMessage&) (Logger.cpp:83)
  by 0x16433D8: LogOperation::call() (LogOperation.cpp:29)
  by 0x16428A4: LogWorker::svc() (LogWorker.cpp:45)

1 files changed, 3 insertions, 2 deletions

diff --git a/src/server/shared/Utilities/Util.cpp b/src/server/shared/Utilities/Util.cpp
index 1bba3c2db09..48012b6eea8 100644
--- a/src/server/shared/Utilities/Util.cpp
+++ b/src/server/shared/Utilities/Util.cpp
@@ -215,7 +215,8 @@ uint32 TimeStringToSecs(const std::string& timestring)
 
 std::string TimeToTimestampStr(time_t t)
 {
-    tm* aTm = localtime(&t);
+    tm aTm;
+    ACE_OS::localtime_r(&t, &aTm);
     //       YYYY   year
     //       MM     month (2 digits 01-12)
     //       DD     day (2 digits 01-31)
@@ -223,7 +224,7 @@ std::string TimeToTimestampStr(time_t t)
     //       MM     minutes (2 digits 00-59)
     //       SS     seconds (2 digits 00-59)
     char buf[20];
-    snprintf(buf, 20, "%04d-%02d-%02d_%02d-%02d-%02d", aTm->tm_year+1900, aTm->tm_mon+1, aTm->tm_mday, aTm->tm_hour, aTm->tm_min, aTm->tm_sec);
+    snprintf(buf, 20, "%04d-%02d-%02d_%02d-%02d-%02d", aTm.tm_year+1900, aTm.tm_mon+1, aTm.tm_mday, aTm.tm_hour, aTm.tm_min, aTm.tm_sec);
     return std::string(buf);
 }