Shared/Logs: Make AppenderFile more thread-safe

In case of dynamic file names don't store the FILE* handle in a shared class variable but keep it only at function scope.

Valgrind log:
  at _IO_un_link (genops.c:69)
  by fclose@@GLIBC_2.2.5 (iofclose.c:55)
  by AppenderFile::CloseFile() (AppenderFile.cpp:94)
  by AppenderFile::_write(LogMessage const&) (AppenderFile.cpp:66)
  by Appender::write(LogMessage&) (Appender.cpp:102)
  by Logger::write(LogMessage&) const (Logger.cpp:63)
  by Log::write(LogMessage*) (Log.cpp:279)
  by Log::vlog(std::string const&, LogLevel, char const*, __va_list_tag*) (Log.cpp:267)
  by Log::outMessage(std::string const&, LogLevel, char const*, ...) (Log.h:129)
Address 0x2a1bd2d0 is 0 bytes inside a block of size 568 free'd
  at free (vg_replace_malloc.c:468)
  by fclose@@GLIBC_2.2.5 (iofclose.c:85)
  by AppenderFile::CloseFile() (AppenderFile.cpp:94)
  by AppenderFile::_write(LogMessage const&) (AppenderFile.cpp:66)
  by Appender::write(LogMessage&) (Appender.cpp:102)
  by Logger::write(LogMessage&) const (Logger.cpp:63)
  by Log::write(LogMessage*) (Log.cpp:279)
  by Log::vlog(std::string const&, LogLevel, char const*, __va_list_tag*) (Log.cpp:267)
  by Log::outMessage(std::string const&, LogLevel, char const*, ...) (Log.h:129)

1 files changed, 10 insertions, 5 deletions

diff --git a/src/server/shared/Logging/AppenderFile.cpp b/src/server/shared/Logging/AppenderFile.cpp
index 0d52de89f17..7544dc916df 100644
--- a/src/server/shared/Logging/AppenderFile.cpp
+++ b/src/server/shared/Logging/AppenderFile.cpp
@@ -33,7 +33,8 @@ AppenderFile::AppenderFile(uint8 id, std::string const& name, LogLevel level, co
     dynamicName = std::string::npos != filename.find("%s");
     backup = (_flags & APPENDER_FLAGS_MAKE_FILE_BACKUP) != 0;
 
-    logfile = !dynamicName ? OpenFile(_filename, _mode, mode == "w" && backup) : NULL;
+    if (!dynamicName)
+        logfile = !dynamicName ? OpenFile(_filename, _mode, mode == "w" && backup) : NULL;
 }
 
 AppenderFile::~AppenderFile()
@@ -50,7 +51,14 @@ void AppenderFile::_write(LogMessage const& message)
         char namebuf[TRINITY_PATH_MAX];
         snprintf(namebuf, TRINITY_PATH_MAX, filename.c_str(), message.param1.c_str());
         // always use "a" with dynamic name otherwise it could delete the log we wrote in last _write() call
-        logfile = OpenFile(namebuf, "a", backup || exceedMaxSize);
+        FILE* file = OpenFile(namebuf, "a", backup || exceedMaxSize);
+        if (!file)
+            return;
+        fprintf(file, "%s%s", message.prefix.c_str(), message.text.c_str());
+        fflush(file);
+        fileSize += uint64(message.Size());
+        fclose(file);
+        return;
     }
     else if (exceedMaxSize)
         logfile = OpenFile(filename, "w", true);
@@ -61,9 +69,6 @@ void AppenderFile::_write(LogMessage const& message)
     fprintf(logfile, "%s%s", message.prefix.c_str(), message.text.c_str());
     fflush(logfile);
     fileSize += uint64(message.Size());
-
-    if (dynamicName)
-        CloseFile();
 }
 
 FILE* AppenderFile::OpenFile(std::string const &filename, std::string const &mode, bool backup)