Make logger thread-safe and robust

Author: doyaGu

src/Logger.cpp

@@ -1,21 +1,36 @@
 #include "Logger.h"
 
 #include <cstdio>
+#include <mutex>
+#include <shared_mutex>
 
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
 #endif
 #include <Windows.h>
 
+#if defined(_MSC_VER)
+#define BML_SAFE_FPRINTF(stream, ...) ::fprintf_s(stream, __VA_ARGS__)
+#define BML_SAFE_VFPRINTF(stream, format, args) ::vfprintf_s(stream, format, args)
+#else
+#define BML_SAFE_FPRINTF(stream, ...) std::fprintf(stream, __VA_ARGS__)
+#define BML_SAFE_VFPRINTF(stream, format, args) std::vfprintf(stream, format, args)
+#endif
+
 #include "ModContext.h"
 
+static std::shared_mutex g_DefaultLoggerMutex;
+static std::mutex g_LogWriteMutex;
+
 Logger *Logger::m_DefaultLogger = nullptr;
 
 Logger *Logger::GetDefault() {
+    std::shared_lock lock(g_DefaultLoggerMutex);
     return m_DefaultLogger;
 }
 
 void Logger::SetDefault(Logger *logger) {
+    std::unique_lock lock(g_DefaultLoggerMutex);
     m_DefaultLogger = logger;
 }
 
@@ -43,6 +58,9 @@ void Logger::Error(const char *fmt, ...) {
 }
 
 void Logger::Log(const char *level, const char *fmt, va_list args) {
+    if (!level || !fmt)
+        return;
+
     SYSTEMTIME sys;
     GetLocalTime(&sys);
 
@@ -53,12 +71,31 @@ void Logger::Log(const char *level, const char *fmt, va_list args) {
         BML_GetModContext()->GetLogFile()
     };
 
-    for (FILE *file: outFiles) {
-        fprintf(file, "[%02d/%02d/%d %02d:%02d:%02d.%03d] ", sys.wMonth, sys.wDay,
-                sys.wYear, sys.wHour, sys.wMinute, sys.wSecond, sys.wMilliseconds);
-        fprintf(file, "[%s/%s]: ", m_ModName, level);
-        vfprintf(file, fmt, args);
+    std::lock_guard lock(g_LogWriteMutex);
+    for (FILE *file : outFiles) {
+        if (!file)
+            continue;
+
+        BML_SAFE_FPRINTF(file,
+                 "[%02d/%02d/%d %02d:%02d:%02d.%03d] ",
+                 sys.wMonth,
+                 sys.wDay,
+                 sys.wYear,
+                 sys.wHour,
+                 sys.wMinute,
+                 sys.wSecond,
+                 sys.wMilliseconds);
+        BML_SAFE_FPRINTF(file, "[%s/%s]: ", m_ModName, level);
+
+        va_list argsCopy;
+        va_copy(argsCopy, args);
+        BML_SAFE_VFPRINTF(file, fmt, argsCopy);
+        va_end(argsCopy);
+
         fputc('\n', file);
         fflush(file);
     }
-}
+}
+
+#undef BML_SAFE_FPRINTF
+#undef BML_SAFE_VFPRINTF

src/ModContext.cpp

@@ -1001,15 +1001,27 @@ void ModContext::InitDirectories() {
 
 void ModContext::InitLogger() {
     std::wstring logfilePath = m_LoaderDir + L"\\ModLoader.log";
+    m_Logfile = nullptr;
+#if defined(_MSC_VER)
+    if (_wfopen_s(&m_Logfile, logfilePath.c_str(), L"w") != 0) {
+        m_Logfile = nullptr;
+    }
+#else
     m_Logfile = _wfopen(logfilePath.c_str(), L"w");
+#endif
     auto *logger = new Logger("ModLoader");
     Logger::SetDefault(logger);
     m_Logger = logger;
 
 #ifdef _DEBUG
     AllocConsole();
+#if defined(_MSC_VER)
+    FILE *console = nullptr;
+    freopen_s(&console, "CONOUT$", "w", stdout);
+#else
     freopen("CONOUT$", "w", stdout);
 #endif
+#endif
 }
 
 void ModContext::ShutdownLogger() {
@@ -1019,7 +1031,10 @@ void ModContext::ShutdownLogger() {
 
     Logger::SetDefault(nullptr);
     delete m_Logger;
-    fclose(m_Logfile);
+    if (m_Logfile) {
+        fclose(m_Logfile);
+        m_Logfile = nullptr;
+    }
 }
 
 extern bool HookObjectLoad();