OutputDebugStringF code cleanup

Initialize the OutputDebugStringF mutex and file pointer using
boost::call_once, to be thread-safe.
Make the return value of OutputDebugStringF really be the number of
characters written (*printf() semantics).
Declare the fReopenDebugLog flag volatile, since it is changed from
a signal handler.
And don't declare OutputDebugStringF() as inline.

src/util.cpp

@@ -74,7 +74,7 @@ bool fTestNet = false;
 bool fNoListen = false;
 bool fLogTimestamps = false;
 CMedianFilter<int64> vTimeOffsets(200,0);
-bool fReopenDebugLog = false;
+volatile bool fReopenDebugLog = false;
 
 // Init OpenSSL library multithreading support
 static CCriticalSection** ppmutexOpenSSL;
@@ -195,62 +195,76 @@ uint256 GetRandHash()
 
 
 
+//
+// OutputDebugStringF (aka printf -- there is a #define that we really
+// should get rid of one day) has been broken a couple of times now
+// by well-meaning people adding mutexes in the most straightforward way.
+// It breaks because it may be called by global destructors during shutdown.
+// Since the order of destruction of static/global objects is undefined,
+// defining a mutex as a global object doesn't work (the mutex gets
+// destroyed, and then some later destructor calls OutputDebugStringF,
+// maybe indirectly, and you get a core dump at shutdown trying to lock
+// the mutex).
 
-inline int OutputDebugStringF(const char* pszFormat, ...)
+static boost::once_flag debugPrintInitFlag = BOOST_ONCE_INIT;
+// We use boost::call_once() to make sure these are initialized in
+// in a thread-safe manner the first time it is called:
+static FILE* fileout = NULL;
+static boost::mutex* mutexDebugLog = NULL;
+
+static void DebugPrintInit()
 {
-    int ret = 0;
+    assert(fileout == NULL);
+    assert(mutexDebugLog == NULL);
+
+    boost::filesystem::path pathDebug = GetDataDir() / "debug.log";
+    fileout = fopen(pathDebug.string().c_str(), "a");
+    if (fileout) setbuf(fileout, NULL); // unbuffered
+
+    mutexDebugLog = new boost::mutex();
+}
+
+int OutputDebugStringF(const char* pszFormat, ...)
+{
+    int ret = 0; // Returns total number of characters written
     if (fPrintToConsole)
     {
         // print to console
         va_list arg_ptr;
         va_start(arg_ptr, pszFormat);
-        ret = vprintf(pszFormat, arg_ptr);
+        ret += vprintf(pszFormat, arg_ptr);
         va_end(arg_ptr);
     }
     else if (!fPrintToDebugger)
     {
-        // print to debug.log
+        static bool fStartedNewLine = true;
-        static FILE* fileout = NULL;
+        boost::call_once(&DebugPrintInit, debugPrintInitFlag);
 
-        if (!fileout)
+        if (fileout == NULL)
-        {
+            return ret;
+
+        boost::mutex::scoped_lock scoped_lock(*mutexDebugLog);
+
+        // reopen the log file, if requested
+        if (fReopenDebugLog) {
+            fReopenDebugLog = false;
             boost::filesystem::path pathDebug = GetDataDir() / "debug.log";
-            fileout = fopen(pathDebug.string().c_str(), "a");
+            if (freopen(pathDebug.string().c_str(),"a",fileout) != NULL)
-            if (fileout) setbuf(fileout, NULL); // unbuffered
+                setbuf(fileout, NULL); // unbuffered
         }
-        if (fileout)
-        {
-            static bool fStartedNewLine = true;
 
-            // This routine may be called by global destructors during shutdown.
+        // Debug print useful for profiling
-            // Since the order of destruction of static/global objects is undefined,
+        if (fLogTimestamps && fStartedNewLine)
-            // allocate mutexDebugLog on the heap the first time this routine
+            ret += fprintf(fileout, "%s ", DateTimeStrFormat("%Y-%m-%d %H:%M:%S", GetTime()).c_str());
-            // is called to avoid crashes during shutdown.
+        if (pszFormat[strlen(pszFormat) - 1] == '\n')
-            static boost::mutex* mutexDebugLog = NULL;
+            fStartedNewLine = true;
-            if (mutexDebugLog == NULL) mutexDebugLog = new boost::mutex();
+        else
-            boost::mutex::scoped_lock scoped_lock(*mutexDebugLog);
+            fStartedNewLine = false;
 
-            // reopen the log file, if requested
+        va_list arg_ptr;
-            if (fReopenDebugLog) {
+        va_start(arg_ptr, pszFormat);
-                fReopenDebugLog = false;
+        ret += vfprintf(fileout, pszFormat, arg_ptr);
-                boost::filesystem::path pathDebug = GetDataDir() / "debug.log";
+        va_end(arg_ptr);
-                if (freopen(pathDebug.string().c_str(),"a",fileout) != NULL)
-                    setbuf(fileout, NULL); // unbuffered
-            }
-
-            // Debug print useful for profiling
-            if (fLogTimestamps && fStartedNewLine)
-                fprintf(fileout, "%s ", DateTimeStrFormat("%Y-%m-%d %H:%M:%S", GetTime()).c_str());
-            if (pszFormat[strlen(pszFormat) - 1] == '\n')
-                fStartedNewLine = true;
-            else
-                fStartedNewLine = false;
-
-            va_list arg_ptr;
-            va_start(arg_ptr, pszFormat);
-            ret = vfprintf(fileout, pszFormat, arg_ptr);
-            va_end(arg_ptr);
-        }
     }
 
 #ifdef WIN32
@@ -273,6 +287,7 @@ inline int OutputDebugStringF(const char* pszFormat, ...)
             {
                 OutputDebugStringA(buffer.substr(line_start, line_end - line_start).c_str());
                 line_start = line_end + 1;
+                ret += line_end-line_start;
             }
             buffer.erase(0, line_start);
         }

src/util.h

@@ -138,7 +138,7 @@ extern std::string strMiscWarning;
 extern bool fTestNet;
 extern bool fNoListen;
 extern bool fLogTimestamps;
-extern bool fReopenDebugLog;
+extern volatile bool fReopenDebugLog;
 
 void RandAddSeed();
 void RandAddSeedPerfmon();