Write the debug log to a file within the OSCAR data folder.

Also immediately emit debug messages to console even before the UI is
initialized.

And present a useful error if the OSCAR data folder can't be created.

oscar/logger.cpp

@@ -12,8 +12,6 @@
 #include "version.h"
 #include <QDir>
 
-#define ASSERTS_SUCK
-
 QThreadPool * otherThreadPool = NULL;
 
 void MyOutputHandler(QtMsgType type, const QMessageLogContext &context, const QString &msgtxt)
@@ -51,11 +49,7 @@ void MyOutputHandler(QtMsgType type, const QMessageLogContext &context, const QS
     if (logger && logger->isRunning()) {
         logger->append(msg);
     }
-#ifdef ASSERTS_SUCK
+    fprintf(stderr, "%s\n", msg.toLocal8Bit().constData());
-//    else {
-//        fprintf(stderr, "%s\n", msg.toLocal8Bit().data());
-//    }
-#endif
 
     if (type == QtFatalMsg) {
         abort();
@@ -91,6 +85,25 @@ void LogThread::connectionReady()
     qDebug() << "Logging UI initialized";
 }
 
+void LogThread::logToFile()
+{
+    QString debugLog = GetLogDir() + "/debug.txt";
+    rotateLogs(debugLog);  // keep a limited set of previous logs
+    
+    strlock.lock();
+    m_logFile = new QFile(debugLog);
+    Q_ASSERT(m_logFile);
+    if (m_logFile->open(QFile::ReadWrite | QFile::Text)) {
+        m_logStream = new QTextStream(m_logFile);
+    }
+    strlock.unlock();
+    if (m_logStream) {
+        qDebug().noquote() << "Logging to" << debugLog;
+    } else {
+        qWarning().noquote() << "Unable to open" << debugLog;
+    }
+}
+
 void shutdownLogger()
 {
     if (logger) {
@@ -126,7 +139,16 @@ void LogThread::quit() {
     strlock.lock();
     while (!buffer.isEmpty()) {
         QString msg = buffer.takeFirst();
-        fprintf(stderr, "%s\n", msg.toLocal8Bit().constData());
+        if (m_logStream) {
+            *m_logStream << msg << endl;
+        }
+    }
+    if (m_logStream) {
+        delete m_logStream;
+        m_logStream = nullptr;
+        Q_ASSERT(m_logFile);
+        delete m_logFile;
+        m_logFile = nullptr;
     }
     strlock.unlock();
 }
@@ -139,9 +161,12 @@ void LogThread::run()
     do {
         strlock.lock();
         //int r = receivers(SIGNAL(outputLog(QString())));
-        while (connected && !buffer.isEmpty()) {
+        // Wait to flush the buffer until the UI is connected and the log file has been opened.
+        while (connected && m_logFile && !buffer.isEmpty()) {
             QString msg = buffer.takeFirst();
-                fprintf(stderr, "%s\n", msg.toLocal8Bit().data());
+            if (m_logStream) {
+                *m_logStream << msg << endl;
+            }
             emit outputLog(msg);
         }
         strlock.unlock();
@@ -154,6 +179,7 @@ QString GetLogDir()
 {
     static const QString LOG_DIR_NAME = "logs";
 
+    Q_ASSERT(!GetAppData().isEmpty());  // If GetLogDir gets called before GetAppData() is valid, this would point at root.
     QDir oscarData(GetAppData());
     Q_ASSERT(oscarData.exists());
     if (!oscarData.exists(LOG_DIR_NAME)) {

oscar/logger.h

@@ -20,7 +20,7 @@ class LogThread:public QObject, public QRunnable
 {
     Q_OBJECT
 public:
-    explicit LogThread() : QRunnable() { running = false; logtime.start(); connected = false; }
+    explicit LogThread() : QRunnable() { running = false; logtime.start(); connected = false; m_logFile = nullptr; m_logStream = nullptr; }
     virtual ~LogThread() {}
 
     void run();
@@ -28,6 +28,7 @@ public:
     void appendClean(QString msg);
     bool isRunning() { return running; }
     void connectionReady();
+    void logToFile();
 
     void quit();
 
@@ -40,6 +41,8 @@ protected:
     volatile bool running;
     QTime logtime;
     bool connected;
+    class QFile* m_logFile;
+    class QTextStream* m_logStream;
 };
 
 extern LogThread * logger;

oscar/main.cpp

@@ -545,6 +545,16 @@ int main(int argc, char *argv[]) {
         }
     }
 
+    // Make sure the data directory exists.
+    if (!newDir.mkpath(".")) {
+        QMessageBox::warning(nullptr, QObject::tr("Exiting"),
+                             QObject::tr("Unable to create the OSCAR data folder at")+"\n"+
+                             GetAppData());
+        return 0;
+    }
+
+    // Begin logging to file now that there's a data folder.
+    logger->logToFile();
 
     ///////////////////////////////////////////////////////////////////////////////////////////
     // Initialize preferences system (Don't use p_pref before this point!)

oscar/oscar.pro

@@ -500,6 +500,7 @@ lessThan(QT_MAJOR_VERSION,5)|lessThan(QT_MINOR_VERSION,9) {
 
 # Create a debug GUI build by adding "CONFIG+=memdebug" to your qmake command
 memdebug {
+    CONFIG += debug
     !win32 {  # add memory checking on Linux and macOS debug builds
         QMAKE_CFLAGS += -g -Werror -fsanitize=address -fno-omit-frame-pointer -fno-common -fsanitize-address-use-after-scope
         lessThan(QT_MAJOR_VERSION,5)|lessThan(QT_MINOR_VERSION,9) {