1 files changed, 31 insertions, 5 deletions
diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 1307118bdf..0861763492 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -63,6 +63,9 @@
 #if QT_CONFIG(slog2)
 #include <sys/slog2.h>
 #endif
+#if QT_HAS_INCLUDE(<paths.h>)
+#include <paths.h>
+#endif
 
 #ifdef Q_OS_ANDROID
 #include <android/log.h>
@@ -153,19 +156,39 @@ Q_NORETURN
 static void qt_message_fatal(QtMsgType, const QMessageLogContext &context, const QString &message);
 static void qt_message_print(QtMsgType, const QMessageLogContext &context, const QString &message);
 
+static int checked_var_value(const char *varname)
+{
+    // qEnvironmentVariableIntValue returns 0 on both parsing failure and on
+    // empty, but we need to distinguish between the two for backwards
+    // compatibility reasons.
+    QByteArray str = qgetenv(varname);
+    if (str.isEmpty())
+        return 0;
+
+    bool ok;
+    int value = str.toInt(&ok, 0);
+    return ok ? value : 1;
+}
+
 static bool isFatal(QtMsgType msgType)
 {
     if (msgType == QtFatalMsg)
         return true;
 
     if (msgType == QtCriticalMsg) {
-        static bool fatalCriticals = !qEnvironmentVariableIsEmpty("QT_FATAL_CRITICALS");
-        return fatalCriticals;
+        static QAtomicInt fatalCriticals = checked_var_value("QT_FATAL_CRITICALS");
+
+        // it's fatal if the current value is exactly 1,
+        // otherwise decrement if it's non-zero
+        return fatalCriticals.load() && fatalCriticals.fetchAndAddRelaxed(-1) == 1;
     }
 
     if (msgType == QtWarningMsg || msgType == QtCriticalMsg) {
-        static bool fatalWarnings = !qEnvironmentVariableIsEmpty("QT_FATAL_WARNINGS");
-        return fatalWarnings;
+        static QAtomicInt fatalWarnings = checked_var_value("QT_FATAL_WARNINGS");
+
+        // it's fatal if the current value is exactly 1,
+        // otherwise decrement if it's non-zero
+        return fatalWarnings.load() && fatalWarnings.fetchAndAddRelaxed(-1) == 1;
     }
 
     return false;
@@ -195,8 +218,11 @@ static bool willLogToConsole()
 #  ifdef Q_OS_WIN
     return GetConsoleWindow();
 #  elif defined(Q_OS_UNIX)
+#    ifndef _PATH_TTY
+#    define _PATH_TTY "/dev/tty"
+#    endif
     // if /dev/tty exists, we can only open it if we have a controlling TTY
-    int devtty = qt_safe_open("/dev/tty", O_RDONLY);
+    int devtty = qt_safe_open(_PATH_TTY, O_RDONLY);
     if (devtty == -1 && (errno == ENOENT || errno == EPERM || errno == ENXIO)) {
         // no /dev/tty, fall back to isatty on stderr
         return isatty(STDERR_FILENO);