Ensure a single Follow Stream is running only

When changing one of the selection parameters in the Follow Stream
dialog while a filtering task is already running, the result is
inaccurate.
While a filtering task is already running in the Follow Stream
dialog, any filter change which triggers a new filtering gives a
wrong result. Both the displayed data and the Save As functions
are impacted. Closes #15637

ui/qt/follow_stream_dialog.cpp

@@ -47,6 +47,7 @@
 #include <QElapsedTimer>
 #include <QKeyEvent>
 #include <QMessageBox>
+#include <QMutex>
 #include <QPrintDialog>
 #include <QPrinter>
 #include <QScrollBar>
@@ -63,6 +64,9 @@
 // Matches SplashOverlay.
 static int info_update_freq_ = 100;
 
+// Handle the loop breaking notification properly
+static QMutex loop_break_mutex;
+
 FollowStreamDialog::FollowStreamDialog(QWidget &parent, CaptureFile &cf, follow_type_t type) :
     WiresharkDialog(parent, cf),
     ui(new Ui::FollowStreamDialog),
@@ -80,6 +84,7 @@ FollowStreamDialog::FollowStreamDialog(QWidget &parent, CaptureFile &cf, follow_
     turns_(0),
     use_regex_find_(false),
     terminating_(false),
+    isReadRunning_(false),
     previous_sub_stream_num_(0)
 {
     ui->setupUi(this);
@@ -544,6 +549,11 @@ frs_return_t
 FollowStreamDialog::readStream()
 {
 
+    // interrupt any reading already running
+    loop_break_mutex.lock();
+    isReadRunning_ = FALSE;
+    loop_break_mutex.unlock();
+
     ui->teStreamContent->clear();
     text_pos_to_packet_.clear();
 
@@ -1215,8 +1225,12 @@ FollowStreamDialog::readFollowStream()
 
     elapsed_timer.start();
 
+    loop_break_mutex.lock();
+    isReadRunning_ = TRUE;
+    loop_break_mutex.unlock();
+
     for (cur = g_list_last(follow_info_.payload); cur; cur = g_list_previous(cur)) {
-        if (dialogClosed()) break;
+        if (dialogClosed() || !isReadRunning_) break;
 
         follow_record = (follow_record_t *)cur->data;
         skip = FALSE;
@@ -1255,5 +1269,9 @@ FollowStreamDialog::readFollowStream()
         }
     }
 
+    loop_break_mutex.lock();
+    isReadRunning_ = FALSE;
+    loop_break_mutex.unlock();
+
     return FRS_OK;
 }

ui/qt/follow_stream_dialog.h

@@ -122,6 +122,7 @@ private:
     bool                    use_regex_find_;
 
     bool                    terminating_;
+    bool                    isReadRunning_;
 
     int                     previous_sub_stream_num_;
 };