Qt: fix crashes when Wireshark is closed while running a capture

if we haven't captured any packets yet, don't display a warning about
unsaved changes

make sure that we're not running into a scenario where
MainWindow::testCaptureFileClose() tries to close the capture file at
the same time as the pipe handler who sees an eof on the pipe

cf_has_unsaved_data() should return false if we have a temporary file
that contains no packets

Change-Id: I18d75bd658b85d45dd3313d49e2cd654c6300de5
Reviewed-on: https://code.wireshark.org/review/9109
Reviewed-by: Evan Huus <eapache@gmail.com>
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Martin Kaiser <wireshark@kaiser.cx>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

2 files changed, 3 insertions, 2 deletions

diff --git a/file.c b/file.c
index 4755394963..39f500448c 100644
--- a/file.c
+++ b/file.c
@@ -4336,7 +4336,7 @@ cf_has_unsaved_data(capture_file *cf)
    * If this is a temporary file, or a file with unsaved changes, it
    * has unsaved data.
    */
-  return cf->is_tempfile || cf->unsaved_changes;
+  return (cf->is_tempfile && cf->count>0) || cf->unsaved_changes;
 }
 
 /*
diff --git a/ui/qt/main_window.cpp b/ui/qt/main_window.cpp
index 2754714c75..abae150c71 100644
--- a/ui/qt/main_window.cpp
+++ b/ui/qt/main_window.cpp
@@ -1334,7 +1334,7 @@ bool MainWindow::testCaptureFileClose(bool from_quit, QString &before_what) {
         return true; /* Already closed, nothing to do */
 
 #ifdef HAVE_LIBPCAP
-    if (capture_file_.capFile()->state == FILE_READ_IN_PROGRESS) {
+    if (capture_file_.capFile()->state == FILE_READ_IN_PROGRESS && capture_file_.capFile()->count>0) {
         /* This is true if we're reading a capture file *or* if we're doing
          a live capture.  If we're reading a capture file, the main loop
          is busy reading packets, and only accepting input from the
@@ -1459,6 +1459,7 @@ bool MainWindow::testCaptureFileClose(bool from_quit, QString &before_what) {
 
         } else {
             /* Unchanged file, just close it */
+            capture_file_.capFile()->state = FILE_READ_ABORTED;
             cf_close(capture_file_.capFile());
         }
     } else {