Qt: Fix library path reset.

g9a3676a reset the Qt library path *after* wsApp was instantiated, which
is too late. Do so before QCoreApplication has a chance to do anything
we might regret.

Change-Id: Ibbdb69d1b7c0ea4bf1042e98a5bb5deba13e954e
Reviewed-on: https://code.wireshark.org/review/6864
Reviewed-by: Gerald Combs <gerald@wireshark.org>

2 files changed, 38 insertions, 29 deletions

diff --git a/ui/qt/wireshark_application.cpp b/ui/qt/wireshark_application.cpp
index 677485ba0a..4288d26a89 100644
--- a/ui/qt/wireshark_application.cpp
+++ b/ui/qt/wireshark_application.cpp
@@ -479,31 +479,6 @@ WiresharkApplication::WiresharkApplication(int &argc,  char **argv) :
     wsApp = this;
     setApplicationName("Wireshark");
 
-#ifdef Q_OS_WIN
-    // Try to avoid library search path collisions. QCoreApplication will
-    // search QT_INSTALL_PREFIX/plugins for platform DLLs before searching
-    // the application directory. If
-    //
-    // - You have Qt version 5.x.y installed in the default location
-    //   (C:\Qt\5.x) on your machine.
-    //
-    // and
-    //
-    // - You install Wireshark that was built on a machine with Qt version
-    //   5.x.z installed in the default location.
-    //
-    // Qt5Core.dll will load qwindows.dll from your local C:\Qt\...\plugins
-    // directory. This may not be compatible with qwindows.dll from that
-    // same path on the build machine. We work around this by removing every
-    // except our application directory.
-
-    foreach (QString path, libraryPaths()) {
-        if (path.compare(applicationDirPath())) {
-            removeLibraryPath(path);
-        }
-    }
-#endif
-
     Q_INIT_RESOURCE(about);
     Q_INIT_RESOURCE(display_filter);
     Q_INIT_RESOURCE(i18n);
diff --git a/wireshark-qt.cpp b/wireshark-qt.cpp
index 6de3e4c54d..75ef28eb81 100644
--- a/wireshark-qt.cpp
+++ b/wireshark-qt.cpp
@@ -397,6 +397,36 @@ check_and_warn_user_startup(const QString &cf_name)
 }
 #endif
 
+#ifdef _WIN32
+// Try to avoid library search path collisions. QCoreApplication will
+// search QT_INSTALL_PREFIX/plugins for platform DLLs before searching
+// the application directory. If
+//
+// - You have Qt version 5.x.y installed in the default location
+//   (C:\Qt\5.x) on your machine.
+//
+// and
+//
+// - You install Wireshark that was built on a machine with Qt version
+//   5.x.z installed in the default location.
+//
+// Qt5Core.dll will load qwindows.dll from your local C:\Qt\5.x\...\plugins
+// directory. This may not be compatible with qwindows.dll from that
+// same path on the build machine. At any rate, loading DLLs from paths
+// you don't control is ill-advised. We work around this by removing every
+// path except our application directory.
+
+static inline void
+reset_library_path(void)
+{
+    QString app_path = QDir(get_progfile_dir()).path();
+    foreach (QString path, QCoreApplication::libraryPaths()) {
+        QCoreApplication::removeLibraryPath(path);
+    }
+    QCoreApplication::addLibraryPath(app_path);
+}
+#endif
+
 /* And now our feature presentation... [ fade to music ] */
 int main(int argc, char *argv[])
 {
@@ -465,15 +495,19 @@ int main(int argc, char *argv[])
         }
     }
 
-    /* Create The Wireshark app */
-    ws_app = new WiresharkApplication(argc, argv);
-
     /*
      * Attempt to get the pathname of the executable file.
      */
-    /* init_progfile_dir_error = */ init_progfile_dir(QCoreApplication::applicationFilePath().toUtf8().constData(), NULL);
+    /* init_progfile_dir_error = */ init_progfile_dir(argv[0], main);
     g_log(NULL, G_LOG_LEVEL_DEBUG, "progfile_dir: %s", get_progfile_dir());
 
+#ifdef _WIN32
+    reset_library_path();
+#endif
+
+    /* Create The Wireshark app */
+    ws_app = new WiresharkApplication(argc, argv);
+
     /* initialize the funnel mini-api */
     // xxx qtshark
     //initialize_funnel_ops();