QFileDialog: Improve default implementation of getOpenFileContent()

Use QFileDialog::ExistingFile and check whether file can be opened,
fixing warnings like:
QIODevice::read (QFile, "/home/.../blub"): device not open

Change-Id: I7ee1d59f01383c581bc09fb44855835aae8c246b
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index add8e6db91..34c2c4ecb5 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -2438,14 +2438,15 @@ void QFileDialog::getOpenFileContent(const QString &nameFilter, const std::funct
     (*openFileImpl)();
 #else
     QFileDialog *dialog = new QFileDialog();
+    dialog->setFileMode(QFileDialog::ExistingFile);
     dialog->selectNameFilter(nameFilter);
 
     auto fileSelected = [=](const QString &fileName) {
         QByteArray fileContent;
         if (!fileName.isNull()) {
             QFile selectedFile(fileName);
-            selectedFile.open(QIODevice::ReadOnly);
-            fileContent = selectedFile.readAll();
+            if (selectedFile.open(QIODevice::ReadOnly))
+                fileContent = selectedFile.readAll();
         }
         fileOpenCompleted(fileName, fileContent);
     };