Fix write storage permission problem

android/AndroidManifest.xml

@@ -69,6 +69,8 @@
 	<uses-feature android:name="android.hardware.location" android:required="false"/>
 	
 	<uses-permission android:name="android.permission.INTERNET" />
+	<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />
+	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 	
     <!-- The following comment will be replaced upon deployment with default features based on the dependencies of the application.
          Remove the comment if you do not require these default features. -->

src/QmlControls/AppMessages.cc

@@ -76,6 +76,8 @@ void AppLogModel::writeMessages(const QString dest_file)
             QTextStream out(&file);
             out << writebuffer;
             success = out.status() == QTextStream::Ok;
+        } else {
+            qWarning() << "AppLogModel::writeMessages write failed:" << file.errorString();
         }
         emit debug_model->writeFinished(success);
     });

src/QmlControls/AppMessages.qml

@@ -133,6 +133,7 @@ QGCView {
                 id:             writeDialog
                 folder:         QGroundControl.settingsManager.appSettings.logSavePath
                 nameFilters:    [qsTr("Log files (*.txt)"), qsTr("All Files (*)")]
+                fileExtension:  qsTr("txt")
                 selectExisting: false
                 title:          qsTr("Select log save file")
                 qgcView:        _qgcView

src/main.cc

@@ -97,6 +97,21 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved)
 }
 #endif
 
+#ifdef __android__
+#include <QtAndroid>
+bool checkAndroidWritePermission() {
+    QtAndroid::PermissionResult r = QtAndroid::checkPermission("android.permission.WRITE_EXTERNAL_STORAGE");
+    if(r == QtAndroid::PermissionResult::Denied) {
+        QtAndroid::requestPermissionsSync( QStringList() << "android.permission.WRITE_EXTERNAL_STORAGE" );
+        r = QtAndroid::checkPermission("android.permission.WRITE_EXTERNAL_STORAGE");
+        if(r == QtAndroid::PermissionResult::Denied) {
+             return false;
+        }
+   }
+   return true;
+}
+#endif
+
 /**
  * @brief Starts the application
  *
@@ -254,6 +269,10 @@ int main(int argc, char *argv[])
     } else
 #endif
     {
+
+#ifdef __android__
+        checkAndroidWritePermission();
+#endif
         if (!app->_initForNormalAppBoot()) {
             return -1;
         }