3.0 version of previous 2.X change to always prevent deletion of existing sources

git-svn-id: svn://localhost/ardour2/branches/3.0@8842 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/ardour/ardour/file_source.h

@@ -99,6 +99,8 @@ protected:
 	uint16_t    _channel;
 	bool        _within_session;
         std::string _origin;
+
+        void prevent_deletion ();
 };
 
 } // namespace ARDOUR

libs/ardour/file_source.cc

@@ -62,6 +62,8 @@ FileSource::FileSource (Session& session, DataType type, const string& path, con
         , _origin (origin)
 {
 	set_within_session_from_path (path);
+
+        prevent_deletion ();
 }
 
 FileSource::FileSource (Session& session, const XMLNode& node, bool /*must_exist*/)
@@ -75,6 +77,23 @@ FileSource::FileSource (Session& session, const XMLNode& node, bool /*must_exist
 
 	_path = _name;
 	_within_session = true;
+
+        prevent_deletion ();
+}
+
+void
+FileSource::prevent_deletion ()
+{
+        /* if this file already exists, it cannot be removed, ever
+         */
+        
+        if (Glib::file_test (_path, Glib::FILE_TEST_EXISTS)) {
+                if (!(_flags & Destructive)) {
+                        mark_immutable ();
+                } else {
+                        _flags = Flag (_flags & ~(Removable|RemovableIfEmpty|RemoveAtDestroy));
+                }
+        }
 }
 
 bool

libs/ardour/sndfilesource.cc

@@ -612,7 +612,7 @@ bool
 SndFileSource::set_destructive (bool yn)
 {
 	if (yn) {
-		_flags = Flag (_flags | Destructive);
+		_flags = Flag (_flags | Writable | Destructive);
 		if (!xfade_buf) {
 			xfade_buf = new Sample[xfade_frames];
 		}