introduce the idea of an "unnamed" session

libs/ardour/ardour/session.h

@@ -207,7 +207,8 @@ public:
 	         const std::string& fullpath,
 	         const std::string& snapshot_name,
 	         BusProfile const * bus_profile = 0,
-	         std::string mix_template = "");
+	         std::string mix_template = "",
+	         bool unnamed = false);
 
 	virtual ~Session ();
 
@@ -242,6 +243,7 @@ public:
 	bool cannot_save () const                      { return _state_of_the_state & CannotSave; }
 	bool in_cleanup () const                       { return _state_of_the_state & InCleanup; }
 	bool inital_connect_or_deletion_in_progress () { return _state_of_the_state & (InitialConnecting | Deletion); }
+	bool not_named() const;
 
 	PBD::Signal0<void> DirtyChanged;
 
@@ -1270,7 +1272,7 @@ protected:
 	void set_transport_speed (double speed, bool abort, bool clear_state, bool as_default);
 
 private:
-	int  create (const std::string& mix_template, BusProfile const *);
+	int  create (const std::string& mix_template, BusProfile const *, bool unnamed);
 	void destroy ();
 
 	static guint _name_id_counter;

libs/ardour/session.cc

@@ -172,7 +172,8 @@ Session::Session (AudioEngine &eng,
                   const string& fullpath,
                   const string& snapshot_name,
                   BusProfile const * bus_profile,
-                  string mix_template)
+                  string mix_template,
+                  bool unnamed)
 	: _playlists (new SessionPlaylists)
 	, _engine (eng)
 	, process_function (&Session::process_with_events)
@@ -344,7 +345,7 @@ Session::Session (AudioEngine &eng,
 
 		Stateful::loading_state_version = CURRENT_SESSION_FILE_VERSION;
 
-		if (create (mix_template, bus_profile)) {
+		if (create (mix_template, bus_profile, unnamed)) {
 			destroy ();
 			throw SessionException (_("Session initialization failed"));
 		}

libs/ardour/session_state.cc

@@ -44,6 +44,10 @@
 #include <climits>
 #include <signal.h>
 #include <sys/time.h>
+/* for open(2) */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 
 #ifdef HAVE_SYS_VFS_H
 #include <sys/vfs.h>
@@ -80,6 +84,7 @@
 #include "pbd/file_utils.h"
 #include "pbd/pathexpand.h"
 #include "pbd/pthread_utils.h"
+#include "pbd/scoped_file_descriptor.h"
 #include "pbd/stacktrace.h"
 #include "pbd/types_convert.h"
 #include "pbd/localtime_r.h"
@@ -154,6 +159,8 @@ using namespace PBD;
 
 #define DEBUG_UNDO_HISTORY(msg) DEBUG_TRACE (PBD::DEBUG::UndoHistory, string_compose ("%1: %2\n", __LINE__, msg));
 
+static const char* unnamed_file_name = X_(".unnamed");
+
 void
 Session::pre_engine_init (string fullpath)
 {
@@ -569,13 +576,17 @@ Session::ensure_subdirs ()
  *  Caller must not hold process lock.
  */
 int
-Session::create (const string& session_template, BusProfile const * bus_profile)
+Session::create (const string& session_template, BusProfile const * bus_profile, bool unnamed)
 {
 	if (g_mkdir_with_parents (_path.c_str(), 0755) < 0) {
 		error << string_compose(_("Session: cannot create session folder \"%1\" (%2)"), _path, strerror (errno)) << endmsg;
 		return -1;
 	}
 
+	if (unnamed) {
+		PBD::ScopedFileDescriptor fd = g_open (Glib::build_filename (_path, unnamed_file_name).c_str(), O_CREAT|O_TRUNC|O_RDWR, 0666);
+	}
+
 	if (ensure_subdirs ()) {
 		return -1;
 	}
@@ -5637,3 +5648,9 @@ Session::redo (uint32_t n)
 	StateProtector stp (this);
 	_history.redo (n);
 }
+
+bool
+Session::not_named() const
+{
+	return Glib::file_test (Glib::build_filename (_path, unnamed_file_name), Glib::FILE_TEST_EXISTS);
+}