[idd] clipboard: add direct synchronization

idd/LGIdd/transport/IClipboardSource.h

@@ -0,0 +1,77 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#pragma once
+
+#include "CClipboardChannel.h"
+#include "common/KVMFRClipboard.h"
+
+#include <stdint.h>
+
+class IClipboardTarget
+{
+public:
+  virtual ~IClipboardTarget() = default;
+
+  // Sends one client-to-Helper record. record.generation must be the binding
+  // generation most recently supplied by ClipboardState; transports which
+  // expose their own endpoint generation validate and replace it at this
+  // adapter boundary. clipboardGeneration remains the clipboard content
+  // generation and is preserved end-to-end.
+  //
+  // BUSY consumes neither the record nor its borrowed data; the source
+  // retains and retries the exact record from its bounded worker/Process
+  // drain.
+  virtual ClipboardChannelResult SendClipboard(
+    const KVMFRClipboardMessage& record, const uint8_t * data) = 0;
+
+  // The source calls ClipboardReceiveReady after a Helper-to-client record
+  // returned BUSY and it can accept an exact retry of that record.
+  virtual void ClipboardReceiveReady() = 0;
+  virtual void ClipboardFailed() = 0;
+};
+
+class IClipboardSource
+{
+public:
+  virtual ~IClipboardSource() = default;
+
+  // Start attaches the target, but the source must wait for the initial
+  // ClipboardState callback before calling target.SendClipboard. Stop is a
+  // callback-quiescence barrier and leaves no work which can access target;
+  // it also cleans up a partially completed or failed Start.
+  virtual bool Start(IClipboardTarget& target) = 0;
+  virtual void Stop() = 0;
+
+  // All callbacks into the source, including Start and Stop, are serialized.
+  // record.generation is stamped with the current binding generation. A
+  // generation change invalidates records from an earlier generation and
+  // cancels their transfers; clipboardGeneration is unaffected. data is
+  // borrowed only for the duration of SendClipboard. BUSY consumes neither
+  // record nor data, and the channel retries the same record after
+  // ClipboardReceiveReady (or its bounded polling fallback).
+  virtual void ClipboardState(bool available, uint32_t generation) = 0;
+  virtual ClipboardChannelResult SendClipboard(
+    const KVMFRClipboardMessage& record, const uint8_t * data) = 0;
+
+  // Reset advances generation before the callback. The source cancels all
+  // transfers from the preceding generation.
+  virtual void ClipboardReset(uint32_t generation, uint32_t reason) = 0;
+};