[idd] clipboard: add direct synchronization

idd/LGCommon/CClipboardChannel.h

@@ -0,0 +1,129 @@
+/**
+ * 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 "Atomic.h"
+#include "ClipboardRing.h"
+#include "CSRWLock.h"
+
+#include <Windows.h>
+
+#include <atomic>
+#include <stdint.h>
+
+enum class ClipboardChannelResult
+{
+  ACCEPTED,
+  BUSY,
+  FAILED,
+};
+
+class IClipboardChannelHandler
+{
+public:
+  virtual ~IClipboardChannelHandler() = default;
+
+  virtual void ClipboardState(bool available, uint64_t epoch) = 0;
+  // data is borrowed and remains valid only for the duration of this call.
+  // BUSY leaves the shared ring slot occupied so it can be retried later.
+  virtual ClipboardChannelResult ClipboardRecord(
+    const KVMFRClipboardMessage& record, const uint8_t * data) = 0;
+  virtual void ClipboardReset(uint64_t epoch, uint32_t reason) = 0;
+};
+
+class IClipboardChannelDoorbell
+{
+public:
+  virtual ~IClipboardChannelDoorbell() = default;
+
+  virtual bool ClipboardKick(uint64_t epoch) = 0;
+  virtual void ClipboardResetPeer(uint64_t epoch, uint32_t reason) = 0;
+};
+
+class CClipboardChannel
+{
+private:
+  static constexpr DWORD POLL_MS = 50;
+
+  enum class DrainResult
+  {
+    IDLE,
+    BUSY,
+    STOPPED,
+    CORRUPT,
+  };
+
+  CSRWLock m_lifecycleLock;
+  CSRWLock m_handlerLock;
+  CSRWLock m_writeLock;
+
+  HANDLE             m_mapping = nullptr;
+  ClipboardMapping * m_view    = nullptr;
+  ClipboardRing    * m_in      = nullptr;
+  ClipboardRing    * m_out     = nullptr;
+  HANDLE             m_stop    = nullptr;
+  HANDLE             m_kick    = nullptr;
+  HANDLE             m_thread  = nullptr;
+  DWORD              m_threadId = 0;
+  uint64_t           m_epoch   = 0;
+  uint64_t           m_instance = 0;
+  bool               m_deferredDetach = false;
+
+  IClipboardChannelHandler  * m_handler  = nullptr;
+  IClipboardChannelDoorbell * m_doorbell = nullptr;
+  std::atomic<bool>           m_available { false };
+
+  DrainResult Drain();
+  void Thread();
+  void Fail(uint64_t instance, uint32_t reason, bool resetPeer = true);
+  void CleanupDeferredDetach();
+  void PublishState(bool available, uint64_t epoch);
+  ClipboardChannelResult PublishRecord(
+    const KVMFRClipboardMessage& record, const uint8_t * data);
+  void PublishReset(uint64_t epoch, uint32_t reason);
+
+  static DWORD WINAPI ThreadProc(void * context);
+
+public:
+  CClipboardChannel() = default;
+  ~CClipboardChannel();
+
+  CClipboardChannel(const CClipboardChannel&) = delete;
+  CClipboardChannel& operator=(const CClipboardChannel&) = delete;
+
+  bool Attach(HANDLE mapping, uint64_t epoch, bool helper,
+    IClipboardChannelDoorbell& doorbell);
+  void Detach();
+  void Kick(uint64_t epoch);
+  void Reset(uint64_t epoch, uint32_t reason);
+
+  ClipboardChannelResult Send(
+    const KVMFRClipboardMessage& record, const void * data = nullptr);
+
+  void SetHandler(IClipboardChannelHandler * handler);
+  void ClearHandler(IClipboardChannelHandler * handler);
+
+  bool Available() const
+  {
+    return Atomic::Load(m_available, std::memory_order_acquire);
+  }
+  uint64_t Epoch();
+};