[idd] input: preserve reports under backpressure

Move named pipe writes off the LGMP input worker so a stalled LGInput
endpoint cannot block queue draining or lease maintenance.

Coalesce motion only under queue pressure while preserving mode, button,
wheel, and keyboard transitions. Reset HID state after discontinuities
and carry all 32 mouse button bits through the pipe and HID reports.

idd/LGInput/ipc/CInputPipeClient.cpp

@@ -43,7 +43,7 @@ void CInputPipeClient::Stop()
   m_endpoint.Stop();
   m_lastSequence = 0;
   if (wasRunning)
-    CHIDDevice::ClearReports();
+    CHIDDevice::ResetReports();
 }
 
 void CInputPipeClient::OnPipeConnected()
@@ -55,7 +55,7 @@ void CInputPipeClient::OnPipeConnected()
 void CInputPipeClient::OnPipeDisconnected()
 {
   m_lastSequence = 0;
-  CHIDDevice::ClearReports();
+  CHIDDevice::ResetReports();
   DEBUG_INFO("Disconnected from the LGIdd input transport; reconnecting");
 }
 
@@ -78,6 +78,7 @@ bool CInputPipeClient::OnPipeMessage(
       (m_lastSequence && message.sequence != m_lastSequence + 1))
   {
     DEBUG_WARN("LGInput pipe report sequence changed unexpectedly");
+    CHIDDevice::ResetReports();
     return false;
   }
   bool handled = false;
@@ -117,18 +118,41 @@ bool CInputPipeClient::HandleMouseRelative(
 
   LGInputPipeMouseRelative input = {};
   memcpy(&input, payload, sizeof(input));
-  if (input.wheel < LG_INPUT_MOUSE_WHEEL_MIN ||
-      (input.buttons & ~LG_INPUT_MOUSE_BUTTON_MASK))
+  if (input.deltaX < LG_INPUT_MOUSE_DELTA_MIN ||
+      input.deltaX > LG_INPUT_MOUSE_DELTA_MAX ||
+      input.deltaY < LG_INPUT_MOUSE_DELTA_MIN ||
+      input.deltaY > LG_INPUT_MOUSE_DELTA_MAX ||
+      input.wheel < LG_INPUT_MOUSE_WHEEL_MIN_TOTAL ||
+      input.wheel > LG_INPUT_MOUSE_WHEEL_MAX)
     return false;
 
-  const HIDMouseRelativeReport report = {
-    HID_REPORT_ID_MOUSE_RELATIVE,
-    input.buttons,
-    input.deltaX,
-    input.deltaY,
-    input.wheel,
-  };
-  return SubmitReport(&report, sizeof(report));
+  int32_t x     = input.deltaX;
+  int32_t y     = input.deltaY;
+  int32_t wheel = input.wheel;
+  do
+  {
+    const int16_t reportX = x > INT16_MAX ? INT16_MAX :
+      x < INT16_MIN ? INT16_MIN : static_cast<int16_t>(x);
+    const int16_t reportY = y > INT16_MAX ? INT16_MAX :
+      y < INT16_MIN ? INT16_MIN : static_cast<int16_t>(y);
+    const int8_t reportWheel = wheel > INT8_MAX ? INT8_MAX :
+      wheel < LG_INPUT_MOUSE_WHEEL_MIN ? LG_INPUT_MOUSE_WHEEL_MIN :
+      static_cast<int8_t>(wheel);
+    const HIDMouseRelativeReport report = {
+      HID_REPORT_ID_MOUSE_RELATIVE,
+      input.buttons,
+      reportX,
+      reportY,
+      reportWheel,
+    };
+    if (!SubmitReport(&report, sizeof(report)))
+      return false;
+    x     -= reportX;
+    y     -= reportY;
+    wheel -= reportWheel;
+  }
+  while (x || y || wheel);
+  return true;
 }
 
 bool CInputPipeClient::HandleMouseAbsolute(
@@ -142,18 +166,30 @@ bool CInputPipeClient::HandleMouseAbsolute(
   memcpy(&input, payload, sizeof(input));
   if (input.x > LG_INPUT_MOUSE_ABSOLUTE_MAX ||
       input.y > LG_INPUT_MOUSE_ABSOLUTE_MAX ||
-      input.wheel < LG_INPUT_MOUSE_WHEEL_MIN ||
-      (input.buttons & ~LG_INPUT_MOUSE_BUTTON_MASK))
+      input.wheel < LG_INPUT_MOUSE_WHEEL_MIN_TOTAL ||
+      input.wheel > LG_INPUT_MOUSE_WHEEL_MAX ||
+      input.reserved)
     return false;
 
-  const HIDMouseAbsoluteReport report = {
-    HID_REPORT_ID_MOUSE_ABSOLUTE,
-    input.buttons,
-    input.x,
-    input.y,
-    input.wheel,
-  };
-  return SubmitReport(&report, sizeof(report));
+  int32_t wheel = input.wheel;
+  do
+  {
+    const int8_t reportWheel = wheel > INT8_MAX ? INT8_MAX :
+      wheel < LG_INPUT_MOUSE_WHEEL_MIN ? LG_INPUT_MOUSE_WHEEL_MIN :
+      static_cast<int8_t>(wheel);
+    const HIDMouseAbsoluteReport report = {
+      HID_REPORT_ID_MOUSE_ABSOLUTE,
+      input.buttons,
+      input.x,
+      input.y,
+      reportWheel,
+    };
+    if (!SubmitReport(&report, sizeof(report)))
+      return false;
+    wheel -= reportWheel;
+  }
+  while (wheel);
+  return true;
 }
 
 bool CInputPipeClient::HandleKeyboard(
@@ -166,6 +202,10 @@ bool CInputPipeClient::HandleKeyboard(
   LGInputPipeKeyboard input = {};
   memcpy(&input, payload, sizeof(input));
 
+  for (size_t i = 0; i < sizeof(input.reserved); ++i)
+    if (input.reserved[i])
+      return false;
+
   HIDKeyboardReport report = {};
   report.reportId = HID_REPORT_ID_KEYBOARD;
   report.modifiers = input.modifiers;
@@ -189,8 +229,16 @@ bool CInputPipeClient::SubmitReport(
     return false;
 
   if (status == STATUS_BUFFER_OVERFLOW)
-    DEBUG_WARN("LGInput HID report queue is full; dropping a report");
-  else if (!NT_SUCCESS(status) && status != STATUS_DEVICE_NOT_READY)
-    DEBUG_WARN_HR(status, "Failed to submit an LGInput HID report");
+  {
+    DEBUG_WARN("LGInput HID report queue overflowed; resetting input state");
+    CHIDDevice::ResetReports();
+    return false;
+  }
+  if (!NT_SUCCESS(status))
+  {
+    if (status != STATUS_DEVICE_NOT_READY)
+      DEBUG_WARN_HR(status, "Failed to submit an LGInput HID report");
+    return false;
+  }
   return true;
 }

idd/LGInput/ipc/CInputPipeClient.h

@@ -32,7 +32,6 @@ public:
 
   bool Start();
   void Stop();
-  bool IsConnected() const { return m_endpoint.IsConnected(); }
 
 private:
   void OnPipeConnected() override;