From 5241f9783b41e74f719dc4a472c6b0803b0eff8c Mon Sep 17 00:00:00 2001
From: a1xd <68629610+a1xd@users.noreply.github.com>
Date: Fri, 31 Jul 2020 20:04:19 -0400
Subject: add read

add function that makes an ioctl call to return the driver's active mouse_modifier
---
 common/common.vcxitems                |  1 +
 common/external/tagged-union-single.h |  2 +-
 common/rawaccel-io.hpp                | 46 +++++++++++++++++++++++++
 driver/driver.cpp                     | 63 +++++++++++++++++++++++------------
 4 files changed, 89 insertions(+), 23 deletions(-)
 create mode 100644 common/rawaccel-io.hpp

diff --git a/common/common.vcxitems b/common/common.vcxitems
index d1e8db0..aeeaa95 100644
--- a/common/common.vcxitems
+++ b/common/common.vcxitems
@@ -23,6 +23,7 @@
     <ClInclude Include="$(MSBuildThisFileDirectory)accel-power.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)accel-sigmoid.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)accel-error.hpp" />
+    <ClInclude Include="$(MSBuildThisFileDirectory)rawaccel-io.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)rawaccel-userspace.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)rawaccel.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)x64-util.hpp" />
diff --git a/common/external/tagged-union-single.h b/common/external/tagged-union-single.h
index 3353325..f0de097 100644
--- a/common/external/tagged-union-single.h
+++ b/common/external/tagged-union-single.h
@@ -137,7 +137,7 @@ struct tagged_union {
     int tag = 0;
 
     struct storage_t {
-        alignas(max_align_of<First, Rest...>) char bytes[max_size_of<First, Rest...>] = "";
+        alignas(max_align_of<First, Rest...>) char bytes[max_size_of<First, Rest...>] = {};
 
         template <typename T>
         inline constexpr T& as() {
diff --git a/common/rawaccel-io.hpp b/common/rawaccel-io.hpp
new file mode 100644
index 0000000..5d6fad6
--- /dev/null
+++ b/common/rawaccel-io.hpp
@@ -0,0 +1,46 @@
+#pragma once
+
+#include <system_error>
+
+#define NOMINMAX
+#include <Windows.h>
+
+#include "rawaccel.hpp"
+
+#define RA_IOCTL CTL_CODE(0x8888, 0x888, METHOD_BUFFERED, FILE_ANY_ACCESS)
+
+namespace rawaccel {
+
+	mouse_modifier read() {
+		HANDLE ra_handle = INVALID_HANDLE_VALUE;
+
+		ra_handle = CreateFileW(L"\\\\.\\rawaccel", 0, 0, 0, OPEN_EXISTING, 0, 0);
+
+		if (ra_handle == INVALID_HANDLE_VALUE) {
+			throw std::system_error(GetLastError(), std::system_category(), "CreateFile failed");
+		}
+
+		mouse_modifier mod;
+		DWORD dummy;
+
+		BOOL success = DeviceIoControl(
+			ra_handle,
+			RA_IOCTL,
+			NULL,					  // input buffer
+			0,						  // input buffer size
+			&mod,                     // output buffer
+			sizeof(mouse_modifier),   // output buffer size
+			&dummy,                   // bytes returned
+			NULL                      // overlapped structure
+		);
+
+		CloseHandle(ra_handle);
+
+		if (!success) {
+			throw std::system_error(GetLastError(), std::system_category(), "DeviceIoControl failed");
+		}
+
+		return mod;
+	}
+
+}
diff --git a/driver/driver.cpp b/driver/driver.cpp
index 1f9cebd..c893b8b 100644
--- a/driver/driver.cpp
+++ b/driver/driver.cpp
@@ -143,41 +143,60 @@ Return Value:
 --*/
 {
     NTSTATUS status;
-    void* input_buffer;
-    size_t input_size;
+    void* buffer;
+    size_t size;
 
     UNREFERENCED_PARAMETER(Queue);
-    UNREFERENCED_PARAMETER(OutputBufferLength);
     UNREFERENCED_PARAMETER(IoControlCode);
 
     PAGED_CODE();
 
     DebugPrint(("Ioctl received into filter control object.\n"));
 
-    if (InputBufferLength != sizeof(ra::mouse_modifier)) {
-        DebugPrint(("Received unknown request of %u bytes\n", InputBufferLength));
-        // status maps to win32 error code 1784: ERROR_INVALID_USER_BUFFER
-        WdfRequestComplete(Request, STATUS_INVALID_BUFFER_SIZE);
-        return;
-    }
+    if (InputBufferLength == sizeof(ra::mouse_modifier)) {
+        status = WdfRequestRetrieveInputBuffer(
+            Request,
+            sizeof(ra::mouse_modifier),
+            &buffer,
+            &size
+        );
 
-    status = WdfRequestRetrieveInputBuffer(
-        Request,
-        sizeof(ra::mouse_modifier),
-        &input_buffer,
-        &input_size
-    );
+        if (!NT_SUCCESS(status)) {
+            DebugPrint(("RetrieveInputBuffer failed: 0x%x\n", status));
+            // status maps to win32 error code 1359: ERROR_INTERNAL_ERROR
+            WdfRequestComplete(Request, STATUS_MESSAGE_LOST);
+            return;
+        }
 
-    if (!NT_SUCCESS(status)) {
-        DebugPrint(("RetrieveInputBuffer failed: 0x%x\n", status));
-        // status maps to win32 error code 1359: ERROR_INTERNAL_ERROR
-        WdfRequestComplete(Request, STATUS_MESSAGE_LOST);
-        return;
+        global.modifier = *reinterpret_cast<ra::mouse_modifier*>(buffer);
+
+        WdfRequestComplete(Request, STATUS_SUCCESS);
     }
+    else if (OutputBufferLength == sizeof(ra::mouse_modifier)) {
+        status = WdfRequestRetrieveOutputBuffer(
+            Request,
+            sizeof(ra::mouse_modifier),
+            &buffer,
+            &size
+        );
+
+        if (!NT_SUCCESS(status)) {
+            DebugPrint(("RetrieveOutputBuffer failed: 0x%x\n", status));
+            // status maps to win32 error code 1359: ERROR_INTERNAL_ERROR
+            WdfRequestComplete(Request, STATUS_MESSAGE_LOST);
+            return;
+        }
+
+        *reinterpret_cast<ra::mouse_modifier*>(buffer) = global.modifier;
 
-    global.modifier = *reinterpret_cast<ra::mouse_modifier*>(input_buffer);
+        WdfRequestComplete(Request, STATUS_SUCCESS);
+    }
+    else {
+        DebugPrint(("Received unknown request: in %uB, out %uB\n", InputBufferLength, OutputBufferLength));
+        // status maps to win32 error code 1784: ERROR_INVALID_USER_BUFFER
+        WdfRequestComplete(Request, STATUS_INVALID_BUFFER_SIZE);
+    }
 
-    WdfRequestComplete(Request, STATUS_SUCCESS);
 }
 #pragma warning(pop) // enable 28118 again
 
-- 
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