From d864b69334aff805c65cbfe0368c92d6bdf990a5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Benjamin=20H=C3=B6glinger-Stelzer?= <nefarius@dhmx.at>
Date: Tue, 14 Mar 2023 21:37:52 +0100
Subject: [PATCH] Added RegisterPowerStateChangeCallback

---
 .../WDM/RegisterPowerStateChangeCallback.md   | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Snippets/WDM/RegisterPowerStateChangeCallback.md

diff --git a/Snippets/WDM/RegisterPowerStateChangeCallback.md b/Snippets/WDM/RegisterPowerStateChangeCallback.md
new file mode 100644
index 0000000..8631ab4
--- /dev/null
+++ b/Snippets/WDM/RegisterPowerStateChangeCallback.md
@@ -0,0 +1,60 @@
+# RegisterPowerStateChangeCallback
+
+```c
+NTSTATUS RegisterPowerStateChangeCallback(_Inout_ DEVICE_EXTENSION* pDeviceExtension)
+{
+#if DBG
+   
+   DbgPrintEx(DPFLTR_IHVNETWORK_ID,
+              DPFLTR_INFO_LEVEL,
+              " ---> RegisterPowerStateChangeCallback()\n");
+
+#endif /// DBG
+   
+   NT_ASSERT(pDeviceExtension);
+
+   NTSTATUS          status           = STATUS_SUCCESS;
+   OBJECT_ATTRIBUTES objectAttributes = {0};
+   UNICODE_STRING    unicodeString    = {0};
+
+   RtlInitUnicodeString(&unicodeString,
+                        L"\\Callback\\PowerState");
+
+   InitializeObjectAttributes(&objectAttributes,
+                              &unicodeString,
+                              OBJ_CASE_INSENSITIVE,
+                              0,
+                              0);
+
+   status = ExCreateCallback(&(pDeviceExtension->pCallbackObject),
+                             &objectAttributes,
+                             FALSE,                                  /// Do not create as the system should already have done this
+                             TRUE);                                  /// Allow multiple callbacks
+   if(status != STATUS_SUCCESS)
+   {
+      DbgPrintEx(DPFLTR_IHVNETWORK_ID,
+                 DPFLTR_ERROR_LEVEL,
+                 " !!!! RegisterPowerStateChangeCallback : ExCreateCallback() [status: %#x]\n",
+                 status);
+
+      HLPR_BAIL;
+   }
+
+   pDeviceExtension->pRegistration = ExRegisterCallback(pDeviceExtension->pCallbackObject,
+                                                        PowerStateCallback,
+                                                        pDeviceExtension);
+
+   HLPR_BAIL_LABEL:
+
+#if DBG
+   
+   DbgPrintEx(DPFLTR_IHVNETWORK_ID,
+              DPFLTR_INFO_LEVEL,
+              " <--- RegisterPowerStateChangeCallback() [status: %#x]\n",
+              status);
+
+#endif /// DBG
+   
+   return status;
+}
+```