From c85a086e9eb8fbf3ea19fb3e28de1ffdfd3f8e2e Mon Sep 17 00:00:00 2001
From: Eric Kohl <eric.kohl@reactos.org>
Date: Thu, 21 Jul 2005 20:30:55 +0000
Subject: [PATCH] Make IoGetDeviceObjectFromDeviceInstance work without using
 the Registry. (experimental)

svn path=/trunk/; revision=16686
---
 reactos/ntoskrnl/io/plugplay.c | 50 +++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/reactos/ntoskrnl/io/plugplay.c b/reactos/ntoskrnl/io/plugplay.c
index a6d2218f6eb..71f11ba42b6 100644
--- a/reactos/ntoskrnl/io/plugplay.c
+++ b/reactos/ntoskrnl/io/plugplay.c
@@ -223,9 +223,36 @@ NtGetPlugPlayEvent(IN ULONG Reserved1,
 }
 
 
+static PDEVICE_OBJECT
+IopTraverseDeviceNode(PDEVICE_NODE Node, PUNICODE_STRING DeviceInstance)
+{
+    PDEVICE_OBJECT DeviceObject;
+    PDEVICE_NODE ChildNode;
+
+    if (RtlEqualUnicodeString(&Node->InstancePath,
+                              DeviceInstance, TRUE))
+        return Node->PhysicalDeviceObject;
+
+    /* Traversal of all children nodes */
+    for (ChildNode = Node->Child;
+         ChildNode != NULL;
+         ChildNode = ChildNode->NextSibling)
+    {
+        DeviceObject = IopTraverseDeviceNode(ChildNode, DeviceInstance);
+        if (DeviceObject != NULL)
+        {
+            return DeviceObject;
+        }
+    }
+
+    return NULL;
+}
+
+
 static PDEVICE_OBJECT
 IopGetDeviceObjectFromDeviceInstance(PUNICODE_STRING DeviceInstance)
 {
+#if 0
     OBJECT_ATTRIBUTES ObjectAttributes;
     UNICODE_STRING KeyName, ValueName;
     LPWSTR KeyNameBuffer;
@@ -308,7 +335,7 @@ IopGetDeviceObjectFromDeviceInstance(PUNICODE_STRING DeviceInstance)
     ZwClose(ControlKeyHandle);
     if (!NT_SUCCESS(Status))
     {
-        DPRINT1("Failed to open the 'Control' key (Status %lx)\n", Status);
+        DPRINT1("Failed to query the 'DeviceReference' value (Status %lx)\n", Status);
         return NULL;
     }
 
@@ -336,9 +363,30 @@ IopGetDeviceObjectFromDeviceInstance(PUNICODE_STRING DeviceInstance)
     DPRINT("IopGetDeviceObjectFromDeviceInstance() done\n");
 
     return DeviceObject;
+#endif
+
+    if (IopRootDeviceNode == NULL)
+        return NULL;
+
+    if (DeviceInstance == NULL ||
+        DeviceInstance->Length == 0
+        )
+    {
+        if (IopRootDeviceNode->PhysicalDeviceObject)
+        {
+            ObReferenceObject(IopRootDeviceNode->PhysicalDeviceObject);
+            return IopRootDeviceNode->PhysicalDeviceObject;
+        }
+        else
+            return NULL;
+    }
+
+    return IopTraverseDeviceNode(IopRootDeviceNode, DeviceInstance);
+
 }
 
 
+
 static NTSTATUS
 IopGetDeviceProperty(PPLUGPLAY_CONTROL_PROPERTY_DATA PropertyData)
 {