Implement device map inheritance

xtoskrnl/includes/ob/devmap.hh

@@ -19,11 +19,14 @@ namespace OB
     {
         private:
             STATIC KPUSH_LOCK DeviceMapLock;
+            STATIC PDEVICE_MAP SystemDeviceMap;
             STATIC BOOLEAN UniqueDeviceMaps;
 
         public:
             STATIC XTAPI POBJECT_DIRECTORY GetGlobalDevicesDirectory(IN POBJECT_DIRECTORY Directory);
             STATIC XTAPI BOOLEAN GetUniqueDeviceMaps(VOID);
+            STATIC VOID InheritDeviceMap(IN PEPROCESS NewProcess,
+                                         IN PEPROCESS ParentProcess);
             STATIC XTAPI XTSTATUS InitializeDeviceMap(VOID);
     };
 }

xtoskrnl/ob/data.cc

@@ -12,6 +12,9 @@
 /* Synchronizes shared read and exclusive write access to system device map structures */
 KPUSH_LOCK OB::DeviceMap::DeviceMapLock;
 
+/* Pointer to the system device map */
+PDEVICE_MAP OB::DeviceMap::SystemDeviceMap = NULLPTR;
+
 /* Indicates whether the system employs unique device maps */
 BOOLEAN OB::DeviceMap::UniqueDeviceMaps;
 

xtoskrnl/ob/devmap.cc

@@ -58,6 +58,51 @@ OB::DeviceMap::GetUniqueDeviceMaps(VOID)
     return UniqueDeviceMaps;
 }
 
+/**
+ * Inherits the device map from a parent process or assigns the system default.
+ *
+ * @param NewProcess
+ *        Supplies the newly created process that will inherit the device map.
+ *
+ * @param ParentProcess
+ *        Supplies the optional parent process to inherit the device map from.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+VOID
+OB::DeviceMap::InheritDeviceMap(IN PEPROCESS NewProcess,
+                                IN PEPROCESS ParentProcess)
+{
+    PDEVICE_MAP TargetDeviceMap;
+
+    /* Acquire the device map lock */
+    KE::PushLockExclusiveGuard PushLock(&DeviceMapLock);
+
+    /* Determine the source of the device map */
+    if(ParentProcess)
+    {
+        /* Inherit the device map from the provided parent process */
+        TargetDeviceMap = (PDEVICE_MAP)ParentProcess->DeviceMap;
+    }
+    else
+    {
+        /* No parent process provided, use system device map */
+        TargetDeviceMap = SystemDeviceMap;
+    }
+
+    /* Check if a valid device map was resolved */
+    if(TargetDeviceMap)
+    {
+        /* Increment the reference count of the target device map */
+        TargetDeviceMap->ReferenceCount++;
+
+        /* Assign the device map to the process */
+        NewProcess->DeviceMap = TargetDeviceMap;
+    }
+}
+
 /**
  * Initializes the Object Manager's device map subsystem.
  *