[safehook] Note the previous INT 0x13 handler

Cache a record of a safe hook's ancestor in the chain.
Sha0 · Dec 13, 2012 · a795c96 · a795c96
1 parent 9470847
commit a795c96
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diff --git a/src/include/safehook.h b/src/include/safehook.h
@@ -127,6 +127,9 @@ struct S_WV_SAFE_HOOK_BUS {
 
     /** PnP bus relations.  A safe hook can only have one child, at most */
     DEVICE_RELATIONS BusRelations[1];
+
+    /** A record of the previous INT 0x13 handler in the chain */
+    S_X86_SEG16OFF16 PreviousInt13hHandler[1];
   };
 
 #endif  /* WV_M_PROBE_H_ */
diff --git a/src/winvblock/safehook/probe.c b/src/winvblock/safehook/probe.c
@@ -238,6 +238,7 @@ static NTSTATUS STDCALL WvSafeHookDriveDevice(
     bus->PhysicalDeviceObject = pdo;
     bus->BusRelations->Count = 0;
     bus->BusRelations->Objects[0] = NULL;
+    bus->PreviousInt13hHandler[0] = hook->PrevHook;
 
     /* Attach the FDO to the PDO */
     if (!WvlAttachDeviceToDeviceStack(fdo, pdo)) {