kernelbase: Implement DiscardVirtualMemory().

dlls/kernel32/kernel32.spec

@@ -371,6 +371,7 @@
 @ stdcall -import DeleteProcThreadAttributeList(ptr)
 # @ stub DisableThreadProfiling
 @ stdcall DisassociateCurrentThreadFromCallback(ptr) NTDLL.TpDisassociateCallback
+@ stdcall DiscardVirtualMemory(ptr long) kernelbase.DiscardVirtualMemory
 @ stdcall DeleteTimerQueue(long)
 @ stdcall -import DeleteTimerQueueEx(long long)
 @ stdcall -import DeleteTimerQueueTimer(long long long)

dlls/kernelbase/kernelbase.spec

@@ -269,7 +269,7 @@
 @ stdcall DisablePredefinedHandleTableInternal(long)
 @ stdcall DisableThreadLibraryCalls(long)
 @ stdcall DisassociateCurrentThreadFromCallback(ptr) ntdll.TpDisassociateCallback
-# @ stub DiscardVirtualMemory
+@ stdcall DiscardVirtualMemory(ptr long)
 @ stdcall DisconnectNamedPipe(long)
 @ stdcall DnsHostnameToComputerNameExW(wstr ptr ptr)
 # @ stub DsBindWithSpnExW

dlls/kernelbase/memory.c

@@ -53,6 +53,19 @@ BOOLEAN WINAPI RtlSetUserValueHeap( HANDLE handle, ULONG flags, void *ptr, void
 
 
 /***********************************************************************
+ *             DiscardVirtualMemory   (kernelbase.@)
+ */
+DWORD WINAPI DECLSPEC_HOTPATCH DiscardVirtualMemory( void *addr, SIZE_T size )
+{
+    NTSTATUS status;
+    LPVOID ret = addr;
+
+    status = NtAllocateVirtualMemory( GetCurrentProcess(), &ret, 0, &size, MEM_RESET, PAGE_NOACCESS );
+    return RtlNtStatusToDosError( status );
+}
+
+
+/***********************************************************************
  *             FlushViewOfFile   (kernelbase.@)
  */
 BOOL WINAPI DECLSPEC_HOTPATCH FlushViewOfFile( const void *base, SIZE_T size )

include/memoryapi.h

@@ -41,5 +41,6 @@ typedef struct WIN32_MEMORY_REGION_INFORMATION
     SIZE_T CommitSize;
 } WIN32_MEMORY_REGION_INFORMATION;
 
+DWORD WINAPI DiscardVirtualMemory(void *addr, SIZE_T size);
 BOOL WINAPI QueryVirtualMemoryInformation(HANDLE process,const void *addr,
         WIN32_MEMORY_INFORMATION_CLASS info_class, void *info, SIZE_T size, SIZE_T *ret_size);