Add a target to run the SyzyAsan RTL unittests in 4G

syzygy/agent/asan/shadow.cc

 // Copyright 2012 Google Inc. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 77 matching lines @@
   DCHECK_NE(static_cast<size_t*>(nullptr), index);
   DCHECK_NE(static_cast<uint8_t*>(nullptr), mask);
 
   size_t i = reinterpret_cast<uintptr_t>(address) / kPageSize;
   *index = i / 8;
   *mask = 1 << (i % 8);
 }
 
 }  // namespace
 
+extern "C" {
+// Provides a dummy static shadow memory array. This is simply to be used as
+// a pointer for the probes to be anchored to. If any of the probes referring
+// to this dummy shadow memory are run they will behave badly until they have
+// been patched using 'PatchMemoryInterceptorShadowReferences'.
+uint8_t asan_memory_interceptors_shadow_memory[1] = {};
+}
+
 Shadow::Shadow() : own_memory_(false), shadow_(nullptr), length_(0) {
   Init(RequiredLength());
 }
 
 Shadow::Shadow(size_t length)
     : own_memory_(false), shadow_(nullptr), length_(0) {
   Init(length);
 }
 
 Shadow::Shadow(void* shadow, size_t length)
@@ skipping 1030 matching lines @@
       // Advance the shadow cursor.
       ++shadow_cursor_;
     }  // while (shadow_cursor_ < end_of_region)
   }
 
   return false;
 }
 
 }  // namespace asan
 }  // namespace agent