Improved support for objects inside persistent memory.

base/metrics/persistent_memory_allocator.cc

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/metrics/persistent_memory_allocator.h"
 
 #include <assert.h>
 #include <algorithm>
 
 #if defined(OS_WIN)
@@ skipping 716 matching lines @@
 // Dereference a block |ref| and ensure that it's valid for the desired
 // |type_id| and |size|. |special| indicates that we may try to access block
 // headers not available to callers but still accessed by this module. By
 // having internal dereferences go through this same function, the allocator
 // is hardened against corruption.
 const volatile PersistentMemoryAllocator::BlockHeader*
 PersistentMemoryAllocator::GetBlock(Reference ref, uint32_t type_id,
                                     uint32_t size, bool queue_ok,
                                     bool free_ok) const {
   // Validation of parameters.
+  if (ref < (queue_ok ? kReferenceQueue : sizeof(SharedMetadata)))
+    return nullptr;
   if (ref % kAllocAlignment != 0)
     return nullptr;
-  if (ref < (queue_ok ? kReferenceQueue : sizeof(SharedMetadata)))
-    return nullptr;
   size += sizeof(BlockHeader);
   if (ref + size > mem_size_)
     return nullptr;
 
   // Validation of referenced block-header.
   if (!free_ok) {
     uint32_t freeptr = std::min(
         shared_meta()->freeptr.load(std::memory_order_relaxed), mem_size_);
     if (ref + size > freeptr)
       return nullptr;
@@ skipping 156 matching lines @@
 
 // static
 bool FilePersistentMemoryAllocator::IsFileAcceptable(
     const MemoryMappedFile& file,
     bool read_only) {
   return IsMemoryAcceptable(file.data(), file.length(), 0, read_only);
 }
 #endif  // !defined(OS_NACL)
 
 }  // namespace base