Refactor our SimpleIndex file format and serialization to use Pickle instead of the previously bugg…

net/disk_cache/simple/simple_index_file.h

+// Copyright (c) 2013 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.
+
+#ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_FILE_H_
+#define NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_FILE_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/files/file_path.h"
+#include "base/gtest_prod_util.h"
+#include "base/hash_tables.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/pickle.h"
+#include "base/port.h"
+#include "net/base/net_export.h"
+#include "net/disk_cache/simple/simple_index.h"
+
+namespace base {
+class TaskRunner;
+}
+
+namespace disk_cache {
+
+const uint64 kSimpleIndexMagicNumber = GG_UINT64_C(0x656e74657220796f);
+
+// Simple Index File format is a pickle serialized data of IndexMetadata and
+// EntryMetadata objects.  The file format is as follows: one instance of
+// serialized |IndexMetadata| followed serialized |EntryMetadata| entries
+// repeated |number_of_entries| amount of times.  To know more about the format,
+// see SimpleIndexFile::Serialize() and SeeSimpleIndexFile::LoadFromDisk()
+// methods.
+class NET_EXPORT_PRIVATE SimpleIndexFile {
+ public:
+  class NET_EXPORT_PRIVATE IndexMetadata {
+   public:
+    IndexMetadata();
+    IndexMetadata(uint64 number_of_entries, uint64 cache_size);
+
+    void Serialize(Pickle* pickle) const;
+    bool Deserialize(PickleIterator* it);
+
+    bool CheckIndexMetadata();
+
+    uint64 GetNumberOfEntries() { return number_of_entries_; }
+
+   private:
+    FRIEND_TEST_ALL_PREFIXES(IndexMetadataTest, Basics);
+    FRIEND_TEST_ALL_PREFIXES(IndexMetadataTest, Serialize);
+
+    uint64 magic_number_;
+    uint32 version_;
+    uint64 number_of_entries_;
+    uint64 cache_size_;  // Total cache storage size in bytes.
+  };
+
+  // Load the index file from disk, deserializing it and returning the
+  // corresponding EntrySet in a scoped_ptr<>, if successful.
+  // Uppon failure, the scoped_ptr<> will contain NULL.
+  static scoped_ptr<SimpleIndex::EntrySet> LoadFromDisk(
+      const base::FilePath& index_filename);
+
+  // Returns a scoped_ptr for a newly allocated Pickle containing the serialized
+  // data to be written to a file.
+  static scoped_ptr<Pickle> Serialize(
+      const SimpleIndexFile::IndexMetadata& index_metadata,
+      const SimpleIndex::EntrySet& entries);
+
+  // Write the serialized data from |pickle| into the index file.
+  static void WriteToDisk(const base::FilePath& index_filename,
+                          const Pickle& pickle);
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(SimpleIndexFileTest, Serialize);
+
+  // Deserialize() is separate from LoadFromDisk() for easier testing.
+  static scoped_ptr<SimpleIndex::EntrySet> Deserialize(const char* data,
+                                                       int data_len);
+
+  struct PickleHeader : public Pickle::Header {
+    uint32 crc;
+  };
+
+  DISALLOW_COPY_AND_ASSIGN(SimpleIndexFile);
+};
+
+
+}  // namespace disk_cache
+
+#endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_FILE_H_