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// Copyright 2013 The Chromium Authors
// 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_VERSION_UPGRADE_H_
#define NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_
// Defines functionality to upgrade the file structure of the Simple Cache
// Backend on disk. Assumes no backend operations are running simultaneously.
// Hence must be run at cache initialization step.
#include <stdint.h>
#include <type_traits>
#include "net/base/cache_type.h"
#include "net/base/net_export.h"
namespace base {
class FilePath;
}
namespace disk_cache {
class BackendFileOperations;
// These values are persisted to logs. Entries should not be renumbered and
// numeric values should never be reused.
enum class SimpleCacheConsistencyResult {
kOK = 0,
kCreateDirectoryFailed = 1,
kBadFakeIndexFile = 2,
kBadInitialMagicNumber = 3,
kVersionTooOld = 4,
kVersionFromTheFuture = 5,
kBadZeroCheck = 6,
kUpgradeIndexV5V6Failed = 7,
kWriteFakeIndexFileFailed = 8,
kReplaceFileFailed = 9,
kBadFakeIndexReadSize = 10,
kMaxValue = kBadFakeIndexReadSize,
};
// Performs all necessary disk IO to upgrade the cache structure if it is
// needed.
//
// Returns true iff no errors were found during consistency checks and all
// necessary transitions succeeded. If this function fails, there is nothing
// left to do other than dropping the whole cache directory.
NET_EXPORT_PRIVATE SimpleCacheConsistencyResult
UpgradeSimpleCacheOnDisk(BackendFileOperations* file_operations,
const base::FilePath& path);
// Check if the cache structure at the given path is empty except for index
// files. If so, then delete the index files. Returns true if any files
// were deleted.
NET_EXPORT_PRIVATE bool DeleteIndexFilesIfCacheIsEmpty(
const base::FilePath& path);
struct NET_EXPORT_PRIVATE FakeIndexData {
FakeIndexData();
// Must be equal to kSimpleInitialMagicNumber.
uint64_t initial_magic_number = 0;
// Must be equal kSimpleVersion when the cache backend is instantiated.
uint32_t version = 0;
// These must be zero. The first was used for experiment type (With a max
// valid value of 2), and the second was used for an experiment parameter.
uint32_t zero = 0;
uint32_t zero2 = 0;
// Avoid implicit padding so `std::has_unique_object_representations_v<>` will
// hold.
uint32_t unused_padding = 0;
};
static_assert(std::has_unique_object_representations_v<FakeIndexData>);
// Exposed for testing.
NET_EXPORT_PRIVATE bool UpgradeIndexV5V6(BackendFileOperations* file_operations,
const base::FilePath& cache_directory);
} // namespace disk_cache
#endif // NET_DISK_CACHE_SIMPLE_SIMPLE_VERSION_UPGRADE_H_
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