root/chrome/browser/extensions/api/storage/policy_value_store.cc

DEFINITIONS

1. ReadOnlyError
2. delegate_
3. SetCurrentPolicy
4. DeleteStorage
5. GetBytesInUse
6. GetBytesInUse
7. GetBytesInUse
8. Get
9. Get
10. Get
11. Set
12. Set
13. Remove
14. Remove
15. Clear
16. Restore
17. RestoreKey

// Copyright (c) 2012 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 "chrome/browser/extensions/api/storage/policy_value_store.h"

#include "base/logging.h"
#include "base/values.h"
#include "components/policy/core/common/policy_map.h"
#include "components/policy/core/common/policy_types.h"
#include "content/public/browser/browser_thread.h"
#include "extensions/browser/api/storage/settings_namespace.h"
#include "extensions/browser/value_store/value_store_change.h"
#include "extensions/browser/value_store/value_store_util.h"

using content::BrowserThread;

namespace util = value_store_util;

namespace extensions {

namespace {

scoped_ptr<ValueStore::Error> ReadOnlyError(scoped_ptr<std::string> key) {
  return make_scoped_ptr(new ValueStore::Error(
      ValueStore::READ_ONLY, "This is a read-only store.", key.Pass()));
}

}  // namespace

PolicyValueStore::PolicyValueStore(
    const std::string& extension_id,
    const scoped_refptr<SettingsObserverList>& observers,
    scoped_ptr<ValueStore> delegate)
    : extension_id_(extension_id),
      observers_(observers),
      delegate_(delegate.Pass()) {}

PolicyValueStore::~PolicyValueStore() {}

void PolicyValueStore::SetCurrentPolicy(const policy::PolicyMap& policy) {
  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
  // Convert |policy| to a dictionary value. Only include mandatory policies
  // for now.
  base::DictionaryValue current_policy;
  for (policy::PolicyMap::const_iterator it = policy.begin();
       it != policy.end(); ++it) {
    if (it->second.level == policy::POLICY_LEVEL_MANDATORY) {
      current_policy.SetWithoutPathExpansion(
          it->first, it->second.value->DeepCopy());
    }
  }

  // Get the previous policies stored in the database.
  // TODO(joaodasilva): it'd be better to have a less expensive way of
  // determining which keys are currently stored, or of determining which keys
  // must be removed.
  base::DictionaryValue previous_policy;
  ValueStore::ReadResult read_result = delegate_->Get();

  // If the database is corrupted, try to restore it.
  // This may have the unfortunate side-effect of incorrectly informing the
  // extension of a "new" key, which isn't new and was corrupted. Unfortunately,
  // there's not always a way around this - if the database is corrupted, there
  // may be no way of telling which keys were previously present.
  if (read_result->IsCorrupted()) {
    if (delegate_->Restore())
      read_result = delegate_->Get();
  }

  if (read_result->HasError()) {
    LOG(WARNING) << "Failed to read managed settings for extension "
        << extension_id_ << ": " << read_result->error().message;
    // Leave |previous_policy| empty, so that events are generated for every
    // policy in |current_policy|.
  } else {
    read_result->settings().Swap(&previous_policy);
  }

  // Now get two lists of changes: changes after setting the current policies,
  // and changes after removing old policies that aren't in |current_policy|
  // anymore.
  std::vector<std::string> removed_keys;
  for (base::DictionaryValue::Iterator it(previous_policy);
       !it.IsAtEnd(); it.Advance()) {
    if (!current_policy.HasKey(it.key()))
      removed_keys.push_back(it.key());
  }

  ValueStoreChangeList changes;

  WriteResult result = delegate_->Remove(removed_keys);
  if (!result->HasError()) {
    changes.insert(
        changes.end(), result->changes().begin(), result->changes().end());
  }

  // IGNORE_QUOTA because these settings aren't writable by the extension, and
  // are configured by the domain administrator.
  ValueStore::WriteOptions options = ValueStore::IGNORE_QUOTA;
  result = delegate_->Set(options, current_policy);
  if (!result->HasError()) {
    changes.insert(
        changes.end(), result->changes().begin(), result->changes().end());
  }

  if (!changes.empty()) {
    observers_->Notify(
        &SettingsObserver::OnSettingsChanged,
        extension_id_,
        settings_namespace::MANAGED,
        ValueStoreChange::ToJson(changes));
  }
}

void PolicyValueStore::DeleteStorage() {
  // This is called from our owner, indicating that storage for this extension
  // should be removed.
  delegate_->Clear();
}

size_t PolicyValueStore::GetBytesInUse(const std::string& key) {
  // LeveldbValueStore doesn't implement this; and the underlying database
  // isn't acccessible to the extension in any case; from the extension's
  // perspective this is a read-only store.
  return 0;
}

size_t PolicyValueStore::GetBytesInUse(const std::vector<std::string>& keys) {
  // See note above.
  return 0;
}

size_t PolicyValueStore::GetBytesInUse() {
  // See note above.
  return 0;
}

ValueStore::ReadResult PolicyValueStore::Get(const std::string& key) {
  return delegate_->Get(key);
}

ValueStore::ReadResult PolicyValueStore::Get(
    const std::vector<std::string>& keys) {
  return delegate_->Get(keys);
}

ValueStore::ReadResult PolicyValueStore::Get() {
  return delegate_->Get();
}

ValueStore::WriteResult PolicyValueStore::Set(
    WriteOptions options, const std::string& key, const base::Value& value) {
  return MakeWriteResult(ReadOnlyError(util::NewKey(key)));
}

ValueStore::WriteResult PolicyValueStore::Set(
    WriteOptions options, const base::DictionaryValue& settings) {
  return MakeWriteResult(ReadOnlyError(util::NoKey()));
}

ValueStore::WriteResult PolicyValueStore::Remove(const std::string& key) {
  return MakeWriteResult(ReadOnlyError(util::NewKey(key)));
}

ValueStore::WriteResult PolicyValueStore::Remove(
    const std::vector<std::string>& keys) {
  return MakeWriteResult(ReadOnlyError(util::NoKey()));
}

ValueStore::WriteResult PolicyValueStore::Clear() {
  return MakeWriteResult(ReadOnlyError(util::NoKey()));
}

bool PolicyValueStore::Restore() { return delegate_->Restore(); }

bool PolicyValueStore::RestoreKey(const std::string& key) {
  return delegate_->RestoreKey(key);
}

}  // namespace extensions