The chrome.lockScreen.data API implementation

extensions/browser/api/lock_screen_data/item_storage.cc

Index: extensions/browser/api/lock_screen_data/item_storage.cc
diff --git a/extensions/browser/api/lock_screen_data/item_storage.cc b/extensions/browser/api/lock_screen_data/item_storage.cc
new file mode 100644
index 0000000000000000000000000000000000000000..68d9b5f3dd1919c7a843a22e0299355135230cb3
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+++ b/extensions/browser/api/lock_screen_data/item_storage.cc
@@ -0,0 +1,353 @@
+// Copyright 2017 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 "extensions/browser/api/lock_screen_data/item_storage.h"
+
+#include <set>
+#include <utility>
+
+#include "base/files/file_util.h"
+#include "base/guid.h"
+#include "base/memory/ptr_util.h"
+#include "base/task_scheduler/post_task.h"
+#include "base/task_scheduler/task_traits.h"
+#include "base/values.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+#include "components/prefs/scoped_user_pref_update.h"
+#include "extensions/browser/api/lock_screen_data/data_item.h"
+#include "extensions/browser/api/lock_screen_data/operation_result.h"
+#include "extensions/browser/event_router.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/browser/extensions_browser_client.h"
+#include "extensions/common/api/lock_screen_data.h"
+
+namespace extensions {
+
+namespace lock_screen_data {
+
+namespace {
+
+ItemStorage* g_data_item_storage = nullptr;
+
+ItemStorage::ItemFactoryCallback* g_test_item_factory_callback = nullptr;
+
+const char kLockScreenDataPrefKey[] = "lockScreenDataItems";
+
+void DeleteImpl(const base::FilePath& file_path, bool recursive) {
+  base::DeleteFile(file_path, recursive);
+}
+
+void DoNothingOnDelete(OperationResult result) {}
+
+std::unique_ptr<DataItem> CreateDataItem(const std::string& item_id) {
+  return g_test_item_factory_callback
+             ? g_test_item_factory_callback->Run(item_id)
+             : base::MakeUnique<DataItem>(item_id);
+}
+
+}  // namespace
+
+// static
+ItemStorage* ItemStorage::Get(content::BrowserContext* context) {
+  if (g_data_item_storage && !g_data_item_storage->IsContextAllowed(context))
+    return nullptr;
+  return g_data_item_storage;

[rkc, 2017/06/22 18:35:47]

Nothing guarantees g_data_item_storage is not nullptr. Is it okay for this
method to return a null pointer even for an allowed context?

[tbarzic, 2017/06/26 22:21:42]

Yes it's OK - what would happen is that the API methods would start failing;

+}
+
+// static
+void ItemStorage::RegisterLocalState(PrefRegistrySimple* registry) {
+  registry->RegisterDictionaryPref(kLockScreenDataPrefKey);
+}
+
+ItemStorage::ItemStorage(content::BrowserContext* context,
+                         PrefService* local_state,
+                         const std::string& crypto_key,
+                         const base::FilePath& storage_root)
+    : context_(context),
+      user_id_(
+          ExtensionsBrowserClient::Get()->GetUserIdHashFromContext(context)),
+      crypto_key_(crypto_key),
+      local_state_(local_state),
+      storage_root_(storage_root.Append(user_id_)),
+      extension_registry_observer_(this) {
+  CHECK(!user_id_.empty());
+  extension_registry_observer_.Add(ExtensionRegistry::Get(context));
+  task_runner_ = base::CreateSequencedTaskRunnerWithTraits(
+      {base::MayBlock(), base::TaskPriority::BACKGROUND,
+       base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN});
+
+  ReloadDataItems();
+
+  DCHECK(!g_data_item_storage);
+  g_data_item_storage = this;
+}
+
+ItemStorage::~ItemStorage() {
+  DCHECK_EQ(g_data_item_storage, this);
+  g_data_item_storage = nullptr;
+}
+
+// static
+void ItemStorage::SetItemFactoryForTesting(ItemFactoryCallback* callback) {
+  g_test_item_factory_callback = callback;
+}
+
+void ItemStorage::SetSessionLocked(bool session_locked) {
+  SessionLockedState new_state = session_locked
+                                     ? SessionLockedState::kLocked
+                                     : SessionLockedState::kNotLocked;
+  if (new_state == session_locked_state_)
+    return;
+
+  bool was_locked = session_locked_state_ == SessionLockedState::kLocked;
+  session_locked_state_ = new_state;
+
+  for (auto& extension_items : data_items_) {
+    if (extension_items.second.empty())
+      continue;
+
+    // If the session state is unlocked, dispatch Item availability events to
+    // apps with available data items.
+    if (session_locked_state_ == SessionLockedState::kNotLocked) {
+      api::lock_screen_data::DataItemsAvailableEvent event_args;
+      event_args.was_locked = was_locked;
+
+      std::unique_ptr<Event> event = base::MakeUnique<Event>(
+          events::LOCK_SCREEN_DATA_ON_DATA_ITEMS_AVAILABLE,
+          api::lock_screen_data::OnDataItemsAvailable::kEventName,
+          api::lock_screen_data::OnDataItemsAvailable::Create(event_args));
+      EventRouter::Get(context_)->DispatchEventToExtension(
+          extension_items.first /* extension ID */, std::move(event));
+    }
+  }
+}
+
+const DataItem* ItemStorage::CreateItem(const std::string& extension_id) {
+  if (!ExtensionRegistry::Get(context_)->GetExtensionById(
+          extension_id, ExtensionRegistry::ENABLED)) {
+    return nullptr;
+  }
+
+  const std::string item_id = base::GenerateGUID();
+  std::unique_ptr<DataItem> item = CreateDataItem(item_id);
+  DataItem* item_ptr = item.get();
+
+  {
+    // Create item entry in local state prefs, ensuring that all parent paths
+    // are properly set-up (in case this is the first entry added for a
+    // user/extension).
+    DictionaryPrefUpdate update(local_state_, kLockScreenDataPrefKey);
+    if (!update->HasKey(user_id_)) {
+      update->SetDictionary(user_id_,
+                            base::MakeUnique<base::DictionaryValue>());
+    }
+
+    base::DictionaryValue* user_dict = nullptr;
+    if (!update->GetDictionary(user_id_, &user_dict))
+      return nullptr;
+
+    if (!user_dict->HasKey(extension_id)) {
+      user_dict->SetDictionary(extension_id,
+                               base::MakeUnique<base::DictionaryValue>());
+    }
+
+    base::DictionaryValue* extension_dict = nullptr;
+    if (!user_dict->GetDictionary(extension_id, &extension_dict))
+      return nullptr;
+
+    extension_dict->SetDictionary(item_id, item->ToValue());
+  }
+
+  data_items_[extension_id].emplace(item_id, std::move(item));
+  return item_ptr;
+}
+
+std::vector<const DataItem*> ItemStorage::GetAllForExtension(
+    const std::string& extension_id) {
+  std::vector<const DataItem*> items;
+  ExtensionDataItemMap::iterator extension_items =
+      data_items_.find(extension_id);
+  if (extension_items == data_items_.end())
+    return items;
+
+  for (const auto& item : extension_items->second) {
+    if (!item.second)
+      continue;
+    items.push_back(item.second.get());
+  }
+
+  return items;
+}
+
+OperationResult ItemStorage::SetItemContent(
+    const std::string& extension_id,
+    const std::string& item_id,
+    const std::vector<char>& data,
+    const ItemStorage::WriteCallback& callback) {
+  DataItem* item = FindItem(extension_id, item_id);
+  if (!item)
+    return OperationResult::kNotFound;
+
+  if (item->backing_file().empty()) {
+    item->set_backing_file(storage_root_.Append(extension_id).Append(item_id));
+
+    DictionaryPrefUpdate update(local_state_, kLockScreenDataPrefKey);
+    update->SetDictionary(GetDataItemPrefKey(extension_id, item->id()),
+                          item->ToValue());
+  }
+
+  return item->Write(data, crypto_key_, task_runner_, callback);
+}
+
+OperationResult ItemStorage::GetItemContent(
+    const std::string& extension_id,
+    const std::string& item_id,
+    const ItemStorage::ReadCallback& callback) {
+  DataItem* item = FindItem(extension_id, item_id);
+  if (!item)
+    return OperationResult::kNotFound;
+
+  if (item->backing_file().empty())
+    return OperationResult::kNoBackingFile;
+
+  return item->Read(crypto_key_, task_runner_, callback);
+}
+
+OperationResult ItemStorage::DeleteItem(const std::string& extension_id,
+                                        const std::string& item_id) {
+  DataItem* item = FindItem(extension_id, item_id);
+  if (!item)
+    return OperationResult::kNotFound;
+
+  {
+    DictionaryPrefUpdate update(local_state_, kLockScreenDataPrefKey);
+    update->Remove(GetDataItemPrefKey(extension_id, item_id), nullptr);
+  }
+
+  if (!item->backing_file().empty())
+    item->Delete(task_runner_, base::Bind(&DoNothingOnDelete));
+
+  data_items_[extension_id].erase(item_id);
+  return OperationResult::kSuccess;
+}
+
+void ItemStorage::OnExtensionUninstalled(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UninstallReason reason) {
+  ClearDataForExtension(extension->id());
+}
+
+std::string ItemStorage::GetDataItemPrefKey(const std::string& extension_id,
+                                            const std::string& item_id) {
+  return user_id_ + "." + extension_id + "." + item_id;
+}
+
+bool ItemStorage::IsContextAllowed(content::BrowserContext* context) {
+  switch (session_locked_state_) {
+    case SessionLockedState::kUnknown:
+      return false;
+    case SessionLockedState::kLocked:
+      return ExtensionsBrowserClient::Get()->IsLockScreenContext(context);
+    case SessionLockedState::kNotLocked:
+      return context_ == context;
+  }
+  NOTREACHED() << "Unknown session locked state";
+  return false;
+}
+
+void ItemStorage::ReloadDataItems() {
+  data_items_.clear();

[rkc, 2017/06/22 18:35:47]

Since this is called exactly once and only from the constructor, this clear
seems superfluous. The function could also just be renamed to LoadDataItems().

[tbarzic, 2017/06/26 22:21:42]

Done.

+
+  const base::DictionaryValue* user_data = nullptr;
+  const base::DictionaryValue* items =
+      local_state_->GetDictionary(kLockScreenDataPrefKey);
+  if (!items || !items->GetDictionary(user_id_, &user_data) || !user_data)
+    return;
+
+  // Set of extensions pref entries that should be remove from prefs (for
+  // example, entries for extensions that are not installed anymore).
+  // Note that entries are not removed directly during iteration over the
+  // dictionary to avoid invalidating data under the iterator.
+  std::set<std::string> extensions_to_remove;
+
+  for (base::DictionaryValue::Iterator extension_iter(*user_data);
+       !extension_iter.IsAtEnd(); extension_iter.Advance()) {
+    if (!ExtensionRegistry::Get(context_)->GetInstalledExtension(
+            extension_iter.key())) {
+      extensions_to_remove.insert(extension_iter.key());
+    } else {
+      if (!LoadDataItemsForExtension(extension_iter.key(),
+                                     extension_iter.value())) {
+        extensions_to_remove.insert(extension_iter.key());
+      }
+    }
+  }
+
+  // Remove stale/invalid entries.
+  for (const auto& extension_id : extensions_to_remove)
+    ClearDataForExtension(extension_id);
+}
+
+bool ItemStorage::LoadDataItemsForExtension(const std::string& extension_id,
+                                            const base::Value& extension_pref) {
+  const base::DictionaryValue* items = nullptr;
+  if (!extension_pref.GetAsDictionary(&items))
+    return false;
+
+  std::set<std::string> items_to_remove;
+  base::FilePath expected_file_parent = storage_root_.Append(extension_id);
+  for (base::DictionaryValue::Iterator item_iter(*items); !item_iter.IsAtEnd();
+       item_iter.Advance()) {
+    std::unique_ptr<DataItem> item = CreateDataItem(item_iter.key());
+
+    // Invalid items (including items pointing to an unexpected location) should
+    // be removed from prefs - schedule removal after the loop to avoid
+    // invalidating the iterator.
+    if (!item->InitFromValue(item_iter.value()) ||
+        (!item->backing_file().empty() &&
+         !expected_file_parent.IsParent(item->backing_file()))) {
+      items_to_remove.insert(item_iter.key());
+      continue;
+    }
+    data_items_[extension_id].emplace(item_iter.key(), std::move(item));
+  }
+
+  DictionaryPrefUpdate update(local_state_, kLockScreenDataPrefKey);
+  for (const auto& item_id : items_to_remove) {
+    update->Remove(GetDataItemPrefKey(extension_id, item_id), nullptr);
+  }
+  return true;
+}
+
+void ItemStorage::ClearDataForExtension(const std::string& extension_id) {
+  task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&DeleteImpl, storage_root_.Append(extension_id), true));
+
+  data_items_.erase(extension_id);
+
+  DictionaryPrefUpdate update(local_state_, kLockScreenDataPrefKey);
+  update->Remove(user_id_ + "." + extension_id, nullptr);
+}
+
+DataItem* ItemStorage::FindItem(const std::string& extension_id,
+                                const std::string& item_id) {
+  ExtensionDataItemMap::iterator extension_items =
+      data_items_.find(extension_id);
+  if (extension_items == data_items_.end())
+    return nullptr;
+
+  DataItemMap::iterator item_it = extension_items->second.find(item_id);
+  if (item_it == extension_items->second.end())
+    return nullptr;
+
+  if (!item_it->second)
+    return nullptr;
+  return item_it->second.get();
+}
+
+}  // namespace lock_screen_data
+}  // namespace extensions