Add support for persistent file access in apps.

apps/saved_files_service.cc

Index: apps/saved_files_service.cc
diff --git a/apps/saved_files_service.cc b/apps/saved_files_service.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b3713e3d0ad90fe38bc313d1f5e7fd504bb0e006
--- /dev/null
+++ b/apps/saved_files_service.cc
@@ -0,0 +1,406 @@
+// Copyright 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.
+
+#include "apps/saved_files_service.h"
+
+#include <algorithm>
+
+#include "apps/saved_files_service_factory.h"
+#include "base/basictypes.h"
+#include "base/hash_tables.h"
+#include "base/value_conversions.h"
+#include "chrome/browser/extensions/extension_host.h"
+#include "chrome/browser/extensions/extension_prefs.h"
+#include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/extension_system.h"
+#include "chrome/common/extensions/permissions/api_permission.h"
+#include "chrome/common/extensions/permissions/permission_set.h"
+
+namespace apps {
+
+using extensions::APIPermission;
+using extensions::Extension;
+using extensions::ExtensionHost;
+using extensions::ExtensionPrefs;
+
+namespace {
+
+// Preference keys
+
+// The file entries that an extension has permission to access.
+const char kFileEntries[] = "file_entries";
+
+// The path to a file entry that an extension had permission to access.
+const char kFileEntryPath[] = "path";
+
+// Whether or not an extension had write access to a file entry.
+const char kFileEntryWritable[] = "writable";
+
+// The sequence number in the LRU of the file entry.
+const char kFileEntrySequenceNumber[] = "sequence_number";
+
+const size_t kMaxSavedFileEntries = 500;
+const int kMaxSequenceNumber = kint32max;
+
+// These might be different to the constant values in tests.
+size_t g_max_saved_file_entries = kMaxSavedFileEntries;
+int g_max_sequence_number = kMaxSequenceNumber;
+
+void AddSavedFileEntry(ExtensionPrefs* prefs,
+                       const std::string& extension_id,
+                       const SavedFileEntry& file_entry) {
+  ExtensionPrefs::ScopedDictionaryUpdate update(
+      prefs, extension_id, kFileEntries);
+  DictionaryValue* file_entries = update.Get();
+  if (!file_entries)
+    file_entries = update.Create();
+  DCHECK(!file_entries->GetDictionaryWithoutPathExpansion(file_entry.id, NULL));
+
+  DictionaryValue* file_entry_dict = new DictionaryValue();
+  file_entry_dict->Set(kFileEntryPath, CreateFilePathValue(file_entry.path));
+  file_entry_dict->SetBoolean(kFileEntryWritable, file_entry.writable);
+  file_entry_dict->SetInteger(kFileEntrySequenceNumber,
+                              file_entry.sequence_number);
+  file_entries->SetWithoutPathExpansion(file_entry.id, file_entry_dict);
+}
+
+void UpdateSavedFileEntry(ExtensionPrefs* prefs,
+                          const std::string& extension_id,
+                          const SavedFileEntry& file_entry) {
+  ExtensionPrefs::ScopedDictionaryUpdate update(
+      prefs, extension_id, kFileEntries);
+  DictionaryValue* file_entries = update.Get();
+  DCHECK(file_entries);
+  DictionaryValue* file_entry_dict = NULL;
+  file_entries->GetDictionaryWithoutPathExpansion(file_entry.id,
+                                                  &file_entry_dict);
+  DCHECK(file_entry_dict);
+  file_entry_dict->SetInteger(kFileEntrySequenceNumber,
+                              file_entry.sequence_number);
+}
+
+void RemoveSavedFileEntry(ExtensionPrefs* prefs,
+                          const std::string& extension_id,
+                          const std::string& file_entry_id) {
+  ExtensionPrefs::ScopedDictionaryUpdate update(
+      prefs, extension_id, kFileEntries);
+  DictionaryValue* file_entries = update.Get();
+  if (!file_entries)
+    file_entries = update.Create();
+  file_entries->RemoveWithoutPathExpansion(file_entry_id, NULL);
+}
+
+void ClearSavedFileEntries(ExtensionPrefs* prefs,
+                           const std::string& extension_id) {
+  prefs->UpdateExtensionPref(extension_id, kFileEntries, NULL);
+}
+
+void GetSavedFileEntries(ExtensionPrefs* prefs,
+                         const std::string& extension_id,
+                         std::vector<SavedFileEntry>* out) {
+  const DictionaryValue* file_entries = NULL;
+  if (!prefs->ReadPrefAsDictionary(extension_id, kFileEntries, &file_entries))
+    return;
+
+  for (DictionaryValue::Iterator it(*file_entries); !it.IsAtEnd();
+       it.Advance()) {
+    const DictionaryValue* file_entry = NULL;
+    if (!it.value().GetAsDictionary(&file_entry))
+      continue;
+    const base::Value* path_value;
+    if (!file_entry->Get(kFileEntryPath, &path_value))
+      continue;
+    base::FilePath file_path;
+    if (!GetValueAsFilePath(*path_value, &file_path))
+      continue;
+    bool writable = false;
+    if (!file_entry->GetBoolean(kFileEntryWritable, &writable))
+      continue;
+    int sequence_number = 0;
+    if (!file_entry->GetInteger(kFileEntrySequenceNumber, &sequence_number))
+      continue;
+    if (!sequence_number)
+      continue;
+    out->push_back(
+        SavedFileEntry(it.key(), file_path, writable, sequence_number));
+  }
+}
+
+}  // namespace
+
+class SavedFilesService::SavedFiles {
+ public:
+  SavedFiles(Profile* profile, const std::string& extension_id);
+  ~SavedFiles();
+
+  void RetainFileEntry(const std::string& id,
+                       const base::FilePath& file_path,
+                       bool writable);
+  void MoveEntryToFrontOfQueue(const std::string& id);
+  bool IsRetained(const std::string& id) const;
+  bool GetFileEntry(const std::string& id, SavedFileEntry* out) const;
+  std::vector<SavedFileEntry> GetAllFileEntries() const;
+
+ private:
+  void MaybeCompactSequenceNumbers();
+
+  Profile* profile_;
+  const std::string extension_id_;
+
+  // Owns values.
+  base::hash_map<std::string, SavedFileEntry*> file_id_to_file_entry_map_;
+
+  STLValueDeleter<base::hash_map<std::string, SavedFileEntry*> >
+      file_id_to_file_entry_map_deleter_;
+
+  // Values are a subset of values in file_id_to_file_entry_map_.
+  std::map<int, SavedFileEntry*> saved_file_lru_;
+
+  DISALLOW_COPY_AND_ASSIGN(SavedFiles);
+};
+
+// static
+SavedFilesService* SavedFilesService::Get(Profile* profile) {
+  return SavedFilesServiceFactory::GetForProfile(profile);
+}
+
+SavedFilesService::SavedFilesService(Profile* profile)
+    : extension_id_to_saved_files_deleter_(&extension_id_to_saved_files_),
+      profile_(profile) {
+  registrar_.Add(this,
+                 chrome::NOTIFICATION_EXTENSION_HOST_DESTROYED,
+                 content::NotificationService::AllSources());
+  registrar_.Add(this,
+                 chrome::NOTIFICATION_APP_TERMINATING,
+                 content::NotificationService::AllSources());
+}
+
+SavedFilesService::~SavedFilesService() {}
+
+void SavedFilesService::Observe(int type,
+                                const content::NotificationSource& source,
+                                const content::NotificationDetails& details) {
+  switch (type) {
+    case chrome::NOTIFICATION_EXTENSION_HOST_DESTROYED: {
+      ExtensionHost* host = content::Details<ExtensionHost>(details).ptr();
+      const Extension* extension = host->extension();
+      if (extension)
+        ClearRetainedFiles(extension);
+      break;
+    }
+
+    case chrome::NOTIFICATION_APP_TERMINATING: {
+      // Stop listening to NOTIFICATION_EXTENSION_HOST_DESTROYED in particular
+      // as all extension hosts will be destroyed as a result of shutdown.
+      registrar_.RemoveAll();
+      break;
+    }
+  }
+}
+
+void SavedFilesService::RetainFileEntry(const std::string& extension_id,
+                                        const std::string& id,
+                                        const base::FilePath& file_path,
+                                        bool writable) {
+  GetOrInsert(extension_id)->RetainFileEntry(id, file_path, writable);
+}
+
+void SavedFilesService::MoveEntryToFrontOfQueue(const std::string& extension_id,
+                                                const std::string& id) {
+  GetOrInsert(extension_id)->MoveEntryToFrontOfQueue(id);
+}
+
+std::vector<SavedFileEntry> SavedFilesService::GetAllFileEntries(
+    const std::string& extension_id) {
+  return GetOrInsert(extension_id)->GetAllFileEntries();
+}
+
+bool SavedFilesService::IsRetained(const std::string& extension_id,
+                                   const std::string& id) {
+  return GetOrInsert(extension_id)->IsRetained(id);
+}
+
+bool SavedFilesService::GetFileEntry(const std::string& extension_id,
+                                     const std::string& id,
+                                     SavedFileEntry* out) {
+  return GetOrInsert(extension_id)->GetFileEntry(id, out);
+}
+
+void SavedFilesService::ClearRetainedFiles(const Extension* extension) {
+  Cleanup(extension->id());
+  if (!extension->GetActivePermissions()->HasAPIPermission(
+          APIPermission::kFileSystemRetainFiles)) {
+    ClearSavedFileEntries(ExtensionPrefs::Get(profile_), extension->id());
+  }
+}
+
+SavedFilesService::SavedFiles* SavedFilesService::GetOrInsert(
+    const std::string& extension_id) {
+  std::map<std::string, SavedFiles*>::iterator it =
+      extension_id_to_saved_files_.find(extension_id);
+  if (it != extension_id_to_saved_files_.end())
+    return it->second;
+
+  SavedFiles* saved_files = new SavedFiles(profile_, extension_id);
+  extension_id_to_saved_files_.insert(
+      std::make_pair(extension_id, saved_files));
+  return saved_files;
+}
+
+void SavedFilesService::Cleanup(const std::string& extension_id) {
+  std::map<std::string, SavedFiles*>::iterator it =
+      extension_id_to_saved_files_.find(extension_id);
+  if (it != extension_id_to_saved_files_.end()) {
+    delete it->second;
+    extension_id_to_saved_files_.erase(it);
+  }
+}
+
+SavedFilesService::SavedFiles::SavedFiles(Profile* profile,
+                                          const std::string& extension_id)
+    : profile_(profile),
+      extension_id_(extension_id),
+      file_id_to_file_entry_map_deleter_(&file_id_to_file_entry_map_) {
+  std::vector<SavedFileEntry> saved_entries;
+  ExtensionPrefs* prefs = ExtensionPrefs::Get(profile_);
+  GetSavedFileEntries(prefs, extension_id_, &saved_entries);
+  for (std::vector<SavedFileEntry>::iterator it = saved_entries.begin();
+       it != saved_entries.end(); ++it) {
+    SavedFileEntry* file_entry = new SavedFileEntry(*it);
+    file_id_to_file_entry_map_.insert(
+        std::make_pair(file_entry->id, file_entry));
+    saved_file_lru_.insert(
+        std::make_pair(file_entry->sequence_number, file_entry));
+  }
+}
+
+SavedFilesService::SavedFiles::~SavedFiles() {}
+
+void SavedFilesService::SavedFiles::RetainFileEntry(
+    const std::string& id,
+    const base::FilePath& file_path,
+    bool writable) {
+  if (ContainsKey(file_id_to_file_entry_map_, id))
+    return;
+
+  file_id_to_file_entry_map_.insert(
+      std::make_pair(id, new SavedFileEntry(id, file_path, writable, 0)));
+}
+
+void SavedFilesService::SavedFiles::MoveEntryToFrontOfQueue(
+    const std::string& id) {
+  base::hash_map<std::string, SavedFileEntry*>::iterator it =
+      file_id_to_file_entry_map_.find(id);
+  if (it == file_id_to_file_entry_map_.end())
+    return;
+
+  SavedFileEntry* file_entry = it->second;
+  int old_sequence_number = file_entry->sequence_number;
+  if (!saved_file_lru_.empty()) {
+    std::map<int, SavedFileEntry*>::reverse_iterator it =
+        saved_file_lru_.rbegin();
+    if (it->second == file_entry)
+      return;
+
+    file_entry->sequence_number = it->first + 1;
+  } else {
+    file_entry->sequence_number = 1;
+  }
+  saved_file_lru_.insert(
+      std::make_pair(file_entry->sequence_number, file_entry));
+  ExtensionPrefs* prefs = ExtensionPrefs::Get(profile_);
+  if (old_sequence_number) {
+    saved_file_lru_.erase(old_sequence_number);
+    UpdateSavedFileEntry(prefs, extension_id_, *file_entry);
+  } else {
+    AddSavedFileEntry(prefs, extension_id_, *file_entry);
+    if (saved_file_lru_.size() > g_max_saved_file_entries) {
+      std::map<int, SavedFileEntry*>::iterator it = saved_file_lru_.begin();
+      it->second->sequence_number = 0;
+      RemoveSavedFileEntry(prefs, extension_id_, it->second->id);
+      saved_file_lru_.erase(it);
+    }
+  }
+  MaybeCompactSequenceNumbers();
+}
+
+bool SavedFilesService::SavedFiles::IsRetained(const std::string& id) const {
+  return ContainsKey(file_id_to_file_entry_map_, id);
+}
+
+bool SavedFilesService::SavedFiles::GetFileEntry(const std::string& id,
+                                                 SavedFileEntry* out) const {
+  base::hash_map<std::string, SavedFileEntry*>::const_iterator it =
+      file_id_to_file_entry_map_.find(id);
+  if (it == file_id_to_file_entry_map_.end())
+    return false;
+
+  *out = *it->second;
+  return true;
+}
+
+std::vector<SavedFileEntry>
+SavedFilesService::SavedFiles::GetAllFileEntries() const {
+  std::vector<SavedFileEntry> result;
+  for (base::hash_map<std::string, SavedFileEntry*>::const_iterator it =
+       file_id_to_file_entry_map_.begin();
+       it != file_id_to_file_entry_map_.end(); ++it) {
+    result.push_back(*it->second);
+  }
+  return result;
+}
+
+void SavedFilesService::SavedFiles::MaybeCompactSequenceNumbers() {
+  std::map<int, SavedFileEntry*>::reverse_iterator it =
+      saved_file_lru_.rbegin();
+  if (it == saved_file_lru_.rend())
+    return;
+
+  if (it->first < g_max_sequence_number)
+    return;
+
+  int sequence_number = 0;
+  ExtensionPrefs* prefs = ExtensionPrefs::Get(profile_);
+  for (std::map<int, SavedFileEntry*>::iterator it = saved_file_lru_.begin();
+       it != saved_file_lru_.end(); ++it) {
+    sequence_number++;
+    if (it->second->sequence_number == sequence_number)
+      continue;
+
+    SavedFileEntry* file_entry = it->second;
+    file_entry->sequence_number = sequence_number;
+    UpdateSavedFileEntry(prefs, extension_id_, *file_entry);
+    if (it == saved_file_lru_.begin()) {
+      saved_file_lru_.erase(it);
+      it = saved_file_lru_.insert(std::make_pair(file_entry->sequence_number,
+                                                 file_entry)).first;
+    } else {
+      saved_file_lru_.erase(it--);
+      it = saved_file_lru_.insert(
+          it, std::make_pair(file_entry->sequence_number, file_entry));
+    }
+  }
+}
+
+// static
+void SavedFilesService::SetMaxSequenceNumberForTest(int max_value) {
+  g_max_sequence_number = max_value;
+}
+
+// static
+void SavedFilesService::ClearMaxSequenceNumberForTest() {
+  g_max_sequence_number = kMaxSequenceNumber;
+}
+
+// static
+void SavedFilesService::SetLruSizeForTest(int size) {
+  g_max_saved_file_entries = size;
+}
+
+// static
+void SavedFilesService::ClearLruSizeForTest() {
+  g_max_saved_file_entries = kMaxSavedFileEntries;
+}
+
+}  // namespace apps