[fsp] Let extensions decide about the file system id.

chrome/browser/chromeos/file_system_provider/service.cc

 // Copyright 2014 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/chromeos/file_system_provider/service.h"
 
 #include "base/files/file_path.h"
 #include "base/stl_util.h"
 #include "chrome/browser/chromeos/file_system_provider/mount_path_util.h"
 #include "chrome/browser/chromeos/file_system_provider/observer.h"
@@ skipping 25 matching lines @@
   return new ProvidedFileSystem(event_router, file_system_info);
 }
 
 }  // namespace
 
 Service::Service(Profile* profile,
                  extensions::ExtensionRegistry* extension_registry)
     : profile_(profile),
       extension_registry_(extension_registry),
       file_system_factory_(base::Bind(CreateProvidedFileSystem)),
-      next_id_(1),
+      next_index_(1),
       weak_ptr_factory_(this) {
   extension_registry_->AddObserver(this);
 }
 
 Service::~Service() {
   extension_registry_->RemoveObserver(this);
 
   ProvidedFileSystemMap::iterator it = file_system_map_.begin();
   while (it != file_system_map_.end()) {
-    const int file_system_id = it->first;
+    const std::string file_system_id =
+        it->second->GetFileSystemInfo().file_system_id();
     const std::string extension_id =
         it->second->GetFileSystemInfo().extension_id();
     ++it;
     UnmountFileSystem(extension_id, file_system_id);
   }
 
   DCHECK_EQ(0u, file_system_map_.size());
   STLDeleteValues(&file_system_map_);
 }
 
@@ skipping 11 matching lines @@
   DCHECK(observer);
   observers_.RemoveObserver(observer);
 }
 
 void Service::SetFileSystemFactoryForTests(
     const FileSystemFactoryCallback& factory_callback) {
   DCHECK(!factory_callback.is_null());
   file_system_factory_ = factory_callback;
 }
 
-int Service::MountFileSystem(const std::string& extension_id,
-                             const std::string& file_system_name) {
+bool Service::MountFileSystem(const std::string& extension_id,
+                              const std::string& file_system_id,
+                              const std::string& file_system_name) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
+  // If already exists a file system provided by the same extension with this
+  // id, then abort.
+  if (GetProvidedFileSystem(extension_id, file_system_id)) {
+    FOR_EACH_OBSERVER(Observer,
+                      observers_,
+                      OnProvidedFileSystemMount(ProvidedFileSystemInfo(),
+                                                base::File::FILE_ERROR_EXISTS));
+    return false;
+  }
+
   // Restrict number of file systems to prevent system abusing.
   if (file_system_map_.size() + 1 > kMaxFileSystems) {
     FOR_EACH_OBSERVER(
         Observer,
         observers_,
         OnProvidedFileSystemMount(ProvidedFileSystemInfo(),
                                   base::File::FILE_ERROR_TOO_MANY_OPENED));
-    return 0;
+    return false;
   }
 
-  // The provided file system id is unique per service, so per profile.
-  int file_system_id = next_id_;
+  // The provided file system index is unique per service, so per profile.
+  // The index is used internally. Externally a file system id is used, which
+  // is unique per extension.
+  int index = next_index_;
 
   fileapi::ExternalMountPoints* const mount_points =
       fileapi::ExternalMountPoints::GetSystemInstance();
   DCHECK(mount_points);
 
   // The mount point path and name are unique per system, since they are system
   // wide. This is necessary for copying between profiles.
   const base::FilePath& mount_path =
-      util::GetMountPath(profile_, extension_id, file_system_id);
+      util::GetMountPath(profile_, extension_id, index);
   const std::string mount_point_name = mount_path.BaseName().AsUTF8Unsafe();
 
   if (!mount_points->RegisterFileSystem(mount_point_name,
                                         fileapi::kFileSystemTypeProvided,
                                         fileapi::FileSystemMountOption(),
                                         mount_path)) {
     FOR_EACH_OBSERVER(
         Observer,
         observers_,
         OnProvidedFileSystemMount(ProvidedFileSystemInfo(),
                                   base::File::FILE_ERROR_INVALID_OPERATION));
-    return 0;
+    return false;
   }
 
   // Store the file system descriptor. Use the mount point name as the file
   // system provider file system id.
   // Examples:
   //   file_system_id = 41
   //   mount_point_name =  b33f1337-41-5aa5
   //   mount_path = /provided/b33f1337-41-5aa5
   ProvidedFileSystemInfo file_system_info(
       extension_id, file_system_id, file_system_name, mount_path);
 
   // The event router may be NULL for unit tests.
   extensions::EventRouter* router = extensions::EventRouter::Get(profile_);
 
   ProvidedFileSystemInterface* file_system =
       file_system_factory_.Run(router, file_system_info);
   DCHECK(file_system);
-  file_system_map_[file_system_id] = file_system;
-  mount_point_name_to_id_map_[mount_point_name] = file_system_id;
+  file_system_map_[FileSystemKey(extension_id, file_system_id)] = file_system;
+  mount_point_name_to_key_map_[mount_point_name] =
+      FileSystemKey(extension_id, file_system_id);
 
   FOR_EACH_OBSERVER(
       Observer,
       observers_,
       OnProvidedFileSystemMount(file_system_info, base::File::FILE_OK));
 
-  next_id_++;
-  return file_system_id;
+  next_index_++;
+  return true;
 }
 
 bool Service::UnmountFileSystem(const std::string& extension_id,
-                                int file_system_id) {
+                                const std::string& file_system_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   const ProvidedFileSystemMap::iterator file_system_it =
-      file_system_map_.find(file_system_id);
-  if (file_system_it == file_system_map_.end() ||
-      file_system_it->second->GetFileSystemInfo().extension_id() !=
-          extension_id) {
+      file_system_map_.find(FileSystemKey(extension_id, file_system_id));
+  if (file_system_it == file_system_map_.end()) {
     const ProvidedFileSystemInfo empty_file_system_info;
     FOR_EACH_OBSERVER(
         Observer,
         observers_,
         OnProvidedFileSystemUnmount(empty_file_system_info,
                                     base::File::FILE_ERROR_NOT_FOUND));
     return false;
   }
 
   fileapi::ExternalMountPoints* const mount_points =
@@ skipping 12 matching lines @@
         OnProvidedFileSystemUnmount(file_system_info,
                                     base::File::FILE_ERROR_INVALID_OPERATION));
     return false;
   }
 
   FOR_EACH_OBSERVER(
       Observer,
       observers_,
       OnProvidedFileSystemUnmount(file_system_info, base::File::FILE_OK));
 
-  mount_point_name_to_id_map_.erase(mount_point_name);
+  mount_point_name_to_key_map_.erase(mount_point_name);
 
   delete file_system_it->second;
   file_system_map_.erase(file_system_it);
 
   return true;
 }
 
-bool Service::RequestUnmount(int file_system_id) {
+bool Service::RequestUnmount(const std::string& extension_id,
+                             const std::string& file_system_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   ProvidedFileSystemMap::iterator file_system_it =
-      file_system_map_.find(file_system_id);
+      file_system_map_.find(FileSystemKey(extension_id, file_system_id));
   if (file_system_it == file_system_map_.end())
     return false;
 
   file_system_it->second->RequestUnmount(
       base::Bind(&Service::OnRequestUnmountStatus,
                  weak_ptr_factory_.GetWeakPtr(),
                  file_system_it->second->GetFileSystemInfo()));
   return true;
 }
 
 std::vector<ProvidedFileSystemInfo> Service::GetProvidedFileSystemInfoList() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   std::vector<ProvidedFileSystemInfo> result;
   for (ProvidedFileSystemMap::const_iterator it = file_system_map_.begin();
        it != file_system_map_.end();
        ++it) {
     result.push_back(it->second->GetFileSystemInfo());
   }
   return result;
 }
 
 ProvidedFileSystemInterface* Service::GetProvidedFileSystem(
     const std::string& extension_id,
-    int file_system_id) {
+    const std::string& file_system_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   const ProvidedFileSystemMap::const_iterator file_system_it =
-      file_system_map_.find(file_system_id);
-  if (file_system_it == file_system_map_.end() ||
-      file_system_it->second->GetFileSystemInfo().extension_id() !=
-          extension_id) {
+      file_system_map_.find(FileSystemKey(extension_id, file_system_id));
+  if (file_system_it == file_system_map_.end())
     return NULL;
-  }
 
   return file_system_it->second;
 }
 
 void Service::OnExtensionUnloaded(
     content::BrowserContext* browser_context,
     const extensions::Extension* extension,
     extensions::UnloadedExtensionInfo::Reason reason) {
   // Unmount all of the provided file systems associated with this extension.
   ProvidedFileSystemMap::iterator it = file_system_map_.begin();
   while (it != file_system_map_.end()) {
     const ProvidedFileSystemInfo& file_system_info =
         it->second->GetFileSystemInfo();
     // Advance the iterator beforehand, otherwise it will become invalidated
     // by the UnmountFileSystem() call.
     ++it;
     if (file_system_info.extension_id() == extension->id()) {
       bool result = UnmountFileSystem(file_system_info.extension_id(),
                                       file_system_info.file_system_id());
       DCHECK(result);
     }
   }
 }
 
 ProvidedFileSystemInterface* Service::GetProvidedFileSystem(
     const std::string& mount_point_name) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  const MountPointNameToIdMap::const_iterator mapping_it =
-      mount_point_name_to_id_map_.find(mount_point_name);
-  if (mapping_it == mount_point_name_to_id_map_.end())
+  const MountPointNameToKeyMap::const_iterator mapping_it =
+      mount_point_name_to_key_map_.find(mount_point_name);
+  if (mapping_it == mount_point_name_to_key_map_.end())
     return NULL;
 
   const ProvidedFileSystemMap::const_iterator file_system_it =
       file_system_map_.find(mapping_it->second);
   if (file_system_it == file_system_map_.end())
     return NULL;
 
   return file_system_it->second;
 }
 
 void Service::OnRequestUnmountStatus(
     const ProvidedFileSystemInfo& file_system_info,
     base::File::Error error) {
   // Notify observers about failure in unmounting, since mount() will not be
   // called by the provided file system. In case of success mount() will be
   // invoked, and observers notified, so there is no need to call them now.
   if (error != base::File::FILE_OK) {
     FOR_EACH_OBSERVER(Observer,
                       observers_,
                       OnProvidedFileSystemUnmount(file_system_info, error));
   }
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos