Extract external file systems handling from isolated context.

webkit/fileapi/external_mount_points.cc

+// 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 "webkit/fileapi/external_mount_points.h"
+
+#include "base/file_path.h"
+#include "base/lazy_instance.h"
+#include "base/path_service.h"
+#include "base/stl_util.h"
+#include "webkit/fileapi/remote_file_system_proxy.h"
+
+namespace fileapi {
+
+static base::LazyInstance<scoped_refptr<ExternalMountPoints> >::Leaky
+    g_external_mount_points = LAZY_INSTANCE_INITIALIZER;
+
+class ExternalMountPoints::Instance {
+ public:
+  // |remote_proxy| is allowed only for drive file system.
+  Instance(FileSystemType type,
+           const FilePath& path,
+           RemoteFileSystemProxyInterface* remote_proxy);
+
+  ~Instance();
+
+  FileSystemType type() const { return type_; }
+  const FilePath& path() const { return path_; }
+  RemoteFileSystemProxyInterface* remote_proxy() const {
+    return remote_proxy_.get();
+  }
+
+ private:
+  const FileSystemType type_;
+  const FilePath path_;
+
+  // For file systems that have a remote file system proxy.
+  scoped_refptr<RemoteFileSystemProxyInterface> remote_proxy_;
+
+  DISALLOW_COPY_AND_ASSIGN(Instance);
+};
+
+ExternalMountPoints::Instance::Instance(FileSystemType type,
+                                        const FilePath& path,
+                                        RemoteFileSystemProxyInterface* proxy)
+    : type_(type),
+      path_(path),
+      remote_proxy_(proxy) {
+  DCHECK(!proxy || (kFileSystemTypeDrive == type_));
+}
+
+ExternalMountPoints::Instance::~Instance() {}
+
+//--------------------------------------------------------------------------
+
+// static
+ExternalMountPoints* ExternalMountPoints::GetSystemInstance() {
+  if (!g_external_mount_points.Pointer()->get())
+    g_external_mount_points.Get() = new ExternalMountPoints(true);
+  return g_external_mount_points.Pointer()->get();

[kinuko, 2013/01/08 12:22:43]

Hmm, this is not thread safe and we seem to be losing the point of using
LazyInstance.  I think we should split the class for SystemMountPoints.

[tbarzic, 2013/01/09 01:26:34]

Yeah, I was concerned about that too. I think the new implementation should be
fine.

+}
+
+// static
+scoped_refptr<ExternalMountPoints> ExternalMountPoints::CreateRefCounted() {
+  return new ExternalMountPoints(false);
+}
+
+bool ExternalMountPoints::RegisterFileSystem(
+    const std::string& mount_name,
+    FileSystemType type,
+    const FilePath& path) {
+  return RegisterRemoteFileSystem(mount_name, type, NULL, path);
+}
+
+bool ExternalMountPoints::RegisterRemoteFileSystem(
+    const std::string& mount_name,
+    FileSystemType type,
+    RemoteFileSystemProxyInterface* remote_proxy,
+    const FilePath& path) {
+  base::AutoLock locker(lock_);
+
+  if (!ValidateNewMountPoint(mount_name, path))
+    return false;
+
+  instance_map_[mount_name] = new Instance(type, path, remote_proxy);
+  if (!path.empty())
+    path_to_name_map_.insert(std::make_pair(path, mount_name));
+  return true;
+}
+
+RemoteFileSystemProxyInterface* ExternalMountPoints::GetRemoteFileSystemProxy(
+    const std::string& mount_name) const {
+  base::AutoLock locker(lock_);
+  NameToInstance::const_iterator found = instance_map_.find(mount_name);
+  if (found == instance_map_.end())
+    return NULL;
+  return found->second->remote_proxy();
+}
+
+void ExternalMountPoints::AppendMountPoints(
+    std::vector<MountPointInfo>* mount_points) const {
+  base::AutoLock locker(lock_);
+  DCHECK(mount_points);
+  for (NameToInstance::const_iterator iter = instance_map_.begin();
+       iter != instance_map_.end(); ++iter) {
+    mount_points->push_back(MountPointInfo(iter->first, iter->second->path()));
+  }
+}
+
+bool ExternalMountPoints::CanCrackMountType(FileSystemType type) const {
+  return type == kFileSystemTypeExternal;
+}
+
+bool ExternalMountPoints::GetRegisteredPath(
+    const std::string& filesystem_id, FilePath* path) const {
+  DCHECK(path);
+  base::AutoLock locker(lock_);
+  NameToInstance::const_iterator found = instance_map_.find(filesystem_id);
+  if (found == instance_map_.end())
+    return false;
+  *path = found->second->path();
+  return true;
+}
+
+bool ExternalMountPoints::RevokeFileSystem(const std::string& mount_name) {
+  base::AutoLock locker(lock_);
+  NameToInstance::iterator found = instance_map_.find(mount_name);
+  if (found == instance_map_.end())
+    return false;
+  Instance* instance = found->second;
+  path_to_name_map_.erase(instance->path());
+  delete found->second;
+  instance_map_.erase(found);
+  return true;
+}
+
+FilePath ExternalMountPoints::CreateVirtualRootPath(
+    const std::string& mount_name) const {
+  return FilePath().AppendASCII(mount_name);
+}
+
+ExternalMountPoints::ExternalMountPoints(bool is_system_instance) {

[kinuko, 2013/01/08 12:22:43]

Can we avoid using boolean here? (It's discouraged in general)

[tbarzic, 2013/01/09 01:26:34]

Done.

+#if defined(OS_CHROMEOS)
+  // Add default system mount points.
+  if (is_system_instance) {
+    RegisterFileSystem("archive",
+                       kFileSystemTypeNativeLocal,
+                       FilePath(FILE_PATH_LITERAL("/media/archive")));
+    RegisterFileSystem("removable",
+                       kFileSystemTypeNativeLocal,
+                       FilePath(FILE_PATH_LITERAL("/media/removable")));
+    RegisterFileSystem("oem",
+                       kFileSystemTypeRestrictedNativeLocal,
+                       FilePath(FILE_PATH_LITERAL("/usr/share/oem")));
+
+    // TODO(tbarzic): Move this out of here.
+    FilePath home_path;
+    if (PathService::Get(base::DIR_HOME, &home_path)) {
+      RegisterFileSystem("Downloads",
+                         kFileSystemTypeNativeLocal,
+                         home_path.AppendASCII("Downloads"));
+    }
+  }
+#endif  // defined(OS_CHROMEOS)
+}
+
+ExternalMountPoints::~ExternalMountPoints() {
+  STLDeleteContainerPairSecondPointers(instance_map_.begin(),
+                                       instance_map_.end());
+}
+
+bool ExternalMountPoints::ValidateNewMountPoint(const std::string& mount_name,
+                                                const FilePath& path) {
+  // Mount name must not be empty.
+  if (mount_name.empty())
+    return false;
+
+  // Verify there is no registered mount point with the same name.
+  NameToInstance::iterator found = instance_map_.find(mount_name);
+  if (found != instance_map_.end())
+    return false;
+
+  // Allow empty paths.
+  if (path.empty())
+    return true;
+
+  // Verify path is legal.
+  if (path.ReferencesParent() || !path.IsAbsolute())
+    return false;
+
+  // Check there the new path does not overlap with one of the existing ones.
+  std::map<FilePath, std::string>::reverse_iterator potential_parent(
+      path_to_name_map_.upper_bound(path));
+  if (potential_parent != path_to_name_map_.rend()) {
+    if (potential_parent->first == path ||
+        potential_parent->first.IsParent(path)) {
+      return false;
+    }
+  }
+
+  std::map<FilePath, std::string>::iterator potential_child =
+      path_to_name_map_.upper_bound(path);
+  if (potential_child == path_to_name_map_.end())
+    return true;
+  return !(potential_child->first == path) &&
+         !path.IsParent(potential_child->first);
+}
+
+bool ExternalMountPoints::GetVirtualPath(const FilePath& absolute_path,
+                                         FilePath* virtual_path) {
+  DCHECK(virtual_path);
+  base::AutoLock locker(lock_);
+  std::map<FilePath, std::string>::reverse_iterator iter(
+      path_to_name_map_.upper_bound(absolute_path));
+  if (iter == path_to_name_map_.rend())
+    return false;
+
+  *virtual_path = CreateVirtualRootPath(iter->second);
+  if (iter->first == absolute_path)
+    return true;
+  return iter->first.AppendRelativePath(absolute_path, virtual_path);
+}
+
+bool ExternalMountPoints::CrackExternalPath(const FilePath& virtual_path,
+                                            std::string* mount_name,
+                                            FileSystemType* type,
+                                            FilePath* path) const {
+  DCHECK(mount_name);
+  DCHECK(path);
+
+  // This should not contain any '..' references.
+  if (virtual_path.ReferencesParent())
+    return false;
+
+  // The virtual_path should comprise <mount_name> and <relative_path> parts.
+  std::vector<FilePath::StringType> components;
+  virtual_path.GetComponents(&components);
+  if (components.size() < 1)
+    return false;
+
+  std::vector<FilePath::StringType>::iterator component_iter =
+      components.begin();
+  std::string maybe_mount_name = FilePath(*component_iter++).MaybeAsASCII();
+  if (maybe_mount_name.empty())
+    return false;
+
+  FilePath cracked_path;
+  {
+    base::AutoLock locker(lock_);
+    NameToInstance::const_iterator found_instance =
+        instance_map_.find(maybe_mount_name);
+    if (found_instance == instance_map_.end())
+      return false;
+
+    *mount_name = maybe_mount_name;
+    const Instance* instance = found_instance->second;
+    if (type)
+      *type = instance->type();
+    cracked_path = instance->path();
+  }
+
+  for (; component_iter != components.end(); ++component_iter)
+    cracked_path = cracked_path.Append(*component_iter);
+  *path = cracked_path;
+  return true;
+}
+
+ScopedExternalFileSystem::ScopedExternalFileSystem(
+    const std::string& mount_name,
+    FileSystemType type,
+    const FilePath& path)
+    : mount_name_(mount_name) {
+  ExternalMountPoints::GetSystemInstance()->RegisterFileSystem(
+      mount_name, type, path);
+}
+
+FilePath ScopedExternalFileSystem::GetVirtualRootPath() const {
+  return ExternalMountPoints::GetSystemInstance()->
+      CreateVirtualRootPath(mount_name_);
+}
+
+ScopedExternalFileSystem::~ScopedExternalFileSystem() {
+  ExternalMountPoints::GetSystemInstance()->RevokeFileSystem(mount_name_);
+}
+
+}  // namespace fileapi