Extract external file systems handling from isolated context.

webkit/fileapi/external_mount_points.h

Index: webkit/fileapi/external_mount_points.h
diff --git a/webkit/fileapi/external_mount_points.h b/webkit/fileapi/external_mount_points.h
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+// 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.
+
+#ifndef WEBKIT_FILEAPI_EXTERNAL_MOUNT_POINTS_H_
+#define WEBKIT_FILEAPI_EXTERNAL_MOUNT_POINTS_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "webkit/fileapi/file_system_types.h"
+#include "webkit/fileapi/mount_points.h"
+#include "webkit/storage/webkit_storage_export.h"
+
+class FilePath;
+
+namespace fileapi {
+class RemoteFileSystemProxyInterface;
+}
+
+namespace fileapi {
+
+// Manages external filesystem namespaces that are identified by 'mount name'
+// and are persisted until RevokeFileSystem is called.
+// Files in an external filesystem are identified by a filesystem URL like:
+//
+//   filesystem:<origin>/external/<mount_name>/relative/path
+//
+class WEBKIT_STORAGE_EXPORT ExternalMountPoints
+    : public base::RefCountedThreadSafe<ExternalMountPoints>,
+      public MountPoints {
+ public:
+  static ExternalMountPoints* GetSystemInstance();
+  static scoped_refptr<ExternalMountPoints> CreateRefCounted();
+
+  // Registers a new named external filesystem.
+  // The |path| is registered as the root path of the mount point which
+  // is identified by a URL "filesystem:.../external/mount_name".
+  //
+  // For example, if the path "/media/removable" is registered with
+  // the mount_name "removable", a filesystem URL like
+  // "filesystem:.../external/removable/a/b" will be resolved as
+  // "/media/removable/a/b".
+  //
+  // The |mount_name| should NOT contain a path separator '/'.
+  // Returns false if the given name is already registered.
+  //
+  // Overlapping mount points in a single MountPoints instance are not allowed.
+  // Adding mount point whose path overlaps with an existing mount point will
+  // fail.
+  //
+  // If not empty, |path| must be absolute. It is allowed for the path to be
+  // empty, but |GetVirtualPath| will not work for those mount points.
+  //
+  // An external file system registered by this method can be revoked
+  // by calling RevokeFileSystem with |mount_name|.
+  bool RegisterFileSystem(const std::string& mount_name,
+                          FileSystemType type,
+                          const FilePath& path);
+
+  // Same as |RegisterExternalFileSystem|, but registers a remote file system
+  // proxy for the file system.
+  bool RegisterRemoteFileSystem(const std::string& mount_name,
+                                FileSystemType type,
+                                RemoteFileSystemProxyInterface* remote_proxy,
+                                const FilePath& path);
+
+  // Retrieves the remote file system proxy for the registered file system.
+  // Returns NULL if there is no file system with given name, or if the file
+  // system does not have a remote file system proxy.
+  RemoteFileSystemProxyInterface* GetRemoteFileSystemProxy(
+      const std::string& mount_name) const;
+
+  // Returns a list of registered MountPointInfos (of <mount_name, path>).
+  void AddMountPointInfosTo(std::vector<MountPointInfo>* mount_points) const;
+
+  // MountPoints overrides.
+  virtual bool CanCrackMountType(FileSystemType type) const OVERRIDE;
+  virtual bool GetRegisteredPath(const std::string& mount_name,
+                                 FilePath* path) const OVERRIDE;
+  virtual bool RevokeFileSystem(const std::string& mount_name) OVERRIDE;
+
+  // Converts a path on a registered file system to virtual path relative to the
+  // file system root. E.g. if 'Downloads' file system is mapped to
+  // '/usr/local/home/Downloads', and |absolute| path is set to
+  // 'usr/local/home/Downloads/foo', the method will set |virtual_path| to
+  // 'Downloads/foo'.
+  bool GetVirtualPath(const FilePath& absolute_path, FilePath* virtual_path);
+
+  // Cracks the given |virtual_path| (which is the path part of a filesystem URL
+  // without /'/external' prefix part) and populates the
+  // |mount_name|, |type|, and |path| if the <mount_name> part embedded in
+  // the |virtual_path| (i.e. the first component of the |virtual_path|) is a
+  // valid registered filesystem ID or mount name for an external filesystem.
+  //
+  // Returns false if the given virtual_path or the cracked mount_name
+  // is not valid.
+  bool CrackExternalPath(const FilePath& virtual_path,
+                         std::string* mount_name,
+                         FileSystemType* type,
+                         FilePath* path) const;
+
+  // Returns the virtual root path that looks like /<mount_name>.
+  FilePath CreateVirtualRootPath(const std::string& mount_name) const;
+
+ private:
+  friend class base::RefCountedThreadSafe<ExternalMountPoints>;
+
+  // Represents each file system instance (defined in the .cc).
+  class Instance;
+
+  typedef std::map<std::string, Instance*> NameToInstance;
+
+  // Reverse map from registered path to its corresponding mount name.
+  typedef std::map<FilePath, std::string> PathToName;
+
+  // Use |GetSystemInstance| of |CreateRefCounted| to get an instance.
+  explicit ExternalMountPoints();
+  virtual ~ExternalMountPoints();
+
+  // Performs sanity checks on the new mount point.
+  // Checks following:
+  //  - there is no registered mount point with mount_name
+  //  - path does not reference parent
+  //  - path is absolute
+  //  - path does not overlap with an existing mount point path.
+  //
+  // |lock_| should be taken before calling this method.
+  bool ValidateNewMountPoint(const std::string& mount_name,
+                             const FilePath& path);
+
+  // This lock needs to be obtained when accessing the instance_map_.
+  mutable base::Lock lock_;
+
+  NameToInstance instance_map_;
+  PathToName path_to_name_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExternalMountPoints);
+};
+
+// Registers a scoped external filesystem which gets revoked when it scopes out.
+class WEBKIT_STORAGE_EXPORT ScopedExternalFileSystem {
+ public:
+  ScopedExternalFileSystem(const std::string& mount_name,
+                           FileSystemType type,
+                           const FilePath& path);
+  ~ScopedExternalFileSystem();
+
+  FilePath GetVirtualRootPath() const;
+
+ private:
+  const std::string mount_name_;
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_FILEAPI_EXTERNAL_MOUNT_POINTS_H_