storage/browser/fileapi/external_mount_points.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef STORAGE_BROWSER_FILEAPI_EXTERNAL_MOUNT_POINTS_H_
   6 #define STORAGE_BROWSER_FILEAPI_EXTERNAL_MOUNT_POINTS_H_
   7
   8 #include <map>
   9 #include <string>
  10 #include <vector>
  11
  12 #include "base/memory/ref_counted.h"
  13 #include "base/synchronization/lock.h"
  14 #include "storage/browser/fileapi/mount_points.h"
  15 #include "storage/browser/storage_browser_export.h"
  16 #include "storage/common/fileapi/file_system_mount_option.h"
  17 #include "storage/common/fileapi/file_system_types.h"
  18
  19 namespace base {
  20 class FilePath;
  21 }
  22
  23 namespace storage {
  24
  25 class FileSystemURL;
  26
  27 // Manages external filesystem namespaces that are identified by 'mount name'
  28 // and are persisted until RevokeFileSystem is called.
  29 // Files in an external filesystem are identified by a filesystem URL like:
  30 //
  31 //   filesystem:<origin>/external/<mount_name>/relative/path
  32 //
  33 class STORAGE_EXPORT ExternalMountPoints
  34     : public base::RefCountedThreadSafe<ExternalMountPoints>,
  35       public MountPoints {
  36  public:
  37   static ExternalMountPoints* GetSystemInstance();
  38   static scoped_refptr<ExternalMountPoints> CreateRefCounted();
  39
  40   // Registers a new named external filesystem.
  41   // The |path| is registered as the root path of the mount point which
  42   // is identified by a URL "filesystem:.../external/mount_name".
  43   //
  44   // For example, if the path "/media/removable" is registered with
  45   // the mount_name "removable", a filesystem URL like
  46   // "filesystem:.../external/removable/a/b" will be resolved as
  47   // "/media/removable/a/b".
  48   //
  49   // The |mount_name| should NOT contain a path separator '/'.
  50   // Returns false if the given name is already registered.
  51   //
  52   // Overlapping mount points in a single MountPoints instance are not allowed.
  53   // Adding mount point whose path overlaps with an existing mount point will
  54   // fail except for media galleries, which do not count toward registered
  55   // paths for overlap calculation.
  56   //
  57   // If not empty, |path| must be absolute. It is allowed for the path to be
  58   // empty, but |GetVirtualPath| will not work for those mount points.
  59   //
  60   // An external file system registered by this method can be revoked
  61   // by calling RevokeFileSystem with |mount_name|.
  62   bool RegisterFileSystem(const std::string& mount_name,
  63                           FileSystemType type,
  64                           const FileSystemMountOption& mount_option,
  65                           const base::FilePath& path);
  66
  67   // MountPoints overrides.
  68   bool HandlesFileSystemMountType(FileSystemType type) const override;
  69   bool RevokeFileSystem(const std::string& mount_name) override;
  70   bool GetRegisteredPath(const std::string& mount_name,
  71                          base::FilePath* path) const override;
  72   bool CrackVirtualPath(const base::FilePath& virtual_path,
  73                         std::string* mount_name,
  74                         FileSystemType* type,
  75                         std::string* cracked_id,
  76                         base::FilePath* path,
  77                         FileSystemMountOption* mount_option) const override;
  78   FileSystemURL CrackURL(const GURL& url) const override;
  79   FileSystemURL CreateCrackedFileSystemURL(
  80       const GURL& origin,
  81       FileSystemType type,
  82       const base::FilePath& path) const override;
  83
  84   // Returns a list of registered MountPointInfos (of <mount_name, path>).
  85   void AddMountPointInfosTo(std::vector<MountPointInfo>* mount_points) const;
  86
  87   // Converts a path on a registered file system to virtual path relative to the
  88   // file system root. E.g. if 'Downloads' file system is mapped to
  89   // '/usr/local/home/Downloads', and |absolute| path is set to
  90   // '/usr/local/home/Downloads/foo', the method will set |virtual_path| to
  91   // 'Downloads/foo'.
  92   // Returns false if the path cannot be resolved (e.g. if the path is not
  93   // part of any registered filesystem).
  94   //
  95   // Media gallery type file systems do not count for this calculation. i.e.
  96   // if only a media gallery is registered for the path, false will be returned.
  97   // If a media gallery and another file system are registered for related
  98   // paths, only the other registration is taken into account.
  99   //
 100   // Returned virtual_path will have normalized path separators.
 101   bool GetVirtualPath(const base::FilePath& absolute_path,
 102                       base::FilePath* virtual_path) const;
 103
 104   // Returns the virtual root path that looks like /<mount_name>.
 105   base::FilePath CreateVirtualRootPath(const std::string& mount_name) const;
 106
 107   FileSystemURL CreateExternalFileSystemURL(
 108       const GURL& origin,
 109       const std::string& mount_name,
 110       const base::FilePath& path) const;
 111
 112   // Revoke all registered filesystems. Used only by testing (for clean-ups).
 113   void RevokeAllFileSystems();
 114
 115  private:
 116   friend class base::RefCountedThreadSafe<ExternalMountPoints>;
 117
 118   // Represents each file system instance (defined in the .cc).
 119   class Instance;
 120
 121   typedef std::map<std::string, Instance*> NameToInstance;
 122
 123   // Reverse map from registered path to its corresponding mount name.
 124   typedef std::map<base::FilePath, std::string> PathToName;
 125
 126   // Use |GetSystemInstance| of |CreateRefCounted| to get an instance.
 127   ExternalMountPoints();
 128   ~ExternalMountPoints() override;
 129
 130   // MountPoint overrides.
 131   FileSystemURL CrackFileSystemURL(const FileSystemURL& url) const override;
 132
 133   // Performs sanity checks on the new mount point.
 134   // Checks the following:
 135   //  - there is no registered mount point with mount_name
 136   //  - path does not contain a reference to a parent
 137   //  - path is absolute
 138   //  - path does not overlap with an existing mount point path unless it is a
 139   //    media gallery type.
 140   //
 141   // |lock_| should be taken before calling this method.
 142   bool ValidateNewMountPoint(const std::string& mount_name,
 143                              FileSystemType type,
 144                              const base::FilePath& path);
 145
 146   // This lock needs to be obtained when accessing the instance_map_.
 147   mutable base::Lock lock_;
 148
 149   NameToInstance instance_map_;
 150   PathToName path_to_name_map_;
 151
 152   DISALLOW_COPY_AND_ASSIGN(ExternalMountPoints);
 153 };
 154
 155 }  // namespace storage
 156
 157 #endif  // STORAGE_BROWSER_FILEAPI_EXTERNAL_MOUNT_POINTS_H_