storage/browser/fileapi/isolated_context.h

   1 // Copyright (c) 2012 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_ISOLATED_CONTEXT_H_
   6 #define STORAGE_BROWSER_FILEAPI_ISOLATED_CONTEXT_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11 #include <vector>
  12
  13 #include "base/basictypes.h"
  14 #include "base/files/file_path.h"
  15 #include "base/lazy_instance.h"
  16 #include "base/memory/singleton.h"
  17 #include "base/synchronization/lock.h"
  18 #include "storage/browser/fileapi/mount_points.h"
  19 #include "storage/browser/storage_browser_export.h"
  20 #include "storage/common/fileapi/file_system_types.h"
  21
  22 namespace storage {
  23 class FileSystemURL;
  24 }
  25
  26 namespace storage {
  27
  28 // Manages isolated filesystem mount points which have no well-known names
  29 // and are identified by a string 'filesystem ID', which usually just looks
  30 // like random value.
  31 // This type of filesystem can be created on the fly and may go away when it has
  32 // no references from renderers.
  33 // Files in an isolated filesystem are registered with corresponding names and
  34 // identified by a filesystem URL like:
  35 //
  36 //   filesystem:<origin>/isolated/<filesystem_id>/<name>/relative/path
  37 //
  38 // Some methods of this class are virtual just for mocking.
  39 //
  40 class STORAGE_EXPORT IsolatedContext : public MountPoints {
  41  public:
  42   class STORAGE_EXPORT FileInfoSet {
  43    public:
  44     FileInfoSet();
  45     ~FileInfoSet();
  46
  47     // Add the given |path| to the set and populates |registered_name| with
  48     // the registered name assigned for the path. |path| needs to be
  49     // absolute and should not contain parent references.
  50     // Return false if the |path| is not valid and could not be added.
  51     bool AddPath(const base::FilePath& path, std::string* registered_name);
  52
  53     // Add the given |path| with the |name|.
  54     // Return false if the |name| is already registered in the set or
  55     // is not valid and could not be added.
  56     bool AddPathWithName(const base::FilePath& path, const std::string& name);
  57
  58     const std::set<MountPointInfo>& fileset() const { return fileset_; }
  59
  60    private:
  61     std::set<MountPointInfo> fileset_;
  62   };
  63
  64   // The instance is lazily created per browser process.
  65   static IsolatedContext* GetInstance();
  66
  67   // Returns true if the given filesystem type is managed by IsolatedContext
  68   // (i.e. if the given |type| is Isolated or External).
  69   // TODO(kinuko): needs a better function name.
  70   static bool IsIsolatedType(FileSystemType type);
  71
  72   // Registers a new isolated filesystem with the given FileInfoSet |files|
  73   // and returns the new filesystem_id.  The files are registered with their
  74   // register_name as their keys so that later we can resolve the full paths
  75   // for the given name.  We only expose the name and the ID for the
  76   // newly created filesystem to the renderer for the sake of security.
  77   //
  78   // The renderer will be sending filesystem requests with a virtual path like
  79   // '/<filesystem_id>/<registered_name>/<relative_path_from_the_dropped_path>'
  80   // for which we could crack in the browser process by calling
  81   // CrackIsolatedPath to get the full path.
  82   //
  83   // For example: if a dropped file has a path like '/a/b/foo' and we register
  84   // the path with the name 'foo' in the newly created filesystem.
  85   // Later if the context is asked to crack a virtual path like '/<fsid>/foo'
  86   // it can properly return the original path '/a/b/foo' by looking up the
  87   // internal mapping.  Similarly if a dropped entry is a directory and its
  88   // path is like '/a/b/dir' a virtual path like '/<fsid>/dir/foo' can be
  89   // cracked into '/a/b/dir/foo'.
  90   //
  91   // Note that the path in |fileset| that contains '..' or is not an
  92   // absolute path is skipped and is not registered.
  93   std::string RegisterDraggedFileSystem(const FileInfoSet& files);
  94
  95   // Registers a new isolated filesystem for a given |path| of filesystem
  96   // |type| filesystem with |filesystem_id| and returns a new filesystem ID.
  97   // |path| must be an absolute path which has no parent references ('..').
  98   // If |register_name| is non-null and has non-empty string the path is
  99   // registered as the given |register_name|, otherwise it is populated
 100   // with the name internally assigned to the path.
 101   std::string RegisterFileSystemForPath(FileSystemType type,
 102                                         const std::string& filesystem_id,
 103                                         const base::FilePath& path,
 104                                         std::string* register_name);
 105
 106   // Registers a virtual filesystem. This is different from
 107   // RegisterFileSystemForPath because register_name is required, and
 108   // cracked_path_prefix is allowed to be non-absolute.
 109   // |register_name| is required, since we cannot infer one from the path.
 110   // |cracked_path_prefix| has no parent references, but can be relative.
 111   std::string RegisterFileSystemForVirtualPath(
 112       FileSystemType type,
 113       const std::string& register_name,
 114       const base::FilePath& cracked_path_prefix);
 115
 116   // Revokes all filesystem(s) registered for the given path.
 117   // This is assumed to be called when the registered path becomes
 118   // globally invalid, e.g. when a device for the path is detached.
 119   //
 120   // Note that this revokes the filesystem no matter how many references it has.
 121   // It is ok to call this for the path that has no associated filesystems.
 122   // Note that this only works for the filesystems registered by
 123   // |RegisterFileSystemForPath|.
 124   void RevokeFileSystemByPath(const base::FilePath& path);
 125
 126   // Adds a reference to a filesystem specified by the given filesystem_id.
 127   void AddReference(const std::string& filesystem_id);
 128
 129   // Removes a reference to a filesystem specified by the given filesystem_id.
 130   // If the reference count reaches 0 the isolated context gets destroyed.
 131   // It is OK to call this on the filesystem that has been already deleted
 132   // (e.g. by RevokeFileSystemByPath).
 133   void RemoveReference(const std::string& filesystem_id);
 134
 135   // Returns a set of dragged MountPointInfos registered for the
 136   // |filesystem_id|.
 137   // The filesystem_id must be pointing to a dragged file system
 138   // (i.e. must be the one registered by RegisterDraggedFileSystem).
 139   // Returns false if the |filesystem_id| is not valid.
 140   bool GetDraggedFileInfo(const std::string& filesystem_id,
 141                           std::vector<MountPointInfo>* files) const;
 142
 143   // MountPoints overrides.
 144   virtual bool HandlesFileSystemMountType(FileSystemType type) const OVERRIDE;
 145   virtual bool RevokeFileSystem(const std::string& filesystem_id) OVERRIDE;
 146   virtual bool GetRegisteredPath(const std::string& filesystem_id,
 147                                  base::FilePath* path) const OVERRIDE;
 148   virtual bool CrackVirtualPath(
 149       const base::FilePath& virtual_path,
 150       std::string* filesystem_id,
 151       FileSystemType* type,
 152       std::string* cracked_id,
 153       base::FilePath* path,
 154       FileSystemMountOption* mount_option) const OVERRIDE;
 155   virtual FileSystemURL CrackURL(const GURL& url) const OVERRIDE;
 156   virtual FileSystemURL CreateCrackedFileSystemURL(
 157       const GURL& origin,
 158       FileSystemType type,
 159       const base::FilePath& path) const OVERRIDE;
 160
 161   // Returns the virtual root path that looks like /<filesystem_id>.
 162   base::FilePath CreateVirtualRootPath(const std::string& filesystem_id) const;
 163
 164  private:
 165   friend struct base::DefaultLazyInstanceTraits<IsolatedContext>;
 166
 167   // Represents each file system instance (defined in the .cc).
 168   class Instance;
 169
 170   typedef std::map<std::string, Instance*> IDToInstance;
 171
 172   // Reverse map from registered path to IDs.
 173   typedef std::map<base::FilePath, std::set<std::string> > PathToID;
 174
 175   // Obtain an instance of this class via GetInstance().
 176   IsolatedContext();
 177   virtual ~IsolatedContext();
 178
 179   // MountPoints overrides.
 180   virtual FileSystemURL CrackFileSystemURL(
 181       const FileSystemURL& url) const OVERRIDE;
 182
 183   // Unregisters a file system of given |filesystem_id|. Must be called with
 184   // lock_ held.  Returns true if the file system is unregistered.
 185   bool UnregisterFileSystem(const std::string& filesystem_id);
 186
 187   // Returns a new filesystem_id.  Called with lock.
 188   std::string GetNewFileSystemId() const;
 189
 190   // This lock needs to be obtained when accessing the instance_map_.
 191   mutable base::Lock lock_;
 192
 193   IDToInstance instance_map_;
 194   PathToID path_to_id_map_;
 195
 196   DISALLOW_COPY_AND_ASSIGN(IsolatedContext);
 197 };
 198
 199 }  // namespace storage
 200
 201 #endif  // STORAGE_BROWSER_FILEAPI_ISOLATED_CONTEXT_H_