Make isolated file system works for a device root (e.g. X:\\)

webkit/fileapi/isolated_context.h

 // 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_ISOLATED_CONTEXT_H_
 #define WEBKIT_FILEAPI_ISOLATED_CONTEXT_H_
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/memory/singleton.h"
 #include "base/synchronization/lock.h"
 #include "base/lazy_instance.h"
 #include "webkit/fileapi/fileapi_export.h"
 
 namespace fileapi {
 
 // Manages isolated filename namespaces.  A namespace is simply defined as a
 // set of file paths and corresponding filesystem ID.  This context class is
 // a singleton and access to the context is thread-safe (protected with a
 // lock).
 // Some methods of this class are virtual just for mocking.
 class FILEAPI_EXPORT IsolatedContext {
  public:
+  struct FILEAPI_EXPORT FileInfo {
+    FileInfo();
+    FileInfo(const std::string& name, const FilePath& path);
+
+    // The name of the file.
+    std::string name;
+    // The path of the file.
+    FilePath path;
+  };
+
   // The instance is lazily created per browser process.
   static IsolatedContext* GetInstance();
 
-  // Registers a new file isolated filesystem with the given set of files
+  // Get a convenient display name of the |path| which could be used as a key
+  // in the toplevel_map_.  Usually this simply returns path.BaseName()
+  // unless the |path| is a root directory (e.g. a device root).
+  // Not that this does not guarantee the uniqueness of the returned name.
+  static std::string GetNameForPath(const FilePath& path);
+
+  // Registers a new isolated filesystem with the given set of FileInfo
   // and returns the new filesystem_id.  The files are registered with their
-  // basenames as their keys so that later we can resolve the full paths
+  // display_name as their names so that later we can resolve the full paths
   // for the given file name in the isolated filesystem.  We only expose the
-  // key and the ID for the newly created filesystem to the renderer for
+  // name and the ID for the newly created filesystem to the renderer for
   // the sake of security.
   //
   // The renderer will be sending filesystem requests with a virtual path like
-  // '/<filesystem_id>/<relative_path_from_the_basename_of_dropped_path>'
+  // '/<filesystem_id>/<relative_path_from_the_dropped_path>'
   // for which we could crack in the browser by calling CrackIsolatedPath to
   // get the full path.
   //
-  // For example: if a dropped file has a path like '/a/b/foo' we register
-  // the path with the key 'foo' in the newly created filesystem.
+  // For example: if a dropped file has a path like '/a/b/foo' and we register
+  // the path with the name 'foo' in the newly created filesystem.
   // Later if the context is asked to crack a virtual path like '/<fsid>/foo'
   // it can properly return the original path '/a/b/foo' by looking up the
   // internal mapping.  Similarly if a dropped entry is a directory and its
   // path is like '/a/b/dir' a virtual path like '/<fsid>/dir/foo' can be
   // cracked into '/a/b/dir/foo'.
   //
   // Note that the path in |fileset| that contains '..' or is not an
   // absolute path is skipped and is not registerred.
-  std::string RegisterIsolatedFileSystem(const std::set<FilePath>& fileset);
+  std::string RegisterFileSystem(const std::vector<FileInfo>& files);

[benwells, 2012/06/28 20:07:39]

Is there a way to make this change that doesn't need an API change at this level
(although I like the new convenience method for when you only have one file)?

[kinuko, 2012/06/29 10:11:32]

The new API is trying to let the caller pick a name for a path rather than
blindly use the basename of the given path. I think this has following
advantages (though the callsite may look noisier):

- The caller can now register paths with arbitrary names. (Though currently we
always call GetNameForPath)
- The caller can register multiple paths with the same base name in one file
system by using different names (e.g. by appending suffix etc) on its own.
- The caller can make sure it uses the same name with the IsolatedContext when
it looks up a file in the file system (*), because the name must be given by the
caller itself.

(*) For example the response.baseName in the code [1] should be same name the
one registered in the context.

[1]
http://code.google.com/searchframe#OAMlx_jo-ck/src/chrome/renderer/resources/...

+
+  // Registers a new isolated filesystem for a given display name and file.
+  std::string RegisterFileSystemForFile(const std::string& display_name,
+                                        const FilePath& path);
 
   // Revokes filesystem specified by the given filesystem_id.
   // Note that this revokes the filesystem no matter how many references it has.
   // It is ok to call this on the filesystem that has been already deleted
   // (if its reference count had reached 0).
-  void RevokeIsolatedFileSystem(const std::string& filesystem_id);
+  void RevokeFileSystem(const std::string& filesystem_id);
 
   // Adds a reference to a filesystem specified by the given filesystem_id.
   void AddReference(const std::string& filesystem_id);
 
   // Removes a reference to a filesystem specified by the given filesystem_id.
   // If the reference count reaches 0 the isolated context gets destroyed.
   // It is ok to call this on the filesystem that has been already deleted
-  // (e.g. by RevokeIsolatedFileSystem).
+  // (e.g. by RevokeFileSystem).
   void RemoveReference(const std::string& filesystem_id);
 
   // Cracks the given |virtual_path| (which should look like
   // "/<filesystem_id>/<relative_path>") and populates the |filesystem_id|
   // and |platform_path| if the embedded <filesystem_id> is registerred
-  // to this context.  |root_path| is also populated to have the platform
-  // root (toplevel) path for the |virtual_path|
-  // (i.e. |platform_path| = |root_path| + <relative_path>).
+  // to this context.  |root_path| is also populated to have the registered
+  // root (toplevel) file info for the |virtual_path|.
   //
   // Returns false if the given virtual_path or the cracked filesystem_id
   // is not valid.
   //
-  // Note that |root_path| and |platform_path| are set to empty paths if
+  // Note that |root_info| and |platform_path| are set to empty paths if
   // |virtual_path| has no <relative_path> part (i.e. pointing to
   // the virtual root).
   bool CrackIsolatedPath(const FilePath& virtual_path,
                          std::string* filesystem_id,
-                         FilePath* root_path,
+                         FileInfo* root_info,
                          FilePath* platform_path) const;
 
-  // Returns a vector of the full paths of the top-level entry paths
-  // registered for the |filesystem_id|.  Returns false if the
-  // |filesystem_is| is not valid.
-  bool GetTopLevelPaths(const std::string& filesystem_id,
-                        std::vector<FilePath>* paths) const;
+  // Returns a vector of FileInfo registered for the |filesystem_id|.
+  // Returns false if the |filesystem_id| is not valid.
+  bool GetRegisteredFileInfo(const std::string& filesystem_id,
+                             std::vector<FileInfo>* files) const;
 
-  // Returns the virtual path that looks like /<filesystem_id>/<relative_path>.
-  FilePath CreateVirtualPath(const std::string& filesystem_id,
-                             const FilePath& relative_path) const;
+  // Returns the virtual root path that looks like /<filesystem_id>.
+  FilePath CreateVirtualRootPath(const std::string& filesystem_id) const;
 
   // Set the filesystem writable if |writable| is true, non-writable
   // if it is false. Returns false if the |filesystem_id| is not valid.
   bool SetWritable(const std::string& filesystem_id, bool writable);
 
   // Returns true if the |filesystem_id| is writable.
   bool IsWritable(const std::string& filesystem_id) const;
 
  private:
   friend struct base::DefaultLazyInstanceTraits<IsolatedContext>;
 
   // Maps from filesystem id to a path conversion map for top-level entries.
-  typedef std::map<FilePath, FilePath> PathMap;
-  typedef std::map<std::string, PathMap> IDToPathMap;
+  typedef std::map<std::string, FileInfo> FileMap;

[tzik, 2012/06/29 02:56:35]

Can we use std::set instead?

[kinuko, 2012/06/29 08:31:22]

Done.

+  typedef std::map<std::string, FileMap> IDToFileMap;
 
   // Obtain an instance of this class via GetInstance().
   IsolatedContext();
   ~IsolatedContext();
 
   // Removes the given filesystem without locking.
   // (The caller must hold a lock)
   void RevokeWithoutLocking(const std::string& filesystem_id);
 
   // Returns a new filesystem_id.  Called with lock.
   std::string GetNewFileSystemId() const;
 
   // This lock needs to be obtained when accessing the toplevel_map_.
   mutable base::Lock lock_;
 
   // Maps the toplevel entries to the filesystem id.
-  IDToPathMap toplevel_map_;
+  IDToFileMap toplevel_map_;
 
   // Holds a set of writable ids.
   // Isolated file systems are created read-only by default, and this set
   // holds a list of exceptions.
   // Detailed filesystem permission may be provided by an external
   // security policy manager, e.g. ChildProcessSecurityPolicy.
   std::set<std::string> writable_ids_;
 
   // Reference counts. Note that an isolated filesystem is created with ref==0.
   // and will get deleted when the ref count reaches <=0.
   std::map<std::string, int> ref_counts_;
 
   DISALLOW_COPY_AND_ASSIGN(IsolatedContext);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_ISOLATED_CONTEXT_H_