chrome/common/extensions/docs/server2/chroot_file_system.py

   1 # Copyright 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 import posixpath
   6
   7 from docs_server_utils import StringIdentity
   8 from file_system import FileSystem
   9 from future import Gettable, Future
  10
  11
  12 class ChrootFileSystem(FileSystem):
  13   '''ChrootFileSystem(fs, path) exposes a FileSystem whose root is |path| inside
  14   |fs|, so ChrootFileSystem(fs, '/hello').Read(['/world']) is equivalent to
  15   fs.Read(['/hello/world']) with the '/hello' prefix stripped from the result.
  16   '''
  17
  18   def __init__(self, file_system, root):
  19     '''Parameters:
  20     |file_system| The FileSystem instance to transpose paths of.
  21     |root|        The path to transpose all Read/Stat calls by.
  22     '''
  23     self._file_system = file_system
  24     self._root = root.strip('/')
  25
  26   def Read(self, paths):
  27     # Maintain reverse mapping so the result can be mapped to the original
  28     # paths given (the result from |file_system| will include |root| in the
  29     # result, which would be wrong).
  30     prefixed_paths = {}
  31     def prefix(path):
  32       prefixed = posixpath.join(self._root, path)
  33       prefixed_paths[prefixed] = path
  34       return prefixed
  35     future_result = self._file_system.Read(
  36         tuple(prefix(path) for path in paths))
  37     def resolve():
  38       return dict((prefixed_paths[path], content)
  39                   for path, content in future_result.Get().iteritems())
  40     return Future(delegate=Gettable(resolve))
  41
  42   def Refresh(self):
  43     return self._file_system.Refresh()
  44
  45   def Stat(self, path):
  46     return self._file_system.Stat(posixpath.join(self._root, path))
  47
  48   def GetIdentity(self):
  49     return StringIdentity(
  50         '%s/%s' % (self._file_system.GetIdentity(), self._root))
  51
  52   def __repr__(self):
  53     return 'ChrootFileSystem(%s, %s)' % (
  54             self._root, repr(self._file_system))