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
5import posixpath
6
7from docs_server_utils import StringIdentity
8from file_system import FileSystem
9from future import Future
10
11
12class 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, skip_not_found=False):
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    def next(results):
36      return dict((prefixed_paths[path], content)
37                  for path, content in results.iteritems())
38    return self._file_system.Read(tuple(prefix(path) for path in paths),
39                                  skip_not_found-skip_not_found).Then(next)
40
41  def Refresh(self):
42    return self._file_system.Refresh()
43
44  def Stat(self, path):
45    return self._file_system.Stat(posixpath.join(self._root, path))
46
47  def GetIdentity(self):
48    return StringIdentity(
49        '%s/%s' % (self._file_system.GetIdentity(), self._root))
50
51  def __repr__(self):
52    return 'ChrootFileSystem(%s, %s)' % (
53            self._root, repr(self._file_system))
54