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

   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 import posixpath
   6 import traceback
   7 import xml.dom.minidom as xml
   8 from xml.parsers.expat import ExpatError
   9
  10 from appengine_url_fetcher import AppEngineUrlFetcher
  11 from appengine_wrappers import IsDownloadError
  12 from docs_server_utils import StringIdentity
  13 from file_system import (
  14     FileNotFoundError, FileSystem, FileSystemError, StatInfo)
  15 from future import Future
  16 import url_constants
  17
  18
  19 def _ParseHTML(html):
  20   '''Unfortunately, the viewvc page has a stray </div> tag, so this takes care
  21   of all mismatched tags.
  22   '''
  23   try:
  24     return xml.parseString(html)
  25   except ExpatError as e:
  26     return _ParseHTML('\n'.join(
  27         line for (i, line) in enumerate(html.split('\n'))
  28         if e.lineno != i + 1))
  29
  30 def _InnerText(node):
  31   '''Like node.innerText in JS DOM, but strips surrounding whitespace.
  32   '''
  33   text = []
  34   if node.nodeValue:
  35     text.append(node.nodeValue)
  36   if hasattr(node, 'childNodes'):
  37     for child_node in node.childNodes:
  38       text.append(_InnerText(child_node))
  39   return ''.join(text).strip()
  40
  41 def _CreateStatInfo(html):
  42   parent_version = None
  43   child_versions = {}
  44
  45   # Try all of the tables until we find the ones that contain the data (the
  46   # directory and file versions are in different tables).
  47   for table in _ParseHTML(html).getElementsByTagName('table'):
  48     # Within the table there is a list of files. However, there may be some
  49     # things beforehand; a header, "parent directory" list, etc. We will deal
  50     # with that below by being generous and just ignoring such rows.
  51     rows = table.getElementsByTagName('tr')
  52
  53     for row in rows:
  54       cells = row.getElementsByTagName('td')
  55
  56       # The version of the directory will eventually appear in the soup of
  57       # table rows, like this:
  58       #
  59       # <tr>
  60       #   <td>Directory revision:</td>
  61       #   <td><a href=... title="Revision 214692">214692</a> (of...)</td>
  62       # </tr>
  63       #
  64       # So look out for that.
  65       if len(cells) == 2 and _InnerText(cells[0]) == 'Directory revision:':
  66         links = cells[1].getElementsByTagName('a')
  67         if len(links) != 2:
  68           raise FileSystemError('ViewVC assumption invalid: directory ' +
  69                                 'revision content did not have 2 <a> ' +
  70                                 ' elements, instead %s' % _InnerText(cells[1]))
  71         this_parent_version = _InnerText(links[0])
  72         int(this_parent_version)  # sanity check
  73         if parent_version is not None:
  74           raise FileSystemError('There was already a parent version %s, and ' +
  75                                 ' we just found a second at %s' %
  76                                 (parent_version, this_parent_version))
  77         parent_version = this_parent_version
  78
  79       # The version of each file is a list of rows with 5 cells: name, version,
  80       # age, author, and last log entry. Maybe the columns will change; we're
  81       # at the mercy viewvc, but this constant can be easily updated.
  82       if len(cells) != 5:
  83         continue
  84       name_element, version_element, _, __, ___ = cells
  85
  86       name = _InnerText(name_element)  # note: will end in / for directories
  87       try:
  88         version = int(_InnerText(version_element))
  89       except StandardError:
  90         continue
  91       child_versions[name] = str(version)
  92
  93     if parent_version and child_versions:
  94       break
  95
  96   return StatInfo(parent_version, child_versions)
  97
  98 def _GetAsyncFetchCallback(paths, fetcher, args=None, skip_not_found=False):
  99   def apply_args(path):
 100     return path if args is None else '%s?%s' % (path, args)
 101
 102   def list_dir(directory):
 103     dom = xml.parseString(directory)
 104     files = [elem.childNodes[0].data for elem in dom.getElementsByTagName('a')]
 105     if '..' in files:
 106       files.remove('..')
 107     return files
 108
 109   # A list of tuples of the form (path, Future).
 110   fetches = [(path, fetcher.FetchAsync(apply_args(path))) for path in paths]
 111
 112   def resolve():
 113     value = {}
 114     for path, future in fetches:
 115       try:
 116         result = future.Get()
 117       except Exception as e:
 118         if skip_not_found and IsDownloadError(e): continue
 119         exc_type = FileNotFoundError if IsDownloadError(e) else FileSystemError
 120         raise exc_type('%s fetching %s for Get: %s' %
 121                        (type(e).__name__, path, traceback.format_exc()))
 122       if result.status_code == 404:
 123         if skip_not_found: continue
 124         raise FileNotFoundError('Got 404 when fetching %s for Get, content %s' %
 125             (path, result.content))
 126       if result.status_code != 200:
 127         raise FileSystemError('Got %s when fetching %s for Get, content %s' %
 128             (result.status_code, path, result.content))
 129       if path.endswith('/'):
 130         value[path] = list_dir(result.content)
 131       else:
 132         value[path] = result.content
 133     return value
 134
 135   return resolve
 136
 137 class SubversionFileSystem(FileSystem):
 138   '''Class to fetch resources from src.chromium.org.
 139   '''
 140   @staticmethod
 141   def Create(branch='trunk', revision=None):
 142     if branch == 'trunk':
 143       svn_path = 'trunk/src'
 144     else:
 145       svn_path = 'branches/%s/src' % branch
 146     return SubversionFileSystem(
 147         AppEngineUrlFetcher('%s/%s' % (url_constants.SVN_URL, svn_path)),
 148         AppEngineUrlFetcher('%s/%s' % (url_constants.VIEWVC_URL, svn_path)),
 149         svn_path,
 150         revision=revision)
 151
 152   def __init__(self, file_fetcher, stat_fetcher, svn_path, revision=None):
 153     self._file_fetcher = file_fetcher
 154     self._stat_fetcher = stat_fetcher
 155     self._svn_path = svn_path
 156     self._revision = revision
 157
 158   def Read(self, paths, skip_not_found=False):
 159     args = None
 160     if self._revision is not None:
 161       # |fetcher| gets from svn.chromium.org which uses p= for version.
 162       args = 'p=%s' % self._revision
 163     return Future(callback=_GetAsyncFetchCallback(
 164         paths,
 165         self._file_fetcher,
 166         args=args,
 167         skip_not_found=skip_not_found))
 168
 169   def Refresh(self):
 170     return Future(value=())
 171
 172   def Stat(self, path):
 173     return self.StatAsync(path).Get()
 174
 175   def StatAsync(self, path):
 176     directory, filename = posixpath.split(path)
 177     if self._revision is not None:
 178       # |stat_fetch| uses viewvc which uses pathrev= for version.
 179       directory += '?pathrev=%s' % self._revision
 180
 181     result_future = self._stat_fetcher.FetchAsync(directory)
 182     def resolve():
 183       try:
 184         result = result_future.Get()
 185       except Exception as e:
 186         exc_type = FileNotFoundError if IsDownloadError(e) else FileSystemError
 187         raise exc_type('%s fetching %s for Stat: %s' %
 188                        (type(e).__name__, path, traceback.format_exc()))
 189
 190       if result.status_code == 404:
 191         raise FileNotFoundError('Got 404 when fetching %s for Stat, '
 192                                 'content %s' % (path, result.content))
 193       if result.status_code != 200:
 194         raise FileNotFoundError('Got %s when fetching %s for Stat, content %s' %
 195                                 (result.status_code, path, result.content))
 196
 197       stat_info = _CreateStatInfo(result.content)
 198       if stat_info.version is None:
 199         raise FileSystemError('Failed to find version of dir %s' % directory)
 200       if path == '' or path.endswith('/'):
 201         return stat_info
 202       if filename not in stat_info.child_versions:
 203         raise FileNotFoundError(
 204             '%s from %s was not in child versions for Stat' % (filename, path))
 205       return StatInfo(stat_info.child_versions[filename])
 206
 207     return Future(callback=resolve)
 208
 209   def GetIdentity(self):
 210     # NOTE: no revision here, since it would mess up the caching of reads. It
 211     # probably doesn't matter since all the caching classes will use the result
 212     # of Stat to decide whether to re-read - and Stat has a ceiling of the
 213     # revision - so when the revision changes, so might Stat. That is enough.
 214     return '@'.join((self.__class__.__name__, StringIdentity(self._svn_path)))