| #!/usr/bin/python |
| |
| # Copyright (c) 2013 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. |
| |
| """ |
| Provides read access to buildbot's global_variables.json . |
| """ |
| |
| |
| from contextlib import closing |
| |
| import HTMLParser |
| import json |
| import svn |
| import sys |
| import urllib2 |
| |
| |
| _global_vars = None |
| |
| |
| GLOBAL_VARS_JSON_URL = ('https://skia.googlesource.com/buildbot/+' |
| '/master/site_config/global_variables.json') |
| |
| |
| class GlobalVarsRetrievalError(Exception): |
| """Exception which is raised when the global_variables.json file cannot be |
| retrieved from the Skia buildbot repository.""" |
| pass |
| |
| |
| class JsonDecodeError(Exception): |
| """Exception which is raised when the global_variables.json file cannot be |
| interpreted as JSON. This may be due to the file itself being incorrectly |
| formatted or due to an incomplete or corrupted downloaded version of the file. |
| """ |
| pass |
| |
| |
| class NoSuchGlobalVariable(KeyError): |
| """Exception which is raised when a given variable is not found in the |
| global_variables.json file.""" |
| pass |
| |
| |
| def retrieve_from_googlesource(url): |
| """Retrieve the given file from GoogleSource's HTTP interface, trimming the |
| extraneous HTML. Intended to be a GoogleSource equivalent of "svn cat". |
| |
| This just returns the unescaped contents of the first <pre> tag which matches |
| our expectations for GoogleSource's HTTP interface. If that interface changes, |
| this function will almost surely break. |
| |
| Args: |
| url: string; the URL of the file to retrieve. |
| Returns: |
| The contents of the file in GoogleSource, stripped of the extra HTML from |
| the HTML interface. |
| """ |
| with closing(urllib2.urlopen(url)) as f: |
| contents = f.read() |
| pre_open = '<pre class="git-blob prettyprint linenums lang-json">' |
| pre_close = '</pre>' |
| start_index = contents.find(pre_open) |
| end_index = contents.find(pre_close) |
| parser = HTMLParser.HTMLParser() |
| return parser.unescape(contents[start_index + len(pre_open):end_index]) |
| |
| |
| def Get(var_name): |
| """Return the value associated with this name in global_variables.json. |
| |
| Args: |
| var_name: string; the variable to look up. |
| Returns: |
| The value of the variable. |
| Raises: |
| NoSuchGlobalVariable if there is no variable with that name. |
| """ |
| global _global_vars |
| if not _global_vars: |
| try: |
| global_vars_text = retrieve_from_googlesource(GLOBAL_VARS_JSON_URL) |
| except Exception: |
| raise GlobalVarsRetrievalError('Failed to retrieve %s.' % |
| GLOBAL_VARS_JSON_URL) |
| try: |
| _global_vars = json.loads(global_vars_text) |
| except ValueError as e: |
| raise JsonDecodeError(e.message + '\n' + global_vars_text) |
| try: |
| return _global_vars[var_name]['value'] |
| except KeyError: |
| raise NoSuchGlobalVariable(var_name) |
| |
| |
| if __name__ == '__main__': |
| print Get(sys.argv[1]) |