tools/metrics/histograms/update_policies.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 """Updates EnterprisePolicies enum in histograms.xml file with policy
   6 definitions read from policy_templates.json.
   7
   8 If the file was pretty-printed, the updated version is pretty-printed too.
   9 """
  10
  11 import os
  12 import re
  13 import sys
  14
  15 from ast import literal_eval
  16 from optparse import OptionParser
  17 from xml.dom import minidom
  18
  19 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
  20 from diff_util import PromptUserToAcceptDiff
  21 import path_util
  22
  23 import print_style
  24
  25 HISTOGRAMS_PATH = path_util.GetHistogramsFile()
  26 POLICY_TEMPLATES_PATH = 'components/policy/resources/policy_templates.json'
  27 ENUM_NAME = 'EnterprisePolicies'
  28
  29 class UserError(Exception):
  30   def __init__(self, message):
  31     Exception.__init__(self, message)
  32
  33   @property
  34   def message(self):
  35     return self.args[0]
  36
  37
  38 def FlattenPolicies(policy_definitions, policy_list):
  39   """Appends a list of policies defined in |policy_definitions| to
  40   |policy_list|, flattening subgroups.
  41
  42   Args:
  43     policy_definitions: A list of policy definitions and groups, as in
  44                         policy_templates.json file.
  45     policy_list: A list that has policy definitions appended to it.
  46   """
  47   for policy in policy_definitions:
  48     if policy['type'] == 'group':
  49       FlattenPolicies(policy['policies'], policy_list)
  50     else:
  51       policy_list.append(policy)
  52
  53
  54 def ParsePlaceholders(text):
  55   """Parse placeholders in |text|, making it more human-readable. The format of
  56   |text| is exactly the same as in captions in policy_templates.json: it can
  57   contain XML tags (ph, ex) and $1-like substitutions. Note that this function
  58   does only a very simple parsing that is not fully correct, but should be
  59   enough for all practical situations.
  60
  61   Args:
  62     text: A string containing placeholders.
  63
  64   Returns:
  65     |text| with placeholders removed or replaced by readable text.
  66   """
  67   text = re.sub(r'\$\d+', '', text)    # Remove $1-like substitutions.
  68   text = re.sub(r'<[^>]+>', '', text)  # Remove XML tags.
  69   return text
  70
  71
  72 def UpdateHistogramDefinitions(policy_templates, doc):
  73   """Sets the children of <enum name="EnterprisePolicies" ...> node in |doc| to
  74   values generated from policy ids contained in |policy_templates|.
  75
  76   Args:
  77     policy_templates: A list of dictionaries, defining policies or policy
  78                       groups. The format is exactly the same as in
  79                       policy_templates.json file.
  80     doc: A minidom.Document object representing parsed histogram definitions
  81          XML file.
  82   """
  83   # Find EnterprisePolicies enum.
  84   for enum_node in doc.getElementsByTagName('enum'):
  85     if enum_node.attributes['name'].value == ENUM_NAME:
  86         policy_enum_node = enum_node
  87         break
  88   else:
  89     raise UserError('No policy enum node found')
  90
  91   # Remove existing values.
  92   while policy_enum_node.hasChildNodes():
  93     policy_enum_node.removeChild(policy_enum_node.lastChild)
  94
  95   # Add a "Generated from (...)" comment
  96   comment = ' Generated from {0} '.format(POLICY_TEMPLATES_PATH)
  97   policy_enum_node.appendChild(doc.createComment(comment))
  98
  99   # Add values generated from policy templates.
 100   ordered_policies = []
 101   FlattenPolicies(policy_templates['policy_definitions'], ordered_policies)
 102   ordered_policies.sort(key=lambda policy: policy['id'])
 103   for policy in ordered_policies:
 104     node = doc.createElement('int')
 105     node.attributes['value'] = str(policy['id'])
 106     node.attributes['label'] = ParsePlaceholders(policy['caption'])
 107     policy_enum_node.appendChild(node)
 108
 109
 110 def main():
 111   if len(sys.argv) > 1:
 112     print >>sys.stderr, 'No arguments expected!'
 113     sys.stderr.write(__doc__)
 114     sys.exit(1)
 115
 116   with open(path_util.GetInputFile(POLICY_TEMPLATES_PATH), 'rb') as f:
 117     policy_templates = literal_eval(f.read())
 118   with open(HISTOGRAMS_PATH, 'rb') as f:
 119     histograms_doc = minidom.parse(f)
 120     f.seek(0)
 121     xml = f.read()
 122
 123   UpdateHistogramDefinitions(policy_templates, histograms_doc)
 124   new_xml = print_style.GetPrintStyle().PrettyPrintNode(histograms_doc)
 125   if PromptUserToAcceptDiff(xml, new_xml, 'Is the updated version acceptable?'):
 126     with open(HISTOGRAMS_PATH, 'wb') as f:
 127       f.write(new_xml)
 128
 129
 130 if __name__ == '__main__':
 131   try:
 132     main()
 133   except UserError as e:
 134     print >>sys.stderr, e.message
 135     sys.exit(1)