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