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