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