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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 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)
    137