tools/post_process_props.py

#!/usr/bin/env python
#
# Copyright (C) 2009 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import sys

# Usage: post_process_props.py file.prop [blacklist_key, ...]
# Blacklisted keys are removed from the property file, if present

# See PROP_NAME_MAX and PROP_VALUE_MAX system_properties.h.
# The constants in system_properties.h includes the termination NUL,
# so we decrease the values by 1 here.
PROP_NAME_MAX = 31
PROP_VALUE_MAX = 91

# Put the modifications that you need to make into the /system/build.prop into this
# function. The prop object has get(name) and put(name,value) methods.
def mangle_build_prop(prop):
  pass

# Put the modifications that you need to make into the /default.prop into this
# function. The prop object has get(name) and put(name,value) methods.
def mangle_default_prop(prop):
  # UsbDeviceManager expects a value here.  If it doesn't get it, it will
  # default to "adb". That might not the right policy there, but it's better
  # to be explicit.
  if not prop.get("persist.sys.usb.config"):
    prop.put("persist.sys.usb.config", "none");

def validate(prop):
  """Validate the properties.

  Returns:
    True if nothing is wrong.
  """
  check_pass = True
  buildprops = prop.to_dict()
  for key, value in buildprops.iteritems():
    # Check build properties' length.
    if len(key) > PROP_NAME_MAX:
      check_pass = False
      sys.stderr.write("error: %s cannot exceed %d bytes: " %
                       (key, PROP_NAME_MAX))
      sys.stderr.write("%s (%d)\n" % (key, len(key)))
    if len(value) > PROP_VALUE_MAX:
      check_pass = False
      sys.stderr.write("error: %s cannot exceed %d bytes: " %
                       (key, PROP_VALUE_MAX))
      sys.stderr.write("%s (%d)\n" % (value, len(value)))
  return check_pass

class PropFile:

  def __init__(self, lines):
    self.lines = [s.strip() for s in lines]

  def to_dict(self):
    props = {}
    for line in self.lines:
      if not line or line.startswith("#"):
        continue
      if "=" in line:
        key, value = line.split("=", 1)
        props[key] = value
    return props

  def get(self, name):
    key = name + "="
    for line in self.lines:
      if line.startswith(key):
        return line[len(key):]
    return ""

  def put(self, name, value):
    key = name + "="
    for i in range(0,len(self.lines)):
      if self.lines[i].startswith(key):
        self.lines[i] = key + value
        return
    self.lines.append(key + value)

  def delete(self, name):
    key = name + "="
    self.lines = [ line for line in self.lines if not line.startswith(key) ]

  def write(self, f):
    f.write("\n".join(self.lines))
    f.write("\n")

def main(argv):
  filename = argv[1]
  f = open(filename)
  lines = f.readlines()
  f.close()

  properties = PropFile(lines)

  if filename.endswith("/build.prop"):
    mangle_build_prop(properties)
  elif filename.endswith("/default.prop"):
    mangle_default_prop(properties)
  else:
    sys.stderr.write("bad command line: " + str(argv) + "\n")
    sys.exit(1)

  if not validate(properties):
    sys.exit(1)

  # Drop any blacklisted keys
  for key in argv[2:]:
    properties.delete(key)

  f = open(filename, 'w+')
  properties.write(f)
  f.close()

if __name__ == "__main__":
  main(sys.argv)