text: from __future__ import unicode_literals
  
  import io
  import json
  import traceback
  import hashlib
  import os
  import subprocess
  import sys
  from zipimport import zipimporter
  
  from .utils import encode_compat_str
  
  from .version import __version__
  
  
  def rsa_verify(message, signature, key):
      from struct import pack
      from hashlib import sha256
  
      assert isinstance(message, bytes)
      block_size = 0
      n = key[0]
      while n:
          block_size += 1
          n >>= 8
      signature = pow(int(signature, 16), key[1], key[0])
      raw_bytes = []
      while signature:
          raw_bytes.insert(0, pack("B", signature & 0xFF))
          signature >>= 8
      signature = (block_size - len(raw_bytes)) * b'\x00' + b''.join(raw_bytes)
      if signature[0:2] != b'\x00\x01':
          return False
      signature = signature[2:]
      if b'\x00' not in signature:
          return False
      signature = signature[signature.index(b'\x00') + 1:]
      if not signature.startswith(b'\x30\x31\x30\x0D\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x01\x05\x00\x04\x20'):
          return False
      signature = signature[19:]
      if signature != sha256(message).digest():
          return False
      return True
  
  
  def update_self(to_screen, verbose, opener):
      """Update the program file with the latest version from the repository"""
  
      UPDATE_URL = "https://rg3.github.io/youtube-dl/update/"
      VERSION_URL = UPDATE_URL + 'LATEST_VERSION'
      JSON_URL = UPDATE_URL + 'versions.json'
      UPDATES_RSA_KEY = (0x9d60ee4d8f805312fdb15a62f87b95bd66177b91df176765d13514a0f1754bcd2057295c5b6f1d35daa6742c3ffc9a82d3e118861c207995a8031e151d863c9927e304576bc80692bc8e094896fcf11b66f3e29e04e3a71e9a11558558acea1840aec37fc396fb6b65dc81a1c4144e03bd1c011de62e3f1357b327d08426fe93, 65537)
  
      if not isinstance(globals().get('__loader__'), zipimporter) and not hasattr(sys, "frozen"):
          to_screen('It looks like you installed youtube-dl with a package manager, pip, setup.py or a tarball. Please use that to update.')
          return
  
      # Check if there is a new version
      try:
          newversion = opener.open(VERSION_URL).read().decode('utf-8').strip()
      except Exception:
          if verbose:
              to_screen(encode_compat_str(traceback.format_exc()))
          to_screen('ERROR: can\'t find the current version. Please try again later.')
          return
      if newversion == __version__:
          to_screen('youtube-dl is up-to-date (' + __version__ + ')')
          return
  
      # Download and check versions info
      try:
          versions_info = opener.open(JSON_URL).read().decode('utf-8')
          versions_info = json.loads(versions_info)
      except Exception:
          if verbose:
              to_screen(encode_compat_str(traceback.format_exc()))
          to_screen('ERROR: can\'t obtain versions info. Please try again later.')
          return
      if 'signature' not in versions_info:
          to_screen('ERROR: the versions file is not signed or corrupted. Aborting.')
          return
      signature = versions_info['signature']
      del versions_info['signature']
      if not rsa_verify(json.dumps(versions_info, sort_keys=True).encode('utf-8'), signature, UPDATES_RSA_KEY):
          to_screen('ERROR: the versions file signature is invalid. Aborting.')
          return
  
      version_id = versions_info['latest']
  
      def version_tuple(version_str):
          return tuple(map(int, version_str.split('.')))
      if version_tuple(__version__) >= version_tuple(version_id):
          to_screen('youtube-dl is up to date (%s)' % __version__)
          return
  
      to_screen('Updating to version ' + version_id + ' ...')
      version = versions_info['versions'][version_id]
  
      print_notes(to_screen, versions_info['versions'])
  
      filename = sys.argv[0]
      # Py2EXE: Filename could be different
      if hasattr(sys, "frozen") and not os.path.isfile(filename):
          if os.path.isfile(filename + '.exe'):
              filename += '.exe'
  
      if not os.access(filename, os.W_OK):
          to_screen('ERROR: no write permissions on %s' % filename)
          return
  
      # Py2EXE
      if hasattr(sys, "frozen"):
          exe = os.path.abspath(filename)
          directory = os.path.dirname(exe)
          if not os.access(directory, os.W_OK):
              to_screen('ERROR: no write permissions on %s' % directory)
              return
  
          try:
              urlh = opener.open(version['exe'][0])
              newcontent = urlh.read()
              urlh.close()
          except (IOError, OSError):
              if verbose:
                  to_screen(encode_compat_str(traceback.format_exc()))
              to_screen('ERROR: unable to download latest version')
              return
  
          newcontent_hash = hashlib.sha256(newcontent).hexdigest()
          if newcontent_hash != version['exe'][1]:
              to_screen('ERROR: the downloaded file hash does not match. Aborting.')
              return
  
          try:
              with open(exe + '.new', 'wb') as outf:
                  outf.write(newcontent)
          except (IOError, OSError):
              if verbose:
                  to_screen(encode_compat_str(traceback.format_exc()))
              to_screen('ERROR: unable to write the new version')
              return
  
          try:
              bat = os.path.join(directory, 'youtube-dl-updater.bat')
              with io.open(bat, 'w') as batfile:
                  batfile.write('''
  @echo off
  echo Waiting for file handle to be closed ...
  ping 127.0.0.1 -n 5 -w 1000 > NUL
  move /Y "%s.new" "%s" > NUL
  echo Updated youtube-dl to version %s.
  start /b "" cmd /c del "%%~f0"&exit /b"
                  \n''' % (exe, exe, version_id))
  
              subprocess.Popen([bat])  # Continues to run in the background
              return  # Do not show premature success messages
          except (IOError, OSError):
              if verbose:
                  to_screen(encode_compat_str(traceback.format_exc()))
              to_screen('ERROR: unable to overwrite current version')
              return
  
      # Zip unix package
      elif isinstance(globals().get('__loader__'), zipimporter):
          try:
              urlh = opener.open(version['bin'][0])
              newcontent = urlh.read()
              urlh.close()
          except (IOError, OSError):
              if verbose:
                  to_screen(encode_compat_str(traceback.format_exc()))
              to_screen('ERROR: unable to download latest version')
              return
  
          newcontent_hash = hashlib.sha256(newcontent).hexdigest()
          if newcontent_hash != version['bin'][1]:
              to_screen('ERROR: the downloaded file hash does not match. Aborting.')
              return
  
          try:
              with open(filename, 'wb') as outf:
                  outf.write(newcontent)
          except (IOError, OSError):
              if verbose:
                  to_screen(encode_compat_str(traceback.format_exc()))
              to_screen('ERROR: unable to overwrite current version')
              return
  
      to_screen('Updated youtube-dl. Restart youtube-dl to use the new version.')
  
  
  def get_notes(versions, fromVersion):
      notes = []
      for v, vdata in sorted(versions.items()):
          if v > fromVersion:
              notes.extend(vdata.get('notes', []))
      return notes
  
  
  def print_notes(to_screen, versions, fromVersion=__version__):
      notes = get_notes(versions, fromVersion)
      if notes:
          to_screen('PLEASE NOTE:')
          for note in notes:
              to_screen(note)
  