client/common_lib/base_check_version.py

   1 # This file must use Python 1.5 syntax.
   2 import sys, string, os, glob, re
   3
   4
   5 class base_check_python_version:
   6     def __init__(self):
   7         version = None
   8         try:
   9             version = sys.version_info[0:2]
  10         except AttributeError:
  11             pass # pre 2.0, no neat way to get the exact number
  12
  13         # The change to prefer 2.4 really messes up any systems which have both
  14         # the new and old version of Python, but where the newer is default.
  15         # This is because packages, libraries, etc are all installed into the
  16         # new one by default. Some things (like running under mod_python) just
  17         # plain don't handle python restarting properly. I know that I do some
  18         # development under ipython and whenever I run (or do anything that
  19         # runs) 'import common' it restarts my shell. Overall, the change was
  20         # fairly annoying for me (and I can't get around having 2.4 and 2.5
  21         # installed with 2.5 being default).
  22         if not version or version < (2, 4) or version >= (3, 0):
  23             try:
  24                 # We can't restart when running under mod_python.
  25                 from mod_python import apache
  26             except ImportError:
  27                 self.restart()
  28
  29
  30     def extract_version(self, path):
  31         match = re.search(r'/python(\d+)\.(\d+)$', path)
  32         if match:
  33             return (int(match.group(1)), int(match.group(2)))
  34         else:
  35             return None
  36
  37
  38     PYTHON_BIN_GLOB_STRINGS = ['/usr/bin/python2*', '/usr/local/bin/python2*']
  39
  40
  41     def find_desired_python(self):
  42         """Returns the path of the desired python interpreter."""
  43         pythons = []
  44         for glob_str in self.PYTHON_BIN_GLOB_STRINGS:
  45             pythons.extend(glob.glob(glob_str))
  46
  47         possible_versions = []
  48         best_python = (0, 0), ''
  49         for python in pythons:
  50             version = self.extract_version(python)
  51             if version >= (2, 4):
  52                 possible_versions.append((version, python))
  53
  54         possible_versions.sort()
  55
  56         if not possible_versions:
  57             raise ValueError('Python 2.x version 2.4 or better is required')
  58         # Return the lowest possible version so that we use 2.4 if available
  59         # rather than more recent versions.
  60         return possible_versions[0][1]
  61
  62
  63     def restart(self):
  64         python = self.find_desired_python()
  65         sys.stderr.write('NOTE: %s switching to %s\n' %
  66                          (os.path.basename(sys.argv[0]), python))
  67         sys.argv.insert(0, '-u')
  68         sys.argv.insert(0, python)
  69         os.execv(sys.argv[0], sys.argv)