Home | History | Annotate | Download | only in common_lib 
      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)
     70