Lib/os.py

   1 # os.py -- either mac, dos or posix depending on what system we're on.
   2
   3 # This exports:
   4 # - all functions from either posix or mac, e.g., os.unlink, os.stat, etc.
   5 # - os.path is either module posixpath or macpath
   6 # - os.name is either 'posix' or 'mac'
   7 # - os.curdir is a string representing the current directory ('.' or ':')
   8 # - os.pardir is a string representing the parent directory ('..' or '::')
   9 # - os.sep is the (or a most common) pathname separator ('/' or ':')
  10 # - os.pathsep is the component separator used in $PATH etc
  11 # - os.defpath is the default search path for executables
  12
  13 # Programs that import and use 'os' stand a better chance of being
  14 # portable between different platforms.  Of course, they must then
  15 # only use functions that are defined by all platforms (e.g., unlink
  16 # and opendir), and leave all pathname manipulation to os.path
  17 # (e.g., split and join).
  18
  19 _osindex = {
  20           'posix': ('.', '..', '/', ':', ':/bin:/usr/bin'),
  21           'dos':   ('.', '..', '\\', ';', '.;C:\\bin'),
  22           'nt':    ('.', '..', '\\', ';', '.;C:\\bin'),
  23           'mac':   (':', '::', ':', '\n', ':'),
  24 }
  25
  26 # For freeze.py script:
  27 if 0:
  28         import posix
  29         import posixpath
  30
  31 import sys
  32 for name in _osindex.keys():
  33         if name in sys.builtin_module_names:
  34                 curdir, pardir, sep, pathsep, defpath = _osindex[name]
  35                 exec 'from %s import *' % name
  36                 exec 'import %spath' % name
  37                 exec 'path = %spath' % name
  38                 exec 'del %spath' % name
  39                 try:
  40                         exec 'from %s import _exit' % name
  41                 except ImportError:
  42                         pass
  43                 try:
  44                         environ
  45                 except:
  46                         environ = {} # Make sure os.environ exists, at least
  47                 break
  48 else:
  49         del name
  50         raise ImportError, 'no os specific module found'
  51
  52 def execl(file, *args):
  53         execv(file, args)
  54
  55 def execle(file, *args):
  56         env = args[-1]
  57         execve(file, args[:-1], env)
  58
  59 def execlp(file, *args):
  60         execvp(file, args)
  61
  62 def execlpe(file, *args):
  63         env = args[-1]
  64         execvpe(file, args[:-1], env)
  65
  66 def execvp(file, args):
  67         _execvpe(file, args)
  68
  69 def execvpe(file, args, env):
  70         _execvpe(file, args, env)
  71
  72 _notfound = None
  73 def _execvpe(file, args, env = None):
  74         if env:
  75                 func = execve
  76                 argrest = (args, env)
  77         else:
  78                 func = execv
  79                 argrest = (args,)
  80                 env = environ
  81         global _notfound
  82         head, tail = path.split(file)
  83         if head:
  84                 apply(func, (file,) + argrest)
  85                 return
  86         if env.has_key('PATH'):
  87                 envpath = env['PATH']
  88         else:
  89                 envpath = defpath
  90         import string
  91         PATH = string.splitfields(envpath, pathsep)
  92         if not _notfound:
  93                 import tempfile
  94                 # Exec a file that is guaranteed not to exist
  95                 try: execv(tempfile.mktemp(), ())
  96                 except error, _notfound: pass
  97         exc, arg = error, _notfound
  98         for dir in PATH:
  99                 fullname = path.join(dir, file)
 100                 try:
 101                         apply(func, (fullname,) + argrest)
 102                 except error, (errno, msg):
 103                         if errno != arg[0]:
 104                                 exc, arg = error, (errno, msg)
 105         raise exc, arg
 106
 107 # Provide listdir for Windows NT that doesn't have it built in
 108 if name == 'nt':
 109         try:
 110                 _tmp = listdir
 111                 del _tmp
 112         except NameError:
 113                 def listdir(name):
 114                         if path.ismount(name):
 115                                 list = ['.']
 116                         else:
 117                                 list = ['.', '..']
 118                         f = popen('dir/l/b ' + name, 'r')
 119                         line = f.readline()
 120                         while line:
 121                                 list.append(line[:-1])
 122                                 line = f.readline()
 123                         return list