Lib/genericpath.py

   1 """
   2 Path operations common to more than one OS
   3 Do not use directly.  The OS specific modules import the appropriate
   4 functions from this module themselves.
   5 """
   6 import os
   7 import stat
   8
   9 __all__ = ['commonprefix', 'exists', 'getatime', 'getctime', 'getmtime',
  10            'getsize', 'isdir', 'isfile']
  11
  12
  13 # Does a path exist?
  14 # This is false for dangling symbolic links on systems that support them.
  15 def exists(path):
  16     """Test whether a path exists.  Returns False for broken symbolic links"""
  17     try:
  18         st = os.stat(path)
  19     except os.error:
  20         return False
  21     return True
  22
  23
  24 # This follows symbolic links, so both islink() and isdir() can be true
  25 # for the same path ono systems that support symlinks
  26 def isfile(path):
  27     """Test whether a path is a regular file"""
  28     try:
  29         st = os.stat(path)
  30     except os.error:
  31         return False
  32     return stat.S_ISREG(st.st_mode)
  33
  34
  35 # Is a path a directory?
  36 # This follows symbolic links, so both islink() and isdir()
  37 # can be true for the same path on systems that support symlinks
  38 def isdir(s):
  39     """Return true if the pathname refers to an existing directory."""
  40     try:
  41         st = os.stat(s)
  42     except os.error:
  43         return False
  44     return stat.S_ISDIR(st.st_mode)
  45
  46
  47 def getsize(filename):
  48     """Return the size of a file, reported by os.stat()."""
  49     return os.stat(filename).st_size
  50
  51
  52 def getmtime(filename):
  53     """Return the last modification time of a file, reported by os.stat()."""
  54     return os.stat(filename).st_mtime
  55
  56
  57 def getatime(filename):
  58     """Return the last access time of a file, reported by os.stat()."""
  59     return os.stat(filename).st_atime
  60
  61
  62 def getctime(filename):
  63     """Return the metadata change time of a file, reported by os.stat()."""
  64     return os.stat(filename).st_ctime
  65
  66
  67 # Return the longest prefix of all list elements.
  68 def commonprefix(m):
  69     "Given a list of pathnames, returns the longest common leading component"
  70     if not m: return ''
  71     s1 = min(m)
  72     s2 = max(m)
  73     for i, c in enumerate(s1):
  74         if c != s2[i]:
  75             return s1[:i]
  76     return s1
  77
  78 # Split a path in root and extension.
  79 # The extension is everything starting at the last dot in the last
  80 # pathname component; the root is everything before that.
  81 # It is always true that root + ext == p.
  82
  83 # Generic implementation of splitext, to be parametrized with
  84 # the separators
  85 def _splitext(p, sep, altsep, extsep):
  86     """Split the extension from a pathname.
  87
  88     Extension is everything from the last dot to the end, ignoring
  89     leading dots.  Returns "(root, ext)"; ext may be empty."""
  90     # NOTE: This code must work for text and bytes strings.
  91
  92     sepIndex = p.rfind(sep)
  93     if altsep:
  94         altsepIndex = p.rfind(altsep)
  95         sepIndex = max(sepIndex, altsepIndex)
  96
  97     dotIndex = p.rfind(extsep)
  98     if dotIndex > sepIndex:
  99         # skip all leading dots
 100         filenameIndex = sepIndex + 1
 101         while filenameIndex < dotIndex:
 102             if p[filenameIndex:filenameIndex+1] != extsep:
 103                 return p[:dotIndex], p[dotIndex:]
 104             filenameIndex += 1
 105
 106     return p, p[:0]