/Lib/genericpath.py

  1"""
  2Path operations common to more than one OS
  3Do not use directly.  The OS specific modules import the appropriate
  4functions from this module themselves.
  5"""
  6import os
  7import 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.
 15def 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
 26def 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
 38def 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
 47def getsize(filename):
 48    """Return the size of a file, reported by os.stat()."""
 49    return os.stat(filename).st_size
 50
 51
 52def getmtime(filename):
 53    """Return the last modification time of a file, reported by os.stat()."""
 54    return os.stat(filename).st_mtime
 55
 56
 57def getatime(filename):
 58    """Return the last access time of a file, reported by os.stat()."""
 59    return os.stat(filename).st_atime
 60
 61
 62def 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.
 68def 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
 85def _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
 91    sepIndex = p.rfind(sep)
 92    if altsep:
 93        altsepIndex = p.rfind(altsep)
 94        sepIndex = max(sepIndex, altsepIndex)
 95
 96    dotIndex = p.rfind(extsep)
 97    if dotIndex > sepIndex:
 98        # skip all leading dots
 99        filenameIndex = sepIndex + 1
100        while filenameIndex < dotIndex:
101            if p[filenameIndex] != extsep:
102                return p[:dotIndex], p[dotIndex:]
103            filenameIndex += 1
104
105    return p, ''