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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        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, ''
106