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478 lines
15 KiB
Python
478 lines
15 KiB
Python
# Module 'ntpath' -- common operations on WinNT/Win95 pathnames
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"""Common pathname manipulations, WindowsNT/95 version.
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Instead of importing this module directly, import os and refer to this
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module as os.path.
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"""
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import os
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import stat
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__all__ = ["normcase","isabs","join","splitdrive","split","splitext",
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"basename","dirname","commonprefix","getsize","getmtime",
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"getatime","islink","exists","isdir","isfile","ismount",
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"walk","expanduser","expandvars","normpath","abspath","splitunc"]
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# Normalize the case of a pathname and map slashes to backslashes.
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# Other normalizations (such as optimizing '../' away) are not done
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# (this is done by normpath).
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def normcase(s):
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"""Normalize case of pathname.
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Makes all characters lowercase and all slashes into backslashes."""
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return s.replace("/", "\\").lower()
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# Return whether a path is absolute.
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# Trivial in Posix, harder on the Mac or MS-DOS.
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# For DOS it is absolute if it starts with a slash or backslash (current
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# volume), or if a pathname after the volume letter and colon / UNC resource
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# starts with a slash or backslash.
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def isabs(s):
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"""Test whether a path is absolute"""
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s = splitdrive(s)[1]
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return s != '' and s[:1] in '/\\'
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# Join two (or more) paths.
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def join(a, *p):
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"""Join two or more pathname components, inserting "\\" as needed"""
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path = a
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for b in p:
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b_wins = 0 # set to 1 iff b makes path irrelevant
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if path == "":
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b_wins = 1
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elif isabs(b):
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# This probably wipes out path so far. However, it's more
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# complicated if path begins with a drive letter:
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# 1. join('c:', '/a') == 'c:/a'
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# 2. join('c:/', '/a') == 'c:/a'
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# But
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# 3. join('c:/a', '/b') == '/b'
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# 4. join('c:', 'd:/') = 'd:/'
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# 5. join('c:/', 'd:/') = 'd:/'
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if path[1:2] != ":" or b[1:2] == ":":
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# Path doesn't start with a drive letter, or cases 4 and 5.
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b_wins = 1
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# Else path has a drive letter, and b doesn't but is absolute.
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elif len(path) > 3 or (len(path) == 3 and
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path[-1] not in "/\\"):
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# case 3
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b_wins = 1
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if b_wins:
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path = b
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else:
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# Join, and ensure there's a separator.
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assert len(path) > 0
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if path[-1] in "/\\":
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if b and b[0] in "/\\":
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path += b[1:]
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else:
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path += b
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elif path[-1] == ":":
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path += b
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elif b:
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if b[0] in "/\\":
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path += b
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else:
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path += "\\" + b
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else:
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# path is not empty and does not end with a backslash,
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# but b is empty; since, e.g., split('a/') produces
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# ('a', ''), it's best if join() adds a backslash in
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# this case.
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path += '\\'
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return path
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# Split a path in a drive specification (a drive letter followed by a
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# colon) and the path specification.
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# It is always true that drivespec + pathspec == p
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def splitdrive(p):
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"""Split a pathname into drive and path specifiers. Returns a 2-tuple
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"(drive,path)"; either part may be empty"""
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if p[1:2] == ':':
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return p[0:2], p[2:]
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return '', p
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# Parse UNC paths
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def splitunc(p):
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"""Split a pathname into UNC mount point and relative path specifiers.
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Return a 2-tuple (unc, rest); either part may be empty.
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If unc is not empty, it has the form '//host/mount' (or similar
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using backslashes). unc+rest is always the input path.
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Paths containing drive letters never have an UNC part.
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"""
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if p[1:2] == ':':
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return '', p # Drive letter present
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firstTwo = p[0:2]
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if firstTwo == '//' or firstTwo == '\\\\':
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# is a UNC path:
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# vvvvvvvvvvvvvvvvvvvv equivalent to drive letter
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# \\machine\mountpoint\directories...
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# directory ^^^^^^^^^^^^^^^
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normp = normcase(p)
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index = normp.find('\\', 2)
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if index == -1:
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##raise RuntimeError, 'illegal UNC path: "' + p + '"'
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return ("", p)
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index = normp.find('\\', index + 1)
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if index == -1:
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index = len(p)
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return p[:index], p[index:]
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return '', p
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# Split a path in head (everything up to the last '/') and tail (the
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# rest). After the trailing '/' is stripped, the invariant
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# join(head, tail) == p holds.
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# The resulting head won't end in '/' unless it is the root.
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def split(p):
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"""Split a pathname.
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Return tuple (head, tail) where tail is everything after the final slash.
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Either part may be empty."""
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d, p = splitdrive(p)
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# set i to index beyond p's last slash
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i = len(p)
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while i and p[i-1] not in '/\\':
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i = i - 1
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head, tail = p[:i], p[i:] # now tail has no slashes
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# remove trailing slashes from head, unless it's all slashes
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head2 = head
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while head2 and head2[-1] in '/\\':
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head2 = head2[:-1]
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head = head2 or head
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return d + head, tail
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# Split a path in root and extension.
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# The extension is everything starting at the last dot in the last
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# pathname component; the root is everything before that.
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# It is always true that root + ext == p.
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def splitext(p):
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"""Split the extension from a pathname.
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Extension is everything from the last dot to the end.
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Return (root, ext), either part may be empty."""
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root, ext = '', ''
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for c in p:
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if c in ['/','\\']:
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root, ext = root + ext + c, ''
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elif c == '.':
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if ext:
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root, ext = root + ext, c
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else:
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ext = c
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elif ext:
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ext = ext + c
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else:
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root = root + c
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return root, ext
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# Return the tail (basename) part of a path.
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def basename(p):
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"""Returns the final component of a pathname"""
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return split(p)[1]
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# Return the head (dirname) part of a path.
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def dirname(p):
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"""Returns the directory component of a pathname"""
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return split(p)[0]
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# Return the longest prefix of all list elements.
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def commonprefix(m):
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"Given a list of pathnames, returns the longest common leading component"
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if not m: return ''
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prefix = m[0]
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for item in m:
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for i in range(len(prefix)):
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if prefix[:i+1] != item[:i+1]:
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prefix = prefix[:i]
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if i == 0: return ''
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break
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return prefix
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# Get size, mtime, atime of files.
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def getsize(filename):
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"""Return the size of a file, reported by os.stat()"""
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return os.stat(filename).st_size
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def getmtime(filename):
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"""Return the last modification time of a file, reported by os.stat()"""
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return os.stat(filename).st_mtime
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def getatime(filename):
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"""Return the last access time of a file, reported by os.stat()"""
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return os.stat(filename).st_atime
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# Is a path a symbolic link?
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# This will always return false on systems where posix.lstat doesn't exist.
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def islink(path):
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"""Test for symbolic link. On WindowsNT/95 always returns false"""
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return False
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# Does a path exist?
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# This is false for dangling symbolic links.
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def exists(path):
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"""Test whether a path exists"""
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try:
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st = os.stat(path)
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except os.error:
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return False
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return True
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# Is a path a dos directory?
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# This follows symbolic links, so both islink() and isdir() can be true
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# for the same path.
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def isdir(path):
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"""Test whether a path is a directory"""
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try:
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st = os.stat(path)
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except os.error:
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return False
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return stat.S_ISDIR(st.st_mode)
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# Is a path a regular file?
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# This follows symbolic links, so both islink() and isdir() can be true
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# for the same path.
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def isfile(path):
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"""Test whether a path is a regular file"""
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try:
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st = os.stat(path)
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except os.error:
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return False
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return stat.S_ISREG(st.st_mode)
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# Is a path a mount point? Either a root (with or without drive letter)
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# or an UNC path with at most a / or \ after the mount point.
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def ismount(path):
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"""Test whether a path is a mount point (defined as root of drive)"""
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unc, rest = splitunc(path)
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if unc:
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return rest in ("", "/", "\\")
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p = splitdrive(path)[1]
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return len(p) == 1 and p[0] in '/\\'
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# Directory tree walk.
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# For each directory under top (including top itself, but excluding
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# '.' and '..'), func(arg, dirname, filenames) is called, where
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# dirname is the name of the directory and filenames is the list
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# files files (and subdirectories etc.) in the directory.
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# The func may modify the filenames list, to implement a filter,
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# or to impose a different order of visiting.
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def walk(top, func, arg):
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"""Directory tree walk with callback function.
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For each directory in the directory tree rooted at top (including top
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itself, but excluding '.' and '..'), call func(arg, dirname, fnames).
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dirname is the name of the directory, and fnames a list of the names of
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the files and subdirectories in dirname (excluding '.' and '..'). func
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may modify the fnames list in-place (e.g. via del or slice assignment),
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and walk will only recurse into the subdirectories whose names remain in
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fnames; this can be used to implement a filter, or to impose a specific
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order of visiting. No semantics are defined for, or required of, arg,
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beyond that arg is always passed to func. It can be used, e.g., to pass
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a filename pattern, or a mutable object designed to accumulate
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statistics. Passing None for arg is common."""
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try:
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names = os.listdir(top)
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except os.error:
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return
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func(arg, top, names)
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exceptions = ('.', '..')
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for name in names:
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if name not in exceptions:
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name = join(top, name)
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if isdir(name):
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walk(name, func, arg)
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# Expand paths beginning with '~' or '~user'.
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# '~' means $HOME; '~user' means that user's home directory.
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# If the path doesn't begin with '~', or if the user or $HOME is unknown,
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# the path is returned unchanged (leaving error reporting to whatever
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# function is called with the expanded path as argument).
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# See also module 'glob' for expansion of *, ? and [...] in pathnames.
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# (A function should also be defined to do full *sh-style environment
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# variable expansion.)
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def expanduser(path):
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"""Expand ~ and ~user constructs.
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If user or $HOME is unknown, do nothing."""
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if path[:1] != '~':
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return path
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i, n = 1, len(path)
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while i < n and path[i] not in '/\\':
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i = i + 1
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if i == 1:
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if 'HOME' in os.environ:
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userhome = os.environ['HOME']
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elif not 'HOMEPATH' in os.environ:
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return path
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else:
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try:
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drive = os.environ['HOMEDRIVE']
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except KeyError:
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drive = ''
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userhome = join(drive, os.environ['HOMEPATH'])
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else:
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return path
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return userhome + path[i:]
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# Expand paths containing shell variable substitutions.
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# The following rules apply:
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# - no expansion within single quotes
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# - no escape character, except for '$$' which is translated into '$'
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# - ${varname} is accepted.
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# - varnames can be made out of letters, digits and the character '_'
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# XXX With COMMAND.COM you can use any characters in a variable name,
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# XXX except '^|<>='.
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def expandvars(path):
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"""Expand shell variables of form $var and ${var}.
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Unknown variables are left unchanged."""
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if '$' not in path:
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return path
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import string
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varchars = string.ascii_letters + string.digits + '_-'
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res = ''
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index = 0
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pathlen = len(path)
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while index < pathlen:
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c = path[index]
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if c == '\'': # no expansion within single quotes
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path = path[index + 1:]
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pathlen = len(path)
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try:
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index = path.index('\'')
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res = res + '\'' + path[:index + 1]
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except ValueError:
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res = res + path
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index = pathlen - 1
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elif c == '$': # variable or '$$'
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if path[index + 1:index + 2] == '$':
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res = res + c
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index = index + 1
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elif path[index + 1:index + 2] == '{':
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path = path[index+2:]
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pathlen = len(path)
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try:
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index = path.index('}')
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var = path[:index]
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if var in os.environ:
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res = res + os.environ[var]
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except ValueError:
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res = res + path
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index = pathlen - 1
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else:
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var = ''
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index = index + 1
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c = path[index:index + 1]
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while c != '' and c in varchars:
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var = var + c
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index = index + 1
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c = path[index:index + 1]
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if var in os.environ:
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res = res + os.environ[var]
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if c != '':
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res = res + c
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else:
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res = res + c
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index = index + 1
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return res
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# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A\B.
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# Previously, this function also truncated pathnames to 8+3 format,
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# but as this module is called "ntpath", that's obviously wrong!
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def normpath(path):
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"""Normalize path, eliminating double slashes, etc."""
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path = path.replace("/", "\\")
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prefix, path = splitdrive(path)
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while path[:1] == "\\":
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prefix = prefix + "\\"
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path = path[1:]
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comps = path.split("\\")
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i = 0
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while i < len(comps):
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if comps[i] in ('.', ''):
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del comps[i]
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elif comps[i] == '..':
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if i > 0 and comps[i-1] != '..':
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del comps[i-1:i+1]
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i -= 1
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elif i == 0 and prefix.endswith("\\"):
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del comps[i]
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else:
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i += 1
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else:
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i += 1
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# If the path is now empty, substitute '.'
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if not prefix and not comps:
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comps.append('.')
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return prefix + "\\".join(comps)
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# Return an absolute path.
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def abspath(path):
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"""Return the absolute version of a path"""
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try:
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from nt import _getfullpathname
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except ImportError: # Not running on Windows - mock up something sensible.
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global abspath
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def _abspath(path):
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if not isabs(path):
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path = join(os.getcwd(), path)
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return normpath(path)
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abspath = _abspath
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return _abspath(path)
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if path: # Empty path must return current working directory.
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try:
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path = _getfullpathname(path)
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except WindowsError:
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pass # Bad path - return unchanged.
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else:
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path = os.getcwd()
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return normpath(path)
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# realpath is a no-op on systems without islink support
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realpath = abspath
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