mirror of https://github.com/python/cpython.git
307 lines
7.1 KiB
Python
307 lines
7.1 KiB
Python
# Module 'posixpath' -- common operations on POSIX pathnames
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import posix
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import stat
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# Normalize the case of a pathname. Trivial in Posix, string.lower on Mac.
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# On MS-DOS this may also turn slashes into backslashes; however, other
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# normalizations (such as optimizing '../' away) are not allowed
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# (another function should be defined to do that).
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def normcase(s):
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return s
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# Return wheter a path is absolute.
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# Trivial in Posix, harder on the Mac or MS-DOS.
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def isabs(s):
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return s[:1] == '/'
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# Join two pathnames.
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# Ignore the first part if the second part is absolute.
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# Insert a '/' unless the first part is empty or already ends in '/'.
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def join(a, b):
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if b[:1] == '/': return b
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if a == '' or a[-1:] == '/': return a + b
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# Note: join('x', '') returns 'x/'; is this what we want?
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return a + '/' + b
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# Split a path in head (everything up to the last '/') and tail (the
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# rest). If the path ends in '/', tail will be empty. If there is no
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# '/' in the path, head will be empty.
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# Trailing '/'es are stripped from head unless it is the root.
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def split(p):
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import string
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i = string.rfind(p, '/') + 1
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head, tail = p[:i], p[i:]
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if head and head <> '/'*len(head):
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while head[-1] == '/':
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head = head[:-1]
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return head, tail
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# Split a path in root and extension.
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# The extension is everything starting at the first 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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root, ext = '', ''
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for c in p:
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if c == '/':
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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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# Split a pathname into a drive specification and the rest of the
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# path. Useful on DOS/Windows/NT; on Unix, the drive is always empty.
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def splitdrive(p):
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return '', p
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# Return the tail (basename) part of a path.
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def basename(p):
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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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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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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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# 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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try:
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st = posix.lstat(path)
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except (posix.error, AttributeError):
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return 0
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return stat.S_ISLNK(st[stat.ST_MODE])
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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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try:
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st = posix.stat(path)
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except posix.error:
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return 0
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return 1
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# Is a path a posix 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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try:
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st = posix.stat(path)
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except posix.error:
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return 0
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return stat.S_ISDIR(st[stat.ST_MODE])
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# Is a path a regular file?
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# This follows symbolic links, so both islink() and isfile() can be true
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# for the same path.
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def isfile(path):
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try:
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st = posix.stat(path)
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except posix.error:
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return 0
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return stat.S_ISREG(st[stat.ST_MODE])
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# Are two filenames really pointing to the same file?
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def samefile(f1, f2):
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s1 = posix.stat(f1)
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s2 = posix.stat(f2)
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return samestat(s1, s2)
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# Are two open files really referencing the same file?
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# (Not necessarily the same file descriptor!)
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# XXX Oops, posix.fstat() doesn't exist yet!
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def sameopenfile(fp1, fp2):
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s1 = posix.fstat(fp1)
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s2 = posix.fstat(fp2)
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return samestat(s1, s2)
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# Are two stat buffers (obtained from stat, fstat or lstat)
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# describing the same file?
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def samestat(s1, s2):
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return s1[stat.ST_INO] == s2[stat.ST_INO] and \
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s1[stat.ST_DEV] == s2[stat.ST_DEV]
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# Is a path a mount point?
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# (Does this work for all UNIXes? Is it even guaranteed to work by POSIX?)
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def ismount(path):
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try:
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s1 = posix.stat(path)
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s2 = posix.stat(join(path, '..'))
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except posix.error:
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return 0 # It doesn't exist -- so not a mount point :-)
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dev1 = s1[stat.ST_DEV]
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dev2 = s2[stat.ST_DEV]
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if dev1 != dev2:
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return 1 # path/.. on a different device as path
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ino1 = s1[stat.ST_INO]
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ino2 = s2[stat.ST_INO]
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if ino1 == ino2:
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return 1 # path/.. is the same i-node as path
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return 0
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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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try:
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names = posix.listdir(top)
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except posix.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) and not islink(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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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] <> '/':
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i = i+1
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if i == 1:
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if not posix.environ.has_key('HOME'):
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return path
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userhome = posix.environ['HOME']
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else:
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import pwd
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try:
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pwent = pwd.getpwnam(path[1:i])
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except KeyError:
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return path
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userhome = pwent[5]
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return userhome + path[i:]
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# Expand paths containing shell variable substitutions.
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# This expands the forms $variable and ${variable} only.
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# Non-existant variables are left unchanged.
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_varprog = None
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def expandvars(path):
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global _varprog
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if '$' not in path:
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return path
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if not _varprog:
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import regex
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_varprog = regex.compile('$\([a-zA-Z0-9_]+\|{[^}]*}\)')
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i = 0
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while 1:
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i = _varprog.search(path, i)
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if i < 0:
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break
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name = _varprog.group(1)
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j = i + len(_varprog.group(0))
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if name[:1] == '{' and name[-1:] == '}':
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name = name[1:-1]
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if posix.environ.has_key(name):
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tail = path[j:]
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path = path[:i] + posix.environ[name]
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i = len(path)
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path = path + tail
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else:
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i = j
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return path
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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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# It should be understood that this may change the meaning of the path
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# if it contains symbolic links!
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def normpath(path):
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import string
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# Treat initial slashes specially
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slashes = ''
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while path[:1] == '/':
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slashes = slashes + '/'
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path = path[1:]
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comps = string.splitfields(path, '/')
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i = 0
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while i < len(comps):
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if comps[i] == '.':
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del comps[i]
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elif comps[i] == '..' and i > 0 and \
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comps[i-1] not in ('', '..'):
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del comps[i-1:i+1]
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i = i-1
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elif comps[i] == '' and i > 0 and comps[i-1] <> '':
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del comps[i]
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else:
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i = i+1
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# If the path is now empty, substitute '.'
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if not comps and not slashes:
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comps.append('.')
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return slashes + string.joinfields(comps, '/')
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