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- # Module 'posixpath' -- common operations on Posix pathnames.
- # Some of this can actually be useful on non-Posix systems too, e.g.
- # for manipulation of the pathname component of URLs.
- # The "os.path" name is an alias for this module on Posix systems;
- # on other systems (e.g. Mac, Windows), os.path provides the same
- # operations in a manner specific to that platform, and is an alias
- # to another module (e.g. macpath, ntpath).
- """Common pathname manipulations, Posix version.
- Instead of importing this module
- directly, import os and refer to this module as os.path.
- """
-
- import os
- import stat
-
-
- # Normalize the case of a pathname. Trivial in Posix, string.lower on Mac.
- # On MS-DOS this may also turn slashes into backslashes; however, other
- # normalizations (such as optimizing '../' away) are not allowed
- # (another function should be defined to do that).
-
- def normcase(s):
- """Normalize case of pathname. Has no effect under Posix"""
- return s
-
-
- # Return wheter a path is absolute.
- # Trivial in Posix, harder on the Mac or MS-DOS.
-
- def isabs(s):
- """Test whether a path is absolute"""
- return s[:1] == '/'
-
-
- # Join pathnames.
- # Ignore the previous parts if a part is absolute.
- # Insert a '/' unless the first part is empty or already ends in '/'.
-
- def join(a, *p):
- """Join two or more pathname components, inserting '/' as needed"""
- path = a
- for b in p:
- if b[:1] == '/':
- path = b
- elif path == '' or path[-1:] == '/':
- path = path + b
- else:
- path = path + '/' + b
- return path
-
-
- # Split a path in head (everything up to the last '/') and tail (the
- # rest). If the path ends in '/', tail will be empty. If there is no
- # '/' in the path, head will be empty.
- # Trailing '/'es are stripped from head unless it is the root.
-
- def split(p):
- """Split a pathname. Returns tuple "(head, tail)" where "tail" is
- everything after the final slash. Either part may be empty"""
- import string
- i = string.rfind(p, '/') + 1
- head, tail = p[:i], p[i:]
- if head and head <> '/'*len(head):
- while head[-1] == '/':
- head = head[:-1]
- return head, tail
-
-
- # Split a path in root and extension.
- # The extension is everything starting at the last dot in the last
- # pathname component; the root is everything before that.
- # It is always true that root + ext == p.
-
- def splitext(p):
- """Split the extension from a pathname. Extension is everything from the
- last dot to the end. Returns "(root, ext)", either part may be empty"""
- root, ext = '', ''
- for c in p:
- if c == '/':
- root, ext = root + ext + c, ''
- elif c == '.':
- if ext:
- root, ext = root + ext, c
- else:
- ext = c
- elif ext:
- ext = ext + c
- else:
- root = root + c
- return root, ext
-
-
- # Split a pathname into a drive specification and the rest of the
- # path. Useful on DOS/Windows/NT; on Unix, the drive is always empty.
-
- def splitdrive(p):
- """Split a pathname into drive and path. On Posix, drive is always
- empty"""
- return '', p
-
-
- # Return the tail (basename) part of a path.
-
- def basename(p):
- """Returns the final component of a pathname"""
- return split(p)[1]
-
-
- # Return the head (dirname) part of a path.
-
- def dirname(p):
- """Returns the directory component of a pathname"""
- return split(p)[0]
-
-
- # Return the longest prefix of all list elements.
-
- def commonprefix(m):
- "Given a list of pathnames, returns the longest common leading component"
- if not m: return ''
- prefix = m[0]
- for item in m:
- for i in range(len(prefix)):
- if prefix[:i+1] <> item[:i+1]:
- prefix = prefix[:i]
- if i == 0: return ''
- break
- return prefix
-
-
- # Get size, mtime, atime of files.
-
- def getsize(filename):
- """Return the size of a file, reported by os.stat()."""
- st = os.stat(filename)
- return st[stat.ST_SIZE]
-
- def getmtime(filename):
- """Return the last modification time of a file, reported by os.stat()."""
- st = os.stat(filename)
- return st[stat.ST_MTIME]
-
- def getatime(filename):
- """Return the last access time of a file, reported by os.stat()."""
- st = os.stat(filename)
- return st[stat.ST_MTIME]
-
-
- # Is a path a symbolic link?
- # This will always return false on systems where os.lstat doesn't exist.
-
- def islink(path):
- """Test whether a path is a symbolic link"""
- try:
- st = os.lstat(path)
- except (os.error, AttributeError):
- return 0
- return stat.S_ISLNK(st[stat.ST_MODE])
-
-
- # Does a path exist?
- # This is false for dangling symbolic links.
-
- def exists(path):
- """Test whether a path exists. Returns false for broken symbolic links"""
- try:
- st = os.stat(path)
- except os.error:
- return 0
- return 1
-
-
- # Is a path a directory?
- # This follows symbolic links, so both islink() and isdir() can be true
- # for the same path.
-
- def isdir(path):
- """Test whether a path is a directory"""
- try:
- st = os.stat(path)
- except os.error:
- return 0
- return stat.S_ISDIR(st[stat.ST_MODE])
-
-
- # Is a path a regular file?
- # This follows symbolic links, so both islink() and isfile() can be true
- # for the same path.
-
- def isfile(path):
- """Test whether a path is a regular file"""
- try:
- st = os.stat(path)
- except os.error:
- return 0
- return stat.S_ISREG(st[stat.ST_MODE])
-
-
- # Are two filenames really pointing to the same file?
-
- def samefile(f1, f2):
- """Test whether two pathnames reference the same actual file"""
- s1 = os.stat(f1)
- s2 = os.stat(f2)
- return samestat(s1, s2)
-
-
- # Are two open files really referencing the same file?
- # (Not necessarily the same file descriptor!)
-
- def sameopenfile(fp1, fp2):
- """Test whether two open file objects reference the same file"""
- s1 = os.fstat(fp1)
- s2 = os.fstat(fp2)
- return samestat(s1, s2)
-
-
- # Are two stat buffers (obtained from stat, fstat or lstat)
- # describing the same file?
-
- def samestat(s1, s2):
- """Test whether two stat buffers reference the same file"""
- return s1[stat.ST_INO] == s2[stat.ST_INO] and \
- s1[stat.ST_DEV] == s2[stat.ST_DEV]
-
-
- # Is a path a mount point?
- # (Does this work for all UNIXes? Is it even guaranteed to work by Posix?)
-
- def ismount(path):
- """Test whether a path is a mount point"""
- try:
- s1 = os.stat(path)
- s2 = os.stat(join(path, '..'))
- except os.error:
- return 0 # It doesn't exist -- so not a mount point :-)
- dev1 = s1[stat.ST_DEV]
- dev2 = s2[stat.ST_DEV]
- if dev1 != dev2:
- return 1 # path/.. on a different device as path
- ino1 = s1[stat.ST_INO]
- ino2 = s2[stat.ST_INO]
- if ino1 == ino2:
- return 1 # path/.. is the same i-node as path
- return 0
-
-
- # Directory tree walk.
- # For each directory under top (including top itself, but excluding
- # '.' and '..'), func(arg, dirname, filenames) is called, where
- # dirname is the name of the directory and filenames is the list
- # of files (and subdirectories etc.) in the directory.
- # The func may modify the filenames list, to implement a filter,
- # or to impose a different order of visiting.
-
- def walk(top, func, arg):
- """walk(top,func,args) calls func(arg, d, files) for each directory "d"
- in the tree rooted at "top" (including "top" itself). "files" is a list
- of all the files and subdirs in directory "d".
- """
- try:
- names = os.listdir(top)
- except os.error:
- return
- func(arg, top, names)
- exceptions = ('.', '..')
- for name in names:
- if name not in exceptions:
- name = join(top, name)
- if isdir(name) and not islink(name):
- walk(name, func, arg)
-
-
- # Expand paths beginning with '~' or '~user'.
- # '~' means $HOME; '~user' means that user's home directory.
- # If the path doesn't begin with '~', or if the user or $HOME is unknown,
- # the path is returned unchanged (leaving error reporting to whatever
- # function is called with the expanded path as argument).
- # See also module 'glob' for expansion of *, ? and [...] in pathnames.
- # (A function should also be defined to do full *sh-style environment
- # variable expansion.)
-
- def expanduser(path):
- """Expand ~ and ~user constructions. If user or $HOME is unknown,
- do nothing"""
- if path[:1] <> '~':
- return path
- i, n = 1, len(path)
- while i < n and path[i] <> '/':
- i = i+1
- if i == 1:
- if not os.environ.has_key('HOME'):
- return path
- userhome = os.environ['HOME']
- else:
- import pwd
- try:
- pwent = pwd.getpwnam(path[1:i])
- except KeyError:
- return path
- userhome = pwent[5]
- if userhome[-1:] == '/': i = i+1
- return userhome + path[i:]
-
-
- # Expand paths containing shell variable substitutions.
- # This expands the forms $variable and ${variable} only.
- # Non-existant variables are left unchanged.
-
- _varprog = None
-
- def expandvars(path):
- """Expand shell variables of form $var and ${var}. Unknown variables
- are left unchanged"""
- global _varprog
- if '$' not in path:
- return path
- if not _varprog:
- import re
- _varprog = re.compile(r'\$(\w+|\{[^}]*\})')
- i = 0
- while 1:
- m = _varprog.search(path, i)
- if not m:
- break
- i, j = m.span(0)
- name = m.group(1)
- if name[:1] == '{' and name[-1:] == '}':
- name = name[1:-1]
- if os.environ.has_key(name):
- tail = path[j:]
- path = path[:i] + os.environ[name]
- i = len(path)
- path = path + tail
- else:
- i = j
- return path
-
-
- # Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
- # It should be understood that this may change the meaning of the path
- # if it contains symbolic links!
-
- def normpath(path):
- """Normalize path, eliminating double slashes, etc."""
- import string
- # Treat initial slashes specially
- slashes = ''
- while path[:1] == '/':
- slashes = slashes + '/'
- path = path[1:]
- comps = string.splitfields(path, '/')
- i = 0
- while i < len(comps):
- if comps[i] == '.':
- del comps[i]
- while i < len(comps) and comps[i] == '':
- del comps[i]
- elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'):
- del comps[i-1:i+1]
- i = i-1
- elif comps[i] == '' and i > 0 and comps[i-1] <> '':
- del comps[i]
- else:
- i = i+1
- # If the path is now empty, substitute '.'
- if not comps and not slashes:
- comps.append('.')
- return slashes + string.joinfields(comps, '/')
-
-
- # Return an absolute path.
- def abspath(path):
- if not isabs(path):
- path = join(os.getcwd(), path)
- return normpath(path)
-