Make nicer comments.
Added expanduser() and normcase() and isabs() and isfile().
This commit is contained in:
Guido van Rossum
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6a3f9a841a
commit
7ac4878773
132
Lib/posixpath.py
132
Lib/posixpath.py
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@ -4,11 +4,26 @@ 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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# Ignore the first part altogether if the second part is absolute
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# (begins with '/').
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#
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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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@ -16,13 +31,14 @@ def join(a, b):
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return a + '/' + b
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cat = join # For compatibility
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# Split a path in head (empty or ending in '/') and tail (no '/').
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# The tail will be empty if the path ends in '/'.
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# It is always true that head+tail = p.
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#
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# It is always true that head + tail == p; also join(head, tail) == p.
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# Note that because head ends in '/', if you want to find all components
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# of a path by repeatedly getting the head, you will have to strip off
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# the trailing '/' yourself (another function should be defined to
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# split an entire path into components.)
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def split(p):
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head, tail = '', ''
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for c in p:
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@ -35,8 +51,8 @@ def split(p):
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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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#
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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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@ -50,13 +66,13 @@ def splitext(p):
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# Return the tail (basename) part of a path.
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#
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def basename(p):
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return split(p)[1]
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# Return the longest prefix of all list elements.
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#
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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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@ -69,8 +85,20 @@ def commonprefix(m):
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return prefix
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# Does a file/directory exist?
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#
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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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@ -80,7 +108,9 @@ def exists(path):
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# Is a path a posix directory?
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#
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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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@ -89,19 +119,20 @@ def isdir(path):
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return stat.S_ISDIR(st[stat.ST_MODE])
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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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#
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def islink(path):
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# Is a path a regulat 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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try:
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st = posix.lstat(path)
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except (posix.error, AttributeError):
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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_ISLNK(st[stat.ST_MODE])
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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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#
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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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@ -111,7 +142,7 @@ def samefile(f1, f2):
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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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#
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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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@ -120,7 +151,7 @@ def sameopenfile(fp1, fp2):
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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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#
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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.STD_DEV]
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@ -143,24 +174,28 @@ def _getmounts():
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# Is a path a mount point?
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# This only works for normalized, absolute paths,
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# This only works for normalized paths,
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# and only if the mount table as printed by /etc/mount is correct.
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# Sorry.
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#
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# It tries to make relative paths absolute by prefixing them with the
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# current directory, but it won't normalize arguments containing '../'
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# or symbolic links.
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def ismount(path):
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if not isabs(path):
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path = join(posix.getcwd(), path)
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if not _mounts:
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_mounts[:] = _getmounts()
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return path in _mounts
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# Directory tree walk.
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# For each directory under top (including top itself),
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# func(arg, dirname, filenames) is called, where dirname
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# is the name of the directory and filenames is the list of
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# files (and subdirectories etc.) in the directory.
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# func may modify the filenames list, to implement a filter,
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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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#
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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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@ -173,3 +208,32 @@ def walk(top, func, arg):
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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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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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