1
"""Common operations on Posix pathnames.
3
Instead of importing this module directly, import os and refer to
4
this module as os.path. The "os.path" name is an alias for this
5
module on Posix systems; on other systems (e.g. Mac, Windows),
6
os.path provides the same operations in a manner specific to that
7
platform, and is an alias to another module (e.g. macpath, ntpath).
9
Some of this can actually be useful on non-Posix systems too, e.g.
10
for manipulation of the pathname component of URLs.
17
from genericpath import *
19
__all__ = ["normcase","isabs","join","splitdrive","split","splitext",
20
"basename","dirname","commonprefix","getsize","getmtime",
21
"getatime","getctime","islink","exists","lexists","isdir","isfile",
22
"ismount", "expanduser","expandvars","normpath","abspath",
23
"samefile","sameopenfile","samestat",
24
"curdir","pardir","sep","pathsep","defpath","altsep","extsep",
25
"devnull","realpath","supports_unicode_filenames","relpath"]
27
# Strings representing various path-related bits and pieces.
28
# These are primarily for export; internally, they are hardcoded.
34
defpath = ':/bin:/usr/bin'
39
if isinstance(path, bytes):
44
# Normalize the case of a pathname. Trivial in Posix, string.lower on Mac.
45
# On MS-DOS this may also turn slashes into backslashes; however, other
46
# normalizations (such as optimizing '../' away) are not allowed
47
# (another function should be defined to do that).
50
"""Normalize case of pathname. Has no effect under Posix"""
51
# TODO: on Mac OS X, this should really return s.lower().
55
# Return whether a path is absolute.
56
# Trivial in Posix, harder on the Mac or MS-DOS.
59
"""Test whether a path is absolute"""
61
return s.startswith(sep)
65
# Ignore the previous parts if a part is absolute.
66
# Insert a '/' unless the first part is empty or already ends in '/'.
69
"""Join two or more pathname components, inserting '/' as needed.
70
If any component is an absolute path, all previous path components
77
elif not path or path.endswith(sep):
84
# Split a path in head (everything up to the last '/') and tail (the
85
# rest). If the path ends in '/', tail will be empty. If there is no
86
# '/' in the path, head will be empty.
87
# Trailing '/'es are stripped from head unless it is the root.
90
"""Split a pathname. Returns tuple "(head, tail)" where "tail" is
91
everything after the final slash. Either part may be empty."""
94
head, tail = p[:i], p[i:]
95
if head and head != sep*len(head):
96
head = head.rstrip(sep)
100
# Split a path in root and extension.
101
# The extension is everything starting at the last dot in the last
102
# pathname component; the root is everything before that.
103
# It is always true that root + ext == p.
106
if isinstance(p, bytes):
112
return genericpath._splitext(p, sep, None, extsep)
113
splitext.__doc__ = genericpath._splitext.__doc__
115
# Split a pathname into a drive specification and the rest of the
116
# path. Useful on DOS/Windows/NT; on Unix, the drive is always empty.
119
"""Split a pathname into drive and path. On Posix, drive is always
124
# Return the tail (basename) part of a path, same as split(path)[1].
127
"""Returns the final component of a pathname"""
133
# Return the head (dirname) part of a path, same as split(path)[0].
136
"""Returns the directory component of a pathname"""
140
if head and head != sep*len(head):
141
head = head.rstrip(sep)
145
# Is a path a symbolic link?
146
# This will always return false on systems where os.lstat doesn't exist.
149
"""Test whether a path is a symbolic link"""
152
except (os.error, AttributeError):
154
return stat.S_ISLNK(st.st_mode)
156
# Being true for dangling symbolic links is also useful.
159
"""Test whether a path exists. Returns True for broken symbolic links"""
167
# Are two filenames really pointing to the same file?
169
def samefile(f1, f2):
170
"""Test whether two pathnames reference the same actual file"""
173
return samestat(s1, s2)
176
# Are two open files really referencing the same file?
177
# (Not necessarily the same file descriptor!)
179
def sameopenfile(fp1, fp2):
180
"""Test whether two open file objects reference the same file"""
183
return samestat(s1, s2)
186
# Are two stat buffers (obtained from stat, fstat or lstat)
187
# describing the same file?
189
def samestat(s1, s2):
190
"""Test whether two stat buffers reference the same file"""
191
return s1.st_ino == s2.st_ino and \
192
s1.st_dev == s2.st_dev
195
# Is a path a mount point?
196
# (Does this work for all UNIXes? Is it even guaranteed to work by Posix?)
199
"""Test whether a path is a mount point"""
202
if isinstance(path, bytes):
203
parent = join(path, b'..')
205
parent = join(path, '..')
206
s2 = os.lstat(parent)
208
return False # It doesn't exist -- so not a mount point :-)
212
return True # path/.. on a different device as path
216
return True # path/.. is the same i-node as path
220
# Expand paths beginning with '~' or '~user'.
221
# '~' means $HOME; '~user' means that user's home directory.
222
# If the path doesn't begin with '~', or if the user or $HOME is unknown,
223
# the path is returned unchanged (leaving error reporting to whatever
224
# function is called with the expanded path as argument).
225
# See also module 'glob' for expansion of *, ? and [...] in pathnames.
226
# (A function should also be defined to do full *sh-style environment
227
# variable expansion.)
229
def expanduser(path):
230
"""Expand ~ and ~user constructions. If user or $HOME is unknown,
232
if isinstance(path, bytes):
236
if not path.startswith(tilde):
239
i = path.find(sep, 1)
243
if 'HOME' not in os.environ:
245
userhome = pwd.getpwuid(os.getuid()).pw_dir
247
userhome = os.environ['HOME']
251
if isinstance(name, bytes):
252
name = str(name, 'ASCII')
254
pwent = pwd.getpwnam(name)
257
userhome = pwent.pw_dir
258
if isinstance(path, bytes):
259
userhome = userhome.encode(sys.getfilesystemencoding())
260
userhome = userhome.rstrip(sep)
261
return userhome + path[i:]
264
# Expand paths containing shell variable substitutions.
265
# This expands the forms $variable and ${variable} only.
266
# Non-existent variables are left unchanged.
271
def expandvars(path):
272
"""Expand shell variables of form $var and ${var}. Unknown variables
273
are left unchanged."""
274
global _varprog, _varprogb
275
if isinstance(path, bytes):
280
_varprogb = re.compile(br'\$(\w+|\{[^}]*\})', re.ASCII)
281
search = _varprogb.search
289
_varprog = re.compile(r'\$(\w+|\{[^}]*\})', re.ASCII)
290
search = _varprog.search
300
if name.startswith(start) and name.endswith(end):
302
if isinstance(name, bytes):
303
name = str(name, 'ASCII')
304
if name in os.environ:
306
value = os.environ[name]
307
if isinstance(path, bytes):
308
value = value.encode('ASCII')
309
path = path[:i] + value
317
# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
318
# It should be understood that this may change the meaning of the path
319
# if it contains symbolic links!
322
"""Normalize path, eliminating double slashes, etc."""
323
if isinstance(path, bytes):
335
initial_slashes = path.startswith(sep)
336
# POSIX allows one or two initial slashes, but treats three or more
338
if (initial_slashes and
339
path.startswith(sep*2) and not path.startswith(sep*3)):
341
comps = path.split(sep)
344
if comp in (empty, dot):
346
if (comp != dotdot or (not initial_slashes and not new_comps) or
347
(new_comps and new_comps[-1] == dotdot)):
348
new_comps.append(comp)
352
path = sep.join(comps)
354
path = sep*initial_slashes + path
359
"""Return an absolute path."""
361
if isinstance(path, bytes):
365
path = join(cwd, path)
366
return normpath(path)
369
# Return a canonical path (i.e. the absolute location of a file on the
372
def realpath(filename):
373
"""Return the canonical path of the specified filename, eliminating any
374
symbolic links encountered in the path."""
375
if isinstance(filename, bytes):
382
bits = [sep] + filename.split(sep)[1:]
384
bits = [empty] + filename.split(sep)
386
for i in range(2, len(bits)+1):
387
component = join(*bits[0:i])
388
# Resolve symbolic links.
389
if islink(component):
390
resolved = _resolve_link(component)
392
# Infinite loop -- return original component + rest of the path
393
return abspath(join(*([component] + bits[i:])))
395
newpath = join(*([resolved] + bits[i:]))
396
return realpath(newpath)
398
return abspath(filename)
401
def _resolve_link(path):
402
"""Internal helper function. Takes a path and follows symlinks
403
until we either arrive at something that isn't a symlink, or
404
encounter a path we've seen before (meaning that there's a loop).
408
if path in paths_seen:
409
# Already seen this path, so we must have a symlink loop
412
# Resolve where the link points to
413
resolved = os.readlink(path)
414
if not isabs(resolved):
416
path = normpath(join(dir, resolved))
418
path = normpath(resolved)
421
supports_unicode_filenames = False
423
def relpath(path, start=None):
424
"""Return a relative version of a path"""
427
raise ValueError("no path specified")
429
if isinstance(path, bytes):
441
start_list = abspath(start).split(sep)
442
path_list = abspath(path).split(sep)
444
# Work out how much of the filepath is shared by start and path.
445
i = len(commonprefix([start_list, path_list]))
447
rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
450
return join(*rel_list)