295 lines
7.0 KiB
Python
295 lines
7.0 KiB
Python
# Module 'posixpath' -- common operations on POSIX pathnames
|
|
|
|
import posix
|
|
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):
|
|
return s
|
|
|
|
|
|
# Return wheter a path is absolute.
|
|
# Trivial in Posix, harder on the Mac or MS-DOS.
|
|
|
|
def isabs(s):
|
|
return s[:1] == '/'
|
|
|
|
|
|
# Join two pathnames.
|
|
# Ignore the first part if the second part is absolute.
|
|
# Insert a '/' unless the first part is empty or already ends in '/'.
|
|
|
|
def join(a, b):
|
|
if b[:1] == '/': return b
|
|
if a == '' or a[-1:] == '/': return a + b
|
|
# Note: join('x', '') returns 'x/'; is this what we want?
|
|
return a + '/' + b
|
|
|
|
|
|
# Split a path in head (everything up to the last '/') and tail (the
|
|
# rest). If the original path ends in '/' but is not the root, this
|
|
# '/' is stripped. After the trailing '/' is stripped, the invariant
|
|
# join(head, tail) == p holds.
|
|
# The resulting head won't end in '/' unless it is the root.
|
|
|
|
def split(p):
|
|
if p[-1:] == '/' and p <> '/'*len(p):
|
|
while p[-1] == '/':
|
|
p = p[:-1]
|
|
head, tail = '', ''
|
|
for c in p:
|
|
tail = tail + c
|
|
if c == '/':
|
|
head, tail = head + tail, ''
|
|
if head[-1:] == '/' 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 first dot in the last
|
|
# pathname component; the root is everything before that.
|
|
# It is always true that root + ext == p.
|
|
|
|
def splitext(p):
|
|
root, ext = '', ''
|
|
for c in p:
|
|
if c == '/':
|
|
root, ext = root + ext + c, ''
|
|
elif c == '.' or ext:
|
|
ext = ext + c
|
|
else:
|
|
root = root + c
|
|
return root, ext
|
|
|
|
|
|
# Return the tail (basename) part of a path.
|
|
|
|
def basename(p):
|
|
return split(p)[1]
|
|
|
|
|
|
# Return the head (dirname) part of a path.
|
|
|
|
def dirname(p):
|
|
return split(p)[0]
|
|
|
|
|
|
# Return the longest prefix of all list elements.
|
|
|
|
def commonprefix(m):
|
|
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
|
|
|
|
|
|
# Is a path a symbolic link?
|
|
# This will always return false on systems where posix.lstat doesn't exist.
|
|
|
|
def islink(path):
|
|
try:
|
|
st = posix.lstat(path)
|
|
except (posix.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):
|
|
try:
|
|
st = posix.stat(path)
|
|
except posix.error:
|
|
return 0
|
|
return 1
|
|
|
|
|
|
# Is a path a posix directory?
|
|
# This follows symbolic links, so both islink() and isdir() can be true
|
|
# for the same path.
|
|
|
|
def isdir(path):
|
|
try:
|
|
st = posix.stat(path)
|
|
except posix.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 isdir() can be true
|
|
# for the same path.
|
|
|
|
def isfile(path):
|
|
try:
|
|
st = posix.stat(path)
|
|
except posix.error:
|
|
return 0
|
|
return stat.S_ISREG(st[stat.ST_MODE])
|
|
|
|
|
|
# Are two filenames really pointing to the same file?
|
|
|
|
def samefile(f1, f2):
|
|
s1 = posix.stat(f1)
|
|
s2 = posix.stat(f2)
|
|
return samestat(s1, s2)
|
|
|
|
|
|
# Are two open files really referencing the same file?
|
|
# (Not necessarily the same file descriptor!)
|
|
# XXX Oops, posix.fstat() doesn't exist yet!
|
|
|
|
def sameopenfile(fp1, fp2):
|
|
s1 = posix.fstat(fp1)
|
|
s2 = posix.fstat(fp2)
|
|
return samestat(s1, s2)
|
|
|
|
|
|
# Are two stat buffers (obtained from stat, fstat or lstat)
|
|
# describing the same file?
|
|
|
|
def samestat(s1, s2):
|
|
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):
|
|
try:
|
|
s1 = posix.stat(path)
|
|
s2 = posix.stat(join(path, '..'))
|
|
except posix.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
|
|
# files 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):
|
|
try:
|
|
names = posix.listdir(top)
|
|
except posix.error:
|
|
return
|
|
func(arg, top, names)
|
|
exceptions = ('.', '..')
|
|
for name in names:
|
|
if name not in exceptions:
|
|
name = join(top, name)
|
|
if isdir(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 $HOME is unknown,
|
|
# the path is returned unchanged (leaving error reporting to whatever
|
|
# function is called with the expanded path as argument).
|
|
# See also module 'glob' for expansion of *, ? and [...] in pathnames.
|
|
# (A function should also be defined to do full *sh-style environment
|
|
# variable expansion.)
|
|
|
|
def expanduser(path):
|
|
if path[:1] <> '~':
|
|
return path
|
|
i, n = 1, len(path)
|
|
while i < n and path[i] <> '/':
|
|
i = i+1
|
|
if i == 1:
|
|
if not posix.environ.has_key('HOME'):
|
|
return path
|
|
userhome = posix.environ['HOME']
|
|
else:
|
|
import pwd
|
|
try:
|
|
pwent = pwd.getpwnam(path[1:i])
|
|
except KeyError:
|
|
return path
|
|
userhome = pwent[5]
|
|
return userhome + path[i:]
|
|
|
|
|
|
# Expand paths containing shell variable substitutions.
|
|
# This is done by piping it through the shell.
|
|
# Shell quoting characters (\ " ' `) are protected by a backslash.
|
|
# NB: a future version may avoid starting a subprocess and do the
|
|
# substitutions internally. This may slightly change the syntax
|
|
# for variables.
|
|
|
|
def expandvars(path):
|
|
if '$' not in path:
|
|
return path
|
|
q = ''
|
|
for c in path:
|
|
if c in ('\\', '"', '\'', '`'):
|
|
c = '\\' + c
|
|
q = q + c
|
|
d = '!'
|
|
if q == d:
|
|
d = '+'
|
|
p = posix.popen('cat <<' + d + '\n' + q + '\n' + d + '\n', 'r')
|
|
res = p.read()
|
|
del p
|
|
if res[-1:] == '\n':
|
|
res = res[:-1]
|
|
return res
|
|
|
|
|
|
# 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):
|
|
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]
|
|
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, '/')
|