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# Module 'path' -- common operations on POSIX pathnames
import posix
import stat
# Intelligent pathname concatenation.
# Inserts a '/' unless the first part is empty or already ends in '/'.
# Ignores the first part altogether if the second part is absolute
# (begins with '/').
#
def cat(a, b):
if b[:1] = '/': return b
if a = '' or a[-1:] = '/': return a + b
return a + '/' + b
# Split a path in head (empty or ending in '/') and tail (no '/').
# The tail will be empty if the path ends in '/'.
#
def split(p):
head, tail = '', ''
for c in p:
tail = tail + c
if c = '/':
head, tail = head + tail, ''
return head, tail
# Return the tail (basename) part of a path.
#
def basename(p):
return split(p)[1]
# 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
# Does a file/directory exist?
#
def exists(path):
try:
st = posix.stat(path)
except posix.error:
return 0
return 1
# Is a path a posix directory?
#
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 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, NameError):
return 0
return stat.S_ISLNK(st[stat.ST_MODE])
_mounts = []
def _getmounts():
import commands, string
mounts = []
data = commands.getoutput('/etc/mount')
lines = string.splitfields(data, '\n')
for line in lines:
words = string.split(line)
if len(words) >= 3 and words[1] = 'on':
mounts.append(words[2])
return mounts
# Is a path a mount point?
# This only works for normalized, absolute paths,
# and only if the mount table as printed by /etc/mount is correct.
# Sorry.
#
def ismount(path):
if not _mounts:
_mounts[:] = _getmounts()
return path in _mounts
# Directory tree walk.
# For each directory under top (including top itself),
# 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.
# 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 = cat(top, name)
if isdir(name):
walk(name, func, arg)
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