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# Module 'path' -- common operations on POSIX pathnames
import posix
import stat
# Join two pathnames.
# Insert a '/' unless the first part is empty or already ends in '/'.
# Ignore the first part altogether if the second part is absolute
# (begins with '/').
#
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
cat = join # For compatibility
# Split a path in head (empty or ending in '/') and tail (no '/').
# The tail will be empty if the path ends in '/'.
# It is always true that head+tail = p.
#
def split(p):
head, tail = '', ''
for c in p:
tail = tail + c
if c == '/':
head, tail = head + tail, ''
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 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, AttributeError):
return 0
return stat.S_ISLNK(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.STD_DEV]
# Subroutine and global data used by ismount().
_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 = join(top, name)
if isdir(name):
walk(name, func, arg)
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