"""Common operations on DOS pathnames."""
import os
import stat
import string
def normcase(s):
"""Normalize the case of a pathname.
On MS-DOS it maps the pathname to lowercase, turns slashes into
backslashes.
Other normalizations (such as optimizing '../' away) are not allowed
(this is done by normpath).
Previously, this version mapped invalid consecutive characters to a
single '_', but this has been removed. This functionality should
possibly be added as a new function."""
return string.lower(string.replace(s, "/", "\\"))
def isabs(s):
"""Return whether a path is absolute.
Trivial in Posix, harder on the Mac or MS-DOS.
For DOS it is absolute if it starts with a slash or backslash (current
volume), or if a pathname after the volume letter and colon starts with
a slash or backslash."""
s = splitdrive(s)[1]
return s != '' and s[:1] in '/\\'
def join(a, *p):
"""Join two (or more) paths."""
path = a
for b in p:
if isabs(b):
path = b
elif path == '' or path[-1:] in '/\\':
path = path + b
else:
path = path + os.sep + b
return path
def splitdrive(p):
"""Split a path into a drive specification (a drive letter followed
by a colon) and path specification.
It is always true that drivespec + pathspec == p."""
if p[1:2] == ':':
return p[0:2], p[2:]
return '', p
def split(p):
"""Split a path into head (everything up to the last '/') and tail
(the rest). After the trailing '/' is stripped, the invariant
join(head, tail) == p holds.
The resulting head won't end in '/' unless it is the root."""
d, p = splitdrive(p)
# set i to index beyond p's last slash
i = len(p)
while i and p[i-1] not in '/\\':
i = i - 1
head, tail = p[:i], p[i:] # now tail has no slashes
# remove trailing slashes from head, unless it's all slashes
head2 = head
while head2 and head2[-1] in '/\\':
head2 = head2[:-1]
head = head2 or head
return d + head, tail
def splitext(p):
"""Split a path into 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."""
root, ext = '', ''
for c in p:
if c in '/\\':
root, ext = root + ext + c, ''
elif c == '.' or ext:
ext = ext + c
else:
root = root + c
return root, ext
def basename(p):
"""Return the tail (basename) part of a path."""
return split(p)[1]
def dirname(p):
"""Return the head (dirname) part of a path."""
return split(p)[0]
def commonprefix(m):
"""Return the longest prefix of all list elements."""
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
# Get size, mtime, atime of files.
def getsize(filename):
"""Return the size of a file, reported by os.stat()."""
st = os.stat(filename)
return st[stat.ST_SIZE]
def getmtime(filename):
"""Return the last modification time of a file, reported by os.stat()."""
st = os.stat(filename)
return st[stat.ST_MTIME]
def getatime(filename):
"""Return the last access time of a file, reported by os.stat()."""
st = os.stat(filename)
return st[stat.ST_MTIME]
def islink(path):
"""Is a path a symbolic link?
This will always return false on systems where posix.lstat doesn't exist."""
return 0
def exists(path):
"""Does a path exist?
This is false for dangling symbolic links."""
try:
st = os.stat(path)
except os.error:
return 0
return 1
def isdir(path):
"""Is a path a dos directory?"""
try:
st = os.stat(path)
except os.error:
return 0
return stat.S_ISDIR(st[stat.ST_MODE])
def isfile(path):
"""Is a path a regular file?"""
try:
st = os.stat(path)
except os.error:
return 0
return stat.S_ISREG(st[stat.ST_MODE])
def ismount(path):
"""Is a path a mount point?"""
# XXX This degenerates in: 'is this the root?' on DOS
return isabs(splitdrive(path)[1])
def walk(top, func, arg):
"""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."""
try:
names = os.listdir(top)
except os.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)
def expanduser(path):
"""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.)"""
if path[:1] <> '~':
return path
i, n = 1, len(path)
while i < n and path[i] not in '/\\':
i = i+1
if i == 1:
if not os.environ.has_key('HOME'):
return path
userhome = os.environ['HOME']
else:
return path
return userhome + path[i:]
varchars = string.letters + string.digits + '_-'
def expandvars(path):
"""Expand paths containing shell variable substitutions.
The following rules apply:
- no expansion within single quotes
- no escape character, except for '$$' which is translated into '$'
- ${varname} is accepted.
- varnames can be made out of letters, digits and the character '_'"""
# XXX With COMMAND.COM you can use any characters in a variable name,
# XXX except '^|<>='.
if '$' not in path:
return path
res = ''
index = 0
pathlen = len(path)
while index < pathlen:
c = path[index]
if c == '\'': # no expansion within single quotes
path = path[index + 1:]
pathlen = len(path)
try:
index = string.index(path, '\'')
res = res + '\'' + path[:index + 1]
except string.index_error:
res = res + path
index = pathlen -1
elif c == '$': # variable or '$$'
if path[index + 1:index + 2] == '$':
res = res + c
index = index + 1
elif path[index + 1:index + 2] == '{':
path = path[index+2:]
pathlen = len(path)
try:
index = string.index(path, '}')
var = path[:index]
if os.environ.has_key(var):
res = res + os.environ[var]
except string.index_error:
res = res + path
index = pathlen - 1
else:
var = ''
index = index + 1
c = path[index:index + 1]
while c != '' and c in varchars:
var = var + c
index = index + 1
c = path[index:index + 1]
if os.environ.has_key(var):
res = res + os.environ[var]
if c != '':
res = res + c
else:
res = res + c
index = index + 1
return res
def normpath(path):
"""Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
Also, components of the path are silently truncated to 8+3 notation."""
path = string.replace(path, "/", "\\")
prefix, path = splitdrive(path)
while path[:1] == os.sep:
prefix = prefix + os.sep
path = path[1:]
comps = string.splitfields(path, os.sep)
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]
elif '.' in comps[i]:
comp = string.splitfields(comps[i], '.')
comps[i] = comp[0][:8] + '.' + comp[1][:3]
i = i+1
elif len(comps[i]) > 8:
comps[i] = comps[i][:8]
i = i+1
else:
i = i+1
# If the path is now empty, substitute '.'
if not prefix and not comps:
comps.append('.')
return prefix + string.joinfields(comps, os.sep)
def abspath(path):
"""Return an absolute path."""
if not isabs(path):
path = join(os.getcwd(), path)
return normpath(path)
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