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175 lines
3.7 KiB
Python
175 lines
3.7 KiB
Python
# Module 'path' -- common operations on POSIX pathnames
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import posix
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import stat
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# Join two pathnames.
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# Insert a '/' unless the first part is empty or already ends in '/'.
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# Ignore the first part altogether if the second part is absolute
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# (begins with '/').
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#
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def join(a, b):
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if b[:1] = '/': return b
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if a = '' or a[-1:] = '/': return a + b
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# Note: join('x', '') returns 'x/'; is this what we want?
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return a + '/' + b
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cat = join # For compatibility
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# Split a path in head (empty or ending in '/') and tail (no '/').
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# The tail will be empty if the path ends in '/'.
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# It is always true that head+tail = p.
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#
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def split(p):
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head, tail = '', ''
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for c in p:
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tail = tail + c
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if c = '/':
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head, tail = head + tail, ''
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return head, tail
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# Split a path in root and extension.
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# The extension is everything starting at the first dot in the last
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# pathname component; the root is everything before that.
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# It is always true that root+ext = p.
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#
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def splitext(p):
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root, ext = '', ''
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for c in p:
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if c = '/':
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root, ext = root + ext + c, ''
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elif c = '.' or ext:
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ext = ext + c
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else:
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root = root + c
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return root, ext
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# Return the tail (basename) part of a path.
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#
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def basename(p):
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return split(p)[1]
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# Return the longest prefix of all list elements.
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#
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def commonprefix(m):
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if not m: return ''
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prefix = m[0]
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for item in m:
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for i in range(len(prefix)):
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if prefix[:i+1] <> item[:i+1]:
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prefix = prefix[:i]
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if i = 0: return ''
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break
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return prefix
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# Does a file/directory exist?
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#
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def exists(path):
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try:
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st = posix.stat(path)
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except posix.error:
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return 0
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return 1
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# Is a path a posix directory?
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#
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def isdir(path):
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try:
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st = posix.stat(path)
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except posix.error:
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return 0
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return stat.S_ISDIR(st[stat.ST_MODE])
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# Is a path a symbolic link?
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# This will always return false on systems where posix.lstat doesn't exist.
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#
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def islink(path):
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try:
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st = posix.lstat(path)
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except (posix.error, AttributeError):
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return 0
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return stat.S_ISLNK(st[stat.ST_MODE])
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# Are two filenames really pointing to the same file?
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#
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def samefile(f1, f2):
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s1 = posix.stat(f1)
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s2 = posix.stat(f2)
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return samestat(s1, s2)
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# Are two open files really referencing the same file?
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# (Not necessarily the same file descriptor!)
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# XXX Oops, posix.fstat() doesn't exist yet!
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#
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def sameopenfile(fp1, fp2):
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s1 = posix.fstat(fp1)
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s2 = posix.fstat(fp2)
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return samestat(s1, s2)
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# Are two stat buffers (obtained from stat, fstat or lstat)
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# describing the same file?
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#
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def samestat(s1, s2):
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return s1[stat.ST_INO] = s2[stat.ST_INO] and \
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s1[stat.ST_DEV] = s2[stat.STD_DEV]
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# Subroutine and global data used by ismount().
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_mounts = []
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def _getmounts():
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import commands, string
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mounts = []
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data = commands.getoutput('/etc/mount')
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lines = string.splitfields(data, '\n')
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for line in lines:
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words = string.split(line)
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if len(words) >= 3 and words[1] = 'on':
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mounts.append(words[2])
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return mounts
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# Is a path a mount point?
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# This only works for normalized, absolute paths,
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# and only if the mount table as printed by /etc/mount is correct.
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# Sorry.
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#
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def ismount(path):
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if not _mounts:
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_mounts[:] = _getmounts()
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return path in _mounts
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# Directory tree walk.
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# For each directory under top (including top itself),
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# func(arg, dirname, filenames) is called, where dirname
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# is the name of the directory and filenames is the list of
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# files (and subdirectories etc.) in the directory.
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# func may modify the filenames list, to implement a filter,
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# or to impose a different order of visiting.
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#
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def walk(top, func, arg):
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try:
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names = posix.listdir(top)
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except posix.error:
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return
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func(arg, top, names)
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exceptions = ('.', '..')
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for name in names:
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if name not in exceptions:
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name = join(top, name)
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if isdir(name):
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walk(name, func, arg)
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