| # 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) |