#! /usr/bin/python2.7 # 3) System Test # # Given a list of directories, report any bogus symbolic links contained # anywhere in those subtrees. A bogus symbolic link is one that cannot # be resolved because it points to a nonexistent or otherwise # unresolvable file. Do *not* use an external find executable. # Directories may be very very deep. Print a warning immediately if the # system you're running on doesn't support symbolic links. # This implementation: # - takes one optional argument, using the current directory as default # - uses chdir to increase performance # - sorts the names per directory # - prints output lines of the form "path1 -> path2" as it goes # - prints error messages about directories it can't list or chdir into import os import sys from stat import * def main(): try: # Note: can't test for presence of lstat -- it's always there dummy = os.readlink except AttributeError: print "This system doesn't have symbolic links" sys.exit(0) if sys.argv[1:]: prefix = sys.argv[1] else: prefix = '' if prefix: os.chdir(prefix) if prefix[-1:] != '/': prefix = prefix + '/' reportboguslinks(prefix) else: reportboguslinks('') def reportboguslinks(prefix): try: names = os.listdir('.') except os.error, msg: print "%s%s: can't list: %s" % (prefix, '.', msg) return names.sort() for name in names: if name == os.curdir or name == os.pardir: continue try: mode = os.lstat(name)[ST_MODE] except os.error: print "%s%s: can't stat: %s" % (prefix, name, msg) continue if S_ISLNK(mode): try: os.stat(name) except os.error: print "%s%s -> %s" % \ (prefix, name, os.readlink(name)) elif S_ISDIR(mode): try: os.chdir(name) except os.error, msg: print "%s%s: can't chdir: %s" % \ (prefix, name, msg) continue try: reportboguslinks(prefix + name + '/') finally: os.chdir('..') main()