Demo/comparisons/systemtest.py

   1 #! /usr/bin/env python
   2
   3 # 3)  System Test
   4 #
   5 #     Given a list of directories, report any bogus symbolic links contained
   6 #     anywhere in those subtrees.  A bogus symbolic link is one that cannot
   7 #     be resolved because it points to a nonexistent or otherwise
   8 #     unresolvable file.  Do *not* use an external find executable.
   9 #     Directories may be very very deep.  Print a warning immediately if the
  10 #     system you're running on doesn't support symbolic links.
  11
  12 # This implementation:
  13 # - takes one optional argument, using the current directory as default
  14 # - uses chdir to increase performance
  15 # - sorts the names per directory
  16 # - prints output lines of the form "path1 -> path2" as it goes
  17 # - prints error messages about directories it can't list or chdir into
  18
  19 import os
  20 import sys
  21 from stat import *
  22
  23 def main():
  24         try:
  25                 # Note: can't test for presence of lstat -- it's always there
  26                 dummy = os.readlink
  27         except AttributeError:
  28                 print "This system doesn't have symbolic links"
  29                 sys.exit(0)
  30         if sys.argv[1:]:
  31                 prefix = sys.argv[1]
  32         else:
  33                 prefix = ''
  34         if prefix:
  35                 os.chdir(prefix)
  36                 if prefix[-1:] != '/': prefix = prefix + '/'
  37                 reportboguslinks(prefix)
  38         else:
  39                 reportboguslinks('')
  40
  41 def reportboguslinks(prefix):
  42         try:
  43                 names = os.listdir('.')
  44         except os.error, msg:
  45                 print "%s%s: can't list: %s" % (prefix, '.', msg)
  46                 return
  47         names.sort()
  48         for name in names:
  49                 if name == os.curdir or name == os.pardir:
  50                         continue
  51                 try:
  52                         mode = os.lstat(name)[ST_MODE]
  53                 except os.error:
  54                         print "%s%s: can't stat: %s" % (prefix, name, msg)
  55                         continue
  56                 if S_ISLNK(mode):
  57                         try:
  58                                 os.stat(name)
  59                         except os.error:
  60                                 print "%s%s -> %s" % \
  61                                       (prefix, name, os.readlink(name))
  62                 elif S_ISDIR(mode):
  63                         try:
  64                                 os.chdir(name)
  65                         except os.error, msg:
  66                                 print "%s%s: can't chdir: %s" % \
  67                                       (prefix, name, msg)
  68                                 continue
  69                         try:
  70                                 reportboguslinks(prefix + name + '/')
  71                         finally:
  72                                 os.chdir('..')
  73
  74 main()