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()