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