[tor-bugs] #18025 [Tor]: test_util_touch_file is racy and *does* fail

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#18025: test_util_touch_file is racy and *does* fail
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 Reporter:  weasel  |          Owner:  nickm
     Type:  defect  |         Status:  assigned
 Priority:  Medium  |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor     |        Version:  Tor: 0.2.7.6
 Severity:  Normal  |     Resolution:
 Keywords:          |  Actual Points:
Parent ID:          |         Points:
  Sponsor:          |
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Comment (by weasel):

 {{{
 <ron> weasel: oh ...  it could also be a small difference between the wall
 clock and the monotonic clock.
 <ron> it looks like current_fs_time() reads the monotonic clock.
 <ron> Mithrandir: so yeah, the kernel code seems to show it is updating
 the vsyscall cache too.  just not from the same clock :)
 <Mithrandir> fun
 <Mithrandir> so there's a kernel<->userspace clock skew. :-P
 <ron> yeah, looks like someone needs to add an option to date(1) to read
 the monotonic clock ...
 <ron> you should see the same thing if you pick different clock sources in
 a call to clock_gettime(3)
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18025#comment:10>
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