[tor-bugs] #19661 [Core Tor/Tor]: tor refuses to use /dev/null as a config file

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#19661: tor refuses to use /dev/null as a config file
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 Reporter:  weasel                               |          Owner:
                                                 |  cypherpunks
     Type:  defect                               |         Status:
                                                 |  needs_review
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.0.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.2.8.5-rc
 Severity:  Normal                               |     Resolution:
 Keywords:  easy, lorax, integration, review-    |  Actual Points:
  group-14                                       |
Parent ID:                                       |         Points:  .1
 Reviewer:  nickm                                |        Sponsor:
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Comment (by nickm):

 I think it would be much better to stop using file_status() whenever we
 don't absolutely have to do so.  That's for a couple of reasons:

    * The st_size field is not reliable on S_IFCHR devices, so anything
 that distinguishes between FN_EMPTY and FN_FILE will get the wrong answer.
    * Generally, when we want to see whether we can read a file, it's
 better to just try to read the file and see what happens.  To do otherwise
 invites race conditions.  The only time when it makes sense to have a
 separate "does this file exist" check is when we *aren't* going to open
 the file.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19661#comment:17>
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