[tahoe-dev] [tahoe-lafs] #833: reject mutable children when *reading* an immutable dirnode

[tahoe-lafs]

#833: reject mutable children when *reading* an immutable dirnode
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 Reporter:  warner                           |           Owner:  warner  
     Type:  defect                           |          Status:  assigned
 Priority:  critical                         |       Milestone:  1.6.0   
Component:  code-dirnodes                    |         Version:  1.5.0   
 Keywords:  integrity forward-compatibility  |   Launchpad_bug:          
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Comment(by zooko):

 Brian wrote:
   So if we want to promise users who are listing an immutable directory
 that they'll only see immutable caps, we'd have to filter out anything
 that we don't explicitly recognize as immutable, which means removing all
 caps-from-the-future.

 David-Sarah wrote:
   Not necessarily. If the directory is immutable, we could just omit
 rw_uri.

 I wrote:
   Good idea!

 No wait, that's a ''bad'' idea.  A read-only cap to a mutable directory is
 not a read-cap to an immutable directory.  I keep getting confused about
 this, and in the history of Tahoe-LAFS Brian and I have been confused
 about it more than once.  I'm going to get a post-it note and affix it to
 my monitor, saying:

   "READ-ONLY DOESN'T MEAN IMMUTABLE."

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Ticket URL: <http://allmydata.org/trac/tahoe/ticket/833#comment:16>
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