[tahoe-dev] [tahoe-lafs] #835: "tahoe cp -r --mutable": make mutable copy of immutable directories, vice versa

tahoe-lafs trac at allmydata.org
Fri Nov 20 04:02:57 UTC 2009


#835: "tahoe cp -r --mutable": make mutable copy of immutable directories, vice
versa
-------------------------------+--------------------------------------------
 Reporter:  warner             |           Owner:           
     Type:  enhancement        |          Status:  new      
 Priority:  major              |       Milestone:  undecided
Component:  code-frontend-cli  |         Version:  1.5.0    
 Keywords:                     |   Launchpad_bug:           
-------------------------------+--------------------------------------------
 Now that we have immutable directories (#607), we could use some CLI
 commands to take advantage of them. #828 is about having "tahoe backup"
 create immutable directories, but what if you want to convert those
 immutable directories into a form that you can modify again? {{{tahoe
 cp}}} seems like the most appropriate tool.

 There are a couple of interesting forms of copying that could be done. (In
 each case, we're talking about directories, and not files.)

  * original is immutable: make immutable copy (re-use same object)
  * original is immutable: make mutable copy
  * original is mutable: make mutable copy
  * original is mutable: make immutable copy

 The default for {{{cp -r}}} should be to use the same type of object:
 mutable-to-mutable or immutable-to-immutable (and of course, immutable-to-
 immutable means we just re-use the original dircap).

 I think that {{{tahoe cp}}} should acquire a {{{--mutable}}} flag which
 tells it to always create mutable directories, even if the original was
 immutable. This would be used to convert your "tahoe backup" -created
 immutable directories into a form that you can modify.

 Likewise, I think it should have a {{{--immutable}}} flag which tells it
 to always create immutable directories.

 I think that files should be handled differently: basically the default
 should be mutable-to-mutable and immutable-gets-shared. If you copy with
 {{{--immutable}}}, then clearly that will trigger mutable-to-immutable
 (since immutable dirnodes are deep-immutable, so we can't fill them with
 mutable files). But if you copy with {{{--mutable}}}, I think we should
 create mutable dirnodes with immutable files. A separate flag (maybe
 {{{--mutable-files}}}) could be used if you really do want to turn all of
 your immutable files into mutable ones.

-- 
Ticket URL: <http://allmydata.org/trac/tahoe/ticket/835>
tahoe-lafs <http://allmydata.org>
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