BIND 10 #435: if cfgmgr can't read configs then runs anyways with defaults

[BIND 10 Development]

#435: if cfgmgr can't read configs then runs anyways with defaults
----------------------------+-----------------------------------------------
  Reporter:  jreed          |            Owner:  jelte
      Type:  defect         |           Status:  new  
  Priority:  major          |        Milestone:       
 Component:  configuration  |         Keywords:       
 Sensitive:  0              |   Estimatedhours:  0    
     Hours:  0              |         Billable:  1    
Totalhours:  0              |         Internal:  0    
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 I had been running cfgmgr as root. I had a custom configuration to run
 recurse and not auth. I restarted bind10 as a less privileged user (I
 forgot) and it started auth but not recurse. I cat the b10-config.db file
 (as root) and see my old settings. I exit bind10 to restart and all my
 b10-config.db is lost (overwritten with only version setting). This is
 because the directory had write permission for the non-root.

 Fix is:

 - complain loudly at startup if can't read existing configuration

 - don't overwrite configuration at shutdown. (Keep track if knows of new
 changes where it would even want to do this.)

 - maybe backup existing config if overwriting?

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Ticket URL: <http://bind10.isc.org/ticket/435>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development