[tor-bugs] #5891 [Tor Directory Authority]: rep_hist_desc_stats_write() segfaults on empty stats

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#5891: rep_hist_desc_stats_write() segfaults on empty stats
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 Reporter:  ln5                      |          Owner:                    
     Type:  defect                   |         Status:  needs_review      
 Priority:  normal                   |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Directory Authority  |        Version:                    
 Keywords:                           |         Parent:                    
   Points:                           |   Actualpoints:                    
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Comment(by karsten):

 Looks like the problem is that rep_hist_format_desc_stats() returns NULL
 if size == 0.  I wonder if it should instead return a string saying it
 didn't serve a single descriptor, e.g., `"served-descs-stats-end
 2012-05-15 09:18:27 (86400 s) total=0 unique=0 max=0 q3=0 md=0 q1=0
 min=0\n"`.  That's different from not having any statistics for the time
 period.  Btw, the docs also don't say that the function returns NULL if
 size == 0.  So, the better fix would be to fix
 rep_hist_format_desc_stats().  If I prepare a patch, can you test it?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5891#comment:2>
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