[mythtv-commits] Ticket #11318: Segfault in mythbackend (mainserver/autoexpire?)

[MythTV]

#11318: Segfault in mythbackend (mainserver/autoexpire?)
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 Reporter:  verycoldpenguin@…   |          Owner:  stuartm
     Type:  Bug Report - Crash  |         Status:  accepted
 Priority:  minor               |      Milestone:  0.26.1
Component:  MythTV - General    |        Version:  Master Head
 Severity:  medium              |     Resolution:
 Keywords:                      |  Ticket locked:  0
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Comment (by verycoldpenguin@…):

 Please do not use patch.txt (Patch 1).
 Although it neatly stops the segfault, it completely renders useless the
 two pieces of code :)


 Hello Gregorio,
 I am sorry, it looks like you might be right. I made the assumption that
 if the protocol versions were different, then the master and slave
 backends would not communicate. However, it appears that although the
 slave may not connect to the master if the version is different, the
 master can connect to the slave. Perhaps this should be listed as a
 separate bug, or perhaps it is intentional, either way it is a pain in
 this instance.


 I have attached a patch2. This is an ugly patch, it has many debug/log
 prints and areas commented out.
 With this, it can be seen that the system correctly determines information
 from the local database.
 It also shows that often it does manage to communicate with the remote
 backend (although again whilst this was running, there was a protocol mis-
 match, 76 slave ->77 master).
 A lot of the time the correct information was returned (the number of
 lines being a multiple of 8).
 However, often, the number of lines being returned (after the local
 determination) is not a multiple of 8. This would suggest that the
 information returned was truncated. In these instances, the patch2
 supplied will ignore data that doesn't divide by 8. This masks the
 symptoms of the problems, meaning that the segfault will not occur.
 However, investigation should be made as to how to fix these truncations.

 I will apply the patch from 11316 and see whether I see any more instances
 of 11318. I think however that a refined version of patch2 would be
 worthwhile incorporating anyway, in case communication problems occur from
 elsewhere in the future.

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Ticket URL: <http://code.mythtv.org/trac/ticket/11318#comment:5>
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