[mythtv-commits] Ticket #1887: invalid PAT in recordings causes Frontend Crash, Backtrace Attached...
MythTV
mythtv at cvs.mythtv.org
Thu Jun 1 01:48:05 UTC 2006
#1887: invalid PAT in recordings causes Frontend Crash, Backtrace Attached...
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Reporter: jochen | Owner: danielk
Type: defect | Status: new
Priority: minor | Milestone: 0.20
Component: mythtv | Version: head
Severity: medium | Resolution:
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Changes (by Janne <janne-mythtv at grunau.be>):
* summary: Frontend Crash, Backtrace Attached... => invalid PAT in
recordings causes Frontend Crash, Backtrace
Attached...
Comment:
psofa from irc got a stream that crashes mythfrontend or mythtv
reproducably. The backtraces look very similar to the attached.
The problem in this stream [http://www.grunau.be/invalid_pat.ts] is an
invalid PAT.
Following block is from the mythtv output with DEBUG_SI in mpegts.c.
The first 3 PAT look like this one:
{{{
PAT:
00000000 00 b0 0d 00 01 c7 00 00 00 01 e4 09 fa 3f 23 d6 .............?#.
sid=0x1 sec_num=0/0
MPEG Program Number=0x1 pid=0x409 req_sid=0x1
Found program number!
}}}
But the next contains 0x00 as program number:
{{{
PAT:
00000000 00 b0 0d 00 01 c9 00 00 00 01 e0 00 49 d9 e4 47 ............I..G
sid=0x1 sec_num=0/0
MPEG Program Number=0x1 pid=0x0 req_sid=0x1
New PAT!
new_service: sid=0x0001 provider='' name='MPEG Program 1'
Found program number!
Closing Filter: pid=0x409
Closing PMT Filter: pid=0x409
Opening Filter: pid=0x0
Filter Already Exists
Closing Filter: pid=0x0
Closing PAT Filter: pid=0x0
zsh: segmentation fault mythtv -v all /pub/1747_20060601015601.mpg
}}}
this recreates the original PAT filter and the segfault is caused by a
dangling pointer to the old one.
It seems that there is a race condition in the writing PAT code.
psofa sees this error while channel zapping with his DVB-S card but not
with DVB-T.
--
Ticket URL: <http://svn.mythtv.org/trac/ticket/1887>
MythTV <http://www.mythtv.org/>
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