[mythtv] RE: Segfault in mythfrontend when returning to playl

Chris Pinkham cpinkham at bc2va.org
Fri Apr 4 11:46:21 EST 2003

I've been seeing this happen on my dev box ever since the new playback and
delete screens went into place.  It happens almost 100% of the time and
I traced it down a little and saw the same 'h < 0' situation that was
reported at the start of this thread.  I haven't had any time to check into
it more to see if h<0 is a valid case.  I believe that for some reason
the showList is being cleared or overwritten because of a bug or pointer
problem somewhere.  I believe I inserted printf statements and saw
that the problem popped up whenever showList.count was 0 and the following
section of code then caused h to be less than 0.

This is from around like 845.

    if (i < 0)
        h = i + showList.count();
    if (i > (signed int)(showList.count() - 1))
        h = i - showList.count();

If i < 0 which is a valid case, then h = i + showList.count() would set
h to be the same as i which would make h negative as well.  Since h is used
as an index into titleData then I assume this would cause not find anything
since titleData should be full of positive references.  This may be a side
effect of the real problem, but I think the problem is with one or more
variables getting clobbered.  I believe when I had my debug printf's
installed that titleData was also clobbered as well.  The line that
checks titleData[h] != "***FILLER***" was causing a segfault for me
sometimes on operator == or !=.  Would this make sense if titleData
was corrupted by some other part of the program?

Needless to say, I started experiencing this problem on the day the
new playback box went into place which would make sense since it appears
to be segfaulting in the new playbackbox code.  Of course the problem
could be in the playbackbox code or something else could be hosing up the
playbackbox vars.

I don't have much debugging time this week due to out of town guests, but
if someone else is looking into this, this may help point them in the
right direction.

> Still segfaults with blue theme and blue osd.
> -----Original Message-----
> From: William Preston [mailto:bpreston at networkusa.net]
> Sent: Friday, April 04, 2003 9:00 AM
> To: Development of mythtv
> Subject: Re: [mythtv] RE: Segfault in mythfrontend when returning to
> playlist from watc hing recording...
> Grasping at straws, but I observed the exact same behavior when using the
> new iliusosd OSD theme posted recently (I used it with the patch posted,
> but haven't tried with the most recent CVS.)  Switching to blue or default
> OSD cleared it up.


** Chris Pinkham                  Linux v2.2.18, Sane v1.0.4, Cajun v3.0-8 **
** cpinkham at bc2va.org                          http://www.bc2va.org/chris/ **

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