Segfault when ogg123 exits

Segfault when ogg123 exits

[Stuart Brady]

Hi,

It seems ogg123 segfaults when it finishes playing.  Note that I'm not
pressing ^C -- I'm not even sure whether the "^C bug" is still around.
>From the backtrace, it looks like this may well be the same problem I
reported with SDL_Quit() and timer_create():

#0  0x00000000 in ?? ()
#1  0x400a7aac in _dl_close_worker () from /lib/ld.so.1
#2  0x400a7c08 in _dl_close () from /lib/ld.so.1
#3  0x400190dc in dlclose_doit () from /lib/libdl.so.2
#4  0x400a1834 in _dl_catch_error () from /lib/ld.so.1
#5  0x40019590 in _dlerror_run () from /lib/libdl.so.2
#6  0x40019118 in dlclose () from /lib/libdl.so.2
#7  0x402f9ffc in ao_shutdown () from /usr/lib/libao.so.2
#8  0x40c57bd4 in exit () from /lib/libc.so.6
#9  0x000182fc in main ()

Would any glibc hackers feel like taking a closer look at this?

Cheers,
-- 
Stuart Brady

Re: Segfault when ogg123 exits

[Carlos O'Donell]

On Wed, Mar 5, 2008 at 5:31 PM, Stuart Brady <sdbrady@ntlworld.com> wrote:
>  It seems ogg123 segfaults when it finishes playing.  Note that I'm not
>  pressing ^C -- I'm not even sure whether the "^C bug" is still around.
>  From the backtrace, it looks like this may well be the same problem I
>  reported with SDL_Quit() and timer_create():
>
>  #0  0x00000000 in ?? ()
>  #1  0x400a7aac in _dl_close_worker () from /lib/ld.so.1
>  #2  0x400a7c08 in _dl_close () from /lib/ld.so.1
>  #3  0x400190dc in dlclose_doit () from /lib/libdl.so.2
>  #4  0x400a1834 in _dl_catch_error () from /lib/ld.so.1
>  #5  0x40019590 in _dlerror_run () from /lib/libdl.so.2
>  #6  0x40019118 in dlclose () from /lib/libdl.so.2
>  #7  0x402f9ffc in ao_shutdown () from /usr/lib/libao.so.2
>  #8  0x40c57bd4 in exit () from /lib/libc.so.6
>  #9  0x000182fc in main ()
>
>  Would any glibc hackers feel like taking a closer look at this?

Can you distill this into a smaller testcase? Maybe a call to dlopen()
to load a library that has a function called by timer_create?

Cheers,
Carlos.

Re: Segfault when ogg123 exits

[Stuart Brady]

On Mon, Mar 10, 2008 at 08:39:12PM -0400, Carlos O'Donell wrote:
> Can you distill this into a smaller testcase? Maybe a call to dlopen()
> to load a library that has a function called by timer_create?

I just ran ogg123 in gdb with a breakpoint set on timer_create(), and it
didn't get triggered, so timer_create() itself seems unlikely to be the
problem, but I can certainly try chopping libao down a bit.

BTW, this happens with both the OSS and ALSA plugins.

Side note: I've found that while running 'while (true); do true; done',
mmapped ALSA output seems to work!  If I drop the brackets, I just get 
noise -- presumably because it doesn't fork without them.
-- 
Stuart Brady

Re: Segfault when ogg123 exits

[Carlos O'Donell]

On Mon, Mar 10, 2008 at 10:09 PM, Stuart Brady <sdbrady@ntlworld.com> wrote:
>  I just ran ogg123 in gdb with a breakpoint set on timer_create(), and it
>  didn't get triggered, so timer_create() itself seems unlikely to be the
>  problem, but I can certainly try chopping libao down a bit.

Excellent, this is exactly the way you want to track this down. You
may wish to run strace to see what types of system calls the program
is making.

Cheers,
Carlos.