[vorbis] Re: Squelch 1.0beta9

[Kenneth Arnold]

On Tue, Feb 06, 2001 at 11:10:57PM -0500, Bill Nottingham wrote:
> Kenneth Arnold (ken at arnoldnet.net) said: 
> > Then just type 'run'. If you get a weird message about being unable to
> > read from some memory location (that maps to /lib/ld-linux.so.2 for
> > me), then you have duplicated the problem I'm trying to track down
> > with very little success. I've segfaulted gdb several times, but I
> > have been able to confirm (with strace) that the writer process is
> > segfaulting, and I don't know why. HELP!
> 
> You certianly appear to be calling ao_play without ever calling
> ao_open on the device, so you end up jumping into the
> middle of nowhere...

Ah crud, you're right: somebody (too late; can't remember who)
committed the open_audio_devices hackish (could be done cleaner)
reopen-on-bitrate-change, and since the buffer isn't reset after each
change, or even given notice when the devices are opened in the first
place, it's dereferencing a pointer-to-nowhere and faulting. The odd
thing is that I knew this, and in fact was in process of doing another
batch of cleanups that included a fix, but still forgot that it was an
issue.

Okay, problem #1 solved with a "duh, I knew that." That leaves problem
#2: gdb. I cannot debug ogg123 on my system, but compiling oggenc with
debug code and gdb'ing that works fine. I haven't conclusively found
if this is unique to my setup. But explain this rough transcript:

cd vorbis-tools/ogg123
cvs -z4 update -dPA
make clean
make CFLAGS=-g
gdb ogg123
[copyright message removed]
(gdb) break main
Breakpoint 1 at 0x80493bd: file ogg123.c, line 100.
(gdb) run
Starting program: /usr/src/cvs/xiph.org-cvs/vorbis-tools/ogg123/ogg123
Cannot access memory at address 0x40017e30
(gdb) bt
#0  0x4000d114 in _dl_debug_state () from /lib/ld-linux.so.2

It's not even getting to main(). gdb bug, ogg123 bug, PEBCAK, or what?
It does run fine (without buffer) when run normally. This is tested on
2.4.0 and 2.4.1, gcc 2.95.3 (may be guilty), gdb 5.0, Debian unstable.
Any other results? Please confirm that it's not just me.


-- 
Kenneth Arnold <ken at arnoldnet.net> / kcarnold / Linux user #180115
http://arnoldnet.net/~kcarnold/



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