Re: [e-users] evolume issue

[<jea...@sp...>]

Hi Folks,

I believe that I found from where the issue is coming.
After a quick look I got a segfault there

Evas_List *
_get_active_mixers(Mixer_System_Name *msn, Config *conf)
{
    Evas_List *l, *l1, *l3;
    Evas_List *ret;

    ret = NULL;
    Config_Mixer *mixer_conf;
    Evas_List *mixers;

===>   mixer_conf = evas_list_data(l3);    <==========

standing into the e_mod_volume.c

The evas_list_data function is

EAPI void *
evas_list_data(Evas_List *list)
{
    if (!list) return NULL;
    return list->data;
}

So the e_volume is calling the evas_list_data with a non initialized 
pointer which could work on some system with clean stack where in that 
case l3 is initialized to 0. On some embedded system suffering from low 
level of memory, the stack could contain some old information which broke 
the entry test of the evas_list_data and try to make a read to a bad 
address pointer causing the segfault.

Jm

On Thu, 22 Jun 2006, jea...@sp... wrote:

> Hi,
>
> I am trying to setup evolume but get a crash when I try to enable the
> module. I can load it without issue. Here is some various output
> from /var/log/e, just after enlightenment_remote --module-enable evolume
>
> _mixer_hash: key = ALSA, hash = 216
> _mixer_hash: key = ATI IXP, hash = 126
> msn = 0x85a01f0
> msn = { "alsa", "ALSA", 0x859c408 }
> **** SEGMENTATION FAULT ****
>
> I have the trace of the e crash, it will follow. My ALSA configuration is
> OK, I can play an MP3 and alsamixer is working fine. I do not have a user
> daemon sound MIXER enabled. So I am fully standing on top of ALSA, this
> could be probably the root of the crash when I look at this gdb trace:
>
> #0  0xb7d60e98 in poll () from /lib/libc.so.0
> #1  0xb7c6b285 in _XWaitForReadable (dpy=0x80fbff8) at XlibInt.c:498
> #2  0xb7c6b6d6 in _XRead (dpy=0x80fbff8, data=0xbfd74acc "", size=32) at
> XlibInt.c:1087
> #3  0xb7c6d197 in _XReadEvents (dpy=0x80fbff8) at XlibInt.c:1003
> #4  0xb7c58121 in XNextEvent (dpy=0x80fbff8, event=0xbfd7537c) at
> NextEvent.c:50
> #5  0x080aa1db in e_alert_show (
>     text=0x80e6e30 "This is very bad. Enlightenment has segfaulted.\nThis
> is not meant to happen and is likely a sign of a\nbug in Enlightenment or
> the libraries it relies on.\n\nYou can gdb attach to this process now to
> try"...)
>     at e_alert.c:137
> #6  0x0809b080 in e_sigseg_act (x=11, info=0xbfd75828, data=0xbfd758a8) at
> e_signals.c:53
> #7  0xb7d50f30 in raise () from /lib/libc.so.0
> #8  0xb7b1de46 in _get_active_mixers (msn=0x85a01f0, conf=0xfffffffc) at
> e_mod_volume.c:84
> #9  0xb7b1e05d in e_volume_init (data=0x0) at e_mod_volume.c:225
> #10 0xb7b1cc37 in e_modapi_init (module=0x825eba0) at e_mod_main.c:47
> #11 0x0808e1bb in e_module_enable (m=0x825eba0) at e_module.c:260
> #12 0x0806a465 in _e_ipc_cb_client_data (data=0xb7e0f590, type=72,
> event=0x81aa690) at e_ipc_handlers.h:1019
> #13 0xb7e05112 in _ecore_event_call () at ecore_events.c:431
> #14 0xb7e0a0d6 in _ecore_main_loop_iterate_internal (once_only=0) at
> ecore_main.c:639
> #15 0xb7e0a2d7 in ecore_main_loop_begin () at ecore_main.c:79
> #16 0x08061637 in main (argc=3, argv=0xbfdb3d14) at e_main.c:685
> (gdb)
>
> But I am definitly not sure of my assumptions. I will have a deeper look
> tomorrow, but if somebody could provide some helps by then, that will be
> great (it is late in Paris now)
>
> Jm
>
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