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Bug 672

Summary: _EFF_PositionDeinit doesn't free memory correctly and can only be called once
Product: SDL_mixer Reporter: Luke Kenneth Casson Leighton <lkcl>
Component: miscAssignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: 1.2.8   
Hardware: x86   
OS: Linux   

Description Luke Kenneth Casson Leighton 2009-01-07 05:14:55 UTC 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=510971

the developer of d2x-xl has tracked down a problem with _Eff_PositionDeinit
and has fixed it with the following code:

void _Eff_PositionDeinit(void)
{
    int i;

     if (pos_args_array) {
        for (i = 0; i < position_channels; i++)
            if (pos_args_array[i])
              free(pos_args_array[i]);
        free(pos_args_array);
         pos_args_array = NULL;
        }
     position_channels = 0;
     if (pos_args_global) {
        free(pos_args_global);
        pos_args_global = NULL;
        }
}

Debian patches the same function but the patch method is not as robust
as the above code from the d2x-xl developer.  as you can see, everything
is re-initialised so that the library can be used again.

he d2x-xl developer is having to advise people to install a custom-built
version of libsdl-mixer due to this bug!
Comment 1 Ryan C. Gordon 2009-01-07 12:53:54 UTC 
The current code in Subversion looks like this...

void _Eff_PositionDeinit(void)
{
    int i;
    for (i = 0; i < position_channels; i++) {
        free(pos_args_array[i]);
    }

    position_channels = 0;

    free(pos_args_global);
    pos_args_global = NULL;
    free(pos_args_array);
    pos_args_array = NULL;
}

...it should give the same results.

The latest change was the addition of "position_channels = 0;" 11 months ago, but we haven't released an SDL_mixer 1.2.9 with the change.

--ryan.