Re: Vads X/Motif & C

[Frank Petranka <fpetran@l10server.nswc.navy.mil>]

On 10 Sep 1996, Mark Bell wrote:

> 
> Folks --
> 
> I'm attempting to interface Ada with an X/Motif government 
> application written in C.  I'm using Vads Ada (V6.2.3) and 
> Vads Ada X Interface to Motif (V3.2.3) The platform is a 
> Sparcstation 20 running Solaris 2.4.
> 
> Initially I had dynamic allocation problems due to the
> ways Vads and Solaris were performing memory allocation.
> I believe I have this solved by modifying the v_usr_confb.a file
> to use malloc() instead of sbrk() in the kernel allocation
> function V_KRN_ALLOC_CALLOUT.  After this was done, I no
> longer get segmentation faults after malloc calls in the
> government C software.
> 
> However, I'm still getting segmentation faults during various
> X/Motif calls, and I'm not 100 percent sure that the above
> fix has totally addressed the problem of the interaction of the
> Vads Ada runtime and Solaris OS in regards to memory allocation.
> Does anyone have any "lessons learned" from doing similar work ??
> 
> I'm also running in problems such as getting a resource's value 
> from a widget, then immediately setting the widget's resource to
> the same value, and getting a segmentation fault.  For Example:
> 
> Xt.Xt_Resource_Management.Xt_Set_Arg(
>   Arg => An_Arg_List(0),
>   Name => Xt_Stringdefs.Xt_N_background,
>   Value => blank_color'Address);
> 
> Xt.Xt_Resource_Management.Xt_Get_Values(
>   W    => Presentation_Drawing_Area,
>   Args => An_Arg_List(0..0));
> 
> Xt.Xt_Resource_Management.Xt_Set_Values(
>    W    => Presentation_Drawing_Area,
>    Args => An_Arg_List(0..0));
> 
> (Segmentation fault occurs)
> 

I believe an Xt_Get_Values requires blank_color'address for Value while
an Xt_Set_Values requires blank_color for Value. 


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and do not, in any manner, reflect that of the Navy.

            Frank J. Petranka          Naval Surface Warfare Center
            (540)653-4849              Dahlgren, Va. 22448
                    fpetran@relay.nswc.navy.mil