[gmx-developers] uninitialized data

[Alexander Herz]

of course it must be

 memset(fr,0,sizeof(t_forcerec)); 

as fr is a pointer

Alex

Alexander Herz schrieb:
> There appears to be a problem with uninitialized data that might affact
> the shifted virial and other things:
>
> in md.c the following code creates the forcerec:
>
>     fr = mk_forcerec();
>     init_forcerec(fplog,fr,fcd,inputrec,mtop,cr,box,FALSE,
>           opt2fn("-table",nfile,fnm),opt2fn("-tablep",nfile,fnm),
>           opt2fn("-tableb",nfile,fnm),FALSE,pforce);
>     fr->bSepDVDL = ((Flags & MD_SEPPOT) == MD_SEPPOT);
>
>
> where mk_forcerec() contains:
>
> t_forcerec *mk_forcerec(void)
> {
>   t_forcerec *fr;
>  
>   snew(fr,1);
>
>     //!!!!!!missing :     memset(fr,0,sizeof(fr));
>   return fr;
> }
>
> and init_forcerec() contains:
> ...
>     if (fr->fshift == NULL)
>         snew(fr->fshift,SHIFTS);
>    
>     if (fr->nbfp == NULL) {
>         fr->ntype = mtop->ffparams.atnr;
>         fr->bBHAM = (mtop->ffparams.functype[0] == F_BHAM);
>         fr->nbfp  = mk_nbfp(&mtop->ffparams,fr->bBHAM);
>     }
> ...
>
> Without the missing memset I added as a comment to mk_forcerec,
> fr->fshift may contain anything
> and might therefore not be initialized. Valgrind also complains about this.
>
> I have not yet had the time to see if this affects the shifted virial
> problems I reported the other day.
> I'll look at that tomorrow!
>
> Alex
>
>
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