Re: Reporting malloc failure in actions

[Christian Schoenebeck]

On Mittwoch, 30. Dezember 2020 19:50:05 CET Joe Nelson wrote:
> >     void* p = malloc(n);
> >     if (!p) {
> >     
> >             fprintf(stderr, "Parser: malloc(%s) with size %zu failed. 
> > Aborting.
\n",
> >             
> >                     expr, n);
> 
> Might be more flexible to call yyerror() than printing directly to
> stderr? Although the name of that function depends on api.prefix, and
> its arguments depend on %param and %parse-param, so I'm not sure how our
> general-purpose parser_alloc() would know what to do. Plus we'd have to
> build the error string ourselves, which probably requires a malloc()...

Yes, the signature of yyerror() depends on several Bison options. There is 
also option %locations that you would need to take into account. It's possible 
to handle these, but obviously more work for you.

> >             abort();
> 
> Rather than aborting, maybe we could do something like this
> 
> #ifdef YYNOMEM
>       /* newer bison version */
>       YYNOMEM;
> #else
>       /* older bison (undocumented feature) */
>       goto yyexhaustedlab;
> #endif

You would be dealing with internals, but AFAICS that internal label already 
exists for decades, so it'll be okay as pragmatic solution I guess.

> >     }
> >     memset(p, 0, n);
> 
> What about using calloc() rather than the combination of malloc() and
> memset()?

Yes, calloc() would be an appropriate replacement.

Best regards,
Christian Schoenebeck