Re: luaO_pushvfstring reads past end of format string on trailing %

Roberto:

On Tue, 11 Aug 2026 at 19:54, Roberto Ierusalimschy
<[email protected]> wrote:
> > [...] but a case for '\0' may be
> > useful, specially since the default behaviour is adding unknown
> > formats .
>
> You can use '%c' with a corresponding 0 to insert '\0'.

Thanks, but I was not referring to that. I meant, since "%#", as "%$"
and all other invalid sequences just "keep unknown format in the
result", do the same for "%\0". Null inserting is not common enough
for the ( perceived by my ) target of this function to even suggest
"%0" for it, the %c combo is fine.

OTOH, as I commented, the input, fmt,  is a C string, so "%\0" is not
really a two char substring but more of a OOB access, so I would
prefer some fix along the lines of testing e[1], if it is considered (
or just let it fall to a "unespecified ( by the manual ) behaviour",
but I think it would be better to just fix it, as well as keeping the
default handling, because formats like "Done up to %d%" or "Reached
%d% phase" are easy to key by mistake ( they plague my C code, thank
god GCC as printf checking ).

Francisco Olarte.

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