Re: [PATCH] assume sprintf formatting of wide characters may fail (PR 86853)

[Eric Gallager <egall@gwmail.gwu.edu>]

On 8/4/18, Martin Sebor <msebor@gmail.com> wrote:
> The sprintf handling of wide characters neglects to consider
> that calling the function may fail due to a conversion error
> (when the wide character is invalid or not representable in
> the current locale).  The handling also misinterprets
> the POSIX %S wide string directive as a plain narrow %s and
> doesn't include %C (the POSIX equivalent of %lc).

I was worried about portability to non-POSIX platforms, but after
checking the documentation for the gnulib sprintf-posix module,
apparently there are no portability issues with platforms that don't
support the %C directive, so I guess it should be fine:
https://www.gnu.org/software/gnulib/manual/html_node/sprintf.html

> The attached patch corrects these oversights by extending the data
> structures to indicate when a directive may fail, and extending the
> UNDER4K member of the format_result structure to also encode
> calls with such directives.
>
> Tested on x86_64-linux.
>
> Besides the trunk, since this bug can affect code correctness
> I'd like to backport this patch to both release branches (7
> and 8).
>
> Martin
>