bug#73985: fix: charset.max_char may be used before being set

[Eli Zaretskii]

> Cc: 73985@debbugs.gnu.org
> Date: Thu, 24 Oct 2024 17:42:36 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > Thanks.  You are right that the original code is incorrect, but the
> > code you propose has a subtle problem: the sum
> > 
> >   i + charset.code_offset
> > 
> > could overflow.  So we need to find a safer way of explaining the
> > problem.
> 
> I fixed that (on the master branch) like this:
> 
> diff --git a/src/charset.c b/src/charset.c
> index e8d0826..f7d80cc 100644
> --- a/src/charset.c
> +++ b/src/charset.c
> @@ -1007,7 +1007,8 @@ DEFUN ("define-charset-internal", 
> Fdefine_charset_internal,
>  
>        i = CODE_POINT_TO_INDEX (&charset, charset.max_code);
>        if (MAX_CHAR - charset.code_offset < i)
> -     error ("Unsupported max char: %d", charset.max_char);
> +     error ("Unsupported max char: %d + %ud > MAX_CHAR (%d)",
> +            i, charset.max_code, MAX_CHAR);
>        charset.max_char = i + charset.code_offset;
>        i = CODE_POINT_TO_INDEX (&charset, charset.min_code);
>        charset.min_char = i + charset.code_offset;

No further comments, so I'm now closing this bug.