Re: [PATCH v1 1/2] enter.c: Use wmem*() functions with wide-character strings

Alejandro Colomar via Mutt-dev <[email protected]> Fri, 13 Feb 2026 14:36:29 +0100

Newsgroups	gmane.mail.mutt.devel
Message-ID	<aY8oLP_sxe7PLseK@devuan>

Hi Greg,

On 2026-02-13T08:34:14+0100, Greg KH wrote:
> On Thu, Feb 12, 2026 at 11:56:19PM +0100, Alejandro Colomar via Mutt-dev wrote:
> > This avoids an explicit size multiplication, which can overflow the
> > calculation.
> > 
> > Signed-off-by: Alejandro Colomar <[email protected]>
> > Cherry-picked-from: neomutt.git 7df621a105e2 (2024-05-09, "Use wmem*() functions with wide-character strings")
> > [alx: Adapted diff and message to mutt(1)]
> > Signed-off-by: Alejandro Colomar <[email protected]>
> > ---
[...]
> > @@ -175,7 +176,7 @@ static void replace_part (ENTER_STATE *state, size_t from, char *buf)
> >    if (savelen)
> >    {
> >      savebuf = safe_calloc (savelen, sizeof (wchar_t));
> > -    memcpy (savebuf, state->wbuf + state->curpos, savelen * sizeof (wchar_t));
> > +    wmemcpy (savebuf, state->wbuf + state->curpos, savelen);
> 
> If there was going to be an overflow, safe_calloc() would have crashed
> the system, so we can "know" that if it returns, it's all good so there
> will not be any overflow happening.

True; and I've made that same argument elsewhere; I don't understand why
I wrote that in the commit message.  It was a long time ago...

> 
> So I don't think this patch actually does anything except make code
> checking tools happy because it can not actually read the logic :)

Actually, it improves the readability.  I would do it even if only for
that.  Also, wmemcpy(3) is more type-safe, as it doesn't use void*.

> 
> thanks,
> 
> greg k-h


Have a lovely day!
Alex

-- 
<https://www.alejandro-colomar.es>

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