Re: [PATCH 2/3] getpwuid(mingw): provide a better default for the user name

From: Eric Sunshine <sunshine@sunshineco.com>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: gitgitgadget@gmail.com, Git List <git@vger.kernel.org>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 2/3] getpwuid(mingw): provide a better default for the user name
Date: Tue, 16 Oct 2018 08:41:30 -0400	[thread overview]
Message-ID: <CAPig+cTvKicLKZO38AcVzXJJhZ1CajOhiADotRJ0V7EJXBicUA@mail.gmail.com> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.1810161436480.4546@tvgsbejvaqbjf.bet>

On Tue, Oct 16, 2018 at 8:38 AM Johannes Schindelin
<Johannes.Schindelin@gmx.de> wrote:
> On Mon, 15 Oct 2018, Eric Sunshine wrote:
> > On Mon, Oct 15, 2018 at 5:47 AM Johannes Schindelin via GitGitGadget
> > <gitgitgadget@gmail.com> wrote:
> > > +       len = ARRAY_SIZE(wbuffer);
> > > +       if (GetUserNameExW(type, wbuffer, &len)) {
> > > +               char *converted = xmalloc((len *= 3));
>
> Oh wow. I *just* realized this. It is an off-by-one: the `xmalloc()` call
> needs to receive `len + 1` to accommodate for the trailing NUL. Will fix,
> too.

Or, xmallocz() (note the "z") which gives you overflow-checking of the
+1 for free.