bug#62216: Odd file corruption in clojure mode and emacs 30 HEAD

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 31 Aug 2023 14:46:01 +0000
> From: Jonathon McKitrick <jcm@SDF.ORG>
> Cc: Eli Zaretskii <eliz@gnu.org>, luangruo@yahoo.com, eggert@cs.ucla.edu,
>         62216@debbugs.gnu.org
> 
> On Wed, Aug 30, 2023 at 02:07:35PM +0200, Gerd Mllmann wrote:
> : On 30.08.23 14:00, Eli Zaretskii wrote:
> : > > From: Gerd Möllmann <gerd.moellmann@gmail.com>
> : > > Cc: Jonathon McKitrick <jcm@SDF.ORG>,  Eli Zaretskii <eliz@gnu.org>,  Paul
> : > >   Eggert <eggert@cs.ucla.edu>,  62216@debbugs.gnu.org
> : > > Date: Wed, 30 Aug 2023 10:59:08 +0200
> : > > 
> : > > Po Lu <luangruo@yahoo.com> writes:
> : > > 
> : > > > Jonathon McKitrick <jcm@SDF.ORG> writes:
> : > > > 
> : > > > > What's the best mechanism to log these values in emacs?
> : > > > 
> : > > > In this case, printf.
> : > > 
> : > > When I add this assumption:
> : > > 
> : > > modified   src/fileio.c
> : > > @@ -4805,8 +4805,11 @@ DEFUN ("insert-file-contents", Finsert_file_contents, Sinsert_file_contents,
> : > >   	/* 'try' is reserved in some compilers (Microsoft C).  */
> : > >   	ptrdiff_t trytry = min (gap_size, READ_BUF_SIZE);
> : > > +	ptrdiff_t trytry_old = min (total - inserted, READ_BUF_SIZE);
> : > >   	if (!NILP (end))
> : > >   	  trytry = min (trytry, total - inserted);
> : > > +	if (trytry != trytry_old)
> : > > +	  abort ();
> : > >   	if (!seekable && NILP (end))
> : > >   	  {
> : > > 
> : > > and make bootstrap, temacs aborts.
> : > > 
> : > > Can someone tell if this assumption should hold?
> : > 
> : > You expect READ_BUF_SIZE to never be greater than gap_size?
> : 
> : Don't know.  This is how I understood Jonathan's nail saying works with this
> : old code, doesn't work with this new code.
> 
> I'm willing to log some meaningful stats if that would help. Last time I logged these values, I was inundated with info, but if I could
> narrow it down to the most useful cases, I could log the relevant bits and report back.

you mean, the fix I installed on master yesterday didn't fix your
problem?  It did fix Gerd's problem.