Re: Finalizing 'inhibit-automatic-native-compilation'

[Eli Zaretskii <eliz@gnu.org>]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: Tatsuya Kinoshita <tats@debian.org>,  emacs-devel@gnu.org,
>   spwhitton@spwhitton.name,  1021842@bugs.debian.org,  Eli Zaretskii
>  <eliz@gnu.org>
> Date: Mon, 20 Feb 2023 09:18:02 +0000
> 
> Andrea Corallo <akrl@sdf.org> writes:
> 
> > Stefan Monnier <monnier@iro.umontreal.ca> writes:
> >
> >>> Shouldn't make-temp-file-internal return a non predictable file name?
> >>
> >> Nope.  It's less predictable but it's still predictable.
> >>
> >>> Otherwise what's the point of using make-temp-file in the first place if
> >>> the temporary name is predictable?
> >>
> >> `make-temp-name` uses `O_EXCL | O_CREAT` so as to close the race
> >> condition: if someone predicated the filename, we detect it atomically
> >> and we try again.
> >>
> >> You might like to check
> >>
> >>     https://wiki.sei.cmu.edu/confluence/display/c/FIO21-C.+Do+not+create+temporary+files+in+shared+directories
> >
> > Thanks for the pointer.
> >
> > I'm still not really convinced we have a problem here with trampolines.
> > With `make-temp-file' we are really only choosing the filename and
> > suggesting it to libgccjit, this last one will perform the file
> > creation.  I'd be surprised if GCC does not handle this correctly, and
> > in case shouldn't this be a GCC bug?
> >
> > OTOH on a slightly differnt subject and in light of this, I think we
> > should probably backport e6043641d30 into emacs-30, so that eln files
> > are created onace and only by libgccjit.  Eli WDYT?
> 
> And BTW, probably also in emacs-28 if we are doing another release.

We don't want to make any enhancements in Emacs 28.3, just to plug the
security hole.  People who want enhancements will need to wait for
Emacs 29.1, hopefully not too long.