Re: [Texmacs-dev] Re: [Bug #1789] temporary files are created in an insecure way

[Joris van der Hoeven]

> The only good reason I see not to put temporary files in "~/.TeXmacs",
> is that on big systems, the admin will typically tune differently the
> filesystems of /home and of /tmp. Also, using /tmp ensures that
> garbage is periodically cleant by the system.

Well, TeXmacs may clear the garbage itself, as it does already
(hmm, maybe I forgot about some stuff in ~/.TeXmacs/system)...

> By the way, it seems that TeXmacs already use ~/.TeXmacs as a
> repository for temporary files, mostly cached stuff. I hate that kind
> of thing. Storing cache in $HOME (as Navigator does) cause backups
> tools to copy a lot of junk if they are not configured specifically to
> avoid that.

No, the caching may improve performance over *several* runs.
For instance, I typically dislike systems where TeX fonts are
created in a directory which is periodically cleant by the system.
Indeed, this forces me to recreate the same fonts many times,
although the sizes of these files have become particularly small,
so I prefer not to delete them.

So I think that caching is a good thing, but it is true that
we might create some user preference later on to finetune
the behaviour.

> However, I find no reason (excepted potential portability issues) not
> to use mkdtemp to create a private directory in /tmp.

That remains a possibility, but why bother, if using ~/.TeXmacs is as good?

> I think the right solution for TeXmacs is using mkdtemp to create a
> private directory in /tmp and have an exit handler clear it. For
> debugging purpose it might be useful to have an option to disable the
> exit handler.
> 
> For additional safety we may check that all files and directories in
> .TeXmacs are only writable by the user, and refuse to run otherwise.

So I think that

  1) I will use ~/.TeXmacs/system/tmp for temporary files.
  2) Clean temporary files as soon as they are no longer needed.
  3) Clean ~/.TeXmacs/system/tmp when booting and at (clean) exit.
  4) Restrict permissions inside ~/.TeXmacs except for ~/.TeXmacs/texts.