Re: patch to fileio.c

[Chong Yidong <cyd@stupidchicken.com>]

"Fabrice Popineau" <fabrice.popineau@supelec.fr> writes:

> You should consider adding the following patch. As I reported earlier,
> the fd file descriptor may be closed twice in insert-file-contents. It
> happens every time a file is visited and this same file is modified
> outside emacs. In this case, you can ask to visit the file again (or
> emacs will ask you if you try to save it)
>
> "File foobar.txt changed on disk. Reread from disk? (yes or no)"
>
> The fd file descriptor in this case is closed by emacs_close() at line
> 3654 and by close_file_unwind() registered at line 3233. When
> emacs_close(fd) is reached, the unwind_protect registered function
> should be removed. Unfortunately, in the mean time other stuff has
> been put in the unwind_protect stack, so you can't just decrement the
> pointer. It can be done when the handled: label is reached. Hence the
> flag in my patch.

Thanks for the patch.  Your analysis sounds correct.

However, I would like to test it first.  Do you have a recipe for
demonstrating incorrect specpdl_ptr handling (e.g. a crash)?