[PATCH] fhandler_pipe: add sanity limit to handle loops

[Jeremy Drake]

On Fri, 24 Dec 2021, Ken Brown wrote:

> I agree that it's hard to see how the line you quoted could cause an
> exception.  But you were using an optimized build, so I'm not sure how
> reliable the line-number information is.
>
> Is it feasible to run your test under strace?  If so, you could add some
> debug_printf statements to examine the values of n_handle and
> phi->NumberOfHandles.  Or what about simply adding an assertion that
> phi->NumberOfHandles <= n_handle?
>
> Ken

This issue is not consistent, I was able to reproduce once on x64 by
running commands in a loop overnight, but the next time I tried to
reproduce I ran for over 24 hours without hitting it.

It does seem to happen much more often on Windows on ARM64 (so much so
that at first I thought it was an issue with their emulation).  With this
patch I have not seen the issue again.

Also, it seems to have started cropping up in msys2's CI when the GHA
runner was switched from "windows-2019" to "windows-2022".

I forgot to give a full link to the MSYS2 issue where I have been
investigating this:
https://github.com/msys2/MSYS2-packages/issues/2752