Subject: bug#29170: Infinite loop noticed on Emacs in OpenBSD

From: Stefan Kangas <[email-masked]>
Date: Mon, 24 Aug 2020 07:45:11 -0400

[Accidentally sent off-list, forwarding message to bug tracker.]

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From: Stefan Kangas <[email-masked]>
To: Manuel Giraud <[email-masked]>
Subject: Re: bug#29170: Infinite loop noticed on Emacs in OpenBSD
Date: Mon, 10 Aug 2020 09:25:29 -0700

Manuel Giraud <[email-masked]> writes:

> Hi,
>
> Here is a patch against HEAD to avoid the hang in infinite loop. The
> 'x-selection-timeout' pause will still be there even with this patch.
>
> My understandings:
>
> On OpenBSD, most of the time, the function
> "xselect.c/x_get_foreign_selection" won't get a SelectNotify with
> (SECONDARY, TEXT) as arguments (that I did not understand and it might
> never happen on other oses).
>
> But then, while waiting at most 'x-selection-timeout' into
> "process.c/wait_reading_process_output" the 'now' variable won't have a
> chance of being invalidated or updated and that is what cause the
> infinite loop.
>
> Someone more knowledgeable of "process.c/wait_reading_process_output"
> might have a better solution to this problem.
>
> diff --git a/src/process.c b/src/process.c
> index fc46e74332..25bd28a82b 100644
> --- a/src/process.c
> +++ b/src/process.c
> @@ -5115,8 +5115,7 @@ wait_reading_process_output (intmax_t time_limit, int nsecs, int read_kbd,
>        /* Exit if already run out.  */
>        if (wait == TIMEOUT)
>  	{
> -	  if (!timespec_valid_p (now))
> -	    now = current_timespec ();
> +	  now = current_timespec ();
>  	  if (timespec_cmp (end_time, now) <= 0)
>  	    break;
>  	  timeout = timespec_sub (end_time, now);

That was almost 3 years ago.  Is this still an issue on recent versions
of Emacs?

Best regards,
Stefan Kangas
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