From: Frank Terbeck <ft@bewatermyfriend.org>
To: Mark H Weaver <mhw@netris.org>
Cc: 18592@debbugs.gnu.org
Subject: bug#18592: FFI should have portable access to ‘errno’
Date: Tue, 11 Nov 2014 21:02:20 +0100 [thread overview]
Message-ID: <87k331v73n.fsf@ft.bewatermyfriend.org> (raw)
In-Reply-To: <87wq71ixtw.fsf@yeeloong.lan> (Mark H. Weaver's message of "Tue, 11 Nov 2014 10:03:23 -0500")
Mark H. Weaver wrote:
> Frank Terbeck <ft@bewatermyfriend.org> writes:
[...]
>> Mark Weaver on IRC thought it would be a good idea to add portable
>> access to the contents of ‘errno’ (however it's actually implemented) to
>> Guile's FFI. And now the idea has entered the bug tracker. :)
>
> Indeed, thanks for filing this ticket.
>
> I see a problem with this idea: something (e.g. a system async) might
> change 'errno' before the Scheme code fetches the 'errno' value.
Yes. Ludovic hinted at the use of ‘call-with-blocked-asyncs’ to avoid
this. To deal with that, I wrote a macro for guile-termios¹:
(define-syntax-rule (call-with-errno (errno exp) fail0 fail1 ...)
(let-values (((failed? errno) (call-with-blocked-asyncs
(lambda ()
(let* ((f? (termios-failure? exp))
(err (if f? (get-errno) 0)))
(values f? err))))))
(if failed?
(begin fail0 fail1 ...)
#t)))
That seems to work fine, unless I'm missing something.
Regards, Frank
¹ https://github.com/ft/guile-termios
next prev parent reply other threads:[~2014-11-11 20:02 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-30 20:17 bug#18592: FFI should have portable access to ‘errno’ Frank Terbeck
2014-11-11 15:03 ` Mark H Weaver
2014-11-11 20:02 ` Frank Terbeck [this message]
2014-11-13 17:12 ` Mark H Weaver
2014-11-22 17:53 ` Chaos Eternal
2015-01-19 20:22 ` Ludovic Courtès
2015-01-24 8:08 ` Mark H Weaver
2015-01-24 8:22 ` Mark H Weaver
2015-01-24 10:33 ` Ludovic Courtès
2015-12-31 12:33 ` Nala Ginrut
2016-01-04 12:04 ` Nala Ginrut
2016-01-04 16:12 ` Mark H Weaver
2016-01-04 19:14 ` Nala Ginrut
2016-01-05 2:24 ` Chaos Eternal
2016-01-05 7:49 ` tomas
2016-01-05 8:38 ` Nala Ginrut
2016-01-05 15:08 ` Mark H Weaver
2016-01-05 19:21 ` Nala Ginrut
2016-02-18 8:25 ` Nala Ginrut
2016-02-18 13:30 ` Mark H Weaver
2016-02-19 5:02 ` Nala Ginrut
2016-02-26 11:18 ` Nala Ginrut
2016-03-03 17:36 ` Mark H Weaver
2016-03-03 20:32 ` tomas
2016-03-13 17:06 ` Nala Ginrut
2016-06-20 19:55 ` Mark H Weaver
2016-01-05 15:40 ` Mark H Weaver
2016-01-04 16:21 ` Mark H Weaver
2015-01-25 20:59 ` guile
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