GNU bug report logs - #18592
FFI should have portable access to ‘errno’

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Message #10 received at 18592 <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: Frank Terbeck <ft <at> bewatermyfriend.org>
Cc: 18592 <at> debbugs.gnu.org
Subject: Re: bug#18592: FFI should have portable access to ‘errno’
Date: Tue, 11 Nov 2014 10:03:23 -0500

Frank Terbeck <ft <at> bewatermyfriend.org> writes:

> When accessing POSIX functions from a system's libc via Guile's dynamic
> FFI, you commonly want to access the ‘errno’ variable to be able to
> produce useful diagnostic messages.
>
> Currently there's no such access built-in.
>
> 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.

     Mark

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