From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 039C5C021AA for ; Tue, 18 Feb 2025 13:58:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tkO7L-0000da-Qs; Tue, 18 Feb 2025 08:58:31 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tkO7J-0000dN-Ne for qemu-devel@nongnu.org; Tue, 18 Feb 2025 08:58:29 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tkO7I-0001sT-7y for qemu-devel@nongnu.org; Tue, 18 Feb 2025 08:58:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739887107; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+pOSX5NIHHMPhAaq+sG4UYAAQKCwNrzbgBJkeM7u56w=; b=hZp37o29y1Z5Td9vtOawY6inmo3Jgyr4D4fEjS8yY/zkU1Zz4v5AOMz4L3Lym9fP7pNzdE vAM/QwYPJRif+yd8A+FlLGFPhQAbSj2MCVJEObnzp8VOkLmy9PYtUOK/fLgn3Jqsxv8U0y lcXbJo6hBFqdsSAMBldRmcUiOS3Kmdw= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-192-wQ_QSqnHP2el5GHZEKCSow-1; Tue, 18 Feb 2025 08:57:20 -0500 X-MC-Unique: wQ_QSqnHP2el5GHZEKCSow-1 X-Mimecast-MFC-AGG-ID: wQ_QSqnHP2el5GHZEKCSow_1739887039 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EF0181800264; Tue, 18 Feb 2025 13:57:17 +0000 (UTC) Received: from redhat.com (unknown [10.45.226.66]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 27E8A300018D; Tue, 18 Feb 2025 13:57:14 +0000 (UTC) Date: Tue, 18 Feb 2025 14:57:12 +0100 From: Kevin Wolf To: Paolo Bonzini Cc: qemu-devel@nongnu.org, qemu-rust@nongnu.org, qemu-block@nongnu.org Subject: Re: [PATCH 2/2] rust: add module to convert between -errno and io::Error Message-ID: References: <20250213143216.3910163-1-pbonzini@redhat.com> <20250213143216.3910163-3-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250213143216.3910163-3-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.423, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 13.02.2025 um 15:32 hat Paolo Bonzini geschrieben: > It is a common convention in QEMU to return a positive value in case of > success, and a negated errno value in case of error. Unfortunately, > using errno portably in Rust is a bit complicated; on Unix the errno > values are supported natively by io::Error, but on Windows they are not; > so, use the libc crate. > > This is a set of utility functions that are used by both chardev and > block layer bindings. > > Signed-off-by: Paolo Bonzini In my series, this allows a simplification of sorts: let mapping = match qemu_co_run_future(s.map(&req)) { Ok(mapping) => mapping, - Err(e) => { - return -e - .raw_os_error() - .unwrap_or(bindings::EIO as std::os::raw::c_int) - } + Err(e) => return -i32::from(Errno::from(e).0), }; Not really nice yet, though. > +pub fn into_neg_errno>(value: Result) -> T::Out { > + match value { > + Ok(x) => x.map_ok(), > + Err(err) => -T::Out::from(err.into().0), > + } > +} How about making this a method of a trait that is implemented for Result similar to what you already have, but also directly for io::Error (or actually E: Into)? Then the above could become: let mapping = match qemu_co_run_future(s.map(&req)) { Ok(mapping) => mapping, Err(e) => return e.into_neg_errno(), }; Kevin