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 X-Spam-Level: X-Spam-Status: No, score=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4515C55179 for ; Fri, 30 Oct 2020 09:17:54 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 441B9207DE for ; Fri, 30 Oct 2020 09:17:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C9pzjC99" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 441B9207DE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51208 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kYQXh-00070u-2L for qemu-devel@archiver.kernel.org; Fri, 30 Oct 2020 05:17:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57336) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kYQWQ-0006My-Mx for qemu-devel@nongnu.org; Fri, 30 Oct 2020 05:16:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25653) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kYQWO-0000SF-NQ for qemu-devel@nongnu.org; Fri, 30 Oct 2020 05:16:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1604049392; h=from:from:reply-to: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=08Ota15zfhDnw1Wa82QJvyhl/zON0Cheo9LP/5MheaY=; b=C9pzjC99vnax8notC4hKq2sMSGoJqTByBF2mw+vYDlC7BNsRCRh8YaBsnRu21Up1nq9j8r 8kD5Hyo1ukFbhqBNv7/S9OQB7n3xVndWOB3LRszj0/ppXxmDTdn1709j2j8ebmZAZu/jIx pgmIk8cS9eUiiklCKWwFh0iGor2PMKw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-401-GcZcoCq3MQKI9wj4N62V-A-1; Fri, 30 Oct 2020 05:16:27 -0400 X-MC-Unique: GcZcoCq3MQKI9wj4N62V-A-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F49910066FB; Fri, 30 Oct 2020 09:16:26 +0000 (UTC) Received: from redhat.com (ovpn-113-50.ams2.redhat.com [10.36.113.50]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2790819C71; Fri, 30 Oct 2020 09:16:20 +0000 (UTC) Date: Fri, 30 Oct 2020 09:16:18 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Eric Blake Subject: Re: Our abstract UNIX domain socket support is a mess Message-ID: <20201030091618.GB99222@redhat.com> References: <87o8kmwmjh.fsf@dusky.pond.sub.org> <20201029140242.GE27369@redhat.com> <20201029160744.GB6271@merkur.fritz.box> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/30 02:24:40 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , xiaoqiang zhao , qemu-devel@nongnu.org, Markus Armbruster , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Oct 29, 2020 at 01:47:02PM -0500, Eric Blake wrote: > On 10/29/20 11:07 AM, Kevin Wolf wrote: > > >>> > >>> QEMU's interface is differently messy. > >>> > >>> Our equivalent to struct sockaddr_un is QAPI type UnixSocketAddress: > >>> > >>> { 'struct': 'UnixSocketAddress', > >>> 'data': { > >>> 'path': 'str' } > >>> > >>> @path corresponds to sockaddr_un member sun_path. sun_family = AF_UNIX > >>> and socklen_t sizeof(sockaddr_un) are implied. > >>> > >>> We didn't repurpose @path for abstract sockets like the Linux kernel did > >>> with sun_path. Instead, we added a flag @abstract (default false). > >>> When it's on, we make a binary blob by prefixing @path with a 0 byte, > >>> and pad it with more 0 bytes. > >>> > >>> We added a second flag @tight (default true) to optionally cut the > >>> socklen_t to the end of the string (the terminating 0 byte is not > >>> included). > >>> > > > Using magic characters in strings to distinguish different types of > > objects is always wrong in QAPI. If we interpreted leading '@' this way, > > you wouldn't be able to specify a relative filename starting with '@' > > any more. > > > >> Or, just or by having explicit flags "abstract" and "tight" to > >> control the behaviour. The latter is what 'socat' does to allow > >> use of abstract sockets. > >> > >> For QEMU the former approach gives broad interoperabiltiy with > >> userspace applications, so made more sense than using magic "@". > > > > Boolean flags to distinguish different types are better than parsing > > strings, but still not optimal. Documentation like "only matters for > > abstract sockets" is another hint that we're treating things the same > > that aren't the same. > > But why two boolean flags for three sensible states (where it is unclear > if the fourth combination that makes no sense is silently accepted or > loudly rejected), instead of a single tri-state-valued enum? This is simply mirroring what "socat" supports as configuration. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|