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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 7B17DC48BCD for ; Wed, 9 Jun 2021 16:07:05 +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 182A76139A for ; Wed, 9 Jun 2021 16:07:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 182A76139A 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]:51388 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lr0jQ-0002Rw-0t for qemu-devel@archiver.kernel.org; Wed, 09 Jun 2021 12:07:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58176) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lr0a8-0006xB-QX for qemu-devel@nongnu.org; Wed, 09 Jun 2021 11:57:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:40184) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lr0a6-0007Wq-V9 for qemu-devel@nongnu.org; Wed, 09 Jun 2021 11:57:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623254246; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZvW7duW2k0nKDXCzDSinRyfUS+AB28M4QxQdIb2s160=; b=NWyzX0XeVoYoEQM7FGxp1dLk8VOU+b2qwBPh34y2I84j6uZoppskqtXFGKF7rjrea2FAxB R4RcmIzuKC58ea8CDIdKyjaLi1uv3CZ4syzlcksWKi9DkrC11pz8u3S8AhHrORfBscOulJ 1aGel4c27fZbbn8hF8/LrXV7RZdgNBw= 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-406-CutZiuaXOVSEBzqW19W5IA-1; Wed, 09 Jun 2021 11:57:21 -0400 X-MC-Unique: CutZiuaXOVSEBzqW19W5IA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0C899100C664; Wed, 9 Jun 2021 15:57:21 +0000 (UTC) Received: from redhat.com (ovpn-112-49.ams2.redhat.com [10.36.112.49]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CA14E608BA; Wed, 9 Jun 2021 15:57:19 +0000 (UTC) Date: Wed, 9 Jun 2021 16:57:16 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Richard Henderson Subject: Re: [PATCH 05/26] configure, meson: convert pam detection to meson Message-ID: References: <20210608112301.402434-1-pbonzini@redhat.com> <20210608112301.402434-6-pbonzini@redhat.com> <08135c0f-ce6b-53ad-be57-eba428fbfbf5@linaro.org> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.199, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_SBL_A=0.1 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: Paolo Bonzini , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jun 09, 2021 at 08:46:22AM -0700, Richard Henderson wrote: > On 6/8/21 1:20 PM, Daniel P. Berrangé wrote: > > On Tue, Jun 08, 2021 at 12:45:51PM -0700, Richard Henderson wrote: > > > On 6/8/21 4:22 AM, Paolo Bonzini wrote: > > > > +pam = not_found > > > > +if not get_option('auth_pam').auto() or have_system > > > > + pam = cc.find_library('pam', has_headers: ['security/pam_appl.h'], > > > > > > The condition doesn't look right. > > > Why are we looking for pam if --disable-pam-auth? > > > > > > Surely > > > > > > if not get_option('auth_pam').disabled() and have_system > > > > This isn't entirely obvious at first glance, but the line after > > the one you quote with the 'required' param makes it "do the > > right thing (tm)". > > > > The 'auth_pam' option is a tri-state taking 'enabled', 'disabled' > > and 'auto', with 'auto' being the default state. When a tri-state > > value is passed as the value of the 'required' parameter, then > > > > required==enabled is interpreted as 'required=true' > > required==auto is interpreted as 'required=false' > > required==disabled means the entire call is a no-op > > > > So this logic: > > > > if not get_option('auth_pam').auto() or have_system > > pam = cc.find_library('pam', has_headers: ['security/pam_appl.h'], > > required: get_option('auth_pam'), > > ...) > > > > Means > > > > => If 'auto' is set, then only look for the library if we're > > building system emulators. In this case 'required:' will > > evaluate to 'false', and so we'll gracefully degrade > > if the library is missing. > > If not have_system, there's no point in looking for pam *at all* regardless > of get_option(). In theory we can simplify to if have_system pam = cc.find_library('pam', has_headers: ['security/pam_appl.h'], required: get_option('auth_pam'), ...) and this will be fine for builds with system emulators. The only caveat is that if someone disables system emulators while also passing -Dpam=enabled, we won't check for pam. That is a nonsense combination of course, so probably doesn't matter > > > => If 'disabled' is set, then the 'find_library' call > > will not look for anything, immediately return a > > 'not found' result and let the caller carry on. > > This is not true. If 'required: false', find_library *will* look for the > library, but it will allow it to be missing. feature==disabled does not map to required: false https://mesonbuild.com/Build-options.html#features [quote] enabled is the same as passing required : true. auto is the same as passing required : false. disabled do not look for the dependency and always return 'not-found'. [/quote] 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 :|