From patchwork Sat Dec 19 10:55:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Markus Armbruster X-Patchwork-Id: 1418669 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=MQvSpYH0; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 4CyjRd1Tbzz9sT6 for ; Sat, 19 Dec 2020 21:59:41 +1100 (AEDT) Received: from localhost ([::1]:52948 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kqZxb-0002X6-68 for incoming@patchwork.ozlabs.org; Sat, 19 Dec 2020 05:59:39 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50642) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kqZtn-0004gH-IV for qemu-devel@nongnu.org; Sat, 19 Dec 2020 05:55:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:54440) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kqZtj-0007EK-LV for qemu-devel@nongnu.org; Sat, 19 Dec 2020 05:55:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608375338; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vOPPEvGdRvMuw2quKrOVE7sPxJD3SHwa7zeZkOrTbzw=; b=MQvSpYH0bFFYMAxbWsFhkykPLvGpqz8WzUBmjaCkF5f9uKODsIOfSpzNoVSAcPOw66QhpN Q30u+yedN74Sdn0s2Cyn4WykPgpZKcrwhPOAxgMtDKRVd6gAlfR5bCD0p2LwHtrqdXmcte iJl57a4BXk+LRASanL3kijbyhXT42yY= 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-466-u4VOvFIyMYKQYSznvPUCOw-1; Sat, 19 Dec 2020 05:55:36 -0500 X-MC-Unique: u4VOvFIyMYKQYSznvPUCOw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 921D7801AA3; Sat, 19 Dec 2020 10:55:35 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-103.ams2.redhat.com [10.36.112.103]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 65BDF60C62; Sat, 19 Dec 2020 10:55:35 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 739F111275F3; Sat, 19 Dec 2020 11:55:32 +0100 (CET) From: Markus Armbruster To: qemu-devel@nongnu.org Subject: [PULL 11/33] string-output-visitor: Fix to use sufficient precision Date: Sat, 19 Dec 2020 11:55:10 +0100 Message-Id: <20201219105532.1734134-12-armbru@redhat.com> In-Reply-To: <20201219105532.1734134-1-armbru@redhat.com> References: <20201219105532.1734134-1-armbru@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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: , Cc: peter.maydell@linaro.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" The string output visitor should serialize numbers so that the string input visitor deserializes them back to the same number. It fails to do so. print_type_number() uses format %f. This is prone to nasty rounding errors. For instance, numbers between 0 and 0.0000005 get flushed to zero. We currently use this visitor only for HMP info migrate, info network, info qtree, and info memdev. No double values occur there as far as I can tell. Fix anyway by formatting with %.17g. 17 decimal digits always suffice for IEEE double. See also recent commit "qobject: Fix qnum_to_string() to use sufficient precision". Signed-off-by: Markus Armbruster Message-Id: <20201210161452.2813491-9-armbru@redhat.com> --- qapi/string-output-visitor.c | 2 +- tests/test-string-output-visitor.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c index b74aa4d44c..5506c933de 100644 --- a/qapi/string-output-visitor.c +++ b/qapi/string-output-visitor.c @@ -258,7 +258,7 @@ static bool print_type_number(Visitor *v, const char *name, double *obj, Error **errp) { StringOutputVisitor *sov = to_sov(v); - string_output_set(sov, g_strdup_printf("%f", *obj)); + string_output_set(sov, g_strdup_printf("%.17g", *obj)); return true; } diff --git a/tests/test-string-output-visitor.c b/tests/test-string-output-visitor.c index cec20848ea..0dae04b960 100644 --- a/tests/test-string-output-visitor.c +++ b/tests/test-string-output-visitor.c @@ -136,7 +136,7 @@ static void test_visitor_out_number(TestOutputVisitorData *data, visit_type_number(data->ov, NULL, &value, &error_abort); str = visitor_get(data); - g_assert_cmpstr(str, ==, "3.141593"); + g_assert_cmpstr(str, ==, "3.1415926535897931"); } static void test_visitor_out_string(TestOutputVisitorData *data,