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=-5.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 C7325C2BA19 for ; Tue, 14 Apr 2020 17:26:43 +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 9310C20678 for ; Tue, 14 Apr 2020 17:26:43 +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="h98ivOh8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9310C20678 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]:36114 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jOPKc-00047T-Mi for qemu-devel@archiver.kernel.org; Tue, 14 Apr 2020 13:26:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39427) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jOOwj-0007fu-66 for qemu-devel@nongnu.org; Tue, 14 Apr 2020 13:02:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jOOwf-0002r1-AG for qemu-devel@nongnu.org; Tue, 14 Apr 2020 13:02:01 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:43818 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jOMBu-0001l5-3T for qemu-devel@nongnu.org; Tue, 14 Apr 2020 10:05:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586873129; 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=7c+Lu2vsbU84O+Xkqb0dwQFHWNxrp0KfedEvIPj8EBk=; b=h98ivOh87/gwh26U2Hc+cpeqesvuDgD9iPRIbNKToD3AO02yEH6+yklvwB8uo4EFxCIzoi VDS5y2TXvKQTQ0OVDO09NrsTFh3SZ1nJntfeRfj+S6C6qW0ustApDhHKfHRPr3DspALLmn ALxgbwZ3lIwaXEQ/jROKLJnqQgyFqqQ= 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-408-lJxFm8vzNhCKdpuk2MCeYg-1; Tue, 14 Apr 2020 10:05:26 -0400 X-MC-Unique: lJxFm8vzNhCKdpuk2MCeYg-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 D6DC5802568; Tue, 14 Apr 2020 14:05:21 +0000 (UTC) Received: from linux.fritz.box (ovpn-114-1.ams2.redhat.com [10.36.114.1]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7E4039F99D; Tue, 14 Apr 2020 14:05:19 +0000 (UTC) Date: Tue, 14 Apr 2020 16:05:17 +0200 From: Kevin Wolf To: Markus Armbruster Subject: Re: [PATCH for-5.1 2/8] qemu-options: Factor out get_opt_name_value() helper Message-ID: <20200414140517.GF7747@linux.fritz.box> References: <20200409153041.17576-1-armbru@redhat.com> <20200409153041.17576-3-armbru@redhat.com> <5f39e636-f799-55f3-873f-08a3a0f53dca@redhat.com> <87blnuwght.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87blnuwght.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 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: qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 14.04.2020 um 11:42 hat Markus Armbruster geschrieben: > Eric Blake writes: >=20 > > On 4/9/20 10:30 AM, Markus Armbruster wrote: > >> The next commits will put it to use. > >> > >> Signed-off-by: Markus Armbruster > >> --- > >> util/qemu-option.c | 102 +++++++++++++++++++++++++------------------= -- > >> 1 file changed, 56 insertions(+), 46 deletions(-) > >> > > > >> +static const char *get_opt_name_value(const char *params, > >> + const char *firstname, > >> + char **name, char **value) > >> +{ > >> + const char *p, *pe, *pc; > >> + > >> + pe =3D strchr(params, '=3D'); > >> + pc =3D strchr(params, ','); > >> + > >> + if (!pe || (pc && pc < pe)) { > >> + /* found "foo,more" */ > >> + if (firstname) { > >> + /* implicitly named first option */ > >> + *name =3D g_strdup(firstname); > >> + p =3D get_opt_value(params, value); > > > > Is this correct even when params is "foo,,more"? But... > > > >> static void opts_do_parse(QemuOpts *opts, const char *params, > >> const char *firstname, bool prepend, > >> bool *invalidp, Error **errp) > >> { > >> - char *option =3D NULL; > >> - char *value =3D NULL; > >> - const char *p,*pe,*pc; > >> Error *local_err =3D NULL; > >> + char *option, *value; > >> + const char *p; > >> - for (p =3D params; *p !=3D '\0'; p++) { > >> - pe =3D strchr(p, '=3D'); > >> - pc =3D strchr(p, ','); > >> - if (!pe || (pc && pc < pe)) { > >> - /* found "foo,more" */ > >> - if (p =3D=3D params && firstname) { > >> - /* implicitly named first option */ > >> - option =3D g_strdup(firstname); > >> - p =3D get_opt_value(p, &value); > > > > ...in this patch, it is just code motion, so if it is a bug, it's > > pre-existing and worth a separate fix. >=20 > If @p points to "foo,,more", possibly followed by additional characters, > then we have pc && pc < pe, and enter this conditional. This means that >=20 > foo,,more=3D42 >=20 > gets parsed as two name=3Dvalue, either as >=20 > name value > ----------------------- > @firstname "foo,more" > "" "42" >=20 > if @firstname is non-null Hm, how that? get_opt_value() doesn't stop at '=3D', so shouldn't you get a single option @firstname with a value of "foo,more=3D42"? name value ----------------------- @firstname "foo,more=3D42" > or else as >=20 > name value > ----------------- > "foo,,more" "on" > "" "42" Here get_opt_name() stops at the first comma. You get a positive flag "foo" and the remaing option string starts with a comma, so the condition will still be true for the next loop iteration. Now you get a positive flag with an empty name "". Finally, the rest is parsed as an option, so we get: name value ----------------------- "foo" "on" "" "on" "more" "42" Actually, at this point I thought I could just check, and gdb confirms my reading for both cases. This is still crazy, but perhaps less so than the interpretations you suggested. Kevin