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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 D96DCC2BA19 for ; Tue, 14 Apr 2020 17:34:39 +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 A68CD2054F for ; Tue, 14 Apr 2020 17:34:39 +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="jJcK90Ie" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A68CD2054F 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]:36400 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jOPSI-0006GD-SN for qemu-devel@archiver.kernel.org; Tue, 14 Apr 2020 13:34:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45805) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jOP7t-0000aQ-Bf for qemu-devel@nongnu.org; Tue, 14 Apr 2020 13:13:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jOP7r-0004Je-6v for qemu-devel@nongnu.org; Tue, 14 Apr 2020 13:13:32 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:28177 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jOMdm-0000KA-Az for qemu-devel@nongnu.org; Tue, 14 Apr 2020 10:34:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586874858; 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=sFzhb4kAEqasUttGXHDzOYFmUYzd9ujfsvx8e7mBgk0=; b=jJcK90Ie1L9mknYfx9KPCzKiSZqN9Ddi+L+b/3ShKDDgha7ApVVS+bzN0wdI9ZhGJv+D4G 6fWT1KKVF45IECz9xNB/iDKqT8ufhk7Bz8haSacY/FN5fZBraEqFThGPoPFe302qGzArWC AMmxH9eJyFShcK84wDmWfcaQqkAlnSM= 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-292-StHte5k0PMG5agVruekZxA-1; Tue, 14 Apr 2020 10:34:15 -0400 X-MC-Unique: StHte5k0PMG5agVruekZxA-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 954D9107ACCD; Tue, 14 Apr 2020 14:34:14 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-113-20.ams2.redhat.com [10.36.113.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5EA8B99DFD; Tue, 14 Apr 2020 14:34:14 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id BE89411385C8; Tue, 14 Apr 2020 16:34:12 +0200 (CEST) From: Markus Armbruster To: Kevin Wolf Subject: Re: [PATCH for-5.1 8/8] qemu-option: Move is_valid_option_list() to qemu-img.c and rewrite References: <20200409153041.17576-1-armbru@redhat.com> <20200409153041.17576-9-armbru@redhat.com> <87k12ixxlb.fsf@dusky.pond.sub.org> Date: Tue, 14 Apr 2020 16:34:12 +0200 In-Reply-To: <87k12ixxlb.fsf@dusky.pond.sub.org> (Markus Armbruster's message of "Tue, 14 Apr 2020 10:47:44 +0200") Message-ID: <87blnup257.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 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 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 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" Markus Armbruster writes: > Eric Blake writes: > >> On 4/9/20 10:30 AM, Markus Armbruster wrote: >>> is_valid_option_list()'s purpose is ensuring qemu-img.c's can safely >>> join multiple parameter strings separated by ',' like this: >>> >>> g_strdup_printf("%s,%s", params1, params2); >>> >>> How it does that is anything but obvious. A close reading of the code >>> reveals that it fails exactly when its argument starts with ',' or >>> ends with an odd number of ','. Makes sense, actually, because when >>> the argument starts with ',', a separating ',' preceding it would get >>> escaped, and when it ends with an odd number of ',', a separating ',' >>> following it would get escaped. >>> >>> Move it to qemu-img.c and rewrite it the obvious way. >>> >>> Signed-off-by: Markus Armbruster >>> --- >>> include/qemu/option.h | 1 - >>> qemu-img.c | 26 ++++++++++++++++++++++++++ >>> util/qemu-option.c | 22 ---------------------- >>> 3 files changed, 26 insertions(+), 23 deletions(-) >>> >> >>> +++ b/qemu-img.c >>> @@ -223,6 +223,32 @@ static bool qemu_img_object_print_help(const char = *type, QemuOpts *opts) >>> return true; >>> } >>> +/* >>> + * Is @optarg safe for accumulate_options()? >>> + * It is when multiple of them can be joined together separated by ','= . >>> + * To make that work, @optarg must not start with ',' (or else a >>> + * separating ',' preceding it gets escaped), and it must not end with >>> + * an odd number of ',' (or else a separating ',' following it gets >>> + * escaped). >>> + */ >>> +static bool is_valid_option_list(const char *optarg) >>> +{ >>> + size_t len =3D strlen(optarg); >>> + size_t i; >>> + >>> + if (optarg[0] =3D=3D ',') { >>> + return false; >>> + } >>> + >>> + for (i =3D len; i > 0 && optarg[i - 1] =3D=3D ','; i--) { >>> + } >>> + if ((len - i) % 2) { >>> + return false; >>> + } >>> + >>> + return true; >> >> Okay, that's easy to read. Note that is_valid_option_list("") returns >> true. > > Hmm, that's a bug: > > $ qemu-img create -f qcow2 -o backing_file=3Da -o "" -o backing_fmt= =3Draw,size=3D1M new.qcow2 > qemu-img: warning: Could not verify backing image. This may become an= error in future versions. > Could not open 'a,backing_fmt=3Draw': No such file or directory > Formatting 'new.qcow2', fmt=3Dqcow2 size=3D1048576 backing_file=3Da,,= backing_fmt=3Draw cluster_size=3D65536 lazy_refcounts=3Doff refcount_bits= =3D16 > $ qemu-img info new.qcow2=20 > image: new.qcow2 > file format: qcow2 > virtual size: 1 MiB (1048576 bytes) > disk size: 196 KiB > cluster_size: 65536 > --> backing file: a,backing_fmt=3Draw > Format specific information: > compat: 1.1 > lazy refcounts: false > refcount bits: 16 > corrupt: false > > My rewrite preserves this bug. Will fix in v2. Kevin, two obvious fixes: * Make is_valid_option_list() reject -o "" * Make accumulate_options(options, "") return options. Got a preference? [...]