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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 B82E2C433B4 for ; Tue, 6 Apr 2021 14:25:59 +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 2D353613AE for ; Tue, 6 Apr 2021 14:25:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D353613AE 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]:33436 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lTmeU-0000wS-45 for qemu-devel@archiver.kernel.org; Tue, 06 Apr 2021 10:25:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41208) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lTmdO-0008O0-GT for qemu-devel@nongnu.org; Tue, 06 Apr 2021 10:24:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45885) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lTmdL-0000cL-RB for qemu-devel@nongnu.org; Tue, 06 Apr 2021 10:24:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617719085; 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=IqDIYISWYBOorDobsTgKcwUBhbKATYdUXcLnNEy5fGg=; b=OMPtSVE3Li7P8xQOxicXnmgkPOr4FD8BqzwMzt0o2HM5rHyHBjpKoBXBVMVr8aRkhRPGhG opzHubbVczQr8kQEYwWo2x9hvlY+RudRTtoh6cDVHO+ZDPUiXm+BMEf46b7h8YNx+ySqOw 0gVoq5RgUnR/IGX2BTv5yTBGROVR914= 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-13-8w891s8HOeeG__pk82Xc8Q-1; Tue, 06 Apr 2021 10:24:43 -0400 X-MC-Unique: 8w891s8HOeeG__pk82Xc8Q-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7CAB8839A42; Tue, 6 Apr 2021 14:24:42 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-113-169.ams2.redhat.com [10.36.113.169]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 527F718A79; Tue, 6 Apr 2021 14:24:37 +0000 (UTC) Subject: Re: [PATCH v2 2/2] block/rbd: Add an escape-aware strchr helper To: Connor Kuehl , qemu-block@nongnu.org References: <20210401210150.2127670-1-ckuehl@redhat.com> <20210401210150.2127670-3-ckuehl@redhat.com> From: Max Reitz Message-ID: Date: Tue, 6 Apr 2021 16:24:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210401210150.2127670-3-ckuehl@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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, NICE_REPLY_A=-0.001, 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 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: kwolf@redhat.com, dillaman@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 01.04.21 23:01, Connor Kuehl wrote: > Sometimes the parser needs to further split a token it has collected > from the token input stream. Right now, it does a cursory check to see > if the relevant characters appear in the token to determine if it should > break it down further. > > However, qemu_rbd_next_tok() will escape characters as it removes tokens > from the token stream and plain strchr() won't. This can make the > initial strchr() check slightly misleading since it implies > qemu_rbd_next_tok() will find the token and split on it, except the > reality is that qemu_rbd_next_tok() will pass over it if it is escaped. > > Use a custom strchr to avoid mixing escaped and unescaped string > operations. > > Reported-by: Han Han > Fixes: https://bugzilla.redhat.com/1873913 > Signed-off-by: Connor Kuehl > --- > block/rbd.c | 20 ++++++++++++++++++-- > tests/qemu-iotests/231 | 4 ++++ > tests/qemu-iotests/231.out | 3 +++ > 3 files changed, 25 insertions(+), 2 deletions(-) > > diff --git a/block/rbd.c b/block/rbd.c > index 9071a00e3f..c0e4d4a952 100644 > --- a/block/rbd.c > +++ b/block/rbd.c > @@ -134,6 +134,22 @@ static char *qemu_rbd_next_tok(char *src, char delim, char **p) > return src; > } > > +static char *qemu_rbd_strchr(char *src, char delim) > +{ > + char *p; > + > + for (p = src; *p; ++p) { > + if (*p == delim) { > + return p; > + } > + if (*p == '\\') { > + ++p; > + } > + } > + > + return NULL; > +} > + So I thought you could make qemu_rbd_do_next_tok() to do this. (I didn’t say you should, but bear with me.) That would be possible by giving it a new parameter (e.g. @find), and if that is set, return @end if *end == delim after the loop, and NULL otherwise. Now, if you add wrapper functions to make it nice, there’s not much more difference in lines added compared to just adding a new function, but it does mean your function should basically be the same as qemu_rbd_next_tok(), except that no splitting happens, that there is no *p, and that @end is returned instead of @src. So there is one difference, and that is that qemu_rbd_next_tok() has this condition to skip escaped characters: if (*end == '\\' && end[1] != '\0') { where qemu_rbd_strchr() has only: if (*p == '\\') { And I think qemu_rbd_next_tok() is right; if the string in question has a trailing backslash, qemu_rbd_strchr() will ignore the final NUL and continue searching past the end of the string. Max