From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.droids-corp.org (zoll.droids-corp.org [94.23.50.67]) by dpdk.org (Postfix) with ESMTP id 1F3941B2C7 for ; Fri, 19 Jan 2018 10:07:05 +0100 (CET) Received: from lfbn-lil-1-110-231.w90-45.abo.wanadoo.fr ([90.45.197.231] helo=droids-corp.org) by mail.droids-corp.org with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1ecSdg-00019r-DS; Fri, 19 Jan 2018 10:07:09 +0100 Received: by droids-corp.org (sSMTP sendmail emulation); Fri, 19 Jan 2018 10:07:02 +0100 Date: Fri, 19 Jan 2018 10:07:02 +0100 From: Olivier Matz To: "Xueming(Steven) Li" Cc: Adrien Mazarguil , "dev@dpdk.org" Message-ID: <20180119090702.fpko3aiz27b3heau@platinum> References: <20171115155402.9967-1-xuemingl@mellanox.com> <20171209153923.19958-1-xuemingl@mellanox.com> <20171214153543.2d2ydissujk55cng@platinum> <20180116124549.32w7g5jmhl633m2v@platinum> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Subject: Re: [dpdk-dev] [PATCH v2] lib/cmdline: init CLI parsing memory X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Jan 2018 09:07:05 -0000 On Thu, Jan 18, 2018 at 04:29:59AM +0000, Xueming(Steven) Li wrote: > > > > -----Original Message----- > > From: Olivier Matz [mailto:olivier.matz@6wind.com] > > Sent: Tuesday, January 16, 2018 8:46 PM > > To: Xueming(Steven) Li > > Cc: Adrien Mazarguil ; dev@dpdk.org > > Subject: Re: [PATCH v2] lib/cmdline: init CLI parsing memory > > > > Hi Xueming, > > > > Sorry for the late response. > > > > On Tue, Dec 26, 2017 at 12:57:41PM +0000, Xueming(Steven) Li wrote: > > > HI Olivier, > > > > > > By reading p1 comments carefully, looks like the pointer to result > > > buffer issue not resolved by result copy. How about this: > > > > > > @@ -263,6 +263,7 @@ > > > #ifdef RTE_LIBRTE_CMDLINE_DEBUG > > > char debug_buf[BUFSIZ]; > > > #endif > > > + char *result_buf = result.buf; > > > > > > if (!cl || !buf) > > > return CMDLINE_PARSE_BAD_ARGS; > > > @@ -312,16 +313,13 @@ > > > debug_printf("INST %d\n", inst_num); > > > > > > /* fully parsed */ > > > - tok = match_inst(inst, buf, 0, tmp_result.buf, > > > - sizeof(tmp_result.buf)); > > > + tok = match_inst(inst, buf, 0, result_buf, sizeof(result.buf)); > > > > If we don't use tmp_result, it is maybe better to also replace > > sizeof(result.buf) by CMDLINE_PARSE_RESULT_BUFSIZE > > Thanks, would like to send out new version soon > > > > > > > > > if (tok > 0) /* we matched at least one token */ > > > err = CMDLINE_PARSE_BAD_ARGS; > > > > > > else if (!tok) { > > > debug_printf("INST fully parsed\n"); > > > - memcpy(&result, &tmp_result, > > > - sizeof(result)); > > > /* skip spaces */ > > > while (isblank2(*curbuf)) { > > > curbuf++; > > > @@ -332,6 +330,7 @@ > > > if (!f) { > > > memcpy(&f, &inst->f, sizeof(f)); > > > memcpy(&data, &inst->data, sizeof(data)); > > > + result_buf = tmp_result.buf; > > > } > > > else { > > > /* more than 1 inst matches */ > > > > > > > > > I guess the issue you are talking about is the one described in > > "cmdline: fix dynamic tokens parsing" in my previous description? > > > > I think this patch is ok, and is probably better than the initial > > suggestion, because it avoids to copy the buffer. However, I don't > > understand why the previous patch was wrong, can you detail? > > Let me quote your last email: > " When using dynamic tokens, the result buffer contains pointers > to some location inside the result buffer. When the content of > the temporary buffer is copied in the final one, these pointers > still point to the temporary buffer." > If pointer exist in buffer, the new copy still pint to the old copy > which very probably being changed. In patch v2, I still think it was correct because there were 2 copies: 1/ tok = match_inst(inst, buf, 0, result.buf, sizeof(result.buf)); result is set, it may contain pointers to itself 2/ result_ok = result; result is copied in result_ok result_ok may contain pointer to result 3/ other calls to match_inst(inst, buf, 0, result...) this can clobber the result buffer 4/ result = result_ok; // before calling f() restores the content of result as it was in 1/ it may contain pointers to itself, which is valid Was there another problem I missed? Anyway, I think your v3 is better because it avoids buffer copies. If it's ok for you, please send a v4 with the small updated regarding sizeof(result.buf) -> CMDLINE_PARSE_RESULT_BUFSIZE. Thanks, Olivier