From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Mon, 08 Jan 2024 08:19:57 +0100 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1rMjvR-008VWU-25 for lore@lore.pengutronix.de; Mon, 08 Jan 2024 08:19:57 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1rMjvR-0004Od-0B for lore@pengutronix.de; Mon, 08 Jan 2024 08:19:57 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=9RGQzjANtcVagt4SwRONb4jU7bCEt1JXm5EwCFiANXQ=; b=oTrMYpFLgHOGwbNjVh/IghZrlm 68q0dURvglYpcmOau96Fas/GWHJQWN/Mv9LMYQDn8+UNl4b2OA+DjgY6SfcExSav/sCgjiqHmLNhn EVna95N5FbWN6qIf2TsjnP+Wyx29GWiRnocjNeNToR4nHNobchX3JOCVVSM9Cfnm962T1buvpo9A7 ju2QkTlfa0MWfjYI0baCwswAw6N6xLeEG6eHSpO9raeb3ISuYoCffMTfBeocoWlYoax0ahSfV0m3Q uANYYauaQShxoljqMFV2AAd9R3CLFjY3VMwXqkfjuuPM+G6IzoD6kgzQGXso5MnL5/yXuLLiID9mM 3LeLuEkQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rMjuP-0049mQ-2S; Mon, 08 Jan 2024 07:18:53 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rMjuL-0049lO-37 for barebox@lists.infradead.org; Mon, 08 Jan 2024 07:18:51 +0000 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.whiteo.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1rMjuJ-0004FL-8F; Mon, 08 Jan 2024 08:18:47 +0100 Message-ID: Date: Mon, 8 Jan 2024 08:18:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: Sascha Hauer Cc: barebox@lists.infradead.org References: <20240103181312.409668-1-a.fatoum@pengutronix.de> <20240103181312.409668-48-a.fatoum@pengutronix.de> <20240108071105.GX1318922@pengutronix.de> From: Ahmad Fatoum In-Reply-To: <20240108071105.GX1318922@pengutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240107_231850_023915_875FE080 X-CRM114-Status: GOOD ( 24.67 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-6.2 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH 047/112] string: reduce strjoin runtime, drop trailing separator X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) On 08.01.24 08:11, Sascha Hauer wrote: > On Wed, Jan 03, 2024 at 07:12:07PM +0100, Ahmad Fatoum wrote: >> The implementation of strjoin is a bit suboptimal. The destination >> string is traversed from the beginning due to strcat and we have a >> left-over separator at the end, while it should only be in-between. >> >> Fix this. >> >> Signed-off-by: Ahmad Fatoum >> --- >> Originally posted at: https://lore.barebox.org/barebox/20221027073334.GS6702@pengutronix.de/ > > Once again I ended up reviewing a suboptimal version of strjoin() first > just to find my potential comments addressed in the next patch. So my > comment to the last version still stands: Please implement a good > version of strjoin() first and then switch over to use it. The first patch just moves code around. I find it completely valid to move code before doing changes to it... > >> >> Changes: >> - remove if statemnt in loop (Sascha) >> Signed-off-by: Ahmad Fatoum >> --- >> lib/string.c | 15 ++++++++++----- >> 1 file changed, 10 insertions(+), 5 deletions(-) >> >> diff --git a/lib/string.c b/lib/string.c >> index d8e5edd40648..695e50bc8fc1 100644 >> --- a/lib/string.c >> +++ b/lib/string.c >> @@ -1005,7 +1005,7 @@ char *strjoin(const char *separator, char **arr, size_t arrlen) >> { >> size_t separatorlen; >> int len = 1; /* '\0' */ >> - char *buf; >> + char *buf, *p; >> int i; >> >> separatorlen = strlen(separator); >> @@ -1013,13 +1013,18 @@ char *strjoin(const char *separator, char **arr, size_t arrlen) >> for (i = 0; i < arrlen; i++) >> len += strlen(arr[i]) + separatorlen; > > Not that it matters much for memory usage, but for consistency you could > drop the final separatorlen just like you did for copying the strings > below. > > Sascha > >> >> - buf = xzalloc(len); >> + if (!arrlen) >> + return xzalloc(1); >> >> - for (i = 0; i < arrlen; i++) { >> - strcat(buf, arr[i]); >> - strcat(buf, separator); >> + p = buf = xmalloc(len); >> + >> + for (i = 0; i < arrlen - 1; i++) { >> + p = stpcpy(p, arr[i]); >> + p = mempcpy(p, separator, separatorlen); >> } >> >> + stpcpy(p, arr[i]); >> + >> return buf; >> } >> EXPORT_SYMBOL(strjoin); >> -- >> 2.39.2 >> >> >> > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |