From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Thu, 27 Oct 2022 09:04:29 +0200 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1onwwH-003nPK-Aj for lore@lore.pengutronix.de; Thu, 27 Oct 2022 09:04:29 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1onwwF-0005W9-9y for lore@pengutronix.de; Thu, 27 Oct 2022 09:04:28 +0200 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:From:In-Reply-To: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vFbk1ItkSFGakSou+8AtDVZVw3YWFAjL/bu5slWK8+w=; b=pJliqAgqTCIaOqYkqQfFFv9/tl 5Zt3OiNGqudd0HQ2K0ter7HF5lTINC3aGrsmuhRpBMQuz7MXEVDSmnrJTQvGMr0guGWYQKEUNHqPj tH688OgC5N1TMo5tloO5zj9x8naBjQzFusOb1rr4PfZjT6iMOAuX6TmHUXoqWm0HOw9CzIGPFoCiy 1a1JRY29oMlxnkj/kzrnhNVPkp0nvV/4vfcL6CeTW9GpcGvwjfY/G9fAj40ICf1uF27EXGyeIIqFh hJZ+IG9bYgx7iOV+ZwucKozJw8MpDgvj91csn2NZCAFi3jeZ51V8eNdP+3rgM4+0cF4a7jujuv3t4 +Z+z39vA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1onwuT-00C4tv-8S; Thu, 27 Oct 2022 07:02:38 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1onwov-00C2QG-MQ for barebox@lists.infradead.org; Thu, 27 Oct 2022 06:56:55 +0000 Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1onwou-0004Ag-3Y; Thu, 27 Oct 2022 08:56:52 +0200 Received: from sha by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1onwot-0000wn-Rn; Thu, 27 Oct 2022 08:56:51 +0200 Date: Thu, 27 Oct 2022 08:56:51 +0200 To: Ahmad Fatoum Cc: barebox@lists.infradead.org Message-ID: <20221027065651.GQ6702@pengutronix.de> References: <20221026064205.2360041-1-a.fatoum@pengutronix.de> <20221026064205.2360041-3-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221026064205.2360041-3-a.fatoum@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) From: Sascha Hauer X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221026_235653_788284_3AF72FE4 X-CRM114-Status: GOOD ( 20.07 ) 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.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-4.9 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, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH 3/6] 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.ext.pengutronix.de) On Wed, Oct 26, 2022 at 08:42:02AM +0200, 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. Rather than fixing a just introduced function I would expect a patch introducing strjoin() and then another one converting the time command over to use it. > +void *mempcpy(void *dest, const void *src, size_t count) > +{ > + return memcpy(dest, src, count) + count; > +} > +EXPORT_SYMBOL(mempcpy); > > #ifndef __HAVE_ARCH_MEMMOVE > /** > @@ -943,7 +948,7 @@ 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); > @@ -951,12 +956,14 @@ char *strjoin(const char *separator, char **arr, size_t arrlen) > for (i = 0; i < arrlen; i++) > len += strlen(arr[i]) + separatorlen; > > - buf = xzalloc(len); > + p = buf = xmalloc(len); > > for (i = 0; i < arrlen; i++) { > - strcat(buf, arr[i]); > - strcat(buf, separator); > + p = stpcpy(p, arr[i]); > + p = mempcpy(p, separator, separatorlen); > } > > + p[-separatorlen] = '\0'; That's a bit hard to read. How about: for (i = 0; i < arrlen; i++) { p = stpcpy(p, arr[i]); if (i < arrlen - 1) p = stpcpy(p, separator); } That would also allow you to optimize the allocated buffer size above. Sascha -- 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 |