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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 E2059C43381 for ; Mon, 18 Feb 2019 17:44:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA9C4217F5 for ; Mon, 18 Feb 2019 17:44:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388101AbfBRRok (ORCPT ); Mon, 18 Feb 2019 12:44:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:43592 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387866AbfBRRok (ORCPT ); Mon, 18 Feb 2019 12:44:40 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 57D4D2146F; Mon, 18 Feb 2019 17:44:39 +0000 (UTC) Date: Mon, 18 Feb 2019 12:44:37 -0500 From: Steven Rostedt To: Slavomir Kaslev Cc: linux-trace-devel@vger.kernel.org, slavomir.kaslev@gmail.com Subject: Re: [RFC PATCH v6 07/11] trace-cmd: Add `trace-cmd setup-guest` command Message-ID: <20190218124437.0761e27b@gandalf.local.home> In-Reply-To: <20190218143746.GD11734@box> References: <20190214141335.28144-1-kaslevs@vmware.com> <20190214141335.28144-8-kaslevs@vmware.com> <20190214154132.43082ece@gandalf.local.home> <20190218143746.GD11734@box> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org On Mon, 18 Feb 2019 16:37:47 +0200 Slavomir Kaslev wrote: > This won't work as proposed: `p` will be NULL on the last iteration but will > still get incremented from the outer for-loop and the check (p && *p) won't get > triggered (p == 0x01 in this case). I still don't like the "end", it just looks awkward. > > A fixed version might look like this: > > static int make_dir(const char *path, mode_t mode) > { > char buf[PATH_MAX+1], *p; > int ret = 0; > > strncpy(buf, path, sizeof(buf)); > for (p = buf; *p; p++) { > for (; *p == '/'; p++); > p = strchr(p, '/'); > > if (p) > *p = '\0'; > ret = mkdir(buf, mode); > if (ret < 0) { > if (errno != EEXIST) { > ret = -errno; > break; > } > ret = 0; > } > if (!p) > break; > *p = '/'; > } > > return ret; > } > > OTOH I find the original version much more readable: > > static int make_dir(const char *path, mode_t mode) > { > char buf[PATH_MAX+1], *end, *p; > int ret = 0; > > end = stpncpy(buf, path, sizeof(buf)); > for (p = buf; p < end; p++) { > for (; p < end && *p == '/'; p++); > for (; p < end && *p != '/'; p++); > > *p = '\0'; > ret = mkdir(buf, mode); > if (ret < 0) { > if (errno != EEXIST) { > ret = -errno; > break; > } > ret = 0; > } > *p = '/'; > } > > return ret; > } > > The intent behind `*p = '\0'; ... *p = '/';` is more clearly expressed in this > version without getting bogged down by strchr() edge case handling. > > Since this is not on a performance critical path how about sticking to the more > readable of the two? > I'd still like to use '*p' as that's very common. Also break up the other for loops into a while loops. for (p = buf; *p; p++) { while (*p == '/') p++; while (*p && *p != '/') p++; if (*p) *p = '\0'; else p--; /* for the for loop */ [...] This would work, and I think is still readable. It matches more the standard way of the Linux kernel as well. -- Steve