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=-6.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 65CF6C48BC2 for ; Sun, 27 Jun 2021 19:46:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 413FF61606 for ; Sun, 27 Jun 2021 19:46:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231516AbhF0TtH (ORCPT ); Sun, 27 Jun 2021 15:49:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231468AbhF0TtG (ORCPT ); Sun, 27 Jun 2021 15:49:06 -0400 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4460FC061574 for ; Sun, 27 Jun 2021 12:46:42 -0700 (PDT) Received: by mail-wm1-x335.google.com with SMTP id p10-20020a05600c430ab02901df57d735f7so12128488wme.3 for ; Sun, 27 Jun 2021 12:46:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=DAErNgS/j8DCnY2ERck8XX1Z4inkZWw1VYk+KrVuhjw=; b=d3IvLBXijKA9l46yQ/gF3Sl1dZ7mbgqFHBwnWpWr0Ym1mERWL/B66G89f8LmQSiiT2 K/qvUkVswZ1mIdDkAKfDo21D1T64OGmQAneu160iTTLF9eBUEYDfnlU7nlxmtZjsMfqz cGoRO4sYs9ltL4MPR1ImZ5SxlHJbesXhhb+tcdQAgK1XPS+SM7yv+ptRaMEg/+Cb5IWo 75Ulw3Sn9OmM8hrx3jHbKwm+z2pxtTw+VZFbnOkdjotJsXkSMr3P3ohzgJKcwx75S0Hh DFVL8d19ZdAMSPMotGz50prA4xdu5F235mEdABJfa3Ql0F7iZk+CUhRdoV+E8SLWhFOV i7OQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=DAErNgS/j8DCnY2ERck8XX1Z4inkZWw1VYk+KrVuhjw=; b=fDuxWHjanIh9pDE6oIkkzSfncnheZMhkm7/fsj51u5sYMpFK9WvyZ1OJQ2M9EFGUL8 U5WcKXLvHW/TvJe27UELypgDnIrGPVCSB0i91ylIPiUuCaq7Vg80lzh2Viz6AHIcW3Kn zg5BniqtolyDIyVpgyd6B82O3jSciz1ottv/XwR7kHhvDxm13qewYsL663Lr8JLbWu8v FWNHCr6QqcLCMl/CPnEvVl1tXhPQxr4gH9sheWgq+QZ17eDJTXowK2VPOdzMsaf50MsD 7ugPE43bke12ZpnZikdIANNLFJIF7kOhOa2VMjNiy6VJIRddYHa0dD2Swh9h/QAE7Th6 wzMA== X-Gm-Message-State: AOAM532zertTrldODdCqsBKxMJVBOGMJXc9TVWLrZfpTq2d0mvV8bxfz SOTLmc9WDcW49TSUNKCA9FVqY81hUOc= X-Google-Smtp-Source: ABdhPJxRN2p0uVsep9uFsS1xMSmExZeXxLSkk0jSME26BDXwBp/th5Be0d6L+/yjmnRb05ilkTMgjQ== X-Received: by 2002:a05:600c:a45:: with SMTP id c5mr23077064wmq.153.1624823200906; Sun, 27 Jun 2021 12:46:40 -0700 (PDT) Received: from [10.8.0.150] ([195.53.121.100]) by smtp.gmail.com with ESMTPSA id g17sm7466428wrw.31.2021.06.27.12.46.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Jun 2021 12:46:40 -0700 (PDT) Subject: Re: [RFC] strcpys(): New function for copying strings safely From: "Alejandro Colomar (man-pages)" To: glibc Cc: tech@openbsd.org, Christoph Hellwig , "linux-kernel@vger.kernel.org" References: <755875ec-baae-6cab-52a8-3c9530db1ce6@gmail.com> Message-ID: <38428d5e-ead2-bf18-e198-cecd4caeb3e7@gmail.com> Date: Sun, 27 Jun 2021 21:46:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <755875ec-baae-6cab-52a8-3c9530db1ce6@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/27/21 9:26 PM, Alejandro Colomar (man-pages) wrote: > > It is designed so that usage requires the minimum number of lines of > code for complete usage (including error handling checks): > > [[ > // When we already checked that 'size' is >= 1 > // and truncation is not an issue: > > strcpys_np(size, dest, src, NULL); Also, given how unlikely this case is, I have in my code: `[[gnu::warn_unused_result]]` I forgot to talk about it in the definition I sent. I would put that attribute in the glibc definition, if this is added to glibc. To ignore it, a simple cast of the result to `(void)` should be enough (or a more complex macro, like `UNUSED(strcpys_np(...));`). > > [[ > > #include > #include > > > [[gnu::nonnull]] > ssize_t strscpy_np(ssize_t size, >                    char dest[static restrict size], >                    const char src[static restrict size]) > { >     ssize_t len; > >     if (size <= 0) >         return -1; > >     len = strnlen(src, size - 1); >     memcpy(dest, src, len); >     dest[len] = '\0'; > >     return len; > } > > [[gnu::nonnull(2, 3)]] [[gnu::warn_unused_result]] > int strcpys_np(ssize_t size, >                char dest[static restrict size], >                const char src[static restrict size], >                ssize_t *restrict len) > { >     ssize_t l; > >     l = strscpy_np(size, dest, src); >     if (len) >         *len = l; > >     if (l == -1) >         return -1; >     if (l >= size) >         return 1; >     return 0; > } > > ]] -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/