From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-x32e.google.com (mail-wm1-x32e.google.com [IPv6:2a00:1450:4864:20::32e]) by sourceware.org (Postfix) with ESMTPS id 458B33858D28 for ; Thu, 6 Apr 2023 22:34:20 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 458B33858D28 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-wm1-x32e.google.com with SMTP id eo6-20020a05600c82c600b003ee5157346cso52362wmb.1 for ; Thu, 06 Apr 2023 15:34:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680820459; x=1683412459; h=in-reply-to:references:to:from:content-language:subject:user-agent :mime-version:date:message-id:from:to:cc:subject:date:message-id :reply-to; bh=GEhC5EPpauHT45QKwvE+KvUZjge+FtUU8Th8XUYgEP4=; b=EjlNDvEL0W0QhdhbYI+irThU33dH5NnxO8Xanjtr24hpLu44zbQ8/HMBs93gtIeFX4 Y7FTd7horoIBRQihEZ5NMehYIUMz+SL49r9mJcqjlMZLLYZB2HJRMjav2QSLQLuv3mOr y2O6ZZVBCL9iZO3c+S+PVBA/Ozs41NCGBUnpWo+0Er4Vs3lFrqElXgP4POCTQ8Yi/Tww 1ENKCm93kM3vNdcTfCQizq8yEVIV/yZs88jyTW9liuHAj+i+Q6/h5SvV7yDVQ+3GxKlr sNTpDgb4W002WVu2e9f6plLNt+kOtMBG/vnsjiIG3P+mExu3fR8JkjhQFxUOqWLXSb4X q03g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680820459; x=1683412459; h=in-reply-to:references:to:from:content-language:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=GEhC5EPpauHT45QKwvE+KvUZjge+FtUU8Th8XUYgEP4=; b=aZWbfIz6OrIIADdCwJtdsfNqS0NAa2BWhRvgPHFHtR81qy0mg1FK9rVIVvCUWpQffX iZvyKXkbdgjRcVBJgFsA3ptwpGKGkuaqKWw9iN3rGr8Ekf4PZJbV5eUTQnLjfKRGf1Pz FujrIOUTb5Xm3TJd5RLfKAwAk5WVlTZuwj/VdZFIvwPgn8jhOt9boHJ/sUQ9TyjDrc7A C2scLrPQGs3JHiBR5rp/EO4FZ3Y4zQ21wMwiI1X7/No/9Vd6f8/MlvSAF/n7R1XWetT7 1f7JZiIF8Be7cSafQ4Ak1l/boBpCUcmc2Jvotp3sUfyRVXTyI/bXT5L/q465YJhPMwl/ hWjQ== X-Gm-Message-State: AAQBX9c8H/P0lGUS3yQWmWCdaHa+p6OoukfcE4sQYuGqpRkvO/ZMNuCX EhneIR6EQ/zTlmKd5Uu2QDo= X-Google-Smtp-Source: AKy350apWjMemT6i5kd2UTNmEO2zNcXtezKi4VdTBGJcGEXRlUwsJ245YnQTR6xMpSRhzRs+v6jKTg== X-Received: by 2002:a05:600c:2294:b0:3ed:2709:2edf with SMTP id 20-20020a05600c229400b003ed27092edfmr8173248wmf.13.1680820458853; Thu, 06 Apr 2023 15:34:18 -0700 (PDT) Received: from [192.168.0.160] ([170.253.51.134]) by smtp.gmail.com with ESMTPSA id u12-20020a5d514c000000b002c561805a4csm2847758wrt.45.2023.04.06.15.34.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Apr 2023 15:34:18 -0700 (PDT) Message-ID: Date: Fri, 7 Apr 2023 00:34:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Subject: Re: [PATCH 1/2] Implement strlcpy and strlcat [BZ #178] Content-Language: en-US From: Alejandro Colomar To: Florian Weimer , libc-alpha@sourceware.org References: <8513afd6-e276-05d5-bc4c-0722de71e0af@gmail.com> In-Reply-To: <8513afd6-e276-05d5-bc4c-0722de71e0af@gmail.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------lYAw00Igquv268HbSB3ySTZf" X-Spam-Status: No, score=-5.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------lYAw00Igquv268HbSB3ySTZf Content-Type: multipart/mixed; boundary="------------0ayPph08UO6nPp09xwM5T99e"; protected-headers="v1" From: Alejandro Colomar To: Florian Weimer , libc-alpha@sourceware.org Message-ID: Subject: Re: [PATCH 1/2] Implement strlcpy and strlcat [BZ #178] References: <8513afd6-e276-05d5-bc4c-0722de71e0af@gmail.com> In-Reply-To: <8513afd6-e276-05d5-bc4c-0722de71e0af@gmail.com> --------------0ayPph08UO6nPp09xwM5T99e Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 4/6/23 23:21, Alejandro Colomar wrote: > strlcat(3) is a slow call that shouldn't be emitted by an optimizing > compiler (similar to how GCC optimizes strcat(3) to stpcpy(3)). >=20 > With that in mind, do we really want all this code? Or maybe we just > want to implement it in the simplest possible way? >=20 > I suggest the following alternative: >=20 >=20 > size_t > strlcat(char *restrict dst, const char *restrict src, size_t dsize) > { > size_t dlen =3D strlen(dst); This needs to be strnlen(dst, dsize), to avoid passing a huge size to strlcpy(3). This seems a good reason for having defined behavior for strlcpy(x, y, 0). >=20 > return strlcpy(dst + dlen, src, dsize - dlen) + dlen; > } >=20 >=20 > In fact, that's the code I would expect that GCC should emit instead > of calls to the actual strlcat(3). >=20 > (Disclaimer: I didn't test the code; it may likely have bugs) >=20 --=20 GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5 --------------0ayPph08UO6nPp09xwM5T99e-- --------------lYAw00Igquv268HbSB3ySTZf Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE6jqH8KTroDDkXfJAnowa+77/2zIFAmQvSOEACgkQnowa+77/ 2zJrwBAAiGWSmZ57PgsvKy/YCS3kXSJiiHwVCwfU5N+hmaq/1XUSaReso0qVbdx2 M+X05pz1nmRP7xXQQ4hUTzvmri+odg2abQMw24fkS3gykDiRtiNTMNfD+THfjNVw 0FqbF/69okVXjMuWHqNfIye3uLrZTPLaO9QM+3JG/I3Sc5VQmp0PD45U299Xmz3h D0y+fsUkEl2mtzlrm2GjoOFVoy407NaOZ3jITnb9BX8xmBaGq15gFAZotu24hMYf fyRIZ4LQYJPOMb2Erz/sRiikOrBcNTEW7MqVwzMK7bWcbwLqYBMp19B/dUhYI9Pl 8wzVHvmq/xzZp7E/Ukgwg6dmUTv1++/mIKBnA8vXvtCJ46mfNfRDc25NZ54U+iif qPLCdPHb8ThpPVWz8hwUFdPNOH5V+U62Av/w5b8HRwJY5s64wBtjBnJXzlE1jHG7 xkxOsjU09fCymvrdFaeAv0ywfQRQjl15WNOnPUVPjecR+7Myr+xgyPnZAXMQa/iC ST6lCXwZouu9OewLBN6g0mUFyE6kAAwJV0pvMVJju0VoDOb4P/9f+0WT+Rrea2N8 /oqK8sopE5lSpXwbOFlSNe4ahpk3+moK+fMMXyyeYNWWBLhY0ZPgs/zWZESnDqAJ fCDWGwFStcYI8PFR9f2JCxOxeyWj9kj4dSRvXkyqskSAL4H+LEY= =eQSv -----END PGP SIGNATURE----- --------------lYAw00Igquv268HbSB3ySTZf--