From owner-svn-src-all@freebsd.org Sat Jan 26 22:26:26 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id AD1FF14B0B6F; Sat, 26 Jan 2019 22:26:26 +0000 (UTC) (envelope-from se@freebsd.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id C75AA70394; Sat, 26 Jan 2019 22:26:25 +0000 (UTC) (envelope-from se@freebsd.org) Received: from Stefans-MBP-402.fritz.box (p200300CD5F2FCF00641090E029F19200.dip0.t-ipconnect.de [IPv6:2003:cd:5f2f:cf00:6410:90e0:29f1:9200]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: se/mail) by smtp.freebsd.org (Postfix) with ESMTPSA id E81B315306; Sat, 26 Jan 2019 22:26:24 +0000 (UTC) (envelope-from se@freebsd.org) Subject: Re: svn commit: r343480 - head/lib/libfigpar To: Colin Percival , rgrimes@freebsd.org Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <201901262136.x0QLaAJv095518@pdx.rh.CN85.dnsmgr.net> <010001688c2cfc3e-e319d851-8b9e-4468-8bd1-f93331f35116-000000@email.amazonses.com> From: Stefan Esser Openpgp: preference=signencrypt Autocrypt: addr=se@freebsd.org; prefer-encrypt=mutual; keydata= mQENBFVxiRIBCADOLNOZBsqlplHUQ3tG782FNtVT33rQli9EjNt2fhFERHIo4NxHlWBpHLnU b0s4L/eItx7au0i7Gegv01A9LUMwOnAc9EFAm4EW3Wmoa6MYrcP7xDClohg/Y69f7SNpEs3x YATBy+L6NzWZbJjZXD4vqPgZSDuMcLU7BEdJf0f+6h1BJPnGuwHpsSdnnMrZeIM8xQ8PPUVQ L0GZkVojHgNUngJH6e21qDrud0BkdiBcij0M3TCP4GQrJ/YMdurfc8mhueLpwGR2U1W8TYB7 4UY+NLw0McThOCLCxXflIeF/Y7jSB0zxzvb/H3LWkodUTkV57yX9IbUAGA5RKRg9zsUtABEB AAG0J1N0ZWZhbiBFw59lciAoRnJlZUJTRCkgPHNlQGZyZWVic2Qub3JnPokBVAQTAQoAPgIb AwULCQgHAwUVCgkICwUWAwIBAAIeAQIXgBYhBKNx6mWcC+zIK3FTE0frte9a/fVEBQJa8u+q BQkLJQETAAoJEEfrte9a/fVEOeMH/icmdK1eZQvB3U8quJo9VMaZsaTuCMbUE4NThyfsIvIm MCd+rb/yULmMYwqNfjyKB1x4ikR4x+94l+yJoz7K0Usks+eNKDmMGJM6pWWssTigaJubFdVd hVVC+C1QJi7JshYSib08uONoPmO4lv5Az0TDYGtsMzsES2sIlc62c9go5WPGYhQFRbX3Lk6y V6m8OHh+G9XGSj3oPO4UteRwu+SzTdOLunZBWG1wu34+IeZm663D+2gOppQLWpLa2qaTerqw THu377ayZ2B2LPJ5JkvkZeHYPkwDQ+b5PGn0UhfkxPnDVYki5F7qKxvQ5uq1/q9YaCX7mmOl H2yO7tgVsrW5AQ0EVXGJEgEIALEj9qCXMZVucjpcd3QxM/TlUr98m5viEd1z4tCnPUyRWcIC EVtj2h5xMH+2iB0q1+KWhq+NsWtvScmEmfHnsr7dJ1K677OdpDhKVaJk61eeRulFY1R4yb6C 1MMxK+WgYB+vvpG0UeyR0M4uBewcPvRsq4yGUHFQKtLAbMdoPTSryJA+ElnmK1vdY+rPcHgi OIMBZM7ahsPXC0C9K4e5SP9clGyIoMpbfHXdx9q+Rp3zVtlbhyk3BS/xccu/+9pk9ICXL6GR js2sNnJ0wxdU1DsAlC59a5MnSruwiZFwRnkQhr3x6wk97Lg7sLS9jjTnCN7LGlVmSmpOEMy6 uq1AWfUAEQEAAYkBPAQYAQoAJgIbDBYhBKNx6mWcC+zIK3FTE0frte9a/fVEBQJa8u+rBQkL JQEZAAoJEEfrte9a/fVEuesH/2DNxGWnHvWwMyiyhlQtafvDKwEn/wAgR8gHJFodB7emf8rA TnukH7MVttCoHtjN5lvv9RSBHjNTZls5wR/ANlwdRuPQHd8ZGxLe3S6IuUB3zDSwFltLGurO N2kOMhs5mTGyypSa+uw3rtQbUAVYf1oPbiR4FLtiM8FLyEvE95hX5fPq9Qvx9FmN79kmCIEw jDKPqDaUf/OR2fEF0LSIbXHEk4tNqCEwx5DIJ0fp5/z5UzICUAmwxyRs5O/Hre1jzPsMVyud Ml9t7UTOJGKVWwRory1PMnOFxN+iz5/d4FhYSKXF7kfMiFgol4LuWaxJRwbBrr71VGBrRy2a L1nw6Bc= Message-ID: Date: Sat, 26 Jan 2019 23:26:23 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <010001688c2cfc3e-e319d851-8b9e-4468-8bd1-f93331f35116-000000@email.amazonses.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: C75AA70394 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.98 / 15.00]; local_wl_from(0.00)[freebsd.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.996,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; NEURAL_HAM_SHORT(-0.99)[-0.986,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 26 Jan 2019 22:26:26 -0000 Am 26.01.19 um 22:59 schrieb Colin Percival: > On 1/26/19 1:36 PM, Rodney W. Grimes wrote: >>> Author: se >>> Date: Sat Jan 26 21:30:26 2019 >>> New Revision: 343480 >>> URL: https://svnweb.freebsd.org/changeset/base/343480 >>> >>> Log: >>> Silence Clang Scan warning about potentially unsafe use of strcpy. >>> >>> While this is a false positive, the use of strdup() simplifies the code. >> >> Though that might be true, it also has to recalculate the >> length of the string which was already known by slen. >> >> I am not sure how often this code is called, >> but that is wasted cycles in a library. > > The length of the string was already being recalculated, by strcpy. > > It seems to me that this could be written as > > temp = malloc(slen + 1); > if (temp == NULL) /* could not allocate memory */ > return (-1); > memcpy(temp, source, slen + 1); > > which avoids both recalculating the string length and using strcpy? In principle you are right, there is a small run-time cost by not using the known length for the allocation. The Clang Scan checks are leading to lots (thousands) of false positives and a I have looked at quite a number and abstained from silencing them in the hope that the scan will be improved. It should learn that at least the trivial case of an allocation of the value of strlen()+1 followed by a strcpy (and no further strcat or the like) is safe. But I have seen cases where the assumption is that "i<0" followed by "i>=0" at the same location and then a warning about potential problem. I have committed the version you suggest in rev. 343482 ... Regards, STefan