From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/7473 Path: news.gmane.org!not-for-mail From: Jean-Marc Pigeon Newsgroups: gmane.linux.lib.musl.general Subject: Re: setenv if value=NULL, what say standard? Bug? Date: Wed, 22 Apr 2015 21:26:57 -0400 Message-ID: <55384A61.5020001@safe.ca> References: <553837F1.5080808@safe.ca> <55383E43.8010505@skarnet.org> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms040309030701010203090207" X-Trace: ger.gmane.org 1429752450 21830 80.91.229.3 (23 Apr 2015 01:27:30 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 23 Apr 2015 01:27:30 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-7486-gllmg-musl=m.gmane.org@lists.openwall.com Thu Apr 23 03:27:19 2015 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1Yl5vC-0004FN-P1 for gllmg-musl@m.gmane.org; Thu, 23 Apr 2015 03:27:18 +0200 Original-Received: (qmail 19550 invoked by uid 550); 23 Apr 2015 01:27:17 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 19532 invoked from network); 23 Apr 2015 01:27:16 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.8.0 In-Reply-To: <55383E43.8010505@skarnet.org> X-Enigmail-Version: 1.6 X-Clement-Version: 2.6-6.7 X-Clement-ID: <00717-20150422212657-a40068b5> X-Clement-Virus-checker: ClamAV 0.98.4/20358/Wed Apr 22 01:07:33 2015 Xref: news.gmane.org gmane.linux.lib.musl.general:7473 Archived-At: This is a cryptographically signed message in MIME format. --------------ms040309030701010203090207 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 04/22/2015 08:35 PM, Laurent Bercot wrote: > On 23/04/2015 02:08, Jean-Marc Pigeon wrote: >> My guess, glibc code is 'blindly" setting the NULL (as "") value >> to the variable. >>=20 >> Is the standard saying otherwise, or do we have a a real bug in >> setenv?? >=20 > The standard at=20 > http://pubs.opengroup.org/onlinepubs/9699919799/functions/setenv.html > >=20 says... >=20 > ... exactly nothing about the possibility of envval being NULL.=20 > This is, in the strictest sense, UB. :) >=20 > Actually, it says "The environment variable shall be set to the > value to which envval points." So, arguably, envval should point to > something, and since NULL does not, it is forbidden. Another valid > interpretation could be that envvar is set to the value to which > envval points, i.e. no value at all, so it is unset; but it doesn't > fit the spirit of setenv() to unset variables. The glibc > interpretation, if it does what you think it does, is wrong in any > case: the empty string is a very different thing from no value at > all. >=20 > I think the only safe conclusion is that the application is > incorrect and should ensure that setenv() is never called with a > NULL value. >=20 Checked glibc, My understanding, it set something as "name=3D" in the environment, so the variable is present but value is "empty"i (top application to decide what to do). uclibc does something similar (as far I can tell looking at source code).. The application is not careful enough, but not incorrect as such. Note: we may have tons of applications with the same problem. if we keep musl setenv like that, musl will be seen as quite unreliable. If this situation is indeed UB, there is 2 options for musl: 1) Swallow the problem nicely... as glibc and uclibc does. 2) Report an error.. EINVAL? (and document it in manual) Crashing at "libc" level is not an option. - --=20 A bient=C3=B4t =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D Jean-Marc Pigeon E-Mail: jmp@safe.ca SAFE Inc. Phone: (514) 493-4280 Clement, 'a kiss solution' to get rid of SPAM (at last) Clement' Home base <"http://www.clement.safe.ca"> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJVOEphAAoJEAtgwJ4bBQU5ryMP/1p/gbq19bmhvWB8EWhuXQvC tunPUHRmeM20J1RaEP437ISVUqcbzoiJAxiyrOBAZYQsM02I4+OPWlncYPfWfGgF oqZ13GvvQn8rPGdBTDmSC5r2MSMI9na/FplWi638IjlKyehejJ/zzwMBszI7WA+H 6/wIgeTK1nh3Gegr6qSQmMcUBSH6GH5JLYqa1JAoN/YCi82JWyqAnnS/lZrfFH/2 HrQ2l4yFv8Ed9ofPJQ2Rz1h9if81zldqCyy2LXx8BZXEfaYdOOXpjoX9y71A671s Cq/zj+nSWocZdLX5Bf1jFdXyvm5YXjQAsX5EMQ4nXdIFmcDZX5Z48+gU/PBgpRM2 +H7fy4aXW0eYSd7LlCVi/0Xf+p/YDm6JJCCNQCKArIUc14M/9Gl0+5y6quvwL8YX tt8ffuj0F/OLwfQybd0pBLATFWsknsXdCA5ADPkDQ+YJIgx5UuHjediFRDo6ooCM 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