From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/3427 Path: news.gmane.org!not-for-mail From: Jens Gustedt Newsgroups: gmane.linux.lib.musl.general Subject: Re: [PATCH] bugfix: initialize a state variable in lio_wait Date: Sun, 16 Jun 2013 17:48:40 +0200 Message-ID: <1371397720.5692.103.camel@eris.loria.fr> References: <1371333657.16425.350.camel@eris.loria.fr> <20130615221627.GB6548@port70.net> <20130616054006.GJ29800@brightrain.aerifal.cx> <1371367371.16425.363.camel@eris.loria.fr> <1371375118.16425.368.camel@eris.loria.fr> <20130616142435.GK29800@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-VB/20/JfaPn6KP0lx5vd" X-Trace: ger.gmane.org 1371397732 24994 80.91.229.3 (16 Jun 2013 15:48:52 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 16 Jun 2013 15:48:52 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-3431-gllmg-musl=m.gmane.org@lists.openwall.com Sun Jun 16 17:48:54 2013 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1UoFCH-0006aH-JT for gllmg-musl@plane.gmane.org; Sun, 16 Jun 2013 17:48:53 +0200 Original-Received: (qmail 30637 invoked by uid 550); 16 Jun 2013 15:48:53 -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 30629 invoked from network); 16 Jun 2013 15:48:52 -0000 X-IronPort-AV: E=Sophos;i="4.87,874,1363129200"; d="scan'";a="22032931" In-Reply-To: <20130616142435.GK29800@brightrain.aerifal.cx> Face: 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 u+rU6wJnprxQf/JvP7beffH5fBIwGIZqEutJUlCKSNoFjYbQiihOkFmih0FJgSUGIpGxstE6RwiLQmsyzcXZesO8N1773YOHKPfUv/uxP726ePjsVNVoT9WZjMq02kRpEKay9+UPXjQmAL1991UuDZ+fGQulSVQrpuqg4pWkkupSjVGshtGZJpzQ9DysfQqZIkgzR7 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 q4emnQ3Df3nxj7z7+t2f+pO/Ysv5U0dm525uKYty3wCetPjRdYNcjaaQabq1Oq1MkVOKkc1reGFhiWIuj7C6JGlKyZNsNor3n7eFStLlkcoKz61fvX/79u3T9cWliTBWvrQEHa0QQmIZgdIK27FQmaKVxIRbN+77z5/4sT/+1PjJEycmosWVmXJvP3YpZM3aNYyuWz 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 xWxyQg9l57BATZZDpuCgH5PMrVxM3G3g513WfNDW3liYRGsPN1ua2LHtq0zM6dOPfmqCDx15227/+ILd58EaNa717/00smp3bsvo7fcS3VpGTcAKV2q1QZJ3MVIC88JsFJN2c+xbrDM+aHPlqE+ji0vY7kWvaFhaaXJzs3nYaoNNq/tJ1/tsiwtnpEOtz/+HHNLMXG 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 1LklihlU2u6NBtNZDaohXHIDKadYWRLsZkZFhgNCaLcB2XzECWalAZhR6v9vzx472v+BF/dxSu3FPf9cY3z0TNLgO+YFNfHzozJHFE4CvW1CPGBvtYabQ5YQuON+aI7YCqUTSX2hgTUeop025IstSiv1wiUQu4fkiz2SBTHaSQ9AQOaZqBk6MTdzFGYAnB0FAvWjD9 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 kELLRU3y0d5Cg1aEZBqSxQJdtprXL5546guXm6QtCwmKOTrvC2NoSq8tw8fYSDx9t8tATVSqNOo16lzdech7Ndrz/a4e/9fqr05+57dCTW7edtz/fE2JIySyHlxqKr8+3OFXooykND8ocf1vwuD1WHO1G5AKPUi5EYVGpLeA4OcqhZtVASKtjkLZFpjM6nZjNG0dnN 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 C3d0WolfKhTp6clRyhcg04xtGCHt1Dh/rExRamYWGyxXa7xn1yYuvkAwP7fClg0Zhx+qr/rM7d+Yesc73nHD5OW7Zh478tRzPxACH/iRa245duzkAdsJfMuy8aXm/FUFlpeWWOm2WZidI9WapaUlFIaTlQ4jfR6/vO9D2NE32LTeYnZOUmnA6PAohx9+qnTy1NnrP/ Cj15cu23XZI4/826Px/xqB37z547sPH374oOvnKTsOb+1zuCoImZARM8ZiLlKkXcWOcoFRJ+Do/CwFO4e2DEe+9Ti+ZXA8ny/cU+X4bMKRZxZIVEiqXI6/+NKuUzPHb7z40ovnX3zx+Ctuq38HyuqWG7Tu+A0AAAAASUVORK5CYII= X-Mailer: Evolution 3.2.3-0ubuntu6 Xref: news.gmane.org gmane.linux.lib.musl.general:3427 Archived-At: --=-VB/20/JfaPn6KP0lx5vd Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Am Sonntag, den 16.06.2013, 10:24 -0400 schrieb Rich Felker: > On Sun, Jun 16, 2013 at 11:31:58AM +0200, Jens Gustedt wrote: > > In all, this re-enforces my opinion to *always* initialize variables, > > unless I know that its address is immediately passed to an >=20 > I disagree with this principle. If you initialize the variable to a > dummy value, the compiler (or other static analysis tools) cannot > catch erroneous use of the variable before a real value is stored in > it. Also valgrind cannot catch them. Your "always initialize" > principle only makes sense when (as in this case) there's an obvious > "default value" the variable should have if it's not set elsewhere. > But often that's not the case, especially for pointers. For pointers and all other types of objects there is the C default initialization with 0. Statically allocated objects are initialized with that, and so in general code should be made "robust" with respect to such an initialization, be it just by failing loud and clear when we run over a pointer that is 0 initialized. (and analysis tools should be capable to tell us potential dereferences of 0-pointers, the same as they should be able to find unitialized use.) The other aspect of that is the possibility of C99 to declare variables as late as possible. 90% of the variables could be declared at their first write, which eliminates most of these problems. Whereas such a 0-initialization strategy mostly works for application code, there might in fact be issues for a C library such as musl. I agree that there are circumstances where it just can't fail. But these code spots need special care, anyhow, I think. The musl functions that I looked into are short and sweet, but unfortunately somewhat "obfuscated" by this top-of-function-declaration mania. I find a style as I posted it earlier for lio_wait much more readable, for me and for the compiler: static int lio_wait(struct lio_state *st) { int got_err =3D 0; struct aiocb **const cbs =3D st->cbs; for (int i=3D0, cnt =3D st->cnt; i