Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932112AbXBPMqe (ORCPT ); Fri, 16 Feb 2007 07:46:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932267AbXBPMqe (ORCPT ); Fri, 16 Feb 2007 07:46:34 -0500 Received: from javad.com ([216.122.176.236]:3136 "EHLO javad.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932112AbXBPMqd (ORCPT ); Fri, 16 Feb 2007 07:46:33 -0500 From: Sergei Organov To: 7eggert@gmx.de Cc: Linus Torvalds , "J.A. =?utf-8?B?TWFn?= =?utf-8?B?YWxsw4PDg8ODw4LCs24=?=" , Jan Engelhardt , Jeff Garzik , Linux Kernel Mailing List , Andrew Morton Subject: Re: somebody dropped a (warning) bomb References: <7Mj5f-3oz-21@gated-at.bofh.it> <7MktH-5EW-35@gated-at.bofh.it> <7Mmvy-vj-17@gated-at.bofh.it> <7MnBC-2fk-13@gated-at.bofh.it> <7MoQx-4p8-11@gated-at.bofh.it> <7MpjE-50z-7@gated-at.bofh.it> <7MpCS-5Fe-9@gated-at.bofh.it> <7MDd7-17w-1@gated-at.bofh.it> <7MGkB-62k-31@gated-at.bofh.it> <7NHoe-2Mb-37@gated-at.bofh.it> <7NMe9-1ZN-7@gated-at.bofh.it> <7Oagl-6bO-1@gated-at.bofh.it> <7ObvW-89N-23@gated-at.bofh.it> <7Oc8t-NS-1@gated-at.bofh.it> Date: Fri, 16 Feb 2007 15:46:05 +0300 In-Reply-To: (Bodo Eggert's message of "Thu, 15 Feb 2007 21:08:35 +0100") Message-ID: <87zm7ei836.fsf@javad.com> User-Agent: Gnus/5.110006 (No Gnus v0.6) XEmacs/21.4.19 (linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1841 Lines: 41 Bodo Eggert <7eggert@gmx.de> writes: > Sergei Organov wrote: >> Linus Torvalds writes: > >>> Exactly because "char" *by*definition* is "indeterminate sign" as far as >>> something like "strlen()" is concerned. >> >> Thanks, I now understand that you either don't see the difference >> between "indeterminate" and "implementation-defined" in this context or >> consider it non-essential, so I think I've got your point. > > If you don't code for a specific compiler with specific settings, there is > no implementation defining the signedness of char, and each part of the code > using char* will be wrong unless it handles both cases correctly. The problem here is that due to historical reasons, there could be code out there that abuses "char" for "signed char" (not sure about "unsigned char"). Old code and old habits are rather persistent. > Therefore it's either always wrong to call your char* function with char*, > unsigned char* _and_ signed char unless you can guarantee not to overflow any > of them, or it's always correct to call char* functions with any kind > of these. How are you sure those who wrote foo(char*) agrees with your opinion or even understands all the involved issues? > Off cause if you happen to code for specific compiler settings, one signedness > of char will become real and one warning will be legit. And if pigs fly, they > should wear googles to protect their eyes ... And if people were writing perfect portable code all the time, there would be no need for warnings in the first place... -- Sergei. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/