Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 20 Apr 2001 05:33:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 20 Apr 2001 05:33:29 -0400 Received: from quechua.inka.de ([212.227.14.2]:21550 "EHLO mail.inka.de") by vger.kernel.org with ESMTP id ; Fri, 20 Apr 2001 05:33:13 -0400 To: linux-kernel@vger.kernel.org Subject: Re: light weight user level semaphores In-Reply-To:

Organization: private Linux site, southern Germany Date: Fri, 20 Apr 2001 11:29:31 +0200 From: Olaf Titz Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > Ehh.. I will bet you $10 USD that if libc allocates the next file > descriptor on the first "malloc()" in user space (in order to use the > semaphores for mm protection), programs _will_ break. Of course, but this is a result from sloppy coding. In general, open() can just return anything and about the only case where you can even think of ignoring its result is this: close(0); close(1); close(2); open("/dev/null", O_RDWR); dup(0); dup(0); (which is even not clean for other reasons). I can't imagine depending on the "fact" that the first fd I open is 3, the next is 4, etc. And what if the routine in question is not malloc() but e.g. getpwuid()? Both are just arbitrary library functions, and one of them clearly does open file descriptors, depending on their implementation. What would the reason[1] be for wanting contiguous fd space anyway? Olaf [1] apart from not having understood how poll() works of course. - 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/