From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.2 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEA55C4338F for ; Thu, 29 Jul 2021 15:44:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C833560F42 for ; Thu, 29 Jul 2021 15:44:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237973AbhG2PoO convert rfc822-to-8bit (ORCPT ); Thu, 29 Jul 2021 11:44:14 -0400 Received: from us-smtp-delivery-44.mimecast.com ([207.211.30.44]:45669 "EHLO us-smtp-delivery-44.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237669AbhG2PoO (ORCPT ); Thu, 29 Jul 2021 11:44:14 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-523-kOcYYMTjPbyj7LO-pN7iTQ-1; Thu, 29 Jul 2021 11:44:05 -0400 X-MC-Unique: kOcYYMTjPbyj7LO-pN7iTQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 533B6760D0; Thu, 29 Jul 2021 15:44:04 +0000 (UTC) Received: from asgard.redhat.com (unknown [10.36.110.5]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 52DD5781E7; Thu, 29 Jul 2021 15:44:03 +0000 (UTC) Date: Thu, 29 Jul 2021 17:44:01 +0200 From: Eugene Syromyatnikov To: linux-man@vger.kernel.org Cc: Alejandro Colomar Subject: [PATCH v3] getrlimit.2: old_getrlimit/ugetrlimit and RLIM_INFINITY discrepancies Message-ID: <20210729154401.GA22699@asgard.redhat.com> MIME-Version: 1.0 User-Agent: Mutt/1.5.23 (2014-03-12) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: gmail.com Content-Type: text/plain; charset=WINDOWS-1252 Content-Disposition: inline Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org Historically, Linux didn't follow SUS with respect to RLIM_INFINITY signedness; it was changed during 2.4 development cycle, but in somewhat peculiar and arch-dependent fashion due to backward compatibility concerns. Signed-off-by: Eugene Syromyatnikov --- man2/getrlimit.2 | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/man2/getrlimit.2 b/man2/getrlimit.2 index 648fd3c..5a360d4 100644 --- a/man2/getrlimit.2 +++ b/man2/getrlimit.2 @@ -646,6 +646,37 @@ The name of the glibc wrapper function is .BR prlimit (); the underlying system call is .BR prlimit64 (). +The corresponding infinity value constant is provided in +.I +as +.BR RLIM64_INFINITY. +.PP +Original Linux implementation used signed types for limits; that was changed +(along with the value of the +.B RLIM_INFINITY +constant) +.\" http://repo.or.cz/davej-history.git/blobdiff/129f8758d8c41e0378ace0b6e2f56bbb8a1ec694..15305d2e69c3a838bacd78962c07077d2821f255:/include/linux/resource.h +during 2.4 development cycle, as it wasn't compatible +with Single UNIX Specification. +However, in order to preserve backward compatibility, the routine +.IR sys_old_getrlimit +has been implemented under +.B __NR_getrlimit +syscall slot, with infinity checks being performed against hard-coded 0x7fffffff +value, and the routine +.I sys_getrlimit +has been exposed under a new name, +.BR ugetrlimit (). +Note that most newer architectures don't have the latter, with +.BR getrlimit () +providing proper implementation. +Also worth noting that several architectures decided not to change +.B RLIM_INFINITY +value: 32-bit mips and sparc (but not 64-bit variants, that switched +to the new value of (~0UL)) retained the old 0x7fffffff value, +and alpha retained 0x7ffffffffffffffful. +.\" ...along with a request to call when one runs into it: +.\" https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/alpha/include/uapi/asm/resource.h#n15 .SH BUGS In older Linux kernels, the .B SIGXCPU -- 2.1.4