From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id C493A388A43B for ; Fri, 9 Apr 2021 12:38:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org C493A388A43B 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-447-wQxKP8WmOMytTq6UEg9JQw-1; Fri, 09 Apr 2021 08:38:47 -0400 X-MC-Unique: wQxKP8WmOMytTq6UEg9JQw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 562C619251A8; Fri, 9 Apr 2021 12:38:46 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-70.ams2.redhat.com [10.36.112.70]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 49CA360BE5; Fri, 9 Apr 2021 12:38:45 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella via Libc-alpha Cc: Adhemerval Zanella , Andreas Schwab Subject: Re: [PATCH v2 1/2] linux: Normalize and return timeout on select (BZ #27651) References: <20210409113639.1124756-1-adhemerval.zanella@linaro.org> Date: Fri, 09 Apr 2021 14:38:54 +0200 In-Reply-To: <20210409113639.1124756-1-adhemerval.zanella@linaro.org> (Adhemerval Zanella via Libc-alpha's message of "Fri, 9 Apr 2021 08:36:38 -0300") Message-ID: <87czv3y6n5.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Apr 2021 12:38:51 -0000 * Adhemerval Zanella via Libc-alpha: > +/* Return true if select modify the timeout to reflect the amount of time > + no slept. */ > +extern bool support_select_modify_timeout (void); > + > +/* Return true if select normalize the timeout input by taking in account > + tv_usec larger than 1000000. */ > +extern bool support_select_normalize_timeout (void); Maybe use support_select_modifies_timeout and support_select_normalizes_timeout? Please commit the support/ bits separately. > diff --git a/sysdeps/unix/sysv/linux/select.c b/sysdeps/unix/sysv/linux/select.c > index 415aa87d3c..d075270ff4 100644 > --- a/sysdeps/unix/sysv/linux/select.c > +++ b/sysdeps/unix/sysv/linux/select.c > @@ -33,12 +33,34 @@ int > __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, > struct __timeval64 *timeout) > { > + __time64_t s = timeout != NULL ? timeout->tv_sec : 0; > + int32_t us = timeout != NULL ? timeout->tv_usec : 0; > + int32_t ns; > + > + if (s < 0 || us < 0) > + return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); > + > + /* Normalize the timeout, as legacy Linux __NR_select and __NR__newselect. > + Different than syscall, it also handle possible overflow. */ > + if (us / USEC_PER_SEC > INT64_MAX - s) > { > + s = INT64_MAX; > + ns = NSEC_PER_SEC - 1; > } > + else > + { > + s += us / USEC_PER_SEC; > + us = us % USEC_PER_SEC; > + ns = us * NSEC_PER_USEC; > + } > + > + struct __timespec64 ts64, *pts64 = NULL; > + if (timeout != NULL) > + { > + ts64.tv_sec = s; > + ts64.tv_nsec = ns; > + pts64 = &ts64; > + } The overflow handling is slightly inconsistent with the in_time_t_range range check below. Here we use silently saturating arithmetic, below it's an error. Thanks, Florian