Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263246AbTFDLmt (ORCPT ); Wed, 4 Jun 2003 07:42:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263250AbTFDLmt (ORCPT ); Wed, 4 Jun 2003 07:42:49 -0400 Received: from 34.mufa.noln.chcgil24.dsl.att.net ([12.100.181.34]:62190 "EHLO tabby.cats.internal") by vger.kernel.org with ESMTP id S263246AbTFDLms (ORCPT ); Wed, 4 Jun 2003 07:42:48 -0400 Content-Type: text/plain; charset=US-ASCII From: Jesse Pollard To: Krzysztof Halasa , Subject: Re: select for UNIX sockets? Date: Wed, 4 Jun 2003 06:55:47 -0500 X-Mailer: KMail [version 1.2] References: In-Reply-To: MIME-Version: 1.0 Message-Id: <03060406554700.28116@tabby> Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1328 Lines: 37 On Monday 02 June 2003 19:08, Krzysztof Halasa wrote: > Hi, > > Should something like this work correctly? > > while(1) { > FD_ZERO(&set); > FD_SET(fd, &set); > select(FD_SETSIZE, NULL, &set, NULL, NULL); <<<<<<< for writing > > if (FD_ISSET(fd, &set)) > sendto(fd, &datagram, 1, 0, ...); > } > > fd is a normal local datagram socket. It looks select() returns with > "fd ready for write" and sendto() then blocks as the queue is full. > > I don't know if it's expected behaviour or just a not yet known bug. > Of course, I have a more complete test program if needed. > > 2.4.21rc6, haven't tried any other version. > > strace shows: > > select(1024, NULL, [3], NULL, NULL) = 1 (out [3]) > sendto(3, "\0", 1, 0, {sa_family=AF_UNIX, path="/tmp/tempUn"}, 13 <<< > blocks Could. There may be room for the buffer, but unless it is set to nonblock, you may have a stream open to another host that may not accept the data (busy, network congestion...) With the required acks, the return may (should?) be delayed until the ack arrives. - 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/