From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: (qmail 5820 invoked from network); 25 Apr 2020 17:55:11 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with UTF8ESMTPZ; 25 Apr 2020 17:55:11 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id E01E79C8BE; Sun, 26 Apr 2020 03:55:09 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 62F309C733; Sun, 26 Apr 2020 03:54:47 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="hgK5nvWZ"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 6E3CE9C733; Sun, 26 Apr 2020 03:54:44 +1000 (AEST) Received: from mail-ua1-f67.google.com (mail-ua1-f67.google.com [209.85.222.67]) by minnie.tuhs.org (Postfix) with ESMTPS id 56AD79B962 for ; Sun, 26 Apr 2020 03:54:43 +1000 (AEST) Received: by mail-ua1-f67.google.com with SMTP id a7so4954004uak.2 for ; Sat, 25 Apr 2020 10:54:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=05cc4i9MPSnE9v+5kLgSdsBWktf3InSJxxF9ibtySz4=; b=hgK5nvWZvRIstb5UTDvaiVuX3b2s8Scq4wL5QhhF/ZL5fsPNs1Q7ZdYoi5gbP8Sw4K UrlBF7Zzw0pQKsFhu+cVvrqbtwqvyUEv5HY/qiaoli7Zg+AKLGaUuyT7FKQqe8Y0oTFd l+hMHdpjb0YR74/DaI5UiMEJbNVf/ftAa9fkfMW6LHTDf/M6exXvnvTpn1a7prC6QCq3 +82ziY49J5KodT61SN75t6Y756Wwvr4eetwXkumdCqTacWATmXbmKe6+P4+K4T01RxDt wkVHuQ/1w1FkaxHXCLIzI6dl2IjL658qj54Ufe3uf/e74QZsHt/fhQaEwOb9zHzVb3Q5 nxxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=05cc4i9MPSnE9v+5kLgSdsBWktf3InSJxxF9ibtySz4=; b=mkY7/Y58r5vp5IOq6ow7XAXuOCCsZQpRkTCHh3RP6+IBvySP2K6HNybo+296QFHO76 r42W94Y5reGqrW0vkw8ixq9auJS2M7NTEqWwdaeiIU4n8eTPa6/s0ZM+RCa1zWj6wHx0 0HMwdOwdeWiKTVTiG4EkHcNsuR+X1VAVMBHNszcVn1wZaT+WUXiVIH1Q4iaRP1hLLCaa Du1MfFmjAUdOn97SdgT3weG/GoTPMCZKhJ4D3b6yhu5LnMSD5xiHhE/ssI3Yj+bYSQnZ KGQqoGc/zkt820nR2STF5EulmBJeHBOPGgaEvrUxRxss3iDZ5dFDs60Dfhz1pdE84RgM HYuQ== X-Gm-Message-State: AGi0PuaGVus/jDJnQYTxHf0IlUkMPGUndtao/qgL98SIYXc7Ejr1t/Kq 1+Ks2y8EIc+V5MgsrdgEf6oiJ5bTpLuxJjWuwD4= X-Google-Smtp-Source: APiQypIexzsU0Xg+pV18IcFqbnIyYcw9AzaPQU3/vUOOuJcRzc2/oUAFN43HcsX5xXnhUYLgsyav+dL7/KSugEj1aBw= X-Received: by 2002:a67:2504:: with SMTP id l4mr11598865vsl.228.1587837282635; Sat, 25 Apr 2020 10:54:42 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:ab0:46d:0:0:0:0:0 with HTTP; Sat, 25 Apr 2020 10:54:42 -0700 (PDT) In-Reply-To: <430B2F35-D250-499E-83F9-58D4C1764CE0@planet.nl> References: <430B2F35-D250-499E-83F9-58D4C1764CE0@planet.nl> From: Paul Winalski Date: Sat, 25 Apr 2020 13:54:42 -0400 Message-ID: To: Paul Ruizendaal Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [TUHS] v3 pipes X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On 4/25/20, Paul Ruizendaal wrote: > > I just tried making both pipe ends readable+writeable in my =E2=80=9CV6.5= =E2=80=9D kernel > and that appears to work. It allows for bi-directional communication in a > half-duplex sense (i.e communicating walky-talky style). The other benefi= t > is using just one file descriptor, at a time when a process had just 15 t= o > work with. If both pipe ends are readable+writeable, you have the Unix equivalent of VMS mailboxes. There's lots of opportunity for both deadlock and livelock, and some "broken pipe" situations become difficult or impossible to detect. -Paul W.