From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org
X-Spam-Level: 
X-Spam-Status: No, score=-3.3 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
	MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,T_SCC_BODY_TEXT_LINE
	autolearn=ham autolearn_force=no version=3.4.4
Received: (qmail 5926 invoked from network); 12 Nov 2023 18:10:36 -0000
Received: from zero.zsh.org (2a02:898:31:0:48:4558:7a:7368)
  by inbox.vuxu.org with ESMTPUTF8; 12 Nov 2023 18:10:36 -0000
ARC-Seal: i=1; cv=none; a=rsa-sha256; d=zsh.org; s=rsa-20210803; t=1699812637;
	 b=ETykdVKfMBWJ7u1knyXjta+8olmmyP5YgWnT73x2eZkZVc1EWIQikQ2aIQ1s9wqWg7pE+di+F6
	  ZoiQah5jkbmy8ULWPf1JExEAAOaMj5fAXx1O9q4oDROIfP9gUReOriNCZreKDFmrN8EHdv0EnE
	  2V6ti6/Ab9n3QiCSbDGQN5uKyx9HPnLpEnsjJdxya8iYCr7cTQL54DG6LmOoJMNPo8HHZ0CRfe
	  sxkvID+QVVZiz/mlUXxoN3QZzVPLrDH8UPetPSUVB7YGfpunAPw0+aVAA9VBZRDbHKTd2F6375
	  p2Dy4pC1jShBLgHKKEZ0p3PV9EJPrUAHtiqpiRV2val2TA==;
ARC-Authentication-Results: i=1; zsh.org;
	iprev=pass (mail-ej1-f44.google.com) smtp.remote-ip=209.85.218.44;
	dkim=pass header.d=brasslantern-com.20230601.gappssmtp.com header.s=20230601 header.a=rsa-sha256;
	dmarc=none header.from=brasslantern.com;
	arc=none
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed; d=zsh.org; s=rsa-20210803; t=1699812637;
	bh=NLopydH9oKKTmuU8H2V/I33zkadR0rpLUhmBjbzx/QY=;
	h=List-Archive:List-Owner:List-Post:List-Unsubscribe:List-Subscribe:List-Help:
	  List-Id:Sender:Content-Transfer-Encoding:Content-Type:Cc:To:Subject:
	  Message-ID:Date:From:In-Reply-To:References:MIME-Version:DKIM-Signature:
	  DKIM-Signature;
	b=Ix+mmdKntXQjiI6kyIu6hOvSqbB+Z/KYVUD4ka/YAR65AzAuDxB/4G6QBLd5aSqmVN8mJbYQjI
	  3xhTpCKuGBYILwdk3FEC2PN2YvwKKURZ+10QcKtLFH7MkVrCR8Pk2VcgzdVgmmUTC3KoAFaKey
	  82dAtXbqiYoOkN/cdvh15sWqtdhzNXd8nHWKmK89nrJDUSv7vbF8YnDhh0561yFpKSPpKbmtJp
	  tcyvj92eFUZfjRtp6BnQOujsyUJD3W1gTNByoEQgEJGtM/eE6DG/CYBgDlWXrp83FTwC4inDeK
	  mcAKa7lRmeAcOvObuTtRM8TPZRHP+6eJXkWm/VYq7o0rlw==;
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=zsh.org;
	s=rsa-20210803; h=List-Archive:List-Owner:List-Post:List-Unsubscribe:
	List-Subscribe:List-Help:List-Id:Sender:Content-Transfer-Encoding:
	Content-Type:Cc:To:Subject:Message-ID:Date:From:In-Reply-To:References:
	MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:
	Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID;
	bh=Zt03pbiNYvAxyFbYCbFXH9SbMJ6kNc1afqmy/iu9uLY=; b=eIm2U3mugKOIj+QzxaZkrD2aU7
	u8HFtsjGA+Vl3qa747DIVJVqxL17RpcLT83leXWZDGAunge/ceyRbbJGhe7PeSdwkJjX0L70tr7b0
	ajnzuWTZXgficZL4czmsl5VMuAyhjEH0fVhfi563E6Q0vtm9/avDcva/kkvElMrkvxHNs7RGORRbl
	yy+he0kw1PTjRgyrB6WEzx0TBsZ3Bgmt3ERwAIMXcu8gjcDvtF/xGY/bsZPlP0Ha6qkgLspZbhbMW
	71Bug+gz1nsFXudkiB/aL1jtXo++hSPY7QePpNc6TLIGYppwtEKqD0ZyalXbKkqTo/Ecg5xjuakLH
	XRiPRD6w==;
Received: by zero.zsh.org with local
	id 1r2Euo-0005zq-Mo;
	Sun, 12 Nov 2023 18:10:34 +0000
Authentication-Results: zsh.org;
	iprev=pass (mail-ej1-f44.google.com) smtp.remote-ip=209.85.218.44;
	dkim=pass header.d=brasslantern-com.20230601.gappssmtp.com header.s=20230601 header.a=rsa-sha256;
	dmarc=none header.from=brasslantern.com;
	arc=none
Received: from mail-ej1-f44.google.com ([209.85.218.44]:52500)
	by zero.zsh.org with esmtps (TLS1.3:TLS_AES_128_GCM_SHA256:128)
	id 1r2EuE-0005gn-44;
	Sun, 12 Nov 2023 18:09:58 +0000
Received: by mail-ej1-f44.google.com with SMTP id a640c23a62f3a-991c786369cso581954566b.1
        for <zsh-workers@zsh.org>; Sun, 12 Nov 2023 10:09:57 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=brasslantern-com.20230601.gappssmtp.com; s=20230601; t=1699812597; x=1700417397; darn=zsh.org;
        h=content-transfer-encoding:cc:to:subject:message-id:date:from
         :in-reply-to:references:mime-version:from:to:cc:subject:date
         :message-id:reply-to;
        bh=Zt03pbiNYvAxyFbYCbFXH9SbMJ6kNc1afqmy/iu9uLY=;
        b=fCblt7aJvXl7SsT11GZlAb79n0YDfXv2rlp3TCko7+yBCRcaiTQska/FbQ9pVl+CFr
         OKv98CpfWsipz5uabR3Lb+2Ge9jgeVoecrMJhxcdF4u8s3F4ia06ls8VMMF36KWTYUOZ
         Yeh5rrdCTwTLij36pn7FsrbmgFj3+dqE+NemSq9x0mXe4sexU4uS4i9Ze0/Mv/kPr3Eg
         bfsXHSgCS97CExfJtvlybgJJvAC0LBweOhhdqGB44Mlaxe482xKu+UpDoD5cxC1WW0kd
         gaEkhd8gVp19aeb8LOnYzT05nxcEzChaaGWO8G5ssAWBtb8G73fYZ9iR7mCBaTIzLCYX
         udjw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20230601; t=1699812597; x=1700417397;
        h=content-transfer-encoding:cc:to:subject:message-id:date:from
         :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc
         :subject:date:message-id:reply-to;
        bh=Zt03pbiNYvAxyFbYCbFXH9SbMJ6kNc1afqmy/iu9uLY=;
        b=O/aRaFXwh9XJMp1gFYczp+ZJnB4KvK4y2TxqnqyYpWfgTpvWp6A9w1BO93QOIYvrx3
         VeWLTfEGdYnOM5ymbz0gaA4GMCiZEcIk7C77UsLO0zOWDeLoJ72uiK4DX+X0dKSoVtXz
         efEu2cvDcpq984G0ubA+Gj5ueXD5gyhOg7wH3M0yRrEMQk7fAc4Nof+jCHl56iRqKpBq
         IVu6xi3zLD62EACpGAN6eu0Rds9bBhbU7VhKkRrsnRV4Ms0qzRP7sBzKcTLS1F/Kad74
         Uy+RZ1rTkNvkJRRDKWDhnuaoJ7d9dxoFWgZDYMCHNQXdOwIofF4HT0EuryD4nQRQlLX4
         IB5A==
X-Gm-Message-State: AOJu0YxIFOI7n+Iw2ZvPSCmcwcPeB78TR/gMiQ3FOG4CcSuiIrKRmddz
	AOJ7d7vjgy7yjiTQsq1/VzKkmsHsFTrNUuW98poWOw==
X-Google-Smtp-Source: AGHT+IFIjeuAtsJGpX0bCyKfkj2aijL/qncC7nzNglqHM0jaDGqfgcy7SfPiyjJaEqptvc6VtKBdHiC9eGjg6cWV8ik=
X-Received: by 2002:a17:906:5653:b0:9c5:158e:f61e with SMTP id
 v19-20020a170906565300b009c5158ef61emr3598238ejr.34.1699812597151; Sun, 12
 Nov 2023 10:09:57 -0800 (PST)
MIME-Version: 1.0
References: <CAA=-s3xCf4wx826U8jEjO_j5-1kcTi8v2=VZPiabKMo-meKq0Q@mail.gmail.com>
In-Reply-To: <CAA=-s3xCf4wx826U8jEjO_j5-1kcTi8v2=VZPiabKMo-meKq0Q@mail.gmail.com>
From: Bart Schaefer <schaefer@brasslantern.com>
Date: Sun, 12 Nov 2023 10:09:45 -0800
Message-ID: <CAH+w=7ZztRXt7R9fDK=yb1=fcvjwjiUGo98j73BgBG7NzWE+iw@mail.gmail.com>
Subject: Re: Bug: reading from tty inside process substitution
To: "Mark J. Reed" <markjreed@gmail.com>
Cc: zsh-workers@zsh.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Seq: 52295
Archived-At: <https://zsh.org/workers/52295>
X-Loop: zsh-workers@zsh.org
Errors-To: zsh-workers-owner@zsh.org
Precedence: list
Precedence: bulk
Sender: zsh-workers-request@zsh.org
X-no-archive: yes
List-Id: <zsh-workers.zsh.org>
List-Help: <http://www.zsh.org/sympa/help>, <mailto:sympa@zsh.org?subject=HELP>
List-Subscribe: <http://www.zsh.org/sympa/subscribe/zsh-workers>, <mailto:sympa@zsh.org?subject=SUB%20zsh-workers>
List-Unsubscribe: <http://www.zsh.org/sympa/signoff/zsh-workers>, <mailto:sympa@zsh.org?subject=SIG%20zsh-workers>
List-Post: <mailto:zsh-workers@zsh.org>
List-Owner: <mailto:zsh-workers-request@zsh.org>
List-Archive: <http://www.zsh.org/sympa/arc/zsh-workers>

On Sun, Nov 12, 2023 at 7:59=E2=80=AFAM Mark J. Reed <markjreed@gmail.com> =
wrote:
>
> The below code hangs after reading the line from the terminal:
>
>     read foo < <(read bar </dev/tty; echo $bar)

I believe it actually hangs before reading the line from the terminal,
or more precisely at the point of trying to read the line.  "read bar"
is being stopped by a SIGTTIN signal because it is not in a process
group that "owns" the TTY.

This has to do with the way zsh backgrounds the process substitution.
It actually works fine in a script or even in a subshell (which
explains why it works in command substitution):

% zsh -fc 'read foo < <(read bar </dev/tty; echo $bar); echo $foo'
the line
the line
%  ( read foo < <(read bar </dev/tty; echo $bar); echo $foo )
subshell
subshell
%

In an interactive shell with job control, though, the process
management is different.

% unsetopt monitor
% read foo < <(read bar </dev/tty; echo $bar); echo $foo
no job control
no job control
%

I doubt there's any easy way to change this without breaking something else=
.