standards/52406: POSIX requires sh(1)ell interactivity for IN/ERR, not IN/OUT

[steffen%sdaoden.eu@localhost]

>Number:         52406
>Category:       standards
>Synopsis:       POSIX requires sh(1)ell interactivity for IN/ERR, not IN/OUT
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    standards-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Jul 15 13:30:00 +0000 2017
>Originator:     Steffen
>Release:        kre
>Organization:
>Environment:
Subject: Re: Future shell work - comments reqyuested
Date: Sat, 15 Jul 2017 19:52:42 +0700
Message-ID: <16608.1500123162%andromeda.noi.kre.to@localhost>
>Description:
In said thread it was revealed that NetBSD shell (and BSD Mail) treat isatty(STDIN/STDOUT) as being interactive, whereas POSIX requires isatty(STDIN/STDERR) for this condition.

POSIX 2008/Cor 2-2016, p. 3226, line 108308 ff.:

If the &#8722;i option is present, or if there are no operands and the shell?s standard input and
standard error are attached to a terminal, the shell is considered to be interactive.

and, ditto, p. 3239, line 108848 ff.:

Standard input and standard error are the files that determine whether a shell is interactive
when &#8722;i is not specified. For example:

       sh > file
       and:
       sh 2> file

create interactive and non-interactive shells, respectively. Although both accept terminal input, the results of error conditions are different, as described in Section 2.8.1 (on page 2363); in the second example a redirection error encountered by a special built-in utility aborts the shell.
>How-To-Repeat:

>Fix:
I expect a painful and lengthy code audit for BSD Mail.   I do not know about the shell.