sit-for + </dev/zero = SIGHUP

[Alexandre Duret-Lutz <adl@gnu.org>]

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In GNU Emacs 21.3.2 (i386-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2003-04-24 on raven, modified by Debian
configured using `configure  i386-linux --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes --with-x=yes --with-x-toolkit=athena --without-gif'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: C
  locale-coding-system: nil
  default-enable-multibyte-characters: nil

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

Hi People,

The following command causes Emacs to die on a SIGHUP.

% emacs -batch -q -no-site-file -eval '(sit-for 1)' </dev/null    
zsh: hangup     emacs --batch -q -no-site-file -eval '(sit-for 1)' < /dev/null

I would expect --batch to work when stdin is empty or closed, but
since sit-for is used in many places in Emacs that is obviously not
the case.


[ FWIW, the above issue can cause a configure test (AM_PATH_LISPDIR)
from Automake to fail.  This test runs the following command to list
all the load paths of Emacs, and will SIGHUP if one of the site
el-files calls sit-for.

% emacs -batch -q -eval '(while load-path (princ (concat (car load-path)
"\n")) (setq load-path (cdr load-path)))' </dev/null
No /etc/mailname. Reverting to default...
zsh: hangup     emacs -batch -q -eval  < /dev/null

The rational for using </dev/null here is that people have run across
flavors of emacs that do not honor any option and would otherwise
start in interactive mode (requiring users to type C-x C-c to continue
the ./configure script!). ]