Bug 57414

The /usr/bin/script utility fails silently if its standard input is not a
terminal.  It does nothing, and does not execute its argument, but exits
with a successful output status.

This is not such a big deal if the user is using 'script' directly -- it's
pretty easy to figure out what happened.  However, this can be *extremely*
surprising -- and dangerous -- if 'script' is called by some other program
which doesn't document this limitation.

In particular, the 'portupgrade' utility wraps its calls to 'make' and 'make
install' of upgraded ports in 'script'.  As a result, if portupgrade is run
with its standard input redirected, out-of-date ports will be deleted and
then not reinstalled, with no warning or indication of any problem.

Fix: The following patch causes /usr/bin/script to error quickly with a non-zero
exit status if tcgetattr or ioctl fail, as they will if stdin is not a tty.
How-To-Repeat: $ script /var/tmp/foo cat /etc/passwd < /dev/null
outputs only
Script started, output file is /var/tmp/foo

Script done, output file is /var/tmp/foo
and /var/tmp/foo is empty.

# BATCH=yes portupgrade -arRv < /dev/null > /var/tmp/portupgrade.log 2>&1 &
(which seems like a perfectly reasonable way of upgrading all one's ports,
without having to stay logged in to watch it happen)
deletes all out-of-date ports from your system, without replacing them with
up-to-date versions.