MFC r315733, r315737, r315740, r330054:

r315733 (imp):
Impelemnt ttys onifexists in init.

Implement a new init(8) option in /etc/ttys. If this option is present
on the entry in /etc/ttys, the entry will be active if and only if it
exists. If the name starts with a '/', it will be considered an
absolute path. If not, it will be a path relative to /dev.

This allows one to turn off video console getty that aren't present
(while running a getty on them even when they aren't the system
console). Likewise with serial ports.

It differs from onifconsole in only requiring the device exist rather
than it be listed as one of the system consoles.

r315737 (ngie):
Unbreak world by adding sys/stat.h for stat(2)

r315740 (imp):
Simplify the code a little.

r330054 (trasz):
Improve missing tty handling in init(8). This removes a check that did
nothing - it was checking for ENXIO, which, with devfs, is no longer
returned - and was badly placed anyway, and replaces it with similar
one that works, and is done just before starting getty, instead of being
done when rereading ttys(5).

From the practical point of view, this makes init(8) handle disappearing
terminals (eg /dev/ttyU*) gracefully, without unneccessary getty restarts
and resulting error messages.

Reported by: Bart Ender, Andre Albsmeier
PR: 228315
Blocks: 11.2-BETA2
Approved by: re (marius)
Sponsored by: The FreeBSD Foundation

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add a new flag to /etc/ttys: onifconsole. This is equivalent to "on" if the
device is an active kernel console and "off" otherwise. This is designed to
allow serial-booting x86 systems to provide a login prompt on the serial line
by default without providing one on all systems by default.

Comments and suggestions by: grehan, dteske, jilles
MFC after: 1 month

Remove the Berkeley clause 3's.
Add a few $FreeBSD$

Breath deep and take __P out of the system include files.

# This appears to not break X11, but I'm having problems compiling the
# glide part of the server with or without this patch, so I can't tell
# for sure.

MF22: prototype fix.

Fixed spelling of isnetworktty.

Fixed stray whitespace.

Add bitflags TTY_NETWORK/TTY_DIALUP and interface functions which
make use of them.

Allow commonly-used "insecure" as a valid keyword in /etc/ttys.
This prevents keywords after "insecure" occurs being errnoeously
parsed as comments.

Added group= facility to /etc/ttys for tty grouping for more
more manageable and convenient referencing by login.conf (login
class database) and (e.g.) login.access.

This is the first of a group of commits which implements the login
class capabilities database.

This commit was generated by cvs2svn to compensate for changes in r1539,
which included commits to RCS files with non-trunk default branches.

BSD 4.4 Lite Include Sources