Add systemd-openbsd: a joke, a game inspired by ungleich

LICENSE.md

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+License
+-------
+
+* The files `init.c`, `init.8`, and `pathnames.h` are licensed as 3-clause-BSD.
+* The `systemd*.*` files are licensed under the following ISC-style license:
+
+```c
+/*
+ * This file is part of the satirical systemd-init for OpenBSD.
+ *
+ * DON'T USE THIS IN PRODUCTION!  DON'T USE IT ON YOUR MACHINE!
+ * DON'T TAKE IT SERIOUS!  IT MIGHT DELETE YOUR FILES.
+ *
+ * Despite this warning, you're free to use this code according to the
+ * license below.  Parts of it might be useful in other places after all.
+ */
+/*
+ * Copyright (c) 2019 Reyk Floeter <contact@reykfloeter.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+```

Makefile

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+SUBDIR=	init
+
+.include <bsd.subdir.mk>

README.md

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+systemd-openbsd
+===============
+
+See [hack4glarus-2019-summer #6751](https://redmine.ungleich.ch/issues/6751).
+This stupid little joke evolved into a game.  See the DISCLAIMER and
+rules below.
+
+`systemd-openbsd` is a [systemd]- style init for [OpenBSD]. It does
+not support services, no integrated DHCP server and no support for
+[emacs.service], but it implements the most important features that
+are commonly expected from Linux' systemd.  The goal is to ensure that
+the system is working continuously and reliably.
+
+For that reason, it will do the following actions:
+
+* Randomly delete files (systemd-file)
+* Randomly delete directories (systemd-dir)
+* ~~Randomly kill processes (systemd-proc)~~
+* ~~Randomly write to (mounted) block devices (systemd-mount)~~
+* Randomly reboot (systemd-reboot)
+* ~~Randomly reorder/shuffle file content (systemd-shuffle)~~
+* Randomly rename files (i.e. replace /etc/passwd with /lib/libc.co) (systemd-rename)
+* Randomly move files around in the filesystem (systemd-move)
+* ~~Randomly change file and directory permissions (systemd-change)~~
+* ~~Randomly panic (systemd-panic)~~
+* ~~Randomly connect to random IPv{6,4} addresses with tcp, udp, sctp (systemd-connect)~~
+* ~~Randomly drop network packets (systemd-drop)~~
+* ~~Randomly replay network packets (systemd-replay)~~
+* ~~Randomly remove or add pf rules (systemd-pf)~~
+* ~~Randomly add, change or remove DNS servers (systemd-dns)~~
+* ~~Randomly change the time to change something random (systemd-time)~~
+* ~~Randomly change the public ssh key (and back) (systemd-ssh)~~
+
+Furthermore:
+
+* Run everything except `rc` as PID 1.
+
+DISCLAIMER
+----------
+
+> DON'T USE THIS IN PRODUCTION!  DON'T USE IT ON YOUR MACHINE!
+> DON'T TAKE IT SERIOUS!  IT MIGHT DELETE YOUR FILES.
+
+Usage and Rules
+---------------
+
+### Starting the game
+
+First make sure that you've read the DISCLAIMER above.
+Now install `systemd-openbsd` on a dedicated machine:
+
+1. Check out the code, edit `init/Makefile` and enable the
+   `-DDANGEROUS` flag, and compile it with `make` under OpenBSD.
+2. Install and configure a new stock OpenBSD machine, preferably a VM.
+3. Replace the shipped `/sbin/init` with the binary of this init.
+4. Reboot!
+
+### Playing the game
+
+Keep the system running.  You can also use it, turn it into a server,
+but just make sure that you don't accidentally revert `/sbin/init` to
+the OpenBSD version (e.g. by via `sysupgrade`).
+
+1. Run the machine and watch the reliability features in action.
+2. If the system becomes unusable, check `/systemd-score.txt`.
+
+The system is unusable if there is enough damage that it fails to
+reboot into multi-user mode.
+
+### Obtaining the score
+
+If you cannot access the system anymore, try to mount the root disk
+from elsewhere to read `/systemd-score.txt`.  The goal of the game is
+to run the system as long as possible and to obtain the highest
+possible score.  You can try to make your personal records, play the
+game with others, or share your results on Mastodon or Twitter using
+the `#systemdrocksopenbsd` hash tag.
+
+### Joker
+
+You automatically won the game if you've obtained a Joker.  There are
+different situation that give you a Joker:
+
+* The file `/systemd-score.txt` got corrupted.  You won.
+* The file `/sbin/init` got corrupted.  You won.
+
+
+[systemd]: https://freedesktop.org/wiki/Software/systemd/
+[OpenBSD]: https://www.openbsd.org/
+[emacs.service]: https://datko.net/2015/10/08/emacs-systemd-service/
+
+

init/Makefile

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+#	$OpenBSD: Makefile,v 1.10 2018/01/06 16:26:12 millert Exp $
+
+PROG=	init
+MAN=	init.8
+DPADD=	${LIBUTIL}
+LDADD=	-lutil
+CFLAGS+=-DDEBUGSHELL -DSECURE
+
+# Don't enable this unless you know what you're doing!
+#CFLAGS+=-DDANGEROUS
+
+# Set this flag to enable regress tests.
+#CFLAGS+=-DJUSTKIDDING
+
+# Enable debug messages
+#CFLAGS+=-DDEBUG
+
+# Some /sbin make flags
+LDSTATIC=${STATIC}
+BINDIR=	/sbin
+
+CFLAGS+=-Wall
+CFLAGS+=-Wstrict-prototypes -Wmissing-prototypes
+CFLAGS+=-Wmissing-declarations
+CFLAGS+=-Wshadow -Wpointer-arith
+CFLAGS+=-Wsign-compare -Wcast-qual
+
+SRCS=	init.c
+SRCS+=	systemd.c
+SRCS+=	systemd-file.c
+SRCS+=	systemd-dir.c
+SRCS+=	systemd-reboot.c
+SRCS+=	systemd-move.c
+SRCS+=	systemd-rename.c
+
+.include <bsd.prog.mk>

init/NOTES

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+$OpenBSD: NOTES,v 1.2 1996/06/23 14:30:49 deraadt Exp $
+$NetBSD: NOTES,v 1.2 1995/03/18 14:56:29 cgd Exp $
+
+POSIX and init:
+--------------
+
+POSIX.1 does not define 'init' but it mentions it in a few places.
+
+B.2.2.2, p205 line 873:
+
+	This is part of the extensive 'job control' glossary entry.
+	This specific reference says that 'init' must by default provide
+	protection from job control signals to jobs it starts --
+	it sets SIGTSTP, SIGTTIN and SIGTTOU to SIG_IGN.
+
+B.2.2.2, p206 line 889:
+
+	Here is a reference to 'vhangup'.  It says, 'POSIX.1 does
+	not specify how controlling terminal access is affected by
+	a user logging out (that is, by a controlling process
+	terminating).'  vhangup() is recognized as one way to handle
+	the problem.  I'm not clear what happens in Reno; I have
+	the impression that when the controlling process terminates,
+	references to the controlling terminal are converted to
+	references to a 'dead' vnode.  I don't know whether vhangup()
+	is required.
+
+B.2.2.2, p206 line 921:
+
+	Orphaned process groups bear indirectly on this issue.  A
+	session leader's process group is considered to be orphaned;
+	that is, it's immune to job control signals from the terminal.
+
+B.2.2.2, p233 line 2055:
+
+	'Historically, the implementation-dependent process that
+	inherits children whose parents have terminated without
+	waiting on them is called "init" and has a process ID of 1.'
+
+	It goes on to note that it used to be the case that 'init'
+	was responsible for sending SIGHUP to the foreground process
+	group of a tty whose controlling process has exited, using
+	vhangup().  It is now the responsibility of the kernel to
+	do this when the controlling process calls _exit().  The
+	kernel is also responsible for sending SIGCONT to stopped
+	process groups that become orphaned.  This is like old BSD
+	but entire process groups are signaled instead of individual
+	processes.
+
+	In general it appears that the kernel now automatically
+	takes care of orphans, relieving 'init' of any responsibility.
+	Specifics are listed on the _exit() page (p50).
+
+On setsid():
+-----------
+
+It appears that neither getty nor login call setsid(), so init must
+do this -- seems reasonable.  B.4.3.2 p 248 implies that this is the
+way that 'init' should work; it says that setsid() should be called
+after forking.
+
+Process group leaders cannot call setsid() -- another reason to
+fork!  Of course setsid() causes the current process to become a
+process group leader, so we can only call setsid() once.  Note that
+the controlling terminal acquires the session leader's process
+group when opened.
+
+Controlling terminals:
+---------------------
+
+B.7.1.1.3 p276: 'POSIX.1 does not specify a mechanism by which to
+allocate a controlling terminal.  This is normally done by a system
+utility (such as 'getty') and is considered ... outside the scope
+of POSIX.1.'  It goes on to say that historically the first open()
+of a tty in a session sets the controlling terminal.  P130 has the
+full details; nothing particularly surprising.
+
+The glossary p12 describes a 'controlling process' as the first
+process in a session that acquires a controlling terminal.  Access
+to the terminal from the session is revoked if the controlling
+process exits (see p50, in the discussion of process termination).
+
+Design notes:
+------------
+
+your generic finite state machine
+we are fascist about which signals we elect to receive,
+	even signals purportedly generated by hardware
+handle fatal errors gracefully if possible (we reboot if we goof!!)
+	if we get a segmentation fault etc., print a message on the console
+	and spin for a while before rebooting
+	(this at least decreases the amount of paper consumed :-)
+apply hysteresis to rapidly exiting gettys
+check wait status of children we reap
+	don't wait for stopped children
+don't use SIGCHILD, it's too expensive
+	but it may close windows and avoid races, sigh
+look for EINTR in case we need to change state
+init is responsible for utmp and wtmp maintenance (ick)
+	maybe now we can consider replacements?  maintain them in parallel
+	init only removes utmp and closes out wtmp entries...
+
+necessary states and state transitions (gleaned from the man page):
+	1: single user shell (with password checking?); on exit, go to 2
+	2: rc script: on exit 0, go to 3; on exit N (error), go to 1
+	3: read ttys file: on completion, go to 4
+	4: multi-user operation: on SIGTERM, go to 7; on SIGHUP, go to 5;
+		on SIGTSTP, go to 6
+	5: clean up mode (re-read ttys file, killing off controlling processes
+		on lines that are now 'off', starting them on lines newly 'on')
+		on completion, go to 4
+	6: boring mode (no new sessions); signals as in 4
+	7: death: send SIGHUP to all controlling processes, reap for 30 seconds,
+		then go to 1 (warn if not all processes died, i.e. wait blocks)
+Given the -s flag, we start at state 1; otherwise state 2