Merge branch 'fix/init-explorer/busybox' into 'master'

[explorer/init] Support more init systems

See merge request !850

cdist/conf/explorer/init

-#!/bin/sh
+#!/bin/sh -e
 #
 # 2016 Daniel Heule (hda at sfs.biz)
 # Copyright 2017, Philippe Gregoire <pg@pgregoire.xyz>
+# 2020 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
 #
 # This file is part of cdist.
 #
@@ -19,21 +20,422 @@
 # along with cdist. If not, see <http://www.gnu.org/licenses/>.
 #
 #
-# Returns the process name of pid 1 ( normaly the init system )
-# for example at linux this value is "init" or "systemd" in most cases
+# Returns the name of the init system (PID 1)
+
+# Expected values:
+# Linux:
+#  Adélie Linux:
+#    sysvinit+openrc
+#  Alpine Linux:
+#    busybox-init+openrc
+#  ArchLinux:
+#    systemd, sysvinit
+#  CRUX:
+#    sysvinit
+#  Debian:
+#    systemd, upstart, sysvinit, openrc, ???
+#  Devuan:
+#    sysvinit, sysvinit+openrc
+#  Gentoo:
+#    sysvinit+openrc, openrc-init, systemd
+#  OpenBMC:
+#    systemd
+#  OpenWrt:
+#    procd, init???
+#  RedHat (RHEL, CentOS, Fedora, RedHat Linux, ...):
+#    systemd, upstart, upstart-legacy, sysvinit
+#  Slackware:
+#    sysvinit
+#  SuSE:
+#    systemd, sysvinit
+#  Ubuntu:
+#    systemd, upstart, upstart-legacy, sysvinit
+#  VoidLinux:
+#    runit
+#
+# GNU:
+#   Debian:
+#     sysvinit, hurd-init
+#
+# BSD:
+#  {Free,Open,Net}BSD:
+#    init
+#
+# Mac OS X:
+#   launchd, init+SystemStarter
 #
+# Solaris/Illumos:
+#   smf, init???
+
+# NOTE: init systems can be stacked. This is popular to run OpenRC on top of
+# sysvinit (Gentoo) or busybox-init (Alpine), but can also be used to run runit
+# as a systemd service.  This makes init system detection very complicated
+# (which result is expected?)  This script tries to untangle some combinations,
+# OpenRC on top of sysv or busybox (X+openrc), but will ignore others (runit as
+# a systemd service)
+
+# NOTE: When we have no idea, nothing will be printed!
+
+# NOTE:
+# When trying to gather information about the init system make sure to do so
+# without calling the binary!   On some systems this triggers a reinitialisation
+# of the system which we don't want (e.g. embedded systems).
+
+
+set -e
+
+KERNEL_NAME=$(uname -s)
+
+KNOWN_INIT_SYSTEMS=$(cat <<EOF
+systemd
+sysvinit
+upstart
+runit
+procd
+smf
+launchd
+init
+hurd_init
+systemstarter
+EOF
+)
+
+
+common_candidates_by_kernel() {
+	case $KERNEL_NAME
+	in
+		FreeBSD|NetBSD|OpenBSD)
+			echo init
+			;;
+		Linux)
+			echo systemd
+			echo sysvinit
+			echo upstart
+			;;
+		GNU)
+			echo sysvinit
+			echo hurd-init
+			;;
+		Darwin)
+			echo launchd
+			echo systemstarter
+			;;
+		SunOS)
+			echo smf
+			;;
+	esac
+}
+
+
+## Helpers
+
+trim() {
+	sed -e 's/^[[:blank:]]*//' -e 's/[[:blank:]]*$//' -e '/^[[:blank:]]*$/d'
+}
+
+unique() {
+	# Delete duplicate lines (keeping input order)
+	# NOTE: Solaris AWK breaks without if/print construct.
+	awk '{ if (!x[$0]++) print }'
+}
+
+
+## Check functions
+# These functions are used to verify if a guess is correct by checking some
+# common property of a running system (presence of a directory in /run etc.)
+
+check_busybox_init() (
+	busybox_path=${1:-/bin/busybox}
+	test -x "${busybox_path}" || return 1
+	grep -q 'BusyBox v[0-9]' "${busybox_path}" || return 1
+
+	# It is quite common to use Busybox init to stack other init systemd
+	# (like OpenRC) on top of it. So we check for that, too.
+	if stacked=$(check_openrc)
+	then
+		echo "busybox-init+${stacked}"
+	else
+		echo busybox-init
+	fi
+)
+
+check_hurd_init() (
+	init_exe=${1:-/hurd/init}
+	test -x "${init_exe}" || return 1
+	grep -q 'GNU Hurd' "${init_exe}" || return 1
+	echo hurd-init
+)
+
+check_init() {
+	# Checks for various BSD inits...
+	test -x /sbin/init || return 1
+
+	if grep -q -E '(Free|Net|Open)BSD' /sbin/init
+	then
+		echo init
+		return 0
+	fi
+}
+
+check_launchd() {
+	command -v launchctl >/dev/null 2>&1 || return 1
+	launchctl getenv PATH >/dev/null || return 1
+	echo launchd
+}
+
+check_openrc() {
+	test -f /run/openrc/softlevel || return 1
+	echo openrc
+}
+
+check_procd() (
+	procd_path=${1:-/sbin/procd}
+	test -x "${procd_path}" || return 1
+	grep -q 'procd' "${procd_path}" || return 1
+	echo procd
+)
+
+check_runit() {
+	test -d /run/runit || return 1
+	echo runit
+}
 
-uname_s="$(uname -s)"
+check_smf() {
+	# XXX: Is this the correct way??
+	test -f /etc/svc/volatile/svc_nonpersist.db || return 1
+	echo smf
+}
+
+check_systemd() {
+	# NOTE: sd_booted(3)
+	test -d /run/systemd/system/ || return 1
+	# systemctl --version | sed -e '/^systemd/!d;s/^systemd //'
+	echo systemd
+}
+
+check_systemstarter() {
+	test -d /System/Library/StartupItems/ || return 1
+	test -f /System/Library/StartupItems/LoginWindow/StartupParameters.plist || return 1
+	echo init+SystemStarter
+}
+
+check_sysvinit() (
+	init_path=${1:-/sbin/init}
+	grep -q 'INIT_VERSION=sysvinit-[0-9.]*' "${init_path}" || return 1
+
+	# It is quite common to use SysVinit to stack other init systemd
+	# (like OpenRC) on top of it. So we check for that, too.
+	if stacked=$(check_openrc)
+	then
+		echo "sysvinit+${stacked}"
+	else
+		echo sysvinit
+	fi
+	unset stacked
+)
+
+check_upstart() {
+	test -x "$(command -v initctl)" || return 1
+	case $(initctl version)
+	in
+		*'(upstart '*')')
+			if test -d /etc/init
+			then
+				# modern (DBus-based?) upstart >= 0.5
+				echo upstart
+			elif test -d /etc/event.d
+			then
+				# ancient upstart
+				echo upstart-legacy
+			else
+				# whatever...
+				echo upstart
+			fi
+			;;
+		*)
+			return 1
+			;;
+	esac
+}
+
+find_init_procfs() (
+	# First, check if the required file in procfs exists...
+	test -h /proc/1/exe || return 1
+
+	# Find init executable
+	init_exe=$(ls -l /proc/1/exe 2>/dev/null) || return 1
+	init_exe=${init_exe#* -> }
+
+	if ! test -x "$init_exe"
+	then
+		# On some rare occasions it can happen that the
+		# running init's binary has been replaced. In this
+		# case Linux adjusts the symlink to "X (deleted)"
+
+		# [root@fedora-12 ~]# readlink /proc/1/exe
+		# /sbin/init (deleted)
+		# [root@fedora-12 ~]# ls -l /proc/1/exe
+		# lrwxrwxrwx. 1 root root 0 2020-01-30 23:00 /proc/1/exe -> /sbin/init (deleted)
+
+		init_exe=${init_exe% (deleted)}
+		test -x "$init_exe" || return 1
+	fi
+
+	echo "${init_exe}"
+)
+
+guess_by_path() {
+	case $1
+	in
+		/bin/busybox)
+			check_busybox_init "$1" && return
+			;;
+		/lib/systemd/systemd)
+			check_systemd "$1" && return
+			;;
+		/hurd/init)
+			check_hurd_init "$1" && return
+			;;
+		/sbin/launchd)
+			check_launchd "$1" && return
+			;;
+		/usr/bin/runit|/sbin/runit)
+			check_runit "$1" && return
+			;;
+		/sbin/openrc-init)
+			if check_openrc "$1" >/dev/null
+			then
+				echo openrc-init
+				return
+			fi
+			;;
+		/sbin/procd)
+			check_procd "$1" && return
+			;;
+		/sbin/init|*/init)
+			# init: it could be anything -> (explicit) no match
+			return 1
+			;;
+	esac
+
+	# No match
+	return 1
+}
+
+guess_by_comm_name() {
+	case $1
+	in
+		busybox)
+			check_busybox_init && return
+			;;
+		openrc-init)
+			if check_openrc >/dev/null
+			then
+				echo openrc-init
+				return 0
+			fi
+			;;
+		init)
+			# init could be anything -> no match
+			return 1
+			;;
+		*)
+			# Run check function by comm name if available.
+			# Fall back to comm name if either it does not exist or
+			# returns non-zero.
+			if type "check_$1" >/dev/null
+			then
+				"check_$1" && return
+			else
+				echo "$1" ; return 0
+			fi
+	esac
+
+	return 1
+}
+
+check_list() (
+	# List must be a multi-line input on stdin (one name per line)
+	while read -r init
+	do
+		"check_${init}" || continue
+		return 0
+	done
+	return 1
+)
+
+
+# BusyBox's versions of ps and pgrep do not support some options
+# depending on which compile-time options have been used.
+
+find_init_pgrep() {
+	pgrep -P0 -fl 2>/dev/null | awk -F '[[:blank:]]' '$1 == 1 { print $2 }'
+}
+
+find_init_ps() {
+	case $KERNEL_NAME
+	in
+		Darwin)
+			ps -o command -p 1 2>/dev/null | tail -n +2
+			;;
+		FreeBSD)
+			ps -o args= -p 1 2>/dev/null | cut -d ' ' -f 1
+			;;
+		Linux)
+			ps -o comm= -p 1 2>/dev/null
+			;;
+		NetBSD)
+			ps -o comm= -p 1 2>/dev/null
+			;;
+		OpenBSD)
+			ps -o args -p 1 2>/dev/null | tail -n +2 | cut -d ' ' -f 1
+			;;
+		*)
+			ps -o args= -p 1 2>/dev/null
+			;;
+	esac | trim  # trim trailing whitespace (some ps like Darwin add it)
+}
+
+find_init() {
+	case $KERNEL_NAME
+	in
+		Linux|GNU|NetBSD)
+			find_init_procfs || find_init_pgrep || find_init_ps
+			;;
+		FreeBSD)
+			find_init_procfs || find_init_ps
+			;;
+		OpenBSD)
+			find_init_pgrep || find_init_ps
+			;;
+		Darwin|SunOS)
+			find_init_ps
+			;;
+		*)
+			echo "Don't know how to determine init." >&2
+			echo 'Please send a patch.' >&2
+			exit 1
+	esac
+}
+
+# -----
+
+init=$(find_init)
+
+# If we got a path, guess by the path first (fall back to file name if no match)
+# else guess by file name directly.
+# shellcheck disable=SC2015
+{
+	test -x "${init}" \
+		&& guess_by_path "${init}" \
+		|| guess_by_comm_name "$(basename "${init}")"
+} && exit 0 || true
+
+
+# Guessing based on the file path and name didn’t lead to a definitive result.
+#
+# We go through all of the checks until we find a match. To speed up the
+# process, common cases will be checked first based on the underlying kernel.
 
-case "$uname_s" in
-    Linux)
-        (pgrep -P0 -l | awk '/^1[ \t]/ {print $2;}') || true
-    ;;
-    FreeBSD|OpenBSD)
-        ps -o comm= -p 1 || true
-    ;;
-    *)
-        # return a empty string as unknown value
-        echo ""
-    ;;
-esac
+{ common_candidates_by_kernel; echo "${KNOWN_INIT_SYSTEMS}"; } \
+	| unique | check_list