#! /bin/bash
# Copyright 1999-2022 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

progname="$(basename "$0")"

T="$(getopt -o "h" --long "help,corecompress:,corerename:,crashemail:,dumpcore:,instance:,maxfd:,nicelevel:,restartdelay:,rundir:,syslog,tty:" -n "$progname" -- "$@")"
eval set -- "${T}"

rundir=/run/asterisk
restartdelay=5
nicelevel=0
maxfd=4096
dumpcore=0
unset tty instance syslog corecompress corerename crashemail

function usage() {
	cat <<USAGE
USAGE: $progname [options] -- asterisk options"
OPTIONS:
	-h|--help
		Output this text and exit.
	--corecompress[=tool]
		asterisk's address space can get quite large, compressing the core dumps can
		save significant space, especially if asterisk core dumps frequently.
	--corerename pattern
		It's assumed core files (if enabled) will go into PWD, this specifies a
		rename pattern.  The following % codes are recognised:
			%h - hostname
			%D - date in format YYYYMMDD
			%T - time in format HHMMSS
		It must be mentioned that if kernel.core_pattern (sysctl) is modified
		from the default 'core' value this option is unlikely to work.
	--crashemail email@address
		This will send an email whenver asterisk crashes (does not terminate
		cleanly with a zero exit code).  You need a working sendmail binary.
	--dumpcore sizelimit
		Maximum size of core limit, or the word unlimited.  Default is disabled
		(sizelimit of 0).
	--instance name
		Updated label for sylog logger.
	--maxfd maxfd
		Sets the maximum number of file descriptors (default 4096).
	--nicelevel nicelevel
		Will set the asterisk nice level to the specified value.
	--restartdelay delay_in_seconds
		Number of seconds to wait before attempting to restart asterisk.  This helps
		to avoid tight-loop crashes.  Defaults to 5s. Minimum 1.
	--rundir path
		Where to store the asterisk asterisk_wrapper.pid file.  In order to terminate the
		wrapper (when asterisk next terminates), remove this file.
	--syslog
		Pass to redirect output to syslog rather than using stdout and stderr.
	--tty tty
		If asterisk should be attached to a TTY device, then pass this, eg --tty /dev/tty8.
		Use of this is not recommended in general.

NOTE:  There are some quirks with bash getopt shunting non-options prior to --
	to asterisk options, so be careful of this.  Typically stuff will break.
USAGE
}

while [ "$1" != "--" ]; do
	case "$1" in
			--corecompress|--corerename|--crashemail|--dumpcore|--instance|--maxfd|--nicelevel|--restartdelay|--rundir|--tty)
			eval "${1:2}=\"\${2}\""
			shift 2
			;;
		--syslog)
			eval "${1:2}=1"
			shift
			;;
		--help|-h)
			usage
			exit 0
			;;
		*)
			echo "BUG: Don't know how to process option $1." >&2
			usage >&2
			exit 1
			;;
	esac
done
shift # --

ast_opts=("$@")

if ! [[ "${restartdelay}" =~ ^[1-9][0-9]*$ ]]; then
	echo "Invalid --restartdelay value ${restartdelay}, resetting to 5." >&2
	restartdelay=5
fi

if [[ -n "${corecompress}" && ! -x "${corecompress}" ]]; then
	corecompress=$(which "${corecompress}" 2>/dev/null)
	[[ -z "${corecompress}" ]] && echo "Error locating core compression tool, disabling core compression." >&2
fi

# Before here will still be output (potentially munged, to the terminal).
if [[ -n "${syslog}" ]]; then
	exec 1> >(logger -t "asterisk_wrapper${instance:+:}${instance}" &>/dev/null)
	exec 2>&1
fi

echo "Initializing ${progname}"

function cleanup(){
	# There is a tiny race here, if this gets replaced inbetween the read and the rm.
	# To fix this is quite complex in that we need to keep an fd, compare inode numbers
	# and manage flock's.
	[[ -r "${rundir}/${progname}.pid" ]] && \
		[[ "$(<"${rundir}/${progname}.pid")" = $$ ]] && \
		rm "${rundir}/${progname}.pid"
}
trap cleanup EXIT

# We could be clobbering an old version's pid, in which case it'll just terminate on
# it's next iteration.  Towards this end, if asterisk.pid exists, attempt to find it's
# config file and request a core stop when convenient so that we can take over.
echo $$ > "${rundir}/${progname}.pid"
if [[ -r "${rundir}/asterisk.pid" ]]; then
	ast_pid="$(<"${rundir}/asterisk.pid")"
	[[ -r "/proc/${ast_pid}/cmdline" ]] && ast_conf="$(tr '\0' '\n' < "/proc/${ast_pid}/cmdline" | grep -A1 '^-C$' | tail -n1)" && /usr/sbin/asterisk -C "${ast_conf:-/etc/asterisk/asterisk.conf}" -rx "core stop when convenient"
	# We may hit a few (depending on how busy the server is a great many number) loop failures still ...
fi

ulimit -c "${dumpcore}"
ulimit -n "${maxfd}"

ast_cmd=()
if [ -n "${nicelevel}" ]; then
	ast_cmd+=(nice -n "${nicelevel}")
fi
ast_cmd+=(/usr/sbin/asterisk "${ast_opts[@]}")

while [[ -r "${rundir}/${progname}.pid" ]]; do
	# Another instance is looking to replace us, so terminate.
	if [[ "$(<"${rundir}/${progname}.pid")" != $$ ]]; then
		break
	fi

	echo "Starting asterisk with ${ast_opts[*]}"
	if [ -n "${tty+yes}" ]; then
		/bin/stty -F "${tty}" sane
		"${ast_cmd[@]}" >"${tty}" 2>&1 <"${tty}"
		result=$?
	else
		# Purposefully leave stderr alone, this will under certain odd cases (like exceptions,
		# and other odd cases logged from glibc) result in those logs at least being captured
		# in syslog.
		"${ast_cmd[@]}" </dev/null >/dev/null
		result=$?
	fi

	if [ "$result" -eq 0 ]; then
		echo "Asterisk terminated normally."
		break
	fi
		
	if [ "$result" -gt 128 ]; then
		signal="$(( result - 128 ))"
		signame="$(kill -l $signal 2>/dev/null)"
		MSG="Asterisk terminated with Signal: $signal (SIG${signame:-???})"

		# TODO: figure out how to use /proc/sys/kernel/core_pattern here, but if someone is using
		# that, chances are they're already dealing with what we want here.
		if [[ -r core ]]; then
			if [[ -n "${corerename+yes}" ]]; then
				core_target="${core_pattern}"
				core_target="${core_target//%h/"$(hostname)"}"
				core_target="${core_target//%D/"$(date +%Y%m%d)"}"
				core_target="${core_target//%T/"$(date +%H%M%S)"}"
				mv core "${core_target}"
				core_target=$(readlink -f "${core_target}")
			else
				core_target=$(readlink -f core)
			fi

			if [[ -n "${corecompress}" && -x "${corecompress}" ]]; then
				"${corecompress}" "${core_target}"
				# TODO: Figure out a way to tag the extension onto core_target.
			fi
			
			MSG="${MSG}\r\nCore dumped: ${core_target}"
		fi
	else
		MSG="Asterisk terminated with return code: $result"
	fi

	[ -n "${tty+yes}" ] \
		&& echo "${MSG}" >"${tty}" \
		|| echo "${MSG}"

	if [[ -n "${crashemail+yes}" && -x /usr/sbin/sendmail ]]; then
		echo -e -n "Subject: Asterisk crashed\r\n${MSG}\r\n" |\
			 /usr/sbin/sendmail "${crashemail}"
	fi
	echo "Restarting asterisk after ${restartdelay}s ..."
	sleep "${restartdelay}"
done

echo "Terminating $progname."
exit 0