# Copyright 2007-2008 Roy Marples <roy@marples.name>
# All rights reserved. Released under the 2-clause BSD license.

# Handy function to handle all our unmounting needs
# mountinfo is a C program to actually find our mounts on our supported OS's
# We rely on fuser being preset, so if it's not then we don't unmount anything.
# This isn't a real issue for the BSD's, but it is for Linux.
do_unmount()
{
	local cmd="$1" retval=0 retry= pids=-
	local f_opts="-m -c" f_kill="-s " mnt=
	if [ "${RC_UNAME}" = "Linux" ]; then
		f_opts="-m"
		f_kill="-"
	fi

	shift
	mountinfo "$@" | while read mnt; do
		# Unmounting a shared mount can unmount other mounts, so
		# we need to check the mount is still valid
		mountinfo --quiet "${mnt}" || continue

		case "${cmd}" in
			umount*)
				ebegin "Unmounting ${mnt}"
				;;
			*)
				ebegin "Remounting ${mnt}"
				;;
		esac

		retry=3
		while ! LC_ALL=C ${cmd} "${mnt}" 2>/dev/null; do
			if type fuser >/dev/null 2>&1; then
				pids="$(fuser ${f_opts} "${mnt}" 2>/dev/null)"
			fi
			case " ${pids} " in
				*" $$ "*)
					eend 1 "failed because we are using" \
					"${mnt}"
					retry=0;;
				" - ")
					eend 1
					retry=0;;
				"  ")
					eend 1 "in use but fuser finds nothing"
					retry=0;;
				*)
					local sig="KILL"
					[ ${retry} -gt 0 ] && sig="TERM"
					fuser ${f_kill}${sig} -k ${f_opts} \
						"${mnt}" >/dev/null 2>&1
					sleep 1
					retry=$((${retry} - 1))
					;;
			esac

			# OK, try forcing things
			if [ ${retry} -le 0 ]; then
				case "${cmd}" in
					umount*)
						LC_ALL=C ${cmd} -f "${mnt}" \
						|| retry=-999
						;;
					*)
						retry=-999
						;;
				esac
				break
			fi
		done
		if [ ${retry} -eq -999 ]; then
			eend 1
			retval=1
		else
			eend 0
		fi
	done
	return ${retval}
}