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|
#!/bin/sh
set -eu
RC_MAGIC='~/rc'
progname=
rc_fifo=
error()
{
local fmt="${1}"
shift 1
printf "%s: ${fmt}\n" "${progname}" "${@}"
return 0
}
valid_session_type()
{
local session_type="${1}"
shift 1
case "${session_type}" in *[!A-Za-z0-9:]* | '' | ':'* | *':')
return 1
esac
return 0
}
# Returns 0 if the session is the first of its type or was last of its type
# TODO: Handle decrement from 0.
inc_session()
{
local s_type="${1}"
local dir=${2}
shift 2
local ret=
ret=1
s_type="$(printf '%s' "${s_type}" | tr ':' '_')"
eval "[ \${sessions_${s_type}:-0} -eq 0 ] && ret=0"
eval "sessions_${s_type}=\$((\${sessions_${s_type}:-0} + ${dir}))"
eval "[ \${sessions_${s_type}} -eq 0 ] && ret=0"
return ${ret}
}
chg_session()
{
local session_type="${1}"
local inc_dir=${2}
local diff="${3}"
shift 3
while :; do
case "${session_type}" in *:*);; *) break;; esac
if inc_session "${session_type}" ${inc_dir}; then
diff="${diff}${session_type},"
fi
session_type="${session_type%:*}"
done
diff="${diff%,}"
}
beg_session()
{
local session_type="${1}"
shift 1
chg_session "${session_type}" 1 '+'
return ${?}
}
end_session()
{
local session_type="${1}"
shift 1
chg_session "${session_type}" -1 '-'
return ${?}
}
listen()
{
local magic=
local cmd=
local arg=
while :; do
if read -r magic cmd arg; then
case "${magic}" in "${RC_MAGIC}");; *)
continue
esac
fi
case "${cmd}" in
'beg')
if valid_session_type "${arg}"; then
beg_session "${arg}"
fi
;;
'end')
if valid_session_type "${arg}"; then
end_session "${arg}"
fi
;;
'bye')
break
;;
*)
continue
;;
esac
done 0<"${rc_fifo}"
}
start()
{
local session_type="${1}"
shift 1
if mkfifo "${rc_fifo}" 2>/dev/null; then
beg_session "${session_type}"
listen
rm "${rc_fifo}"
else
# Signal the running rc daemon.
printf "%s beg %s\n" "${RC_MAGIC}" "${session_type}" \
1>"${rc_fifo}"
fi
return 0
}
stop()
{
local session_type="${1}"
shift 1
if mkfifo "${rc_fifo}" 2>/dev/null; then
# Assuming the daemon role just to end a non-existent session
# makes no sense.
error 'No running daemon found'
rm "${rc_fifo}"
return 1
else
# Signal the running rc daemon.
printf "%s end %s\n" "${RC_MAGIC}" "${session_type}" \
1>"${rc_fifo}"
fi
return 0
}
usage()
{
printf 'Usage: %s {start|stop} <session-type>\n' "${0}"
return 0
}
main()
{
local action=
local session_type=
if [ ${#} -ne 2 ]; then
usage 1>&2
return 1
fi
action="${1}"
session_type="${2}"
if ! valid_session_type; then
error 'Invalid session type'
return 1
fi
progname="${0##*/}"
rc_fifo="/tmp/homercrc-$(id -u)"
case "${action}" in
'start')
start "${session_type}"
;;
'stop')
stop "${session_type}"
;;
*)
usage 1>&2
return 1
;;
esac
return 0
}
main "${@}"
|
