machine-id.init

#!/bin/sh
### BEGIN INIT INFO
# Provides:          machine-id
# Required-Start:    $local_fs
# Required-Stop:     $local_fs
# Should-Start:
# X-Start-Before:    dbus
# Default-Start:     2 3 4 5
# Default-Stop:      0 6
# Short-Description: Handle flexible machine-id modes and session cleanup
# Description:       Controls volatile or static machine-id layout variations
#                    and purges accumulated session bus files on shutdown.
### END INIT INFO

PATH=/sbin:/usr/sbin:/bin:/usr/bin
NAME=machine-id
DESC="Flexible machine-id and session management"

# Source the standard Debian/Devuan LSB logging utility library
. /lib/lsb/init-functions

VOLATILE_MACHINE_ID=""
DRYRUN=""
USE_MAC_FALLBACK=""
CONFIG="/etc/default/${NAME}.rc"
# Source configuration overrides if the file exists
if [ -f "$CONFIG" ]; then
    . "$CONFIG"
fi

EtcMachineID=/etc/machine-id
RunMachineID=/run/machine-id
BaseDbusSessDir=".dbus/session-bus"

clean_dir() {
    local target_dir="$1"
    if [ -d "$target_dir" ] && [ "$(echo "$target_dir"/*)" != "$target_dir/*" ]; then
        if [ "$DRYRUN" = "yes" ]; then
            for item in "$target_dir"/*; do
                log_action_msg "Dry-run: Would remove $item"
            done
        else
            rm -f -- "$target_dir"/*
        fi
    fi
}

fallback_machine_id_gen() {
    local mac_hex=""
    local needed_chars=32
    local machine_id_file="$1"

    local BaseNetDir="/sys/class/net"
    local net_dir
    local raw_mac
    # Only attempt MAC acquisition if explicitly enabled by the administrator
    if [ "$USE_MAC_FALLBACK" = "yes" ]; then
        for net_dir in "$BaseNetDir"/*; do
            if [ -d "$net_dir" ] && [ "${net_dir##*/}" != "lo" ] && [ -f "$net_dir/address" ]; then
                read -r raw_mac < "$net_dir/address"
                mac_hex=$(printf '%s' "$raw_mac" | tr -d ':' | tr '[:upper:]' '[:lower:]')
                if [ ${#mac_hex} -eq 12 ] && [ "$mac_hex" != "000000000000" ]; then
                    break
                fi
                mac_hex=""
            fi
        done
    fi

    # Calculate remainder space (defaults to 32 if MAC loop was bypassed or empty)
    needed_chars=$((32 - ${#mac_hex}))

    # Write out any discovered MAC slice first, then append random entropy
    printf "%s" "$mac_hex" > "$machine_id_file"
    tr -dc 'a-f0-8' < /dev/urandom 2>/dev/null | head -c "$needed_chars" >> "$machine_id_file"
    printf "\n" >> "$machine_id_file"
}

machine_id_gen() {
    local target_file="$1"

    if command -v dbus-uuidgen >/dev/null 2>&1; then
        dbus-uuidgen --ensure="$target_file"
    else
        fallback_machine_id_gen "$target_file"
    fi
}

do_start() {
    if [ -n "$VOLATILE_MACHINE_ID" ] && [ "$VOLATILE_MACHINE_ID" != "no" ]; then
        log_daemon_msg "Setting up volatile machine-id" "$NAME"

        if [ ! -L "$EtcMachineID" ] || [ "$(readlink "$EtcMachineID")" != "$RunMachineID" ]; then
            rm -f "$EtcMachineID"
            ln -sf "$RunMachineID" "$EtcMachineID"
        fi

        if [ ! -s "$RunMachineID" ]; then
            machine_id_gen "$RunMachineID"
        fi
        log_end_msg 0
    else
        log_daemon_msg "Checking persistent static machine-id" "$NAME"

        # If it was a volatile symlink, safely capture its contents to disk before destroying it
        if [ -L "$EtcMachineID" ]; then
            if [ -s "$RunMachineID" ]; then
                local temp_id
                temp_id=$(cat "$RunMachineID")
                rm -f "$EtcMachineID" "$RunMachineID"
                printf "%s\n" "$temp_id" > "$EtcMachineID"
            else
                rm -f "$EtcMachineID"
            fi
        fi

        # Generate a standard static ID ONLY if the static file is genuinely missing or empty
        if [ ! -f "$EtcMachineID" ] || [ ! -s "$EtcMachineID" ]; then
            rm -f "$EtcMachineID"
            machine_id_gen "$EtcMachineID"
        fi
        log_end_msg 0
    fi
}

do_stop() {
    PowerState="/sys/power/state"
    PowerPMStatus="/sys/power/pm_status"
    if [ -f "$PowerState" ]; then
        if [ -f "$PowerPMStatus" ] && grep -q -E "freeze|suspend|hibernate" "$PowerPMStatus" 2>/dev/null; then
            return 0
        fi
    fi

    log_daemon_msg "Removing stale session-bus files" "$NAME"

    clean_dir "/root/${BaseDbusSessDir}"

    getent passwd | cut -d: -f6 | while read -r userhome; do
        if [ -z "$userhome" ] || [ "$userhome" = "/" ]; then
            continue
        fi
        clean_dir "$userhome/${BaseDbusSessDir}"
    done

    log_end_msg 0
}

case "$1" in
    start)
        do_start
        ;;
    stop)
        do_stop
        ;;
    restart|force-reload)
        do_stop
        do_start
        ;;
    status)
        if [ -L "$EtcMachineID" ]; then
            log_success_msg "Machine-ID Mode: Volatile RAM (Value: $(cat "$EtcMachineID"))"
            exit 0
        elif [ -s "$EtcMachineID" ]; then
            log_success_msg "Machine-ID Mode: Persistent Static (Value: $(cat "$EtcMachineID"))"
            exit 0
        else
            log_failure_msg "Machine-ID file missing or uninitialized."
            exit 3
        fi
        ;;
    *)
        echo "Usage: $NAME {start|stop|restart|force-reload|status}" >&2
        exit 3
        ;;
esac