core-agent-linux/qubes-rpc/qubes.RegisterBackupLocation

#!/bin/sh

# Register backup location (path or a command) to be retrieved with qubes
# .RestoreById service.
# Registered location is only valid as long as this service call stays open

set -e

REGISTRY_DIR="$XDG_RUNTIME_DIR/qubes-backup-location"

if ! [ -d "$REGISTRY_DIR" ]; then
    mkdir -p "$REGISTRY_DIR"
fi

read -r backup_location

REGISTRY_FILE=$(mktemp "$REGISTRY_DIR/XXXXXXXX")

PID=$$
# this isn't perfetct, as comm field could contain spaces, but we do control
# this value and we know it doesn't
START_TIME=$(cut -f 22 -d ' ' /proc/$PID/stat)
# add process id at the beginning to help verifying if it's still running;
# record starttime too, to detect PID reuse
printf "%d %d\n%s\n" "$PID" "$START_TIME" "$backup_location" >"$REGISTRY_FILE"
# output registered ID to the user
basename "$REGISTRY_FILE"
# close stdout
exec >&-
# wait for stdin to close
cat >/dev/null
# and cleanup
rm -f "$REGISTRY_FILE"