#!/bin/sh

[ -x /usr/sbin/nvme ] || exit

PROC="$(basename "$0")[$$]"

log() {
  FACILITY="kern.$1"
  shift
  logger -s -p "$FACILITY" -t "$PROC" "$@"
}

raw_ebs_alias() {
  /usr/sbin/nvme id-ctrl "/dev/$BASE" -b 2>/dev/null | dd bs=32 skip=96 count=1 2>/dev/null
}

case $ACTION in
  add|"")
    BASE=$(echo "$MDEV" | sed -re 's/^(nvme[0-9]+n[0-9]+).*/\1/')
    PART=$(echo "$MDEV" | sed -re 's/nvme[0-9]+n[0-9]+p?//g')
    MAXTRY=50
    TRY=0
    until [ -n "$EBS" ]; do
      EBS=$(raw_ebs_alias | sed -nre '/^(\/dev\/)?(s|xv)d[a-z]{1,2} /p' | tr -d ' ')
      [ -n "$EBS" ] && break
      TRY=$((TRY + 1))
      if [ $TRY -eq $MAXTRY ]; then
        log err "Failed to get EBS volume alias for $MDEV after $MAXTRY attempts ($(raw_ebs_alias))"
        exit 1
      fi
      sleep 0.1
    done
    # remove any leading '/dev/', 'sd', or 'xvd', and append partition
    EBS=${EBS#/dev/}
    EBS=${EBS#sd}
    EBS=${EBS#xvd}$PART
    ln -sf "$MDEV" "sd$EBS" && log notice "Added sd$EBS symlink for $MDEV"
    ln -sf "$MDEV" "xvd$EBS" && log notice "Added xvd$EBS symlink for $MDEV"
    ;;
  remove)
    for TARGET in sd* xvd*
    do
      [ "$(readlink "$TARGET" 2>/dev/null)" = "$MDEV" ] && rm -f "$TARGET" && log notice "Removed $TARGET symlink for $MDEV"
    done
    ;;
esac