#!/bin/sh
# GFMN* and GFLT* use sysvar_cmd to read/write flash instead of hnvram.
# ginstall wants to call hnvram like:
# hnvram -w VAR1=val1 -w VAR2=val2 -w VAR3=val3
# hnvram -r VAR1
# hnvram -qr VAR1
#
# This will translate those into sysvar_cmd calls.

# If there is an hnvram partition then redirect the hnvram command to the real
# hnvram binary. This is done in an effort to remove sysvar from the FiberJack
# and other devices that use it.
if [ -e /dev/mtd/hnvram ]; then
  exec hnvram_binary "$@"
  exit 1
fi

SYSVAR_CMD="sysvar_cmd"
QUIET_MODE=""
CAN_ADD_VARS=""

err_log() {
  echo "$@" >&2
}

print_usage() {
  local PROGNAME="$(basename "$0")"
  err_log "Usage: $PROGNAME [[-n] -w key1=val1 key2=val2 ... | -[q]r key]"
  err_log
  err_log "hnvram wrapper with $SYSVAR_CMD backend"
  err_log
  err_log "Options:"
  err_log "-h          Print this message and exit."
  err_log "[-n] -w KEY=VAL"
  err_log "            Variable to write to sysvar.  Must be formatted as KEY=VAL."
  err_log "            Can be declared multiple times. -n allows creation of new keys"
  err_log "[-q] -r KEY"
  err_log "            Attempt to read the key from sysvar (must declare once)."
  err_log "            With -q, print value without KEY= prefix."
  err_log "-k KEY"
  err_log "            Remove key from sysvar. Can only declare once."
  exit 1
}

sysvar_read() {
  local OUTPUT # Needed in seperate statement to capture errors with $?
  OUTPUT=$("$SYSVAR_CMD" --get "$1" 2>/dev/null)
  if [ $? -ne 0 ]; then
    err_log "ERROR: sysvar read failed: '$1'"
    exit 1
  fi

  if [ -n "$QUIET_MODE" ]; then
    echo "$OUTPUT"
  else
    echo "$1=$OUTPUT"
  fi
}

sysvar_write() {
  # Since the '<<<' is not a supported operator in all shells, echo the write
  # argument into a sub shell so that IFS can be set and 'read' can split the
  # "KEY=VAL" string straight from stdin.
  echo "$1" | {
    IFS="="
    read KEY VAL
    if [ -z "$KEY" ]; then
      err_log "ERROR: Malformed key/value pair: $1"
      exit 1
    fi

    if [ -z "$CAN_ADD_VARS" ]; then
      "$SYSVAR_CMD" --get "$KEY" 1>/dev/null 2>/dev/null
      if [ $? -ne 0 ]; then
        err_log "ERROR: sysvar failed to write: $KEY not found. Use -n if new"
        exit 1
      fi
    fi

    "$SYSVAR_CMD" --set "$KEY" "$VAL" 2>/dev/null
    if [ $? -ne 0 ]; then
      err_log "ERROR: sysvar failed to write: $1"
      exit 1
    fi
  }
}

sysvar_clear() {
  local OUTPUT
  local EXITCODE
  OUTPUT=$("$SYSVAR_CMD" --remove "$1" 2>/dev/null)
  EXITCODE=$?
  # No need to throw error if variable already cleared
  # sysvar_cmd returns -14 in this scenario, which is converted
  # to 8-bit unsigned int as 242
  if [ $EXITCODE -ne 0 ] && [ $EXITCODE -ne 242 ]; then
    err_log "ERROR: sysvar clear failed: '$1'"
    exit 1
  fi
}

main() {
  local WRITE_ARR=""
  local READ_KEY=""
  while getopts ":nw:qr:k:dbh" OPT; do
    case "$OPT" in
      w)
        if [ -n "$WRITE_ARR" ]; then
          WRITE_ARR="$WRITE_ARR $OPTARG"
        else
          WRITE_ARR="$OPTARG"
        fi
        ;;
      r)
        if [ ! -z $READ_KEY ]; then
          print_usage
        fi
        READ_KEY="$OPTARG"
        ;;
      k)
        if [ ! -z $CLEAR_KEY ]; then
          print_usage
        fi
        CLEAR_KEY="$OPTARG"
        ;;
      q)
        QUIET_MODE="true"
        ;;
      n)
        CAN_ADD_VARS="true"
        ;;
      d|b)
        :
        ;;
      h)
        print_usage
        ;;
      :)
        print_usage
        ;;
      \?)
        print_usage
        ;;
      *)
        print_usage
        ;;
    esac
  done

  if [ -z "$READ_KEY" ] && [ -z "$WRITE_ARR" ] && [ -z "$CLEAR_KEY" ]; then
    err_log "ERROR: Must read, write or remove something."
    print_usage
  fi

  if [ -n "$READ_KEY" ] && [ -n "$WRITE_ARR" ] && [ -n "$CLEAR_KEY" ]; then
    err_log "ERROR: Can only do one operation at a time. Read, Write, or Remove"
    print_usage
  fi

  if [ -n "$WRITE_ARR" ]; then
    for KEYVAL in "$WRITE_ARR"; do
      sysvar_write "$KEYVAL"
    done
  elif [ -n "$READ_KEY" ]; then
    sysvar_read "$READ_KEY"
  elif [ -n "$CLEAR_KEY" ]; then
    sysvar_clear "$CLEAR_KEY"
  fi
}

main "$@"