#!/usr/bin/env bash
_scriptname="ddv"
set -u
set -e


function log { printf '%s\n' "$*" >&2; }


# print usage
function printusage
{
cat - >&2 <<EOF

Description:
  Runs dd in a pseudo-verbose mode, giving it a USR1 signal every 10 seconds to force status output.

Usage: ${_scriptname} [options] <args>
Options:
  See: $ ${_scriptname} --help

EOF
}
if (($# == 0)); then
	printusage
	exit 0
fi


# exit trap!
function die
{
	{
		((pid != 0)) || return
		trap - CHLD EXIT
		set +e
		kill -TERM "$pid"
		wait "$pid"
		status=$?
		pid=0
		exit $status
	} 2>/dev/null
}
#trap die CHLD
trap 'echo -en "\nAborting..." >&2; die' EXIT


# vars
pcount=10
pid=0


# verbose output
log "status every $pcount seconds"


# dd options
opts=( "oflag=sync" )


# add bs=1M if none is specified
bs=false
for opt; do
	if [[ "${opt,,}" = "bs="* ]]; then
		bs=true
		break
	fi
done
$bs || opts+=( "bs=1M" )


# run dd
set +m
log "dd ${opts[*]} $*"
dd "${opts[@]}" "$@" &
pid=$!
log "pid: $pid"


# print status every $pcount seconds
c=0
while kill -0 "$pid" 2>/dev/null && sleep 1; do
	((++c % pcount != 0 )) || kill -USR1 "$pid" 2>/dev/null || :
done


# explicitly sync drives
log "sync"
sync 2>/dev/null || :


# exit
die