Recursive MD5/SHA1/SHA256/SHA512 checksum validator for TrueNAS CORE (or any other *BSD operating system)

hash-check.sh

#!/bin/bash
# cs@fnx.li (2022-05-31)
###
# License: GNU General Public License v3.0
# Source: https://gist.github.com/3b8ea25c5ca4b473624de6c8a567ebe5
###
set -o pipefail

function usage()
{
	cat << EOF >&2
Usage: $0 ALGO FILE|DIR ...

  Checks lines of FILEs and/or searches checksum files in DIRs.
  It is a nice recursive checksum implementation for TrueNAS CORE.
  Should be compatible with any *BSD system. (Linux unsupported!)

  Supported ALGOrithms:
    md5 sha1 sha256 sha512

  Supported checksum filenames in DIRs:
    *.ALGO *.ALGOsum *.ALGOsums ALGOsum ALGOsums

  Supported checksum format:
    CHECKSUM  FILENAME

    2 spaces between CHECKSUM and FILENAME!
    Checksum must be a hex-string. (0-9 & A-F)

  Output messages:
    STDOUT (1) - Processed filenames and directories.
    STDERR (2) - Command errors and failed checksums.

    Use output redirection to suppress something:
      $(basename "$0")  >/dev/null  # hide progress
      $(basename "$0") 2>/dev/null  # hide errors
      $(basename "$0") &>/dev/null  # no output

  Return codes:
      0 - OK (checksums matched)
    > 0 - ERROR (see STDERR output)

-- $(head -n 2 "$0" | tail -n 1 | cut -b 3-)
EOF
	exit 2
}

function check()
{
	method=${1,,}
	case "$method"
	in
		md5)
			l=32
			;;

		sha1)
			l=40
			;;

		sha256)
			l=64
			;;

		sha512)
			l=128
			;;

		*)
			echo "Invalid algorithm: $method" >&2
			return 1
			;;
	esac

	state=0
	path=$(readlink -f "$2")
	while IFS= read -r line
	do
		sum=${line:0:l}
		file=${line:l+2}

		# shellcheck disable=SC2015
		[[ -n "$file" && "$sum" =~ ^[0-9A-Fa-f]+$ ]] \
		&& echo "Checking file: [$2]  $file" \
		&& "$method" -c "$sum" "$file" &>/dev/null \
		|| \
		{
			state=1
			echo "Failed: [$path]  $line"
		} >&2
	done < "$2"

	return $state
}

function status()
{
	[[ "$status" -ne 0 && "$HC_INTERNAL" -ne 1337 ]] && echo -e "\nFAILED!" >&2
	[[ "$status" -ne 0 || "$finished" -eq 1 ]] && exit "$status"
	exit 1
}

if [[ $# -lt 2 ]]
then
	usage
fi

algo=${1,,}
shift

case "$algo"
in
	md5|sha1|sha256|sha512)
		;;

	*)
		usage
		;;
esac

status=0
finished=0
trap status EXIT INT TERM
for realinput in "$@"
do
	input=$(readlink -f "$realinput")

	if [[ -n "$input" && -e "$realinput" ]]
	then
		if [[ -f "$input" ]]
		then
			echo "Checking file: [$input]"
			check "$algo" "$input" && continue

		elif [[ -d "$input" ]]
		then
			echo "Checking directory: $input"

			# shellcheck disable=SC2016
			find "$input" \
				-type f \
				\( \
					-iname "*.$algo"       -o \
					-iname "*.${algo}sum"  -o \
					-iname "*.${algo}sums" -o \
					-iname "${algo}sum"    -o \
					-iname "${algo}sums"      \
				\) \
				-print0 \
			| xargs -0 -n1 bash -c 'cd "$(dirname "$0")" && HC_INTERNAL=1337 '"$(printf '%q %q' "$0" "$algo")"' "$0" || exit 1' \
			&& continue
		fi
	fi

	{
		status=1
		[[ -n "$input" ]] \
		&& echo "Failed: [$input]" \
		|| echo "Failed: [$realinput]"
	} >&2
done
finished=1