extents-merge

#!/bin/bash

# SPDX-FileCopyrightText: 2016-2020 Graham R. Cobb
# SPDX-License-Identifier: GPL-3.0-or-later
#
# Copyright (C) 2016 Graham R. Cobb
# Released under GPL V3.0 -- see LICENSE
# list of extent start and finish pairs on stdin
# output list with overlapping and adjacent extents merged

# Make sure errors are passed back
set -o pipefail

if [ "$1" = "-s" ]
then
    shift
    $0 "$@" | extents-size
    exit $?
fi

sort -n |
# Merge adjacent or overlapping extents
awk -e '
        BEGIN	{
        	start = -1;
        	end = -2;
	}

                {
                if ($1 <= end + 1) {
			# This extent overlaps the preceeding one, or is adjacent to it
			# so update the end if it is further than the preceding one
			if ($2 > end) end = $2;
                } else {
			# New extent which does not need to be merged
                        if (start >= 0) print start, end, end - start + 1;
                        start = $1; end = $2;
		}
		}

	END	{if (start >= 0) print start, end, end - start + 1}
        '