#!/usr/bin/perl

=head1 block-devices

Display all block devices on system

  hdparm -t `block-devices`

  sfdisk -l `block-devices with-partitions`

=cut

use warnings;
use strict;
#use autodie;

my $with_partitions = { true => 1 } if grep { m/with.?partitions/ } @ARGV;

open(my $proc, '<', '/proc/partitions');

my @header;
my $last_device = '';

my $name2col;
sub col {
	my ( $name, $line ) = @_;
	if ( ! $name2col ) {
		$name2col->{ $header[$_] } = $_ foreach 0 .. $#header;
	}
	$line =~ s/^\s+// || die "expected line to start with space: $_\n";
	my @c = split(/\s+/, $line, $#header + 1 );
	return $c[ $name2col->{ $name } ];
}

while(<$proc>) {
	chomp;
	if ( ! @header ) {
		@header = split(/\s+/, $_);
		next;
	}
	next unless $_;

	my $device = col 'name', $_;
	my $device_like_last = substr( $device, 0, length($last_device) );
	if ( $last_device && $device_like_last eq $last_device ) {
		if ( $with_partitions ) {
			print "/dev/$device_like_last\n" if ! $with_partitions->{ $device_like_last }++;
		} else {
			warn "# partition $device\n";
		}
	} else {
		print "/dev/$device\n" unless $with_partitions;
		$last_device = $device;
	}
}