#!/usr/bin/perl
use strict;
use warnings;
use File::Temp 'tempdir';
use Getopt::Long;
use POSIX 'geteuid';
use Fatal;
Fatal->import('run');

my @RSYNC = qw( rsync -va );
my @MOUNT = qw( mount -t tmpfs );

if (geteuid() != 0) {
    die "This must be executed as root\n";
}

my $size = '250m';
GetOptions('size|s=s' => \$size);

my $dir    = shift or die "Usage: tmpmount [options] dir";
my $tmpdir = tempdir( CLEANUP => 1 );

run(@RSYNC => "$dir/",    "$tmpdir/");
run(@MOUNT => '-o',       "size=$size", 'none', $dir);
run(@RSYNC => "$tmpdir/", "$dir/");

sub run {
    warn "run: @_\n";
    return system(@_) == 0;
}