use strict;
use Data::Dumper;
use Data::Diver qw( DiveVal );
use Storable 'dclone';

my %hash1 = (
        key1 => 'relative_path',
        key2 => {
                key21 => 'another_relative_path',
                key22 => '/an_absolute_path',
                key23 => 'relative_path',
        },
        key3 => '',
        key4 => 4
);

my $hash2 = dclone \%hash1;
my $hash3 = dclone \%hash1;
my $home = '/home';

my @paths = ('key1', 'key2:key22', 'key2:key23');

for my $path (@paths) {
   my @path = split(/:/, $path);
   my $val = dive(\%hash1, @path);
   my $new_val = (substr($val,0,1) eq '/') ?
      $val : "$home/$val";
   DiveVal($hash2, map \$_, @path) = $new_val;
#  dive_val($hash3, map \$_, @path) = $new_val;
}
die Dumper \@paths,\%hash1,$hash2;
sub dive {
   my $r = shift;
   $r = $r->{shift(@_)} while $r && @_;
   return $r;
}
sub dive_val :lvalue {
   my $p = \shift;
   my $r = \( $$p->{$_} ) for @_;
   $$p
}