I just need all the directory names.

Here is yet another portable way to do it, using the read_dir function from the File::Slurp CPAN module to get a directory listing, then selecting only directory names using grep and -d.

read_dir automatically filters out the specially-named dot directories (. and ..):

use strict;
use warnings;
use Data::Dumper;
use File::Slurp;

my $dir = '/path/to/some/dir';
my @folders = grep { -d "$dir/$_" } read_dir($dir);
print Dumper(\@folders);
[download]

I realize this does not solve your funky path name problem (but others have given you solutions for that), and I do not know if this is the 'Quickest way', but it is an alternative to opendir/readdir.