. and .. is not returned for the root of some drives on Windows.

I would have betted against that statement. But it seems Windows is that crazy.

#!/usr/bin/perl

use v5.12;
use warnings;

sub readroot
{
    my $drive=shift;
    my $name="$drive:/";
    if (opendir my $d,$name) {
        my @list=grep /^\.{1,2}$/, readdir $d;
        closedir $d;
        return join(' ',"$drive:",@list);
    }
    return "$drive: $!";
}

say readroot($_) for ('A' .. 'Z');
[download]

X:\>subst
E:\: => C:\windows
F:\: => C:\

X:\>perl readdir.pl
A: No such file or directory
B: Invalid argument
C:
D:
E: . ..
F:
G: No such file or directory
H: . ..
I: . ..
J: No such file or directory
K: No such file or directory
L: No such file or directory
M: . ..
N: No such file or directory
O: No such file or directory
P: No such file or directory
Q: No such file or directory
R: . ..
S: No such file or directory
T: . ..
U:
V: . ..
W: No such file or directory
X:
Y: No such file or directory
Z: Invalid argument

X:\>
[download]

Drive classification:

• B: is an empty cardreader.
• C: and D: are SSDs formatted with NTFS.
• E: and F: are pseudo-drives created by SUBST.
• H:, I:, M:, R:, T: are Samba shares on an ext4 drive (Samba pretends that the filesystem is NTFS).
• U: and V: are shares from another Windows system, U: maps root, V: maps a subdirectory.
• X: is a RAM disk (by SoftPerfect) that appears as a FAT32 formatted hard disk.
• Z: is an empty DVD drive.
• All other drive letters are unused.

Looking at the result, it seems that the real root directories of at least NTFS and FAT on Windows don't have the . and .. directory entries (C:, D:, F:, U:, X:), and that is also visible through SUBST and network sharing. Other directories do have the . and .. directories (E:, V:), and this is also visible through SUBST and network sharing. Samba does not try to fake root directories - at least not for the non-root directories shared by my Linux server, and so the Samba shares also have the dot directories (H:, I:, M:, R:, T:).

(All tested on Windows 7)

Alexander