comment on

. 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

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

In reply to Re^6: readdir() on a sysopen() handle? by afoken
in thread readdir() on a sysopen() handle? by perlhuhn

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