Since you can map UNC pathnames "anonymously", there's really no reason to find a free drive letter.
I use the following in a library I wrote:
sub connect{
my ( $paths, $user, $password, $verbose ) = @_;
# Make $paths an array reference, even if it isn't already
if ( ref $paths ne "ARRAY") {
if( ! ref $paths ){
push my @paths, $paths;
$paths = \@paths;
}else{
die "You must pass a scalar or array in as first argument
+to connect()\n";
}
}
if( $^O eq 'MSWin32' ){
require Win32::NetResource qw( :DEFAULT GetSharedResources Get
+Error AddConnection CancelConnection );
foreach my $path ( @$paths ){
# In case we don't have the leading backslashes,
# add them.
unless( $path =~ m|^\\{4}| ){
$path =~ s/^\\+//;
$path = "\\\\" . $path;
}
my %resources = (
Scope => RESOURCE_GLOBALNET,
Type => RESOURCETYPE_DISK,
DisplayType => RESOURCEDISPLAYTYPE_SHARE,
RemoteName => $path
);
AddConnection( \%resources, $password, $user, 1 );
if( $verbose ){
my $err;
GetError( $err );
warn Win32::FormatMessage( $err );
}
}
}else{
die "Unsupported Operating System: $^O\n";
}
}