[tpm] Net::DBus question

Madison Kelly linux at alteeve.com
Thu Feb 14 06:10:00 PST 2008

Hi all,

   I'm working on a program which needs to keep track of what (block) 
devices are available and what their individual details are. Also, I 
want to be able to keep similar track of what network filesystems are 
currently mounted and their details.

   From what I have been reading, it looks like DBus and HAL are right 
up my alley. To that end, I've been reading up on them and I think I've 
got a fairly good handle on the concepts, but I've not been able find 
much in the way of perl-specific stuff.

   So, has anyone here played much with Net::DBus? I've looked at the 
code in 'examples' in the DBus docs directory, but it's pretty sparse, 
as are the notes on CPAN.

   This is what I am trying to figure out; pointers to more docs would 
be perfect in lieu of code samples!

1: I want to initially query to the system bus for a list of current 
   1.1: For each device detected, see if it is a block device (HDD, USB 
storage, Optical, etc).
   1.2: If it is a block device, query it's details (max/used capacity, 
FS type, mount location [less important is make, model, serial, 
removable, optical media capability, SMART codes, etc).
2: After the initial scan, "subscribe" to the system bus and wait for 
new signals/messages.
   2.1: Whenever a new message arrives, check if it's for a block device 
and, if so, repeat 1.2.
3: Do the same for Network Block devices.

   If anyone can help get me started, I would be much appreciated. As of 
now, I've been able to do this much, which queries the 'Manager' system 
bus, but no more. I am not even sure how to find out what objects are on 
a given (ie: system) bus. =/

A confused Madi.

-=] test.pl [=-
# My crappy Net::DBus script for learning.

use strict;
use warnings;
use IO::Handle;
use Net::DBus;

my @key_words=("volume", "usb", "storage");

# Connect to DBus.
my $bus = Net::DBus->system;

# Get a handle to the HAL service
my $hal = $bus->get_service("org.freedesktop.Hal");

# Get the device manager
# my $manager = $hal->get_object("/org/freedesktop/Hal/Manager", 
my $manager = $hal->get_object("/org/freedesktop/Hal/Manager", 

# Show the devices currently seen by DBus
foreach my $dev (sort { $a cmp $b } @{$manager->GetAllDevices})
	my $want=0;
	foreach my $key (@key_words)
		if ( $dev=~/$key/ )
	if ( $want == 1 )
		print "Yar!: $dev\n";
		print "Boo!: $dev\n";

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