Perl Device::SCSI example code

[ATC]

The Perl module "Device::SCSI" documentation does not provide any example code showing how to construct SCSI commands or parse the result data.

[ATC]

Here is an example showing how to perform a command and fetch the results. Note that this is an EXAMPLE only; your mileage may vary!

sub read_element_status {
  my $self = shift;
  my $element = shift;
  my %options = @_;
  my $hashref = {};

  unless (defined $element) {
    warn "No element id specified for read_element_status()";
    return $hashref;
  }

  my $command = pack("C12",
    0xb8,       # READ ELEMENT STATUS
    ($options{'LUN'} << 5),     # Bits 0-3 is Element Type Code (0), bits 5-7 is LUN
    $element >> 8,              # $element MSB
    $element & 0xff,            # $element LSB
    0,                          # Number of elements, MSB
    1,                          # Number of elements, LSB
    0x00,                       # (reserved)
    0,                          # Allocation length, MSB
    0,                          # Allocation length, ...
    32,                         # Allocation length, LSB (32 bytes)
    0x00,                       # (reserved)
    0x00,                       # (reserved)
  );      
  my $wanted = 32;

  my ($result, $sense) = $self->execute($command, $wanted);

  unless ($self->sense_error($sense)) {

    # Element Status Data - discard this header, we have no use for it
    my $unused = substr($result, 0, 10);
    $result = substr($result, ;  

    # Element Status Page - discard this header, we have no use for it
    $unused = substr($result, 0, ;
    $result = substr($result, ;  

    # Element Status Descriptor
    my $page = substr($result, 0, 16);

    my $flags, $valid;
   
    (
      $hashref->{'ELEMENT'},
      $flags,
      $unused,                  # (reserved)
      $hashref->{'ADDITIONAL_SENSE_CODE'},
      $hashref->{'ADDITIONAL_SENSE_QUALIFIER'},
      $unused,                  # (reserved)
      $unused,                  # (reserved)
      $unused,                  # (reserved)
      $valid,
      $hashref->{'SOURCE_ELEMENT'},
      $unused,                  # (reserved)
      $unused,                  # (reserved)
      $unused,                  # (reserved)
      $unused,                  # (reserved)
    ) = unpack("n1 C8 n1 C4", $result);

    unless ($valid & 0x80) { delete $hashref->{'SOURCE_ELEMENT'}; }
    $hashref->{'FULL'} = ($flags & 0x01) ? 1 : 0;
    $hashref->{'EXCEPTION'} = ($flags & 0x04) ? 1 : 0;
  }  
 
  return $hashref;
}