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|
#!/usr/bin/perl
$debug = 0;
&debug_init;
$MTX = "/usr/sbin/mtx";
if(!$ENV{TAPE}){
&debug("setting TAPE to /dev/tape");
$ENV{TAPE} = "/dev/tape";
}
# initialize the state
@slots = (1..6);
$current_slot = 0;
$tape_device = "/dev/tape";
&changer_init();
&debug("main::current slot: $current_slot");
if($ARGV[0] eq "-eject"){
&debug("main::got eject request");
# eject is a no-op right now...
}
if($ARGV[0] eq "-info"){
&debug("main::got info request");
&print_info();
exit(1);
}
if($ARGV[0] eq "-reset"){
&debug("main::got changer reset request");
&reset_changer();
}
if($ARGV[0] =~ /-slot/){
$slot = $ARGV[1];
if($slot =~ /^(next|prev|current|first|last)$/){
&debug("main::got relative position request ($slot)");
$slot = &get_slot_number($slot);
&debug("main::translated slot number: $slot");
}
if($slot !~ /^[0-9]$/){
&fatal_error("bogus slot number: $slot");
}
&change_to_slot($slot);
}
&print_status();
##### subs ########################################
sub debug {
my $message = shift;
print DEBUG "$message\n" if $debug;
}
sub changer_init {
&debug("changer_init::start");
if(!(@response = `$MTX status`)){
&fatal_error("couldn't run mtx: $!");
}
&debug("changer_init:: @response");
if($response[0] =~ /full .storage element ([1-6]) loaded/i){
$current_slot = $1;
&debug("changer_init::tape loaded: $current_slot");
return();
}
if($response[0] =~ /empty/i) {
&debug("changer_init::no tape loaded, checking for other tapes...");
foreach $slot (@response) {
if($slot =~ /full/i) {
$tape_in_changer = 1;
break;
}
}
if(!$tape_in_changer) {
&debug("changer_init::no tapes in the changer");
&fatal_error("no tapes in changer");
} else {
&debug("changer_init::loading tape 1");
&run_command("$MTX load 1");
$current_slot = 1;
}
}
}
sub print_status {
&debug("print_status::start");
print "$current_slot $tape_device\n";
exit(0);
}
sub run_command {
my $command = shift;
&debug("run_command:: $command");
system("$command 2> /dev/null");
if($? != 0) {
&fatal_error("[$command] returned non zero ($?)");
}
}
sub print_info {
print "$current_slot 6 1\n";
exit(0);
}
sub fatal_error {
my $error = shift;
print "$current_slot $error\n";
exit(2);
}
sub reset_changer {
&debug("reset_changer:: start");
&change_to_slot(1);
}
sub change_to_slot {
my $slot = shift;
&debug("change_to_slot:: $slot");
if(!&in_range($slot)) {
&non_fatal_error("slot $slot out of range");
}
if($slot == $current_slot){
return;
} else {
&run_command("$MTX unload");
&run_command("$MTX load $slot");
}
$current_slot = $slot;
}
sub get_slot_number {
my $description = shift;
&debug("get_slot_number: $description");
if($description eq "first"){
return(1);
}
if($description eq "last"){
return(6);
}
if($description eq "current"){
return($current_slot);
}
# we don't want to destroy $current_slot with post/preincrement
$slot_index = $current_slot;
if($description eq "prev"){
if(&in_range($current_slot)){
return((6,1..6,1)[--$slot_index]);
} else {
&non_fatal_error("current slot number out of range: $current_slot");
}
}
if($description eq "next"){
if(&in_range($current_slot)){
return((6,1..6,1)[++$slot_index]);
} else {
&non_fatal_error("current slot number out of range: $current_slot");
}
}
return(0);
}
sub in_range {
my $slot_num = shift;
&debug("in_range:: $slot_num");
return(($slot_num <= 6) && ($slot_num >= 1));
}
sub non_fatal_error {
my $message = shift;
print "$current_slot $message\n";
exit 1;
}
sub debug_init {
return unless $debug;
open(DEBUG, ">/tmp/x-changer.debug.$$");
$today = localtime();
print DEBUG "Date: $today\n";
print DEBUG "UID: $<\n";
print DEBUG "EUID: $>\n";
print DEBUG "PATH: $ENV{PATH}\n";
}
|
