package Device::SCSI::linux;
BEGIN {
  $Device::SCSI::linux::DIST = 'Device-SCSI';
}
BEGIN {
  $Device::SCSI::linux::VERSION = '1.004';
}
# ABSTRACT: Perl module providing Linux-specific SCSI support
use 5.005;
use warnings;
use strict;
use fields qw( fh name );

use Carp;
use Fcntl ':mode';


# Returns the list of valid device nodes. This sets a hard upper limit on
# the number of devices, but then again, scanning all those /dev/sg* files
# takes ages too. Something clever scanning /dev/ would be, erm, clever.
sub enumerate {
    opendir DIR, "/dev" or croak "Can't read /dev: $!";
    my %devs;
    foreach my $file (sort readdir DIR) {
        my @stat=lstat "/dev/$file";
        next unless scalar @stat;      # next if stat() failed
        next unless S_ISCHR($stat[2]); # next if file isn't character special
        my $major=int($stat[6]/256);
        next unless $major==21; # major number of /dev/sg* is 21
        my $minor=$stat[6]%256;
        next if exists $devs{$minor};
        $devs{$minor}=$file;
    }
    return map {$devs{$_}} sort {$a<=>$b} keys %devs;
}

sub open {
    my($self, $handle) = @_;
    $self->close() if defined $self->{fh};
    if (defined $handle) {
        my $fh=new IO::File("+</dev/$handle");
        return unless defined $fh;
        $self->{fh}=$fh;
        $self->{name}=$handle;
    }
    return $self;
}

sub close {
    my($self) = @_;
    undef $self->{fh};
}

sub execute {
    my($self, $command, $wanted, $data) = @_;

    croak "SCSI command must be 10 or 12 bytes"
        unless(length $command==10 || length $command);
    $data='' unless defined $data;

    my $packet=pack("i4 I x16",
                    36+length($command.$data),
                    36+$wanted, 0, 0,
                    length($command)==12?1:0
                );
    my $iobuf=$packet.$command.$data;
    my $ret=syswrite $self->{fh}, $iobuf, length($iobuf);
    croak "Can't write to $self->{name}: $!"
        unless defined $ret;
    $ret=sysread $self->{fh}, $iobuf, length($packet)+$wanted;
    croak "Can't read from $self->{name}: $!"
        unless defined $ret;
    my @data=unpack("i4 I C16", substr($iobuf, 0, 36));
    croak "SCSI I/O error $data[3] on $self->{name}"
        if $data[3];

    return (substr($iobuf, 36), [ @data[5..20] ]);
}

1;

__END__
=pod

=head1 NAME

Device::SCSI::linux - Perl module providing Linux-specific SCSI support

=head1 VERSION

version 1.004

=head1 DESCRIPTION

Don't use this, use Device::SCSI instead.

This is the Linux-specific SCSI driver that is called upon by the
Device::SCSI module. Normal programs should not use this class directly.
Methods within are documented in the Device::SCSI man page.

=head1 METHODS

The methods listed below are documented in Device::SCSI

=head2 enumerate

=head2 open

=head2 close

=head2 execute

=head1 AUTHOR

Peter Corlett <abuse@cabal.org.uk>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2011 by Peter Corlett.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut