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package Sys::Hostname;
use strict;
use Carp;
use Exporter 'import';
our @EXPORT  = qw/ hostname /;
our $VERSION;
use warnings ();
our $host;
BEGIN {
    $VERSION = '1.25';
    {
        local $SIG{__DIE__};
        eval {
            require XSLoader;
            XSLoader::load();
        };
        warn $@ if $@;
    }
}
sub hostname {
  @_ and croak("hostname() does not accepts arguments (it used to silently discard any provided)");
  # method 1 - we already know it
  return $host if defined $host;
  # method 1' - try to ask the system
  $host = ghname() if defined &ghname;
  return $host if defined $host;
  if ($^O eq 'VMS') {
    # method 2 - no sockets ==> return DECnet node name
    eval { local $SIG{__DIE__}; $host = (gethostbyname('me'))[0] };
    if ($@) { return $host = $ENV{'SYS$NODE'}; }
    # method 3 - has someone else done the job already?  It's common for the
    #    TCP/IP stack to advertise the hostname via a logical name.  (Are
    #    there any other logicals which TCP/IP stacks use for the host name?)
    $host = $ENV{'ARPANET_HOST_NAME'}  || $ENV{'INTERNET_HOST_NAME'} ||
            $ENV{'MULTINET_HOST_NAME'} || $ENV{'UCX$INET_HOST'}      ||
            $ENV{'TCPWARE_DOMAINNAME'} || $ENV{'NEWS_ADDRESS'};
    return $host if $host;
    # method 4 - does hostname happen to work?
    my($rslt) = `hostname`;
    if ($rslt !~ /IVVERB/) { ($host) = $rslt =~ /^(\S+)/; }
    return $host if $host;
    # rats!
    $host = '';
    croak "Cannot get host name of local machine";  
  }
  elsif ($^O eq 'MSWin32') {
    ($host) = gethostbyname('localhost');
    chomp($host = `hostname 2> NUL`) unless defined $host;
    return $host;
  }
  else {  # Unix
    # is anyone going to make it here?
    local $ENV{PATH} = '/usr/bin:/bin:/usr/sbin:/sbin'; # Paranoia.
    # method 2 - syscall is preferred since it avoids tainting problems
    # XXX: is it such a good idea to return hostname untainted?
    eval {
        local $SIG{__DIE__};
        require "syscall.ph";
        $host = "\0" x 65; ## preload scalar
        syscall(&SYS_gethostname, $host, 65) == 0;
    }
    # method 2a - syscall using systeminfo instead of gethostname
    #           -- needed on systems like Solaris
    || eval {
        local $SIG{__DIE__};
        require "sys/syscall.ph";
        require "sys/systeminfo.ph";
        $host = "\0" x 65; ## preload scalar
        syscall(&SYS_systeminfo, &SI_HOSTNAME, $host, 65) != -1;
    }
    # method 3 - trusty old hostname command
    || eval {
        local $SIG{__DIE__};
        local $SIG{CHLD};
        $host = `(hostname) 2>/dev/null`; # BSDish
    }
    # method 4 - use POSIX::uname(), which strictly can't be expected to be
    # correct
    || eval {
        local $SIG{__DIE__};
        require POSIX;
        $host = (POSIX::uname())[1];
    }
    # method 5 - sysV uname command (may truncate)
    || eval {
        local $SIG{__DIE__};
        $host = `uname -n 2>/dev/null`; ## sysVish
    }
    # bummer
    || croak "Cannot get host name of local machine";  
    # remove garbage 
    $host =~ tr/\0\r\n//d;
    $host;
  }
}
1;
__END__
HideShow 29 lines of Pod
=head1 NAME
Sys::Hostname - Try every conceivable way to get hostname
=head1 SYNOPSIS
    use Sys::Hostname;
    my $host = hostname;
=head1 DESCRIPTION
Attempts several methods of getting the system hostname and
then caches the result.  It tries the first available of the C
library's gethostname(), C<`$Config{aphostname}`>, uname(2),
C<syscall(SYS_gethostname)>, C<`hostname`>, C<`uname -n`>,
and the file F</com/host>.  If all that fails it C<croak>s.
All NULs, returns, and newlines are removed from the result.
=head1 AUTHOR
David Sundstrom E<lt>F<sunds@asictest.sc.ti.com>E<gt>
Texas Instruments
XS code added by Greg Bacon E<lt>F<gbacon@cs.uah.edu>E<gt>
=cut