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GSAR / perl5.5.650 / lib / Sys / Hostname.pm 

            

              
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package Sys::Hostname;
use Carp;
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(hostname);
=head1 NAME
Sys::Hostname - Try every conceivable way to get hostname
=head1 SYNOPSIS
    use Sys::Hostname;
    $host = hostname;
=head1 DESCRIPTION
Attempts several methods of getting the system hostname and
then caches the result.  It tries C<syscall(SYS_gethostname)>,
C<`hostname`>, C<`uname -n`>, and the file F</com/host>.
If all that fails it C<croak>s.
All nulls, returns, and newlines are removed from the result.
=head1 AUTHOR
David Sundstrom E<lt>F<sunds@asictest.sc.ti.com>E<gt>
Texas Instruments
=cut
sub hostname {
  # method 1 - we already know it
  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!
    $host = '';
    Carp::croak "Cannot get host name of local machine";  
  }
  elsif ($^O eq 'MSWin32') {
    ($host) = gethostbyname('localhost');
    chomp($host = `hostname 2> NUL`) unless defined $host;
    return $host;
  }
  elsif ($^O eq 'epoc') {
    $host = 'localhost';
    return $host;
  }
  else {  # Unix
    # method 2 - syscall is preferred since it avoids tainting problems
    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
    }
    # method 6 - Apollo pre-SR10
    || eval {
        local $SIG{__DIE__};
        ($host,$a,$b,$c,$d)=split(/[:\. ]/,`/com/host`,6);
    }
    # bummer
    || Carp::croak "Cannot get host name of local machine";  
    # remove garbage 
    $host =~ tr/\0\r\n//d;
    $host;
  }
}
1;