122 lines
2.9 KiB
Perl
122 lines
2.9 KiB
Perl
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package Sys::Hostname;
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use Carp;
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require Exporter;
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@ISA = qw(Exporter);
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@EXPORT = qw(hostname);
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=head1 NAME
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Sys::Hostname - Try every conceivable way to get hostname
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=head1 SYNOPSIS
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use Sys::Hostname;
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$host = hostname;
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=head1 DESCRIPTION
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Attempts several methods of getting the system hostname and
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then caches the result. It tries C<syscall(SYS_gethostname)>,
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C<`hostname`>, C<`uname -n`>, and the file F</com/host>.
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If all that fails it C<croak>s.
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All nulls, returns, and newlines are removed from the result.
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=head1 AUTHOR
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David Sundstrom E<lt>F<sunds@asictest.sc.ti.com>E<gt>
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Texas Instruments
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=cut
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sub hostname {
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# method 1 - we already know it
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return $host if defined $host;
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if ($^O eq 'VMS') {
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# method 2 - no sockets ==> return DECnet node name
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eval { local $SIG{__DIE__}; $host = (gethostbyname('me'))[0] };
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if ($@) { return $host = $ENV{'SYS$NODE'}; }
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# method 3 - has someone else done the job already? It's common for the
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# TCP/IP stack to advertise the hostname via a logical name. (Are
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# there any other logicals which TCP/IP stacks use for the host name?)
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$host = $ENV{'ARPANET_HOST_NAME'} || $ENV{'INTERNET_HOST_NAME'} ||
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$ENV{'MULTINET_HOST_NAME'} || $ENV{'UCX$INET_HOST'} ||
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$ENV{'TCPWARE_DOMAINNAME'} || $ENV{'NEWS_ADDRESS'};
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return $host if $host;
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# method 4 - does hostname happen to work?
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my($rslt) = `hostname`;
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if ($rslt !~ /IVVERB/) { ($host) = $rslt =~ /^(\S+)/; }
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return $host if $host;
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# rats!
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$host = '';
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Carp::croak "Cannot get host name of local machine";
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}
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elsif ($^O eq 'MSWin32') {
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($host) = gethostbyname('localhost');
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chomp($host = `hostname 2> NUL`) unless defined $host;
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return $host;
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}
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else { # Unix
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# method 2 - syscall is preferred since it avoids tainting problems
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eval {
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local $SIG{__DIE__};
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{
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package main;
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require "syscall.ph";
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}
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$host = "\0" x 65; ## preload scalar
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syscall(&main::SYS_gethostname, $host, 65) == 0;
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}
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# method 2a - syscall using systeminfo instead of gethostname
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# -- needed on systems like Solaris
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|| eval {
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local $SIG{__DIE__};
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{
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package main;
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require "sys/syscall.ph";
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require "sys/systeminfo.ph";
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}
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$host = "\0" x 65; ## preload scalar
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syscall(&main::SYS_systeminfo, &main::SI_HOSTNAME, $host, 65) != -1;
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}
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# method 3 - trusty old hostname command
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|| eval {
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local $SIG{__DIE__};
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$host = `(hostname) 2>/dev/null`; # bsdish
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}
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# method 4 - sysV uname command (may truncate)
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local $SIG{__DIE__};
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$host = `uname -n 2>/dev/null`; ## sysVish
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}
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# method 5 - Apollo pre-SR10
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local $SIG{__DIE__};
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($host,$a,$b,$c,$d)=split(/[:\. ]/,`/com/host`,6);
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}
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# bummer
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# remove garbage
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$host =~ tr/\0\r\n//d;
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$host;
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}
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}
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1;
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