=item do_pipe_command

Mostly-simply wrapper around open for piping from a command.
Since we generally want to capture stderr, too, we redirect stderr
to stdout in the command, so we get it all in a single filehandle.

=cut

sub do_pipe_command
{
    print 'Running: ', join(' ', @_[1..$#_]), $/;

    my $pid = open ($_[0], '-|');
    return $pid if $pid;

    # child - pipe the stderr to the stdout before exec'ing.
    open STDERR, '>&', \*STDOUT;
    my @cmd = @_[1..$#_];
    if ($^O =~ /MSWin/i)
    {
        @cmd = (qw(cmd.exe /c), join(' ',@cmd));
    }
    exec @cmd;
}

=item extract_tarball

Tries to untar the tarball.  Returns the directory name thusly
created.

=cut

sub extract_tarball
{
    my $tarball = shift;

    my $cmd = '';
    if ($tarball =~ /\.tar\.gz$/)
    {
        $cmd = "gunzip -c $tarball | ";
    }
    elsif ($tarball =~ /\.tar\.Z$/)
    {
        $cmd = "zcat $tarball | ";
    }
    elsif ($tarball =~ /\.tar$/)
    {
        $cmd = "cat $tarball | ";
    }
    else
    {
        die "Can't figure out how to untar $tarball";
    }

    $cmd .= 'tar -xvf -';
    print "Running $cmd\n";

    my $subdir;
    do_pipe_command my $tar, $cmd or die "Failed to run $cmd: $!";
    while (my $l = <$tar>)
    {
        print $l;
        next if $subdir;
        $subdir = $1 if $l =~ m:^(.*?)[/\\]:;
    }
    $subdir;
}

##</code><code>##

Running gunzip -c Cache-Repository-0.01.tar.gz | tar -xvf -
Running: gunzip -c Cache-Repository-0.01.tar.gz | tar -xvf -
'-' is not recognized as an internal or external command,
operable program or batch file.
Use of uninitialized value in string eq at e:/perl5.8.0/lib/File/Spec/Unix.pm line
 77.

##</code><code>##

sub do_pipe_command
{
    print 'Running: ', join(' ', @_[1..$#_]), $/;
    my @cmd = @_[1..$#_];

    my $wtr;
    require IPC::Open3;
    my $pid = IPC::Open3::open3($wtr, $_[0], undef, @cmd);
}