[Expectperl-discuss] Found Bug -- ttyname in POSIX & IO::Pty

[John W. <exp...@wi...>]

After much fun, I have found the solution to a bug in Expect.pm.  The 
problem surfaces in the attempt to retrieve a slave (e.g. 
clone_winsize_from):


from IO::Pty:

sub slave {
  @_ == 1 or croak 'usage: $pty->slave();';

  my $master = shift;

  if (exists ${*$master}{'io_pty_slave'}) {
    return ${*$master}{'io_pty_slave'};
  }

  my $tty = $master->ttyname();

  my $slave = new IO::Tty;

  $slave->open($tty, O_RDWR | O_NOCTTY) ||
    croak "Cannot open slave $tty: $!";

  return $slave;
}


Note that the creation of the slave (assuming the if test fails), is 
dependent upon retrieving the ttyname.  However, Expect.pm "use"s both 
POSIX and IO::Pty.  The problem with the default 'use POSIX;' is that 
POSIX also has a ttyname declaration and thus once an Expect object is 
blessed, the ttyname function used is NOT the IO::Pty one.  The solution 
is to limit what is being incorporated into Expect from the POSIX 
module.  From my limited tests, I have been able successfully change the 
use line to:

use POSIX qw (WNOHANG);

With this change, the ttyname function can be called and the name 
retrieved.  Thus, window resizing:

$e = new Expect;
$e->slave->clone_winsize_from(\*STDIN);
$SIG{WINCH} = \&winch;
 
 
sub winch {
  $e->slave->clone_winsize_from(\*STDIN);
  kill WINCH => $e->pid if $e->pid;
  $SIG{WINCH} = \&winch;
}


works as well as any other call which needs to retrieve the ttyname from 
the expect object.

Cheers,

John C. Wingenbach


PS... I am assuming that the authors/maintainers of Expect are no longer 
active as I have not seen any kind of involvement from them on the lists 
nor on CPAN.


Is Expect.pm a dead or orphaned module?