my_nihilist has asked for the wisdom of the Perl Monks concerning the following question:

here is THCB.pl. It is a candified "viewer" for telneting into the ChatterBox which does away with line endings but adds some color, a timer, and a log.

I say "viewer" because this can log you in and greet the CB if you enter a valid username and password. Otherwise, it will start telnet anyway and you can watch in anonymity.

My Question: THCB uses IPC w/autoflush because i would like to somehow pipe STDIN->TNOUT but can't figure out how to do that without interrupting the while loop. 

 #!/usr/bin/perl
use warnings;
use strict;

use Term::ANSIColor;
use IO::Handle; 
use IPC::Open2;

$|=1;

print "User: ";
my $User=<>;
print "Pass: ";
my $Pass=<>;

open2(*TNIN, *TNOUT, "telnet desert-island.dynodns.net 4040");
TNOUT->autoflush(1);
open(LOG, ">THCB.log");
LOG->autoflush(1);

print TNOUT "auth ]$User [ $Pass";

my @c=("red","green","yellow","magenta");
my $n=0;

alarm 120; my $m=2;

while (<TNIN>) {
        $SIG{ALRM}=sub{rearm()};
        print LOG "$_"; 
        if ($_ eq "Found you!\n") {print TNOUT "<i>exhaling...</i>\n"}
        my @line = split / /; my $bit = shift @line; chomp @line;
        if ($bit =~ /:$/) {
                print color("blue on_cyan"), "$bit"; 
                print color("reset");
        }   
        else {print color("$c[$n]"), "$bit "}
        print color("$c[$n]"), "@line ";
        if ($n eq 3) {$n=0}
        else {$n++}
}

sub rearm {
        print color("white on_red"), "$m"; print "m";
        print color("reset");
        alarm 120; $m++; $m++;
}

[download]
NOTE: THCB does not yet log you out because you can't log out through telnet. You can log in repeatedly, but i recommend against this; eventually im2 sends little scoldings back.

Update: THCB is probably a *nix event

Replies are listed 'Best First'.
Re: bidirectional challange
by ikegami (Patriarch) on Mar 13, 2008 at 22:26 UTC
    You want to read from STDIN and from TNIN without starving either, so that points to IO::Select.
[reply]

      Based on CB chat, there's some confusion with my solution, so I'll elaborate.

      It's my understanding that you want to do something along the lines of 

      while (<STDIN> or <TNIN>) {
   if (we_read_from_STDIN()) {
      print TNOUT do_this($_);
   } else {
      print STDOUT do_that($_);
   }
}

      [download]

      Of course, that's not valid Perl. That where IO::Select comes in. 

      use IO::Select qw( );

my $sel = IO::Select->new(\*STDIN, \*TNIN);

MAIN_LOOP:
while (my @ready = $sel->can_read()) {
   for my $fh (@ready) {
      my $bytes_read = sysread($fh, my $data='', 4096)
         or last MAIN_LOOP;

      if ($fh == \*STDIN) {
         print TNOUT do_this($data);
      } else {
         print STDOUT do_that($data);
      }
   }
}

      [download]

      We can't use <$fh> since that would block when only part of a line has arrived. If you want to do line-based IO, you'll have to do your own line building: 

      use IO::Select qw( );

my $sel = IO::Select->new(\*STDIN, \*TNIN);
my %bufs;

MAIN_LOOP:
while (my @ready = $sel->can_read()) {
   for my $fh (@ready) {
      our $buf; local *buf = \$bufs{$fh};  # Alias

      my $bytes_read = sysread($fh, $buf, 4096, length($buf))
         or last MAIN_LOOP;

      my $line_end = index($buf, $/);
      next if $line_end < 0;

      my $line = substr($buf, 0, $line_end+1, '');

      if ($fh == \*STDIN) {
         print TNOUT do_this($line);
      } else {
         print STDOUT do_that($line);
      }
   }
}

      [download]

      Update:

      • I'm not sure about the $fh == \*STDIN part. fileno($fh) == fileno(\*STDIN) should definitely work.
      • Note: %bufs may still contain data when last MAIN_LOOP; is executed.
      • Bonus: Since can_read accepts a timeout argument, you can probably do away with your alarm!
      • Won't work on Windows.
[reply]
[d/l]
[select]
Re: bidirectional challange
by halfcountplus (Hermit) on Mar 14, 2008 at 03:48 UTC
    I couldn't figure a way to channel STDIN->TNOUT, but you could use $SIG{INT} as something to "listen for" along with the alarm, so the user can interrupt and input a line. That means you need a new way to conviently kill the whole thing (input DONE). Since TNIN is triggered initially by im2 starting the timer: 
    
$SIG{ALRM}=sub{rearm()};

    [download]
    insert this line after that: 
    
$SIG{INT}=sub{process()};

    [download]
    and for the sub: 
    
sub process {
        print color("black on_white"), ">"; print color("reset");
        my $input=<>;
        if ($input eq "DONE\n") {exit 0}
        else {print TNOUT "$input"}
}

    [download]
    now, when you press ctrl-c, instead of death you get a little ">" prompt so you can talk.

    I just tried it and it werx dandy. ROLL ON
[reply]
[d/l]
[select]
Re: bidirectional challange
by my_nihilist (Sexton) on Mar 14, 2008 at 14:25 UTC
    I posted a working version of THCB in the Code Catacombs, which uses halfcountplus's suggestion w/ the Ctrl-C interrupt. I am still surprised there is no/no one provided a simple way to just "channel STDIN->TNOUT". ikegami also suggested 
    
open2(*TNIN, '<&STDIN', "telnet desert-island. dynodns.net 4040");

    [download]
    Which actually works, except that STDIN then seems to become divorced from keyboard input at a certain point. Frankly, after much tooling around with IO::Select and what have you, i am suspicous of ikegami's ideas here in general. But if anyone can demonstrate them working in THCB, I'd love to see it!
[reply]
[d/l]

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