Skunkware 5/Skunkware 5.iso/lib/perl5/chat2.inter

Text File | 1995-07-03 | 12.7 KB | 496 lines

Article 20992 of comp.lang.perl:
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From: [e-mail] (Eric Arnold)
Newsgroups: comp.lang.perl
Subject: Re: Need a bidirectional filter for interactive Unix applications
Date: 15 Apr 94 21:24:03 GMT
Organization: Sun Microsystems
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In-reply-to: [e-mail]'s message of Fri, 15 Apr 1994 11:01:34 GMT

In article <[e-mail]>
    [e-mail] (Bernard T. French) writes:

>In article <[e-mail]> [e-mail] (David Feldman) writes:
>>I need to write a bidirectional filter that would (ideally) sit between a
..
>>program's stdin & stdout to point to a pty pair known to perl. The perl app-
>>lication would talk to the user's crt/keyboard, translate (application-specific)
>>the input & output streams, and pass these as appropriate to/from the pty pair,
..
>
>     I'm afraid I can't offer you a perl solution, but err..... there is a
>Tcl solution.  There is a Tcl extension called "expect" that is designed to

There *is* an old, established Perl solution:  "chat2.pl" which does
everything (well, basically) "expect" does but you get it in the
expressive Perl environment.  "chat2.pl" is delivered with the Perl
source.

Randal:  "interact()" still hasn't made it into Perl5alpha8
"chat2.pl", so I've included a version which does.

-Eric


## chat.pl: chat with a server
## V2.01.alpha.7 91/06/16
## Randal L. Schwartz

package chat;

$sockaddr = 'S n a4 x8';
chop($thishost = `hostname`); $thisaddr = (gethostbyname($thishost))[4];
$thisproc = pack($sockaddr, 2, 0, $thisaddr);

# *S = symbol for current I/O, gets assigned *chatsymbol....
$next = "chatsymbol000000"; # next one
$nextpat = "^chatsymbol"; # patterns that match next++, ++, ++, ++


## $handle = &chat'open_port("server.address",$port_number);
## opens a named or numbered TCP server

sub open_port { ## public
    local($server, $port) = @_;

    local($serveraddr,$serverproc);

    *S = ++$next;
    if ($server =~ /^(\d+)+\.(\d+)\.(\d+)\.(\d+)$/) {
        $serveraddr = pack('C4', $1, $2, $3, $4);
    } else {
        local(@x) = gethostbyname($server);
        return undef unless @x;
        $serveraddr = $x[4];
    }
    $serverproc = pack($sockaddr, 2, $port, $serveraddr);
    unless (socket(S, 2, 1, 6)) {
        # XXX hardwired $AF_SOCKET, $SOCK_STREAM, 'tcp'
        # but who the heck would change these anyway? (:-)
        ($!) = ($!, close(S)); # close S while saving $!
        return undef;
    }
    unless (bind(S, $thisproc)) {
        ($!) = ($!, close(S)); # close S while saving $!
        return undef;
    }
    unless (connect(S, $serverproc)) {
        ($!) = ($!, close(S)); # close S while saving $!
        return undef;
    }
    select((select(S), $| = 1)[0]);
    $next; # return symbol for switcharound
}

## ($host, $port, $handle) = &chat'open_listen([$port_number]);
## opens a TCP port on the current machine, ready to be listened to
## if $port_number is absent or zero, pick a default port number
## process must be uid 0 to listen to a low port number

sub open_listen { ## public

    *S = ++$next;
    local($thisport) = shift || 0;
    local($thisproc_local) = pack($sockaddr, 2, $thisport, $thisaddr);
    local(*NS) = "__" . time;
    unless (socket(NS, 2, 1, 6)) {
        # XXX hardwired $AF_SOCKET, $SOCK_STREAM, 'tcp'
        # but who the heck would change these anyway? (:-)
        ($!) = ($!, close(NS));
        return undef;
    }
    unless (bind(NS, $thisproc_local)) {
        ($!) = ($!, close(NS));
        return undef;
    }
    unless (listen(NS, 1)) {
        ($!) = ($!, close(NS));
        return undef;
    }
    select((select(NS), $| = 1)[0]);
    local($family, $port, @myaddr) =
        unpack("S n C C C C x8", getsockname(NS));
    $S{"needs_accept"} = *NS; # so expect will open it
    (@myaddr, $port, $next); # returning this
}

## $handle = &chat'open_proc("command","arg1","arg2",...);
## opens a /bin/sh on a pseudo-tty

sub open_proc { ## public
    local(@cmd) = @_;

    *S = ++$next;
    local(*TTY) = "__TTY" . time;
    local($pty,$tty,$pty_handle) = &_getpty(S,TTY);

    #local($pty,$tty,$pty_handle) = &getpty(S,TTY);
    #$Tty = $tty;

    die "Cannot find a new pty" unless defined $pty;
    local($pid) = fork;
    die "Cannot fork: $!" unless defined $pid;
    unless ($pid) {
        close STDIN; close STDOUT; close STDERR;
        #close($pty_handle);
        setpgrp(0,$$);
        if (open(DEVTTY, "/dev/tty")) {
            ioctl(DEVTTY,0x20007471,0);        # XXX s/b &TIOCNOTTY
            close DEVTTY;
        }
        open(STDIN,"<&TTY");
        open(STDOUT,">&TTY");
        open(STDERR,">&STDOUT");
        die "Oops" unless fileno(STDERR) == 2;    # sanity
        close(S);

        exec @cmd;
        die "Cannot exec @cmd: $!";
    }
    close(TTY);
    $PID{$next} = $pid;
    $next; # return symbol for switcharound

}

# $S is the read-ahead buffer

## $return = &chat'expect([$handle,] $timeout_time,
##     $pat1, $body1, $pat2, $body2, ... )
## $handle is from previous &chat'open_*().
## $timeout_time is the time (either relative to the current time, or
## absolute, ala time(2)) at which a timeout event occurs.
## $pat1, $pat2, and so on are regexs which are matched against the input
## stream.  If a match is found, the entire matched string is consumed,
## and the corresponding body eval string is evaled.
##
## Each pat is a regular-expression (probably enclosed in single-quotes
## in the invocation).  ^ and $ will work, respecting the current value of $*.
## If pat is 'TIMEOUT', the body is executed if the timeout is exceeded.
## If pat is 'EOF', the body is executed if the process exits before
## the other patterns are seen.
##
## Pats are scanned in the order given, so later pats can contain
## general defaults that won't be examined unless the earlier pats
## have failed.
##
## The result of eval'ing body is returned as the result of
## the invocation.  Recursive invocations are not thought
## through, and may work only accidentally. :-)
##
## undef is returned if either a timeout or an eof occurs and no
## corresponding body has been defined.
## I/O errors of any sort are treated as eof.

$nextsubname = "expectloop000000"; # used for subroutines

sub expect { ## public
    if ($_[0] =~ /$nextpat/) {
        *S = shift;
    }
    local($endtime) = shift;

    local($timeout,$eof) = (1,1);
    local($caller) = caller;
    local($rmask, $nfound, $timeleft, $thisbuf);
    local($cases, $pattern, $action, $subname);
    $endtime += time if $endtime < 600_000_000;

    if (defined $S{"needs_accept"}) { # is it a listen socket?
        local(*NS) = $S{"needs_accept"};
        delete $S{"needs_accept"};
        $S{"needs_close"} = *NS;
        unless(accept(S,NS)) {
            ($!) = ($!, close(S), close(NS));
            return undef;
        }
        select((select(S), $| = 1)[0]);
    }

    # now see whether we need to create a new sub:

    unless ($subname = $expect_subname{$caller,@_}) {
        # nope.  make a new one:
        $expect_subname{$caller,@_} = $subname = $nextsubname++;

        $cases .= <<"EDQ"; # header is funny to make everything elsif's
sub $subname {
    LOOP: {
        if (0) { ; }
EDQ
        while (@_) {
            ($pattern,$action) = splice(@_,0,2);
            if ($pattern =~ /^eof$/i) {
                $cases .= <<"EDQ";
        elsif (\$eof) {
             package $caller;
            $action;
        }
EDQ
                $eof = 0;
            } elsif ($pattern =~ /^timeout$/i) {
            $cases .= <<"EDQ";
        elsif (\$timeout) {
             package $caller;
            $action;
        }
EDQ
                $timeout = 0;
            } else {
                $pattern =~ s#/#\\/#g;
            $cases .= <<"EDQ";
        elsif (\$S =~ /$pattern/) {
            \$S = \$';
             package $caller;
            $action;
        }
EDQ
            }
        }
        $cases .= <<"EDQ" if $eof;
        elsif (\$eof) {
            undef;
        }
EDQ
        $cases .= <<"EDQ" if $timeout;
        elsif (\$timeout) {
            undef;
        }
EDQ
        $cases .= <<'ESQ';
        else {
            $rmask = "";
            vec($rmask,fileno(S),1) = 1;
            ($nfound, $rmask) =
                 select($rmask, undef, undef, $endtime - time);
            if ($nfound) {
                $nread = sysread(S, $thisbuf, 1024);
                if ($nread > 0) {
                    $S .= $thisbuf;
                } else {
                    $eof++, redo LOOP; # any error is also eof
                }
            } else {
                $timeout++, redo LOOP; # timeout
            }
            redo LOOP;
        }
    }
}
ESQ
        eval $cases; die "$cases:\n$@" if $@;
    }
    $eof = $timeout = 0;
    do $subname();
}

## &chat'print([$handle,] @data)
## $handle is from previous &chat'open().
## like print $handle @data

sub print { ## public
    if ($_[0] =~ /$nextpat/) {
        *S = shift;
    }
    print S @_;
}

## &chat'close([$handle,])
## $handle is from previous &chat'open().
## like close $handle

sub close { ## public
    local($pid);
    if ($_[0] =~ /$nextpat/) {
        $pid = $PID{$_[0]};
         *S = shift;
    } else {
        $pid = $PID{$next};
    }
    close(S);
    waitpid($pid,0);
    if (defined $S{"needs_close"}) { # is it a listen socket?
        local(*NS) = $S{"needs_close"};
        delete $S{"needs_close"};
        close(NS);
    }
}

## @ready_handles = &chat'select($timeout, @handles)
## select()'s the handles with a timeout value of $timeout seconds.
## Returns an array of handles that are ready for I/O.
## Both user handles and chat handles are supported (but beware of
## stdio's buffering for user handles).

sub select { ## public
    local($timeout) = shift;
    local(@handles) = @_;
    local(%handlename) = ();
    local(%ready) = ();
    local($caller) = caller;
    local($rmask) = "";
    for (@handles) {
        if (/$nextpat/o) { # one of ours... see if ready
            local(*SYM) = $_;
            if (length($SYM)) {
                $timeout = 0; # we have a winner
                $ready{$_}++;
            }
            $handlename{fileno($_)} = $_;
        } else {
            $handlename{fileno(/'/ ? $_ : "$caller\'$_")} = $_;
        }
    }
    for (sort keys %handlename) {
        vec($rmask, $_, 1) = 1;
    }
    select($rmask, undef, undef, $timeout);
    for (sort keys %handlename) {
        $ready{$handlename{$_}}++ if vec($rmask,$_,1);
    }
    sort keys %ready;
}

# ($pty,$tty) = $chat'_getpty(PTY,TTY):
# internal procedure to get the next available pty.
# opens pty on handle PTY, and matching tty on handle TTY.
# returns undef if can't find a pty.

sub _getpty { ## private
    local($_PTY,$_TTY) = @_;
    $_PTY =~ s/^([^']+)$/(caller)[$[]."'".$1/e;
    $_TTY =~ s/^([^']+)$/(caller)[$[]."'".$1/e;
    local($pty,$tty);
    for $bank (112..127) {
        next unless -e sprintf("/dev/pty%c0", $bank);
        for $unit (48..57) {
            $pty = sprintf("/dev/pty%c%c", $bank, $unit);
            open($_PTY,"+>$pty") || next;
            select((select($_PTY), $| = 1)[0]);
            ($tty = $pty) =~ s/pty/tty/;
            open($_TTY,"+>$tty") || next;
            select((select($_TTY), $| = 1)[0]);
            system "stty nl>$tty";
            return ($pty,$tty,$_PTY);
        }
    }
    undef;
}


sub getpty {
  local( $pty_handle, $tty_handle ) = @_;

print "--------in getpty----------\n";
  $pty_handle =~ s/^([^']+)$/(caller)[$[]."'".$1/e;
  $pty_handle =~ s/^([^']+)$/(caller)[$[]."'".$1/e;

  #$pty_handle = ++$next_handle;
  chop( @ptys = `ls /dev/pty*` );

  for $pty ( @ptys )
  {
    open($pty_handle,"+>$pty") || next;
    select((select($pty_handle), $| = 1)[0]);
    ($tty = $pty) =~ s/pty/tty/;

    open($tty_handle,"+>$tty") || next;
    select((select($tty_handle), $| = 1)[0]);
    ($tty = $pty) =~ s/pty/tty/;

    return ($pty, $tty, $pty_handle );
  }
  return undef;
}



# from: Randal L. Schwartz

# Usage:
#
# ($chathandle = &chat'open_proc("/bin/sh")) || die "cannot open shell";
# system("stty cbreak raw -echo >/dev/tty\n");
# &chat'interact($chathandle);
# &chat'close($chathandle);
# system("stty -cbreak -raw echo >/dev/tty\n");

sub interact
{
  local( $chathandle ) = @_;

  &chat'print($chathandle, "stty sane\n");
  select(STDOUT) ; $| = 1; # unbuffer STDOUT

  #print "tty=$Tty,whoami=",`whoami`,"\n";
  #&change_utmp( "", $Tty, "eric", "", time() );

  {
    @ready = &chat'select(30, STDIN,$chathandle);
    print "after select, ready=",join(",",@ready),"\n";
    #(warn "[waiting]"), redo unless @ready;
    if (grep($_ eq $chathandle, @ready)) {
        print "checking $chathandle\n";
        last unless $text = &chat'expect($chathandle,0,'[\s\S]+','$&');
        print "$chathandle OK\n";
        print "got=($text)";
        #print $text;
    }
    if (grep($_ eq STDIN, @ready)) {
        print "checking STDIN\n";
        last unless sysread(STDIN,$buf,1024) > 0;
        print "STDIN OK\n";
        &chat'print($chathandle,$buf);
    }
    redo;
  }
  #&change_utmp( $Tty, "$Tty", "", "", 0 );
  print "leaving interact, \$!=$!\n";
}

## $handle = &chat'open_duphandle(handle);
## duplicates an input file handle to conform to chat format

sub open_duphandle { ## public
    *S = ++$next;
    open(S,"<&$_[0]");
    $next; # return symbol for switcharound
}

#Here is an example which uses this routine.
#
#    # The following lines makes stdin unbuffered
#
#    $BSD = -f '/vmunix';
#
#    if ($BSD) {
#        system "stty cbreak </dev/tty >/dev/tty 2>&1";
#    }
#    else {
#        system "stty", '-icanon';
#        system "stty", 'eol', '^A';
#    }
#
#    require 'mychat2.pl';
#
#    &chat'open_duphandle(STDIN);
#
#    print
#    &chat'expect(3,
#      '[A-Z]', '" :-)"',
#      '.', '" :-("',
#      TIMEOUT,  '"-o-"',
#      EOF, '"\$\$"'),
#    "\n";


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