#!/usr/bin/perl -w 
use strict; 
BEGIN { 
        push(@INC, "."); 
} 
use FileHandle; 
use IPC::Open2; 
 
 
my %test_h = (); 
 
sub test { 
        my $in; 
        my $out; 
        #my $pid = open2($in, $out, "cat " ); 
        my $pwd = `pwd`; 
        chomp($pwd); 
    my $pid = open2($test_h{"in"}, $test_h{"out"}, "./XXX.pl" ); 
        printf STDOUT ("%x %d    %x   %d\n", $test_h{"in"}, fileno($test_h{"in"}), $test_h{"out"}, fileno($test_h{"out"})); 
    while(1) { 
                my $out = $test_h{"out"}; 
                printf $out ("%s", "stuff\n");             #PUT STRINGS INTO THE PIPE. 
                printf $out ("stuff\n"); 
 
                my $in = $test_h{"in"}; 
                #my $got = <$in>; 
                #my $got = <{$test_h{"in"}}>; 
                #printf STDOUT ("WE GET: %s\n", $got); 
        my ($eof, @lines) = &nonblockGetLines($in);         #Now try non-block read from the pipe. 
                if($eof) { last; } 
                foreach my $line (@lines) { 
                        printf STDOUT ("GOT: %s\n", $line); 
                } 
        sleep(1); 
    } 
} 
 
# Returns:  ($eof,@lines) 
my %nonblockGetLines_last; 
sub nonblockGetLines { 
        my $fh = $_[0]; 
        my $rfd = ''; 
        $nonblockGetLines_last{$fh} = '' 
                unless defined $nonblockGetLines_last{$fh}; 
 
        #set file handle bit mask 
        vec($rfd, fileno($fh), 1) = 1; 
        #if something's coming 
        my $out_fd = 0; 
        if (not select($out_fd=$rfd, undef, undef, 0)>=0 ) 
        { 
                printf STDERR ("%x select not ready.\n", $fh); 
                return (0); 
        } 
        printf STDERR ("OUT_FD:%x   IN_FD:%x  fileno: %d \n", ord($out_fd), ord($rfd), fileno($fh)); 
 
################################################ 
#the $out_fd is 0, this means no data source is ready?   but it should echo something since I have put something into the pipe. 
################################################ 
        if(not vec($out_fd, fileno($fh), 1)) {   
 
                printf STDERR ("%x not this one.\n", $fh); 
                return (0); 
        } 
        my $buf = ''; 
        my $n = sysread($fh, $buf, 1024*1024, 0); 
        if ( ! defined $n ) { 
                #on error, we just print an error message 
                printf STDERR ("MAPPER: %x got a read error at input line.\n", $fh); 
        }elsif($n == 0) { 
                # If we're done, make sure to send the last unfinished line 
                return (1,$nonblockGetLines_last{$fh}); 
        } 
        # Prepend the last unfinished line 
        $buf = $nonblockGetLines_last{$fh}.$buf; 
        # And save any newly unfinished lines 
        if(substr($buf,-1) !~ /[\r\n]/ && $buf =~ s/([^\r\n]*)$//) { 
                $nonblockGetLines_last{$fh} = $1; 
        } else { 
                $nonblockGetLines_last{$fh} = ''; 
        } 
        return $buf ? (0,split(/\n/,$buf)) : (0); 
} 
 
&test();

 #!/usr/bin/perl -w 
# 
 
 
while(<STDIN>) { 
        print "M2\t", $_; 
}