package IPC::Run::Win32Pump;

=pod

=head1 NAME

IPC::Run::Win32Pump - helper processes to shovel data to/from parent, child

=head1 SYNOPSIS

Internal use only; see IPC::Run::Win32IO and best of luck to you.

=head1 DESCRIPTION

See L<IPC::Run::Win32Helper|IPC::Run::Win32Helper> for details.  This
module is used in subprocesses that are spawned to shovel data to/from
parent processes from/to their child processes.  Where possible, pumps
are optimized away.

NOTE: This is not a real module: it's a script in module form, designed
to be run like

   $^X -MIPC::Run::Win32Pumper -e 1 ...

It parses a bunch of command line parameters from IPC::Run::Win32IO.

=cut

use strict;
use vars qw{$VERSION};

BEGIN {
    $VERSION = '20180523.0';
}

use Win32API::File qw(
  OsFHandleOpen
);

my ( $stdin_fh, $stdout_fh, $debug_fh, $binmode, $parent_pid, $parent_start_time, $debug, $child_label );

BEGIN {
    ( $stdin_fh, $stdout_fh, $debug_fh, $binmode, $parent_pid, $parent_start_time, $debug, $child_label ) = @ARGV;
    ## Rather than letting IPC::Run::Debug export all-0 constants
    ## when not debugging, we do it manually in order to not even
    ## load IPC::Run::Debug.
    if ($debug) {
        eval "use IPC::Run::Debug qw( :default _debug_init ); 1;"
          or die $@;
    }
    else {
        eval <<STUBS_END or die $@;
	 sub _debug {}
	 sub _debug_init {}
	 sub _debugging() { 0 }
	 sub _debugging_data() { 0 }
	 sub _debugging_details() { 0 }
	 sub _debugging_gory_details() { 0 }
	 1;
STUBS_END
    }
}

## For some reason these get created with binmode on.  AAargh, gotta       #### REMOVE
## do it by hand below.       #### REMOVE
if ($debug) {    #### REMOVE
    close STDERR;    #### REMOVE
    OsFHandleOpen( \*STDERR, $debug_fh, "w" )    #### REMOVE
      or print "$! opening STDERR as Win32 handle $debug_fh in pumper $$";    #### REMOVE
}               #### REMOVE
close STDIN;    #### REMOVE
OsFHandleOpen( \*STDIN, $stdin_fh, "r" )    #### REMOVE
  or die "$! opening STDIN as Win32 handle $stdin_fh in pumper $$";    #### REMOVE
close STDOUT;                                                          #### REMOVE
OsFHandleOpen( \*STDOUT, $stdout_fh, "w" )                             #### REMOVE
  or die "$! opening STDOUT as Win32 handle $stdout_fh in pumper $$";  #### REMOVE

binmode STDIN;
binmode STDOUT;
$| = 1;
select STDERR;
$| = 1;
select STDOUT;

$child_label ||= "pump";
_debug_init(
    $parent_pid,
    $parent_start_time,
    $debug,
    fileno STDERR,
    $child_label,
);

_debug "Entered" if _debugging_details;

# No need to close all fds; win32 doesn't seem to pass any on to us.
$| = 1;
my $buf;
my $total_count = 0;
while (1) {
    my $count = sysread STDIN, $buf, 10_000;
    last unless $count;
    if (_debugging_gory_details) {
        my $msg = "'$buf'";
        substr( $msg, 100, -1 ) = '...' if length $msg > 100;
        $msg =~ s/\n/\\n/g;
        $msg =~ s/\r/\\r/g;
        $msg =~ s/\t/\\t/g;
        $msg =~ s/([\000-\037\177-\277])/sprintf "\0x%02x", ord $1/eg;
        _debug sprintf( "%5d chars revc: ", $count ), $msg;
    }
    $total_count += $count;
    $buf =~ s/\r//g unless $binmode;
    if (_debugging_gory_details) {
        my $msg = "'$buf'";
        substr( $msg, 100, -1 ) = '...' if length $msg > 100;
        $msg =~ s/\n/\\n/g;
        $msg =~ s/\r/\\r/g;
        $msg =~ s/\t/\\t/g;
        $msg =~ s/([\000-\037\177-\277])/sprintf "\0x%02x", ord $1/eg;
        _debug sprintf( "%5d chars sent: ", $count ), $msg;
    }
    print $buf;
}

_debug "Exiting, transferred $total_count chars" if _debugging_details;

## Perform a graceful socket shutdown.  Windows defaults to SO_DONTLINGER,
## which should cause a "graceful shutdown in the background" on sockets.
## but that's only true if the process closes the socket manually, it
## seems; if the process exits and lets the OS clean up, the OS is not
## so kind.  STDOUT is not always a socket, of course, but it won't hurt
## to close a pipe and may even help.  With a closed source OS, who
## can tell?
##
## In any case, this close() is one of the main reasons we have helper
## processes; if the OS closed socket fds gracefully when an app exits,
## we'd just redirect the client directly to what is now the pump end
## of the socket.  As it is, however, we need to let the client play with
## pipes, which don't have the abort-on-app-exit behavior, and then
## adapt to the sockets in the helper processes to allow the parent to
## select.
##
## Possible alternatives / improvements:
##
## 1) use helper threads instead of processes.  I don't trust perl's threads
## as of 5.005 or 5.6 enough (which may be myopic of me).
##
## 2) figure out if/how to get at WaitForMultipleObjects() with pipe
## handles.  May be able to take the Win32 handle and pass it to
## Win32::Event::wait_any, dunno.
##
## 3) Use Inline::C or a hand-tooled XS module to do helper threads.
## This would be faster than #1, but would require a ppm distro.
##
close STDOUT;
close STDERR;

1;

=pod

=head1 AUTHOR

Barries Slaymaker <barries@slaysys.com>.  Funded by Perforce Software, Inc.

=head1 COPYRIGHT

Copyright 2001, Barrie Slaymaker, All Rights Reserved.

You may use this under the terms of either the GPL 2.0 ir the Artistic License.

=cut
