[p5sagit/p5-mst-13.2.git] / lib / IPC / Open3.pm

package IPC::Open3;

use strict;
no strict 'refs'; # because users pass me bareword filehandles
our ($VERSION, @ISA, @EXPORT);

require Exporter;

use Carp;
use Symbol qw(gensym qualify);

$VERSION	= 1.0103;
@ISA		= qw(Exporter);
@EXPORT		= qw(open3);

=head1 NAME

IPC::Open3, open3 - open a process for reading, writing, and error handling

=head1 SYNOPSIS

    $pid = open3(\*WTRFH, \*RDRFH, \*ERRFH,
		    'some cmd and args', 'optarg', ...);

    my($wtr, $rdr, $err);
    $pid = open3($wtr, $rdr, $err,
		    'some cmd and args', 'optarg', ...);

=head1 DESCRIPTION

Extremely similar to open2(), open3() spawns the given $cmd and
connects RDRFH for reading, WTRFH for writing, and ERRFH for errors.  If
ERRFH is false, or the same file descriptor as RDRFH, then STDOUT and 
STDERR of the child are on the same filehandle.  The WTRFH will have
autoflush turned on.

If WTRFH begins with C<< <& >>, then WTRFH will be closed in the parent, and
the child will read from it directly.  If RDRFH or ERRFH begins with
C<< >& >>, then the child will send output directly to that filehandle.
In both cases, there will be a dup(2) instead of a pipe(2) made.

If either reader or writer is the null string, this will be replaced
by an autogenerated filehandle.  If so, you must pass a valid lvalue
in the parameter slot so it can be overwritten in the caller, or 
an exception will be raised.

The filehandles may also be integers, in which case they are understood
as file descriptors.

open3() returns the process ID of the child process.  It doesn't return on
failure: it just raises an exception matching C</^open3:/>.  However,
C<exec> failures in the child are not detected.  You'll have to 
trap SIGPIPE yourself.

open3() does not wait for and reap the child process after it exits.  
Except for short programs where it's acceptable to let the operating system
take care of this, you need to do this yourself.  This is normally as 
simple as calling C<waitpid $pid, 0> when you're done with the process.
Failing to do this can result in an accumulation of defunct or "zombie"
processes.  See L<perlfunc/waitpid> for more information.

If you try to read from the child's stdout writer and their stderr
writer, you'll have problems with blocking, which means you'll want
to use select() or the IO::Select, which means you'd best use
sysread() instead of readline() for normal stuff.

This is very dangerous, as you may block forever.  It assumes it's
going to talk to something like B<bc>, both writing to it and reading
from it.  This is presumably safe because you "know" that commands
like B<bc> will read a line at a time and output a line at a time.
Programs like B<sort> that read their entire input stream first,
however, are quite apt to cause deadlock.

The big problem with this approach is that if you don't have control
over source code being run in the child process, you can't control
what it does with pipe buffering.  Thus you can't just open a pipe to
C<cat -v> and continually read and write a line from it.

=head1 WARNING

The order of arguments differs from that of open2().

=cut

# &open3: Marc Horowitz <marc@mit.edu>
# derived mostly from &open2 by tom christiansen, <tchrist@convex.com>
# fixed for 5.001 by Ulrich Kunitz <kunitz@mai-koeln.com>
# ported to Win32 by Ron Schmidt, Merrill Lynch almost ended my career
# fixed for autovivving FHs, tchrist again
# allow fd numbers to be used, by Frank Tobin
#
# $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $
#
# usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...);
#
# spawn the given $cmd and connect rdr for
# reading, wtr for writing, and err for errors.
# if err is '', or the same as rdr, then stdout and
# stderr of the child are on the same fh.  returns pid
# of child (or dies on failure).


# if wtr begins with '<&', then wtr will be closed in the parent, and
# the child will read from it directly.  if rdr or err begins with
# '>&', then the child will send output directly to that fd.  In both
# cases, there will be a dup() instead of a pipe() made.


# WARNING: this is dangerous, as you may block forever
# unless you are very careful.
#
# $wtr is left unbuffered.
#
# abort program if
#   rdr or wtr are null
#   a system call fails

our $Me = 'open3 (bug)';	# you should never see this, it's always localized

# Fatal.pm needs to be fixed WRT prototypes.

sub xfork {
    my $pid = fork;
    defined $pid or croak "$Me: fork failed: $!";
    return $pid;
}

sub xpipe {
    pipe $_[0], $_[1] or croak "$Me: pipe($_[0], $_[1]) failed: $!";
}

# I tried using a * prototype character for the filehandle but it still
# disallows a bearword while compiling under strict subs.

sub xopen {
    open $_[0], $_[1] or croak "$Me: open($_[0], $_[1]) failed: $!";
}

sub xclose {
    close $_[0] or croak "$Me: close($_[0]) failed: $!";
}

sub fh_is_fd {
    return $_[0] =~ /\A=?(\d+)\z/;
}

sub xfileno {
    my ($fh) = @_;
    return $1 if =~ /\A=?(\d+)\z/;  # deal with $fh just being an fd
    return fileno $fh;
}

my $do_spawn = $^O eq 'os2' || $^O eq 'MSWin32';

sub _open3 {
    local $Me = shift;
    my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
    my($dup_wtr, $dup_rdr, $dup_err, $kidpid);

    # simulate autovivification of filehandles because
    # it's too ugly to use @_ throughout to make perl do it for us
    # tchrist 5-Mar-00

    unless (eval  {
	$dad_wtr = $_[1] = gensym unless defined $dad_wtr && length $dad_wtr;
	$dad_rdr = $_[2] = gensym unless defined $dad_rdr && length $dad_rdr;
	1; }) 
    {
	# must strip crud for croak to add back, or looks ugly
	$@ =~ s/(?<=value attempted) at .*//s;
	croak "$Me: $@";
    } 

    $dad_err ||= $dad_rdr;

    $dup_wtr = ($dad_wtr =~ s/^[<>]&//);
    $dup_rdr = ($dad_rdr =~ s/^[<>]&//);
    $dup_err = ($dad_err =~ s/^[<>]&//);

    # force unqualified filehandles into caller's package
    $dad_wtr = qualify $dad_wtr, $package unless fh_is_fd($dad_wtr);
    $dad_rdr = qualify $dad_rdr, $package unless fh_is_fd($dad_rdr);
    $dad_err = qualify $dad_err, $package unless fh_is_fd($dad_err);

    my $kid_rdr = gensym;
    my $kid_wtr = gensym;
    my $kid_err = gensym;

    xpipe $kid_rdr, $dad_wtr if !$dup_wtr;
    xpipe $dad_rdr, $kid_wtr if !$dup_rdr;
    xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr;

    $kidpid = $do_spawn ? -1 : xfork;
    if ($kidpid == 0) {		# Kid
	# If she wants to dup the kid's stderr onto her stdout I need to
	# save a copy of her stdout before I put something else there.
	if ($dad_rdr ne $dad_err && $dup_err
		&& xfileno($dad_err) == fileno(STDOUT)) {
	    my $tmp = gensym;
	    xopen($tmp, ">&$dad_err");
	    $dad_err = $tmp;
	}

	if ($dup_wtr) {
	    xopen \*STDIN,  "<&$dad_wtr" if fileno(STDIN) != xfileno($dad_wtr);
	} else {
	    xclose $dad_wtr;
	    xopen \*STDIN,  "<&=" . fileno $kid_rdr;
	}
	if ($dup_rdr) {
	    xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != xfileno($dad_rdr);
	} else {
	    xclose $dad_rdr;
	    xopen \*STDOUT, ">&=" . fileno $kid_wtr;
	}
	if ($dad_rdr ne $dad_err) {
	    if ($dup_err) {
		# I have to use a fileno here because in this one case
		# I'm doing a dup but the filehandle might be a reference
		# (from the special case above).
		xopen \*STDERR, ">&" . xfileno($dad_err)
		    if fileno(STDERR) != xfileno($dad_err);
	    } else {
		xclose $dad_err;
		xopen \*STDERR, ">&=" . fileno $kid_err;
	    }
	} else {
	    xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
	}
	local($")=(" ");
	exec @cmd # XXX: wrong process to croak from
	    or croak "$Me: exec of @cmd failed";
    } elsif ($do_spawn) {
	# All the bookkeeping of coincidence between handles is
	# handled in spawn_with_handles.

	my @close;
	if ($dup_wtr) {
	  $kid_rdr = \*{$dad_wtr};
	  push @close, $kid_rdr;
	} else {
	  push @close, \*{$dad_wtr}, $kid_rdr;
	}
	if ($dup_rdr) {
	  $kid_wtr = \*{$dad_rdr};
	  push @close, $kid_wtr;
	} else {
	  push @close, \*{$dad_rdr}, $kid_wtr;
	}
	if ($dad_rdr ne $dad_err) {
	    if ($dup_err) {
	      $kid_err = \*{$dad_err};
	      push @close, $kid_err;
	    } else {
	      push @close, \*{$dad_err}, $kid_err;
	    }
	} else {
	  $kid_err = $kid_wtr;
	}
	require IO::Pipe;
	$kidpid = eval {
	    spawn_with_handles( [ { mode => 'r',
				    open_as => $kid_rdr,
				    handle => \*STDIN },
				  { mode => 'w',
				    open_as => $kid_wtr,
				    handle => \*STDOUT },
				  { mode => 'w',
				    open_as => $kid_err,
				    handle => \*STDERR },
				], \@close, @cmd);
	};
	die "$Me: $@" if $@;
    }

    xclose $kid_rdr if !$dup_wtr;
    xclose $kid_wtr if !$dup_rdr;
    xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err;
    # If the write handle is a dup give it away entirely, close my copy
    # of it.
    xclose $dad_wtr if $dup_wtr;

    select((select($dad_wtr), $| = 1)[0]); # unbuffer pipe
    $kidpid;
}

sub open3 {
    if (@_ < 4) {
	local $" = ', ';
	croak "open3(@_): not enough arguments";
    }
    return _open3 'open3', scalar caller, @_
}

sub spawn_with_handles {
    my $fds = shift;		# Fields: handle, mode, open_as
    my $close_in_child = shift;
    my ($fd, $pid, @saved_fh, $saved, %saved, @errs);
    require Fcntl;

    foreach $fd (@$fds) {
	$fd->{tmp_copy} = IO::Handle->new_from_fd($fd->{handle}, $fd->{mode});
	$saved{fileno $fd->{handle}} = $fd->{tmp_copy};
    }
    foreach $fd (@$fds) {
	bless $fd->{handle}, 'IO::Handle'
	    unless eval { $fd->{handle}->isa('IO::Handle') } ;
	# If some of handles to redirect-to coincide with handles to
	# redirect, we need to use saved variants:
	$fd->{handle}->fdopen($saved{fileno $fd->{open_as}} || $fd->{open_as},
			      $fd->{mode});
    }
    unless ($^O eq 'MSWin32') {
	# Stderr may be redirected below, so we save the err text:
	foreach $fd (@$close_in_child) {
	    fcntl($fd, Fcntl::F_SETFD(), 1) or push @errs, "fcntl $fd: $!"
		unless $saved{fileno $fd}; # Do not close what we redirect!
	}
    }

    unless (@errs) {
	$pid = eval { system 1, @_ }; # 1 == P_NOWAIT
	push @errs, "IO::Pipe: Can't spawn-NOWAIT: $!" if !$pid || $pid < 0;
    }

    foreach $fd (@$fds) {
	$fd->{handle}->fdopen($fd->{tmp_copy}, $fd->{mode});
	$fd->{tmp_copy}->close or croak "Can't close: $!";
    }
    croak join "\n", @errs if @errs;
    return $pid;
}

1; # so require is happy
Commit	Line	Data
a0d0e21e	1	package IPC::Open3;
7e1af8bc	2
	3	use strict;
	4	no strict 'refs'; # because users pass me bareword filehandles
2675ae2b	5	our ($VERSION, @ISA, @EXPORT);
7e1af8bc	6
a0d0e21e	7	require Exporter;
7e1af8bc	8
a0d0e21e	9	use Carp;
8b3e92c6	10	use Symbol qw(gensym qualify);
7e1af8bc	11
8b3e92c6	12	$VERSION = 1.0103;
7e1af8bc	13	@ISA = qw(Exporter);
7e1af8bc	14	@EXPORT = qw(open3);
a0d0e21e	15
f06db76b	16	=head1 NAME
	17
	18	IPC::Open3, open3 - open a process for reading, writing, and error handling
	19
	20	=head1 SYNOPSIS
	21
84902520	22	$pid = open3(\WTRFH, \RDRFH, \*ERRFH,
f06db76b	23	'some cmd and args', 'optarg', ...);
f06db76b	24
2675ae2b	25	my($wtr, $rdr, $err);
	26	$pid = open3($wtr, $rdr, $err,
	27	'some cmd and args', 'optarg', ...);
	28
f06db76b	29	=head1 DESCRIPTION
	30
	31	Extremely similar to open2(), open3() spawns the given $cmd and
	32	connects RDRFH for reading, WTRFH for writing, and ERRFH for errors. If
2675ae2b	33	ERRFH is false, or the same file descriptor as RDRFH, then STDOUT and
	34	STDERR of the child are on the same filehandle. The WTRFH will have
	35	autoflush turned on.
f06db76b	36
2675ae2b	37	If WTRFH begins with C<< <& >>, then WTRFH will be closed in the parent, and
4633a7c4	38	the child will read from it directly. If RDRFH or ERRFH begins with
2675ae2b	39	C<< >& >>, then the child will send output directly to that filehandle.
a24d8dfd	40	In both cases, there will be a dup(2) instead of a pipe(2) made.
f06db76b	41
2675ae2b	42	If either reader or writer is the null string, this will be replaced
	43	by an autogenerated filehandle. If so, you must pass a valid lvalue
	44	in the parameter slot so it can be overwritten in the caller, or
	45	an exception will be raised.
cb1a09d0	46
0e4dedf1	47	The filehandles may also be integers, in which case they are understood
	48	as file descriptors.
	49
7e1af8bc	50	open3() returns the process ID of the child process. It doesn't return on
2675ae2b	51	failure: it just raises an exception matching C</^open3:/>. However,
	52	C<exec> failures in the child are not detected. You'll have to
	53	trap SIGPIPE yourself.
f06db76b	54
92d29cee	55	open3() does not wait for and reap the child process after it exits.
227e8dd4	56	Except for short programs where it's acceptable to let the operating system
	57	take care of this, you need to do this yourself. This is normally as
	58	simple as calling C<waitpid $pid, 0> when you're done with the process.
	59	Failing to do this can result in an accumulation of defunct or "zombie"
	60	processes. See L<perlfunc/waitpid> for more information.
	61
2675ae2b	62	If you try to read from the child's stdout writer and their stderr
	63	writer, you'll have problems with blocking, which means you'll want
	64	to use select() or the IO::Select, which means you'd best use
	65	sysread() instead of readline() for normal stuff.
	66
	67	This is very dangerous, as you may block forever. It assumes it's
	68	going to talk to something like B<bc>, both writing to it and reading
	69	from it. This is presumably safe because you "know" that commands
	70	like B<bc> will read a line at a time and output a line at a time.
	71	Programs like B<sort> that read their entire input stream first,
7e1af8bc	72	however, are quite apt to cause deadlock.
	73
	74	The big problem with this approach is that if you don't have control
7a2e2cd6	75	over source code being run in the child process, you can't control
7e1af8bc	76	what it does with pipe buffering. Thus you can't just open a pipe to
	77	C<cat -v> and continually read and write a line from it.
	78
2675ae2b	79	=head1 WARNING
	80
	81	The order of arguments differs from that of open2().
	82
7e1af8bc	83	=cut
a0d0e21e	84
	85	# &open3: Marc Horowitz <marc@mit.edu>
	86	# derived mostly from &open2 by tom christiansen, <tchrist@convex.com>
4633a7c4	87	# fixed for 5.001 by Ulrich Kunitz <kunitz@mai-koeln.com>
f55ee38a	88	# ported to Win32 by Ron Schmidt, Merrill Lynch almost ended my career
2675ae2b	89	# fixed for autovivving FHs, tchrist again
cab27d23	90	# allow fd numbers to be used, by Frank Tobin
a0d0e21e	91	#
	92	# $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $
	93	#
	94	# usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...);
	95	#
	96	# spawn the given $cmd and connect rdr for
	97	# reading, wtr for writing, and err for errors.
	98	# if err is '', or the same as rdr, then stdout and
	99	# stderr of the child are on the same fh. returns pid
7e1af8bc	100	# of child (or dies on failure).
a0d0e21e	101
a0d0e21e	102
4633a7c4	103	# if wtr begins with '<&', then wtr will be closed in the parent, and
a0d0e21e	104	# the child will read from it directly. if rdr or err begins with
	105	# '>&', then the child will send output directly to that fd. In both
	106	# cases, there will be a dup() instead of a pipe() made.
	107
	108
	109	# WARNING: this is dangerous, as you may block forever
	110	# unless you are very careful.
	111	#
	112	# $wtr is left unbuffered.
	113	#
	114	# abort program if
	115	# rdr or wtr are null
7e1af8bc	116	# a system call fails
a0d0e21e	117
2675ae2b	118	our $Me = 'open3 (bug)'; # you should never see this, it's always localized
a0d0e21e	119
7e1af8bc	120	# Fatal.pm needs to be fixed WRT prototypes.
	121
	122	sub xfork {
	123	my $pid = fork;
	124	defined $pid or croak "$Me: fork failed: $!";
	125	return $pid;
	126	}
	127
	128	sub xpipe {
	129	pipe $_[0], $_[1] or croak "$Me: pipe($_[0], $_[1]) failed: $!";
	130	}
	131
	132	# I tried using a * prototype character for the filehandle but it still
	133	# disallows a bearword while compiling under strict subs.
a0d0e21e	134
7e1af8bc	135	sub xopen {
	136	open $_[0], $_[1] or croak "$Me: open($_[0], $_[1]) failed: $!";
	137	}
	138
	139	sub xclose {
	140	close $_[0] or croak "$Me: close($_[0]) failed: $!";
	141	}
	142
a91d27a8	143	sub fh_is_fd {
	144	return $_[0] =~ /\A=?(\d+)\z/;
	145	}
	146
cab27d23	147	sub xfileno {
cab27d23	148	my ($fh) = @_;
a91d27a8	149	return $1 if =~ /\A=?(\d+)\z/; # deal with $fh just being an fd
cab27d23	150	return fileno $fh;
	151	}
	152
f55ee38a	153	my $do_spawn = $^O eq 'os2' \|\| $^O eq 'MSWin32';
a24d8dfd	154
7e1af8bc	155	sub _open3 {
	156	local $Me = shift;
	157	my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
	158	my($dup_wtr, $dup_rdr, $dup_err, $kidpid);
	159
2675ae2b	160	# simulate autovivification of filehandles because
	161	# it's too ugly to use @_ throughout to make perl do it for us
	162	# tchrist 5-Mar-00
	163
	164	unless (eval {
	165	$dad_wtr = $_[1] = gensym unless defined $dad_wtr && length $dad_wtr;
	166	$dad_rdr = $_[2] = gensym unless defined $dad_rdr && length $dad_rdr;
	167	1; })
	168	{
	169	# must strip crud for croak to add back, or looks ugly
	170	$@ =~ s/(?<=value attempted) at .*//s;
	171	croak "$Me: $@";
	172	}
	173
	174	$dad_err \|\|= $dad_rdr;
a0d0e21e	175
4633a7c4	176	$dup_wtr = ($dad_wtr =~ s/^[<>]&//);
	177	$dup_rdr = ($dad_rdr =~ s/^[<>]&//);
	178	$dup_err = ($dad_err =~ s/^[<>]&//);
a0d0e21e	179
2675ae2b	180	# force unqualified filehandles into caller's package
cab27d23	181	$dad_wtr = qualify $dad_wtr, $package unless fh_is_fd($dad_wtr);
	182	$dad_rdr = qualify $dad_rdr, $package unless fh_is_fd($dad_rdr);
	183	$dad_err = qualify $dad_err, $package unless fh_is_fd($dad_err);
7e1af8bc	184
8b3e92c6	185	my $kid_rdr = gensym;
	186	my $kid_wtr = gensym;
	187	my $kid_err = gensym;
7e1af8bc	188
	189	xpipe $kid_rdr, $dad_wtr if !$dup_wtr;
	190	xpipe $dad_rdr, $kid_wtr if !$dup_rdr;
	191	xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr;
	192
a24d8dfd	193	$kidpid = $do_spawn ? -1 : xfork;
a24d8dfd	194	if ($kidpid == 0) { # Kid
7e1af8bc	195	# If she wants to dup the kid's stderr onto her stdout I need to
	196	# save a copy of her stdout before I put something else there.
	197	if ($dad_rdr ne $dad_err && $dup_err
cab27d23	198	&& xfileno($dad_err) == fileno(STDOUT)) {
8b3e92c6	199	my $tmp = gensym;
7e1af8bc	200	xopen($tmp, ">&$dad_err");
	201	$dad_err = $tmp;
	202	}
a0d0e21e	203
a0d0e21e	204	if ($dup_wtr) {
cab27d23	205	xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != xfileno($dad_wtr);
a0d0e21e	206	} else {
8ebc5c01	207	xclose $dad_wtr;
8b3e92c6	208	xopen \*STDIN, "<&=" . fileno $kid_rdr;
a0d0e21e	209	}
a0d0e21e	210	if ($dup_rdr) {
cab27d23	211	xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != xfileno($dad_rdr);
a0d0e21e	212	} else {
8ebc5c01	213	xclose $dad_rdr;
8b3e92c6	214	xopen \*STDOUT, ">&=" . fileno $kid_wtr;
a0d0e21e	215	}
	216	if ($dad_rdr ne $dad_err) {
	217	if ($dup_err) {
8b3e92c6	218	# I have to use a fileno here because in this one case
	219	# I'm doing a dup but the filehandle might be a reference
	220	# (from the special case above).
cab27d23	221	xopen \*STDERR, ">&" . xfileno($dad_err)
cab27d23	222	if fileno(STDERR) != xfileno($dad_err);
a0d0e21e	223	} else {
8ebc5c01	224	xclose $dad_err;
8b3e92c6	225	xopen \*STDERR, ">&=" . fileno $kid_err;
a0d0e21e	226	}
a0d0e21e	227	} else {
8ebc5c01	228	xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
a0d0e21e	229	}
a0d0e21e	230	local($")=(" ");
2675ae2b	231	exec @cmd # XXX: wrong process to croak from
ad973f30	232	or croak "$Me: exec of @cmd failed";
a24d8dfd	233	} elsif ($do_spawn) {
	234	# All the bookkeeping of coincidence between handles is
	235	# handled in spawn_with_handles.
	236
	237	my @close;
	238	if ($dup_wtr) {
8b3e92c6	239	$kid_rdr = \*{$dad_wtr};
8b3e92c6	240	push @close, $kid_rdr;
a24d8dfd	241	} else {
8b3e92c6	242	push @close, \*{$dad_wtr}, $kid_rdr;
a24d8dfd	243	}
a24d8dfd	244	if ($dup_rdr) {
8b3e92c6	245	$kid_wtr = \*{$dad_rdr};
8b3e92c6	246	push @close, $kid_wtr;
a24d8dfd	247	} else {
8b3e92c6	248	push @close, \*{$dad_rdr}, $kid_wtr;
a24d8dfd	249	}
	250	if ($dad_rdr ne $dad_err) {
	251	if ($dup_err) {
8b3e92c6	252	$kid_err = \*{$dad_err};
8b3e92c6	253	push @close, $kid_err;
a24d8dfd	254	} else {
8b3e92c6	255	push @close, \*{$dad_err}, $kid_err;
a24d8dfd	256	}
	257	} else {
	258	$kid_err = $kid_wtr;
	259	}
	260	require IO::Pipe;
	261	$kidpid = eval {
	262	spawn_with_handles( [ { mode => 'r',
8b3e92c6	263	open_as => $kid_rdr,
a24d8dfd	264	handle => \*STDIN },
a24d8dfd	265	{ mode => 'w',
8b3e92c6	266	open_as => $kid_wtr,
a24d8dfd	267	handle => \*STDOUT },
a24d8dfd	268	{ mode => 'w',
8b3e92c6	269	open_as => $kid_err,
a24d8dfd	270	handle => \*STDERR },
	271	], \@close, @cmd);
	272	};
ad973f30	273	die "$Me: $@" if $@;
a0d0e21e	274	}
a0d0e21e	275
7e1af8bc	276	xclose $kid_rdr if !$dup_wtr;
	277	xclose $kid_wtr if !$dup_rdr;
	278	xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err;
	279	# If the write handle is a dup give it away entirely, close my copy
	280	# of it.
	281	xclose $dad_wtr if $dup_wtr;
a0d0e21e	282
	283	select((select($dad_wtr), $\| = 1)[0]); # unbuffer pipe
	284	$kidpid;
	285	}
7e1af8bc	286
7e1af8bc	287	sub open3 {
a24d8dfd	288	if (@_ < 4) {
	289	local $" = ', ';
	290	croak "open3(@_): not enough arguments";
	291	}
7e1af8bc	292	return _open3 'open3', scalar caller, @_
7e1af8bc	293	}
a0d0e21e	294
a24d8dfd	295	sub spawn_with_handles {
	296	my $fds = shift; # Fields: handle, mode, open_as
	297	my $close_in_child = shift;
	298	my ($fd, $pid, @saved_fh, $saved, %saved, @errs);
	299	require Fcntl;
	300
	301	foreach $fd (@$fds) {
	302	$fd->{tmp_copy} = IO::Handle->new_from_fd($fd->{handle}, $fd->{mode});
	303	$saved{fileno $fd->{handle}} = $fd->{tmp_copy};
	304	}
	305	foreach $fd (@$fds) {
	306	bless $fd->{handle}, 'IO::Handle'
	307	unless eval { $fd->{handle}->isa('IO::Handle') } ;
	308	# If some of handles to redirect-to coincide with handles to
	309	# redirect, we need to use saved variants:
	310	$fd->{handle}->fdopen($saved{fileno $fd->{open_as}} \|\| $fd->{open_as},
	311	$fd->{mode});
	312	}
f55ee38a	313	unless ($^O eq 'MSWin32') {
	314	# Stderr may be redirected below, so we save the err text:
	315	foreach $fd (@$close_in_child) {
	316	fcntl($fd, Fcntl::F_SETFD(), 1) or push @errs, "fcntl $fd: $!"
	317	unless $saved{fileno $fd}; # Do not close what we redirect!
	318	}
a24d8dfd	319	}
	320
	321	unless (@errs) {
	322	$pid = eval { system 1, @_ }; # 1 == P_NOWAIT
	323	push @errs, "IO::Pipe: Can't spawn-NOWAIT: $!" if !$pid \|\| $pid < 0;
	324	}
	325
	326	foreach $fd (@$fds) {
	327	$fd->{handle}->fdopen($fd->{tmp_copy}, $fd->{mode});
	328	$fd->{tmp_copy}->close or croak "Can't close: $!";
	329	}
	330	croak join "\n", @errs if @errs;
	331	return $pid;
	332	}
	333
	334	1; # so require is happy