[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.

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

sub fh_is_fd {
    return $_[0] =~ /^=?\d+$/;
}

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