[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	= 1.0106;
@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.

Note if you specify C<-> as the command, in an analogous fashion to
C<open(FOO, "-|")> the child process will just be the forked Perl
process rather than an external command.  This feature isn't yet
supported on Win32 platforms.

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
# allow '-' as command (c.f. open "-|"), by Adam Spiers <perl@adamspiers.org>
#
# $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 {
    return $1 if $_[0] =~ /\A=?(\d+)\z/;  # deal with fh just being an fd
    return fileno $_[0];
}

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
	# A tie in the parent should not be allowed to cause problems.
	untie *STDIN;
	untie *STDOUT;
	# 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 $kid_err;
	    }
	} else {
	    xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
	}
	if ($cmd[0] eq '-') {
	    croak "Arguments don't make sense when the command is '-'"
	      if @cmd > 1;
	    return 0;
	}
	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
20a6717b	12	$VERSION = 1.0106;
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
036b4402	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
a2a63531	55	Note if you specify C<-> as the command, in an analogous fashion to
	56	C<open(FOO, "-\|")> the child process will just be the forked Perl
	57	process rather than an external command. This feature isn't yet
	58	supported on Win32 platforms.
	59
4375e838	60	open3() does not wait for and reap the child process after it exits.
227e8dd4	61	Except for short programs where it's acceptable to let the operating system
	62	take care of this, you need to do this yourself. This is normally as
	63	simple as calling C<waitpid $pid, 0> when you're done with the process.
	64	Failing to do this can result in an accumulation of defunct or "zombie"
	65	processes. See L<perlfunc/waitpid> for more information.
	66
2675ae2b	67	If you try to read from the child's stdout writer and their stderr
	68	writer, you'll have problems with blocking, which means you'll want
	69	to use select() or the IO::Select, which means you'd best use
	70	sysread() instead of readline() for normal stuff.
	71
	72	This is very dangerous, as you may block forever. It assumes it's
	73	going to talk to something like B<bc>, both writing to it and reading
	74	from it. This is presumably safe because you "know" that commands
	75	like B<bc> will read a line at a time and output a line at a time.
	76	Programs like B<sort> that read their entire input stream first,
7e1af8bc	77	however, are quite apt to cause deadlock.
	78
	79	The big problem with this approach is that if you don't have control
7a2e2cd6	80	over source code being run in the child process, you can't control
7e1af8bc	81	what it does with pipe buffering. Thus you can't just open a pipe to
	82	C<cat -v> and continually read and write a line from it.
	83
2675ae2b	84	=head1 WARNING
	85
	86	The order of arguments differs from that of open2().
	87
7e1af8bc	88	=cut
a0d0e21e	89
	90	# &open3: Marc Horowitz <marc@mit.edu>
	91	# derived mostly from &open2 by tom christiansen, <tchrist@convex.com>
4633a7c4	92	# fixed for 5.001 by Ulrich Kunitz <kunitz@mai-koeln.com>
f55ee38a	93	# ported to Win32 by Ron Schmidt, Merrill Lynch almost ended my career
2675ae2b	94	# fixed for autovivving FHs, tchrist again
6662521e	95	# allow fd numbers to be used, by Frank Tobin
a2a63531	96	# allow '-' as command (c.f. open "-\|"), by Adam Spiers <perl@adamspiers.org>
a0d0e21e	97	#
	98	# $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $
	99	#
	100	# usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...);
	101	#
	102	# spawn the given $cmd and connect rdr for
	103	# reading, wtr for writing, and err for errors.
	104	# if err is '', or the same as rdr, then stdout and
	105	# stderr of the child are on the same fh. returns pid
7e1af8bc	106	# of child (or dies on failure).
a0d0e21e	107
a0d0e21e	108
4633a7c4	109	# if wtr begins with '<&', then wtr will be closed in the parent, and
a0d0e21e	110	# the child will read from it directly. if rdr or err begins with
	111	# '>&', then the child will send output directly to that fd. In both
	112	# cases, there will be a dup() instead of a pipe() made.
	113
	114
	115	# WARNING: this is dangerous, as you may block forever
	116	# unless you are very careful.
	117	#
	118	# $wtr is left unbuffered.
	119	#
	120	# abort program if
	121	# rdr or wtr are null
7e1af8bc	122	# a system call fails
a0d0e21e	123
2675ae2b	124	our $Me = 'open3 (bug)'; # you should never see this, it's always localized
a0d0e21e	125
7e1af8bc	126	# Fatal.pm needs to be fixed WRT prototypes.
	127
	128	sub xfork {
	129	my $pid = fork;
	130	defined $pid or croak "$Me: fork failed: $!";
	131	return $pid;
	132	}
	133
	134	sub xpipe {
	135	pipe $_[0], $_[1] or croak "$Me: pipe($_[0], $_[1]) failed: $!";
	136	}
	137
	138	# I tried using a * prototype character for the filehandle but it still
	139	# disallows a bearword while compiling under strict subs.
a0d0e21e	140
7e1af8bc	141	sub xopen {
	142	open $_[0], $_[1] or croak "$Me: open($_[0], $_[1]) failed: $!";
	143	}
	144
	145	sub xclose {
	146	close $_[0] or croak "$Me: close($_[0]) failed: $!";
	147	}
	148
036b4402	149	sub fh_is_fd {
036b4402	150	return $_[0] =~ /\A=?(\d+)\z/;
6662521e	151	}
6662521e	152
036b4402	153	sub xfileno {
	154	return $1 if $_[0] =~ /\A=?(\d+)\z/; # deal with fh just being an fd
	155	return fileno $_[0];
6662521e	156	}
6662521e	157
f55ee38a	158	my $do_spawn = $^O eq 'os2' \|\| $^O eq 'MSWin32';
a24d8dfd	159
7e1af8bc	160	sub _open3 {
	161	local $Me = shift;
	162	my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
	163	my($dup_wtr, $dup_rdr, $dup_err, $kidpid);
	164
2675ae2b	165	# simulate autovivification of filehandles because
	166	# it's too ugly to use @_ throughout to make perl do it for us
	167	# tchrist 5-Mar-00
	168
	169	unless (eval {
	170	$dad_wtr = $_[1] = gensym unless defined $dad_wtr && length $dad_wtr;
	171	$dad_rdr = $_[2] = gensym unless defined $dad_rdr && length $dad_rdr;
	172	1; })
	173	{
	174	# must strip crud for croak to add back, or looks ugly
	175	$@ =~ s/(?<=value attempted) at .*//s;
	176	croak "$Me: $@";
	177	}
	178
	179	$dad_err \|\|= $dad_rdr;
a0d0e21e	180
4633a7c4	181	$dup_wtr = ($dad_wtr =~ s/^[<>]&//);
	182	$dup_rdr = ($dad_rdr =~ s/^[<>]&//);
	183	$dup_err = ($dad_err =~ s/^[<>]&//);
a0d0e21e	184
2675ae2b	185	# force unqualified filehandles into caller's package
6662521e	186	$dad_wtr = qualify $dad_wtr, $package unless fh_is_fd($dad_wtr);
	187	$dad_rdr = qualify $dad_rdr, $package unless fh_is_fd($dad_rdr);
	188	$dad_err = qualify $dad_err, $package unless fh_is_fd($dad_err);
7e1af8bc	189
8b3e92c6	190	my $kid_rdr = gensym;
	191	my $kid_wtr = gensym;
	192	my $kid_err = gensym;
7e1af8bc	193
	194	xpipe $kid_rdr, $dad_wtr if !$dup_wtr;
	195	xpipe $dad_rdr, $kid_wtr if !$dup_rdr;
	196	xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr;
	197
a24d8dfd	198	$kidpid = $do_spawn ? -1 : xfork;
a24d8dfd	199	if ($kidpid == 0) { # Kid
c6770908	200	# A tie in the parent should not be allowed to cause problems.
	201	untie *STDIN;
	202	untie *STDOUT;
7e1af8bc	203	# If she wants to dup the kid's stderr onto her stdout I need to
	204	# save a copy of her stdout before I put something else there.
	205	if ($dad_rdr ne $dad_err && $dup_err
6662521e	206	&& xfileno($dad_err) == fileno(STDOUT)) {
8b3e92c6	207	my $tmp = gensym;
7e1af8bc	208	xopen($tmp, ">&$dad_err");
	209	$dad_err = $tmp;
	210	}
a0d0e21e	211
a0d0e21e	212	if ($dup_wtr) {
6662521e	213	xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != xfileno($dad_wtr);
a0d0e21e	214	} else {
8ebc5c01	215	xclose $dad_wtr;
8b3e92c6	216	xopen \*STDIN, "<&=" . fileno $kid_rdr;
a0d0e21e	217	}
a0d0e21e	218	if ($dup_rdr) {
6662521e	219	xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != xfileno($dad_rdr);
a0d0e21e	220	} else {
8ebc5c01	221	xclose $dad_rdr;
8b3e92c6	222	xopen \*STDOUT, ">&=" . fileno $kid_wtr;
a0d0e21e	223	}
	224	if ($dad_rdr ne $dad_err) {
	225	if ($dup_err) {
8b3e92c6	226	# I have to use a fileno here because in this one case
	227	# I'm doing a dup but the filehandle might be a reference
	228	# (from the special case above).
6662521e	229	xopen \*STDERR, ">&" . xfileno($dad_err)
6662521e	230	if fileno(STDERR) != xfileno($dad_err);
a0d0e21e	231	} else {
8ebc5c01	232	xclose $dad_err;
8b3e92c6	233	xopen \*STDERR, ">&=" . fileno $kid_err;
a0d0e21e	234	}
a0d0e21e	235	} else {
8ebc5c01	236	xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
a0d0e21e	237	}
a2a63531	238	if ($cmd[0] eq '-') {
	239	croak "Arguments don't make sense when the command is '-'"
	240	if @cmd > 1;
	241	return 0;
	242	}
a0d0e21e	243	local($")=(" ");
2675ae2b	244	exec @cmd # XXX: wrong process to croak from
ad973f30	245	or croak "$Me: exec of @cmd failed";
a24d8dfd	246	} elsif ($do_spawn) {
	247	# All the bookkeeping of coincidence between handles is
	248	# handled in spawn_with_handles.
	249
	250	my @close;
	251	if ($dup_wtr) {
8b3e92c6	252	$kid_rdr = \*{$dad_wtr};
8b3e92c6	253	push @close, $kid_rdr;
a24d8dfd	254	} else {
8b3e92c6	255	push @close, \*{$dad_wtr}, $kid_rdr;
a24d8dfd	256	}
a24d8dfd	257	if ($dup_rdr) {
8b3e92c6	258	$kid_wtr = \*{$dad_rdr};
8b3e92c6	259	push @close, $kid_wtr;
a24d8dfd	260	} else {
8b3e92c6	261	push @close, \*{$dad_rdr}, $kid_wtr;
a24d8dfd	262	}
	263	if ($dad_rdr ne $dad_err) {
	264	if ($dup_err) {
8b3e92c6	265	$kid_err = \*{$dad_err};
8b3e92c6	266	push @close, $kid_err;
a24d8dfd	267	} else {
8b3e92c6	268	push @close, \*{$dad_err}, $kid_err;
a24d8dfd	269	}
	270	} else {
	271	$kid_err = $kid_wtr;
	272	}
	273	require IO::Pipe;
	274	$kidpid = eval {
	275	spawn_with_handles( [ { mode => 'r',
8b3e92c6	276	open_as => $kid_rdr,
a24d8dfd	277	handle => \*STDIN },
a24d8dfd	278	{ mode => 'w',
8b3e92c6	279	open_as => $kid_wtr,
a24d8dfd	280	handle => \*STDOUT },
a24d8dfd	281	{ mode => 'w',
8b3e92c6	282	open_as => $kid_err,
a24d8dfd	283	handle => \*STDERR },
	284	], \@close, @cmd);
	285	};
ad973f30	286	die "$Me: $@" if $@;
a0d0e21e	287	}
a0d0e21e	288
7e1af8bc	289	xclose $kid_rdr if !$dup_wtr;
	290	xclose $kid_wtr if !$dup_rdr;
	291	xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err;
	292	# If the write handle is a dup give it away entirely, close my copy
	293	# of it.
	294	xclose $dad_wtr if $dup_wtr;
a0d0e21e	295
	296	select((select($dad_wtr), $\| = 1)[0]); # unbuffer pipe
	297	$kidpid;
	298	}
7e1af8bc	299
7e1af8bc	300	sub open3 {
a24d8dfd	301	if (@_ < 4) {
	302	local $" = ', ';
	303	croak "open3(@_): not enough arguments";
	304	}
7e1af8bc	305	return _open3 'open3', scalar caller, @_
7e1af8bc	306	}
a0d0e21e	307
a24d8dfd	308	sub spawn_with_handles {
	309	my $fds = shift; # Fields: handle, mode, open_as
	310	my $close_in_child = shift;
	311	my ($fd, $pid, @saved_fh, $saved, %saved, @errs);
	312	require Fcntl;
	313
	314	foreach $fd (@$fds) {
	315	$fd->{tmp_copy} = IO::Handle->new_from_fd($fd->{handle}, $fd->{mode});
	316	$saved{fileno $fd->{handle}} = $fd->{tmp_copy};
	317	}
	318	foreach $fd (@$fds) {
	319	bless $fd->{handle}, 'IO::Handle'
	320	unless eval { $fd->{handle}->isa('IO::Handle') } ;
	321	# If some of handles to redirect-to coincide with handles to
	322	# redirect, we need to use saved variants:
	323	$fd->{handle}->fdopen($saved{fileno $fd->{open_as}} \|\| $fd->{open_as},
	324	$fd->{mode});
	325	}
f55ee38a	326	unless ($^O eq 'MSWin32') {
	327	# Stderr may be redirected below, so we save the err text:
	328	foreach $fd (@$close_in_child) {
	329	fcntl($fd, Fcntl::F_SETFD(), 1) or push @errs, "fcntl $fd: $!"
	330	unless $saved{fileno $fd}; # Do not close what we redirect!
	331	}
a24d8dfd	332	}
	333
	334	unless (@errs) {
	335	$pid = eval { system 1, @_ }; # 1 == P_NOWAIT
	336	push @errs, "IO::Pipe: Can't spawn-NOWAIT: $!" if !$pid \|\| $pid < 0;
	337	}
	338
	339	foreach $fd (@$fds) {
	340	$fd->{handle}->fdopen($fd->{tmp_copy}, $fd->{mode});
	341	$fd->{tmp_copy}->close or croak "Can't close: $!";
	342	}
	343	croak join "\n", @errs if @errs;
	344	return $pid;
	345	}
	346
	347	1; # so require is happy