[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	= 1.03;
@ISA		= qw(Exporter);
@EXPORT		= qw(open3);

=head1 NAME

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

=head1 SYNOPSIS

    $pid = open3(\*CHLD_IN, \*CHLD_OUT, \*CHLD_ERR,
		    'some cmd and args', 'optarg', ...);

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

    waitpid( $pid, 0 );
    my $child_exit_status = $? >> 8;

=head1 DESCRIPTION

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

If CHLD_IN begins with C<< <& >>, then CHLD_IN will be closed in the
parent, and the child will read from it directly.  If CHLD_OUT or
CHLD_ERR 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 (such as no such file or permission denied),
are just reported to CHLD_ERR, as it is not possible to trap them.

If the child process dies for any reason, the next write to CHLD_IN is
likely to generate a SIGPIPE in the parent, which is fatal by default.
So you may wish to handle this signal.

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 See Also

=over 4

=item L<IPC::Open2>

Like Open3 but without STDERR catpure.

=item L<IPC::Run>

This is a CPAN module that has better error handling and more facilities
than Open3.

=back

=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);

    if (@cmd > 1 and $cmd[0] eq '-') {
	croak "Arguments don't make sense when the command is '-'"
    }

    # 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 $kid_err;
	    }
	} else {
	    xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
	}
	return 0 if ($cmd[0] eq '-');
	local($")=(" ");
	exec @cmd or do {
	    carp "$Me: exec of @cmd failed";
	    eval { require POSIX; POSIX::_exit(255); };
	    exit 255;
	};
    } 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
ae8d64f5	12	$VERSION = 1.03;
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
3ce239a0	22	$pid = open3(\CHLD_IN, \CHLD_OUT, \*CHLD_ERR,
f06db76b	23	'some cmd and args', 'optarg', ...);
f06db76b	24
2675ae2b	25	my($wtr, $rdr, $err);
	26	$pid = open3($wtr, $rdr, $err,
	27	'some cmd and args', 'optarg', ...);
	28
b2080196	29	waitpid( $pid, 0 );
	30	my $child_exit_status = $? >> 8;
	31
f06db76b	32	=head1 DESCRIPTION
	33
	34	Extremely similar to open2(), open3() spawns the given $cmd and
3ce239a0	35	connects CHLD_OUT for reading from the child, CHLD_IN for writing to
	36	the child, and CHLD_ERR for errors. If CHLD_ERR is false, or the
	37	same file descriptor as CHLD_OUT, then STDOUT and STDERR of the child
	38	are on the same filehandle. The CHLD_IN will have autoflush turned
	39	on.
	40
	41	If CHLD_IN begins with C<< <& >>, then CHLD_IN will be closed in the
	42	parent, and the child will read from it directly. If CHLD_OUT or
	43	CHLD_ERR begins with C<< >& >>, then the child will send output
	44	directly to that filehandle. In both cases, there will be a dup(2)
	45	instead of a pipe(2) made.
f06db76b	46
2675ae2b	47	If either reader or writer is the null string, this will be replaced
	48	by an autogenerated filehandle. If so, you must pass a valid lvalue
	49	in the parameter slot so it can be overwritten in the caller, or
	50	an exception will be raised.
cb1a09d0	51
036b4402	52	The filehandles may also be integers, in which case they are understood
	53	as file descriptors.
	54
7e1af8bc	55	open3() returns the process ID of the child process. It doesn't return on
2675ae2b	56	failure: it just raises an exception matching C</^open3:/>. However,
eee4b3e7	57	C<exec> failures in the child (such as no such file or permission denied),
	58	are just reported to CHLD_ERR, as it is not possible to trap them.
	59
	60	If the child process dies for any reason, the next write to CHLD_IN is
	61	likely to generate a SIGPIPE in the parent, which is fatal by default.
	62	So you may wish to handle this signal.
f06db76b	63
a2a63531	64	Note if you specify C<-> as the command, in an analogous fashion to
	65	C<open(FOO, "-\|")> the child process will just be the forked Perl
	66	process rather than an external command. This feature isn't yet
	67	supported on Win32 platforms.
	68
4375e838	69	open3() does not wait for and reap the child process after it exits.
227e8dd4	70	Except for short programs where it's acceptable to let the operating system
	71	take care of this, you need to do this yourself. This is normally as
	72	simple as calling C<waitpid $pid, 0> when you're done with the process.
	73	Failing to do this can result in an accumulation of defunct or "zombie"
	74	processes. See L<perlfunc/waitpid> for more information.
	75
2675ae2b	76	If you try to read from the child's stdout writer and their stderr
	77	writer, you'll have problems with blocking, which means you'll want
	78	to use select() or the IO::Select, which means you'd best use
	79	sysread() instead of readline() for normal stuff.
	80
	81	This is very dangerous, as you may block forever. It assumes it's
	82	going to talk to something like B<bc>, both writing to it and reading
	83	from it. This is presumably safe because you "know" that commands
	84	like B<bc> will read a line at a time and output a line at a time.
	85	Programs like B<sort> that read their entire input stream first,
7e1af8bc	86	however, are quite apt to cause deadlock.
	87
	88	The big problem with this approach is that if you don't have control
7a2e2cd6	89	over source code being run in the child process, you can't control
7e1af8bc	90	what it does with pipe buffering. Thus you can't just open a pipe to
	91	C<cat -v> and continually read and write a line from it.
	92
eee4b3e7	93	=head1 See Also
	94
	95	=over 4
	96
	97	=item L<IPC::Open2>
	98
	99	Like Open3 but without STDERR catpure.
	100
	101	=item L<IPC::Run>
	102
	103	This is a CPAN module that has better error handling and more facilities
	104	than Open3.
	105
	106	=back
	107
2675ae2b	108	=head1 WARNING
	109
	110	The order of arguments differs from that of open2().
	111
7e1af8bc	112	=cut
a0d0e21e	113
	114	# &open3: Marc Horowitz <marc@mit.edu>
	115	# derived mostly from &open2 by tom christiansen, <tchrist@convex.com>
4633a7c4	116	# fixed for 5.001 by Ulrich Kunitz <kunitz@mai-koeln.com>
f55ee38a	117	# ported to Win32 by Ron Schmidt, Merrill Lynch almost ended my career
2675ae2b	118	# fixed for autovivving FHs, tchrist again
6662521e	119	# allow fd numbers to be used, by Frank Tobin
a2a63531	120	# allow '-' as command (c.f. open "-\|"), by Adam Spiers <perl@adamspiers.org>
a0d0e21e	121	#
	122	# $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $
	123	#
	124	# usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...);
	125	#
	126	# spawn the given $cmd and connect rdr for
	127	# reading, wtr for writing, and err for errors.
	128	# if err is '', or the same as rdr, then stdout and
	129	# stderr of the child are on the same fh. returns pid
7e1af8bc	130	# of child (or dies on failure).
a0d0e21e	131
a0d0e21e	132
4633a7c4	133	# if wtr begins with '<&', then wtr will be closed in the parent, and
a0d0e21e	134	# the child will read from it directly. if rdr or err begins with
	135	# '>&', then the child will send output directly to that fd. In both
	136	# cases, there will be a dup() instead of a pipe() made.
	137
	138
	139	# WARNING: this is dangerous, as you may block forever
	140	# unless you are very careful.
	141	#
	142	# $wtr is left unbuffered.
	143	#
	144	# abort program if
	145	# rdr or wtr are null
7e1af8bc	146	# a system call fails
a0d0e21e	147
2675ae2b	148	our $Me = 'open3 (bug)'; # you should never see this, it's always localized
a0d0e21e	149
7e1af8bc	150	# Fatal.pm needs to be fixed WRT prototypes.
	151
	152	sub xfork {
	153	my $pid = fork;
	154	defined $pid or croak "$Me: fork failed: $!";
	155	return $pid;
	156	}
	157
	158	sub xpipe {
	159	pipe $_[0], $_[1] or croak "$Me: pipe($_[0], $_[1]) failed: $!";
	160	}
	161
	162	# I tried using a * prototype character for the filehandle but it still
	163	# disallows a bearword while compiling under strict subs.
a0d0e21e	164
7e1af8bc	165	sub xopen {
	166	open $_[0], $_[1] or croak "$Me: open($_[0], $_[1]) failed: $!";
	167	}
	168
	169	sub xclose {
	170	close $_[0] or croak "$Me: close($_[0]) failed: $!";
	171	}
	172
036b4402	173	sub fh_is_fd {
036b4402	174	return $_[0] =~ /\A=?(\d+)\z/;
6662521e	175	}
6662521e	176
036b4402	177	sub xfileno {
	178	return $1 if $_[0] =~ /\A=?(\d+)\z/; # deal with fh just being an fd
	179	return fileno $_[0];
6662521e	180	}
6662521e	181
f55ee38a	182	my $do_spawn = $^O eq 'os2' \|\| $^O eq 'MSWin32';
a24d8dfd	183
7e1af8bc	184	sub _open3 {
	185	local $Me = shift;
	186	my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
	187	my($dup_wtr, $dup_rdr, $dup_err, $kidpid);
	188
eee4b3e7	189	if (@cmd > 1 and $cmd[0] eq '-') {
	190	croak "Arguments don't make sense when the command is '-'"
	191	}
	192
2675ae2b	193	# simulate autovivification of filehandles because
	194	# it's too ugly to use @_ throughout to make perl do it for us
	195	# tchrist 5-Mar-00
	196
	197	unless (eval {
	198	$dad_wtr = $_[1] = gensym unless defined $dad_wtr && length $dad_wtr;
	199	$dad_rdr = $_[2] = gensym unless defined $dad_rdr && length $dad_rdr;
	200	1; })
	201	{
	202	# must strip crud for croak to add back, or looks ugly
	203	$@ =~ s/(?<=value attempted) at .*//s;
	204	croak "$Me: $@";
	205	}
	206
	207	$dad_err \|\|= $dad_rdr;
a0d0e21e	208
4633a7c4	209	$dup_wtr = ($dad_wtr =~ s/^[<>]&//);
	210	$dup_rdr = ($dad_rdr =~ s/^[<>]&//);
	211	$dup_err = ($dad_err =~ s/^[<>]&//);
a0d0e21e	212
2675ae2b	213	# force unqualified filehandles into caller's package
6662521e	214	$dad_wtr = qualify $dad_wtr, $package unless fh_is_fd($dad_wtr);
	215	$dad_rdr = qualify $dad_rdr, $package unless fh_is_fd($dad_rdr);
	216	$dad_err = qualify $dad_err, $package unless fh_is_fd($dad_err);
7e1af8bc	217
8b3e92c6	218	my $kid_rdr = gensym;
	219	my $kid_wtr = gensym;
	220	my $kid_err = gensym;
7e1af8bc	221
	222	xpipe $kid_rdr, $dad_wtr if !$dup_wtr;
	223	xpipe $dad_rdr, $kid_wtr if !$dup_rdr;
	224	xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr;
	225
a24d8dfd	226	$kidpid = $do_spawn ? -1 : xfork;
a24d8dfd	227	if ($kidpid == 0) { # Kid
c6770908	228	# A tie in the parent should not be allowed to cause problems.
	229	untie *STDIN;
	230	untie *STDOUT;
7e1af8bc	231	# If she wants to dup the kid's stderr onto her stdout I need to
	232	# save a copy of her stdout before I put something else there.
	233	if ($dad_rdr ne $dad_err && $dup_err
6662521e	234	&& xfileno($dad_err) == fileno(STDOUT)) {
8b3e92c6	235	my $tmp = gensym;
7e1af8bc	236	xopen($tmp, ">&$dad_err");
	237	$dad_err = $tmp;
	238	}
a0d0e21e	239
a0d0e21e	240	if ($dup_wtr) {
6662521e	241	xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != xfileno($dad_wtr);
a0d0e21e	242	} else {
8ebc5c01	243	xclose $dad_wtr;
8b3e92c6	244	xopen \*STDIN, "<&=" . fileno $kid_rdr;
a0d0e21e	245	}
a0d0e21e	246	if ($dup_rdr) {
6662521e	247	xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != xfileno($dad_rdr);
a0d0e21e	248	} else {
8ebc5c01	249	xclose $dad_rdr;
8b3e92c6	250	xopen \*STDOUT, ">&=" . fileno $kid_wtr;
a0d0e21e	251	}
	252	if ($dad_rdr ne $dad_err) {
	253	if ($dup_err) {
8b3e92c6	254	# I have to use a fileno here because in this one case
	255	# I'm doing a dup but the filehandle might be a reference
	256	# (from the special case above).
6662521e	257	xopen \*STDERR, ">&" . xfileno($dad_err)
6662521e	258	if fileno(STDERR) != xfileno($dad_err);
a0d0e21e	259	} else {
8ebc5c01	260	xclose $dad_err;
8b3e92c6	261	xopen \*STDERR, ">&=" . fileno $kid_err;
a0d0e21e	262	}
a0d0e21e	263	} else {
8ebc5c01	264	xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
a0d0e21e	265	}
eee4b3e7	266	return 0 if ($cmd[0] eq '-');
a0d0e21e	267	local($")=(" ");
64ab78e5	268	exec @cmd or do {
	269	carp "$Me: exec of @cmd failed";
	270	eval { require POSIX; POSIX::_exit(255); };
	271	exit 255;
	272	};
a24d8dfd	273	} elsif ($do_spawn) {
	274	# All the bookkeeping of coincidence between handles is
	275	# handled in spawn_with_handles.
	276
	277	my @close;
	278	if ($dup_wtr) {
8b3e92c6	279	$kid_rdr = \*{$dad_wtr};
8b3e92c6	280	push @close, $kid_rdr;
a24d8dfd	281	} else {
8b3e92c6	282	push @close, \*{$dad_wtr}, $kid_rdr;
a24d8dfd	283	}
a24d8dfd	284	if ($dup_rdr) {
8b3e92c6	285	$kid_wtr = \*{$dad_rdr};
8b3e92c6	286	push @close, $kid_wtr;
a24d8dfd	287	} else {
8b3e92c6	288	push @close, \*{$dad_rdr}, $kid_wtr;
a24d8dfd	289	}
	290	if ($dad_rdr ne $dad_err) {
	291	if ($dup_err) {
8b3e92c6	292	$kid_err = \*{$dad_err};
8b3e92c6	293	push @close, $kid_err;
a24d8dfd	294	} else {
8b3e92c6	295	push @close, \*{$dad_err}, $kid_err;
a24d8dfd	296	}
	297	} else {
	298	$kid_err = $kid_wtr;
	299	}
	300	require IO::Pipe;
	301	$kidpid = eval {
	302	spawn_with_handles( [ { mode => 'r',
8b3e92c6	303	open_as => $kid_rdr,
a24d8dfd	304	handle => \*STDIN },
a24d8dfd	305	{ mode => 'w',
8b3e92c6	306	open_as => $kid_wtr,
a24d8dfd	307	handle => \*STDOUT },
a24d8dfd	308	{ mode => 'w',
8b3e92c6	309	open_as => $kid_err,
a24d8dfd	310	handle => \*STDERR },
	311	], \@close, @cmd);
	312	};
ad973f30	313	die "$Me: $@" if $@;
a0d0e21e	314	}
a0d0e21e	315
7e1af8bc	316	xclose $kid_rdr if !$dup_wtr;
	317	xclose $kid_wtr if !$dup_rdr;
	318	xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err;
	319	# If the write handle is a dup give it away entirely, close my copy
	320	# of it.
	321	xclose $dad_wtr if $dup_wtr;
a0d0e21e	322
	323	select((select($dad_wtr), $\| = 1)[0]); # unbuffer pipe
	324	$kidpid;
	325	}
7e1af8bc	326
7e1af8bc	327	sub open3 {
a24d8dfd	328	if (@_ < 4) {
	329	local $" = ', ';
	330	croak "open3(@_): not enough arguments";
	331	}
7e1af8bc	332	return _open3 'open3', scalar caller, @_
7e1af8bc	333	}
a0d0e21e	334
a24d8dfd	335	sub spawn_with_handles {
	336	my $fds = shift; # Fields: handle, mode, open_as
	337	my $close_in_child = shift;
	338	my ($fd, $pid, @saved_fh, $saved, %saved, @errs);
	339	require Fcntl;
	340
	341	foreach $fd (@$fds) {
	342	$fd->{tmp_copy} = IO::Handle->new_from_fd($fd->{handle}, $fd->{mode});
	343	$saved{fileno $fd->{handle}} = $fd->{tmp_copy};
	344	}
	345	foreach $fd (@$fds) {
	346	bless $fd->{handle}, 'IO::Handle'
	347	unless eval { $fd->{handle}->isa('IO::Handle') } ;
	348	# If some of handles to redirect-to coincide with handles to
	349	# redirect, we need to use saved variants:
	350	$fd->{handle}->fdopen($saved{fileno $fd->{open_as}} \|\| $fd->{open_as},
	351	$fd->{mode});
	352	}
f55ee38a	353	unless ($^O eq 'MSWin32') {
	354	# Stderr may be redirected below, so we save the err text:
	355	foreach $fd (@$close_in_child) {
	356	fcntl($fd, Fcntl::F_SETFD(), 1) or push @errs, "fcntl $fd: $!"
	357	unless $saved{fileno $fd}; # Do not close what we redirect!
	358	}
a24d8dfd	359	}
	360
	361	unless (@errs) {
	362	$pid = eval { system 1, @_ }; # 1 == P_NOWAIT
	363	push @errs, "IO::Pipe: Can't spawn-NOWAIT: $!" if !$pid \|\| $pid < 0;
	364	}
	365
	366	foreach $fd (@$fds) {
	367	$fd->{handle}->fdopen($fd->{tmp_copy}, $fd->{mode});
	368	$fd->{tmp_copy}->close or croak "Can't close: $!";
	369	}
	370	croak join "\n", @errs if @errs;
	371	return $pid;
	372	}
	373
	374	1; # so require is happy