[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	= 1.02;
@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', ...);

=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
3ce239a0	12	$VERSION = 1.02;
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
f06db76b	29	=head1 DESCRIPTION
	30
	31	Extremely similar to open2(), open3() spawns the given $cmd and
3ce239a0	32	connects CHLD_OUT for reading from the child, CHLD_IN for writing to
	33	the child, and CHLD_ERR for errors. If CHLD_ERR is false, or the
	34	same file descriptor as CHLD_OUT, then STDOUT and STDERR of the child
	35	are on the same filehandle. The CHLD_IN will have autoflush turned
	36	on.
	37
	38	If CHLD_IN begins with C<< <& >>, then CHLD_IN will be closed in the
	39	parent, and the child will read from it directly. If CHLD_OUT or
	40	CHLD_ERR begins with C<< >& >>, then the child will send output
	41	directly to that filehandle. In both cases, there will be a dup(2)
	42	instead of a pipe(2) made.
f06db76b	43
2675ae2b	44	If either reader or writer is the null string, this will be replaced
	45	by an autogenerated filehandle. If so, you must pass a valid lvalue
	46	in the parameter slot so it can be overwritten in the caller, or
	47	an exception will be raised.
cb1a09d0	48
036b4402	49	The filehandles may also be integers, in which case they are understood
	50	as file descriptors.
	51
7e1af8bc	52	open3() returns the process ID of the child process. It doesn't return on
2675ae2b	53	failure: it just raises an exception matching C</^open3:/>. However,
eee4b3e7	54	C<exec> failures in the child (such as no such file or permission denied),
	55	are just reported to CHLD_ERR, as it is not possible to trap them.
	56
	57	If the child process dies for any reason, the next write to CHLD_IN is
	58	likely to generate a SIGPIPE in the parent, which is fatal by default.
	59	So you may wish to handle this signal.
f06db76b	60
a2a63531	61	Note if you specify C<-> as the command, in an analogous fashion to
	62	C<open(FOO, "-\|")> the child process will just be the forked Perl
	63	process rather than an external command. This feature isn't yet
	64	supported on Win32 platforms.
	65
4375e838	66	open3() does not wait for and reap the child process after it exits.
227e8dd4	67	Except for short programs where it's acceptable to let the operating system
	68	take care of this, you need to do this yourself. This is normally as
	69	simple as calling C<waitpid $pid, 0> when you're done with the process.
	70	Failing to do this can result in an accumulation of defunct or "zombie"
	71	processes. See L<perlfunc/waitpid> for more information.
	72
2675ae2b	73	If you try to read from the child's stdout writer and their stderr
	74	writer, you'll have problems with blocking, which means you'll want
	75	to use select() or the IO::Select, which means you'd best use
	76	sysread() instead of readline() for normal stuff.
	77
	78	This is very dangerous, as you may block forever. It assumes it's
	79	going to talk to something like B<bc>, both writing to it and reading
	80	from it. This is presumably safe because you "know" that commands
	81	like B<bc> will read a line at a time and output a line at a time.
	82	Programs like B<sort> that read their entire input stream first,
7e1af8bc	83	however, are quite apt to cause deadlock.
	84
	85	The big problem with this approach is that if you don't have control
7a2e2cd6	86	over source code being run in the child process, you can't control
7e1af8bc	87	what it does with pipe buffering. Thus you can't just open a pipe to
	88	C<cat -v> and continually read and write a line from it.
	89
eee4b3e7	90	=head1 See Also
	91
	92	=over 4
	93
	94	=item L<IPC::Open2>
	95
	96	Like Open3 but without STDERR catpure.
	97
	98	=item L<IPC::Run>
	99
	100	This is a CPAN module that has better error handling and more facilities
	101	than Open3.
	102
	103	=back
	104
2675ae2b	105	=head1 WARNING
	106
	107	The order of arguments differs from that of open2().
	108
7e1af8bc	109	=cut
a0d0e21e	110
	111	# &open3: Marc Horowitz <marc@mit.edu>
	112	# derived mostly from &open2 by tom christiansen, <tchrist@convex.com>
4633a7c4	113	# fixed for 5.001 by Ulrich Kunitz <kunitz@mai-koeln.com>
f55ee38a	114	# ported to Win32 by Ron Schmidt, Merrill Lynch almost ended my career
2675ae2b	115	# fixed for autovivving FHs, tchrist again
6662521e	116	# allow fd numbers to be used, by Frank Tobin
a2a63531	117	# allow '-' as command (c.f. open "-\|"), by Adam Spiers <perl@adamspiers.org>
a0d0e21e	118	#
	119	# $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $
	120	#
	121	# usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...);
	122	#
	123	# spawn the given $cmd and connect rdr for
	124	# reading, wtr for writing, and err for errors.
	125	# if err is '', or the same as rdr, then stdout and
	126	# stderr of the child are on the same fh. returns pid
7e1af8bc	127	# of child (or dies on failure).
a0d0e21e	128
a0d0e21e	129
4633a7c4	130	# if wtr begins with '<&', then wtr will be closed in the parent, and
a0d0e21e	131	# the child will read from it directly. if rdr or err begins with
	132	# '>&', then the child will send output directly to that fd. In both
	133	# cases, there will be a dup() instead of a pipe() made.
	134
	135
	136	# WARNING: this is dangerous, as you may block forever
	137	# unless you are very careful.
	138	#
	139	# $wtr is left unbuffered.
	140	#
	141	# abort program if
	142	# rdr or wtr are null
7e1af8bc	143	# a system call fails
a0d0e21e	144
2675ae2b	145	our $Me = 'open3 (bug)'; # you should never see this, it's always localized
a0d0e21e	146
7e1af8bc	147	# Fatal.pm needs to be fixed WRT prototypes.
	148
	149	sub xfork {
	150	my $pid = fork;
	151	defined $pid or croak "$Me: fork failed: $!";
	152	return $pid;
	153	}
	154
	155	sub xpipe {
	156	pipe $_[0], $_[1] or croak "$Me: pipe($_[0], $_[1]) failed: $!";
	157	}
	158
	159	# I tried using a * prototype character for the filehandle but it still
	160	# disallows a bearword while compiling under strict subs.
a0d0e21e	161
7e1af8bc	162	sub xopen {
	163	open $_[0], $_[1] or croak "$Me: open($_[0], $_[1]) failed: $!";
	164	}
	165
	166	sub xclose {
	167	close $_[0] or croak "$Me: close($_[0]) failed: $!";
	168	}
	169
036b4402	170	sub fh_is_fd {
036b4402	171	return $_[0] =~ /\A=?(\d+)\z/;
6662521e	172	}
6662521e	173
036b4402	174	sub xfileno {
	175	return $1 if $_[0] =~ /\A=?(\d+)\z/; # deal with fh just being an fd
	176	return fileno $_[0];
6662521e	177	}
6662521e	178
f55ee38a	179	my $do_spawn = $^O eq 'os2' \|\| $^O eq 'MSWin32';
a24d8dfd	180
7e1af8bc	181	sub _open3 {
	182	local $Me = shift;
	183	my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
	184	my($dup_wtr, $dup_rdr, $dup_err, $kidpid);
	185
eee4b3e7	186	if (@cmd > 1 and $cmd[0] eq '-') {
	187	croak "Arguments don't make sense when the command is '-'"
	188	}
	189
2675ae2b	190	# simulate autovivification of filehandles because
	191	# it's too ugly to use @_ throughout to make perl do it for us
	192	# tchrist 5-Mar-00
	193
	194	unless (eval {
	195	$dad_wtr = $_[1] = gensym unless defined $dad_wtr && length $dad_wtr;
	196	$dad_rdr = $_[2] = gensym unless defined $dad_rdr && length $dad_rdr;
	197	1; })
	198	{
	199	# must strip crud for croak to add back, or looks ugly
	200	$@ =~ s/(?<=value attempted) at .*//s;
	201	croak "$Me: $@";
	202	}
	203
	204	$dad_err \|\|= $dad_rdr;
a0d0e21e	205
4633a7c4	206	$dup_wtr = ($dad_wtr =~ s/^[<>]&//);
	207	$dup_rdr = ($dad_rdr =~ s/^[<>]&//);
	208	$dup_err = ($dad_err =~ s/^[<>]&//);
a0d0e21e	209
2675ae2b	210	# force unqualified filehandles into caller's package
6662521e	211	$dad_wtr = qualify $dad_wtr, $package unless fh_is_fd($dad_wtr);
	212	$dad_rdr = qualify $dad_rdr, $package unless fh_is_fd($dad_rdr);
	213	$dad_err = qualify $dad_err, $package unless fh_is_fd($dad_err);
7e1af8bc	214
8b3e92c6	215	my $kid_rdr = gensym;
	216	my $kid_wtr = gensym;
	217	my $kid_err = gensym;
7e1af8bc	218
	219	xpipe $kid_rdr, $dad_wtr if !$dup_wtr;
	220	xpipe $dad_rdr, $kid_wtr if !$dup_rdr;
	221	xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr;
	222
a24d8dfd	223	$kidpid = $do_spawn ? -1 : xfork;
a24d8dfd	224	if ($kidpid == 0) { # Kid
c6770908	225	# A tie in the parent should not be allowed to cause problems.
	226	untie *STDIN;
	227	untie *STDOUT;
7e1af8bc	228	# If she wants to dup the kid's stderr onto her stdout I need to
	229	# save a copy of her stdout before I put something else there.
	230	if ($dad_rdr ne $dad_err && $dup_err
6662521e	231	&& xfileno($dad_err) == fileno(STDOUT)) {
8b3e92c6	232	my $tmp = gensym;
7e1af8bc	233	xopen($tmp, ">&$dad_err");
	234	$dad_err = $tmp;
	235	}
a0d0e21e	236
a0d0e21e	237	if ($dup_wtr) {
6662521e	238	xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != xfileno($dad_wtr);
a0d0e21e	239	} else {
8ebc5c01	240	xclose $dad_wtr;
8b3e92c6	241	xopen \*STDIN, "<&=" . fileno $kid_rdr;
a0d0e21e	242	}
a0d0e21e	243	if ($dup_rdr) {
6662521e	244	xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != xfileno($dad_rdr);
a0d0e21e	245	} else {
8ebc5c01	246	xclose $dad_rdr;
8b3e92c6	247	xopen \*STDOUT, ">&=" . fileno $kid_wtr;
a0d0e21e	248	}
	249	if ($dad_rdr ne $dad_err) {
	250	if ($dup_err) {
8b3e92c6	251	# I have to use a fileno here because in this one case
	252	# I'm doing a dup but the filehandle might be a reference
	253	# (from the special case above).
6662521e	254	xopen \*STDERR, ">&" . xfileno($dad_err)
6662521e	255	if fileno(STDERR) != xfileno($dad_err);
a0d0e21e	256	} else {
8ebc5c01	257	xclose $dad_err;
8b3e92c6	258	xopen \*STDERR, ">&=" . fileno $kid_err;
a0d0e21e	259	}
a0d0e21e	260	} else {
8ebc5c01	261	xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
a0d0e21e	262	}
eee4b3e7	263	return 0 if ($cmd[0] eq '-');
a0d0e21e	264	local($")=(" ");
64ab78e5	265	exec @cmd or do {
	266	carp "$Me: exec of @cmd failed";
	267	eval { require POSIX; POSIX::_exit(255); };
	268	exit 255;
	269	};
a24d8dfd	270	} elsif ($do_spawn) {
	271	# All the bookkeeping of coincidence between handles is
	272	# handled in spawn_with_handles.
	273
	274	my @close;
	275	if ($dup_wtr) {
8b3e92c6	276	$kid_rdr = \*{$dad_wtr};
8b3e92c6	277	push @close, $kid_rdr;
a24d8dfd	278	} else {
8b3e92c6	279	push @close, \*{$dad_wtr}, $kid_rdr;
a24d8dfd	280	}
a24d8dfd	281	if ($dup_rdr) {
8b3e92c6	282	$kid_wtr = \*{$dad_rdr};
8b3e92c6	283	push @close, $kid_wtr;
a24d8dfd	284	} else {
8b3e92c6	285	push @close, \*{$dad_rdr}, $kid_wtr;
a24d8dfd	286	}
	287	if ($dad_rdr ne $dad_err) {
	288	if ($dup_err) {
8b3e92c6	289	$kid_err = \*{$dad_err};
8b3e92c6	290	push @close, $kid_err;
a24d8dfd	291	} else {
8b3e92c6	292	push @close, \*{$dad_err}, $kid_err;
a24d8dfd	293	}
	294	} else {
	295	$kid_err = $kid_wtr;
	296	}
	297	require IO::Pipe;
	298	$kidpid = eval {
	299	spawn_with_handles( [ { mode => 'r',
8b3e92c6	300	open_as => $kid_rdr,
a24d8dfd	301	handle => \*STDIN },
a24d8dfd	302	{ mode => 'w',
8b3e92c6	303	open_as => $kid_wtr,
a24d8dfd	304	handle => \*STDOUT },
a24d8dfd	305	{ mode => 'w',
8b3e92c6	306	open_as => $kid_err,
a24d8dfd	307	handle => \*STDERR },
	308	], \@close, @cmd);
	309	};
ad973f30	310	die "$Me: $@" if $@;
a0d0e21e	311	}
a0d0e21e	312
7e1af8bc	313	xclose $kid_rdr if !$dup_wtr;
	314	xclose $kid_wtr if !$dup_rdr;
	315	xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err;
	316	# If the write handle is a dup give it away entirely, close my copy
	317	# of it.
	318	xclose $dad_wtr if $dup_wtr;
a0d0e21e	319
	320	select((select($dad_wtr), $\| = 1)[0]); # unbuffer pipe
	321	$kidpid;
	322	}
7e1af8bc	323
7e1af8bc	324	sub open3 {
a24d8dfd	325	if (@_ < 4) {
	326	local $" = ', ';
	327	croak "open3(@_): not enough arguments";
	328	}
7e1af8bc	329	return _open3 'open3', scalar caller, @_
7e1af8bc	330	}
a0d0e21e	331
a24d8dfd	332	sub spawn_with_handles {
	333	my $fds = shift; # Fields: handle, mode, open_as
	334	my $close_in_child = shift;
	335	my ($fd, $pid, @saved_fh, $saved, %saved, @errs);
	336	require Fcntl;
	337
	338	foreach $fd (@$fds) {
	339	$fd->{tmp_copy} = IO::Handle->new_from_fd($fd->{handle}, $fd->{mode});
	340	$saved{fileno $fd->{handle}} = $fd->{tmp_copy};
	341	}
	342	foreach $fd (@$fds) {
	343	bless $fd->{handle}, 'IO::Handle'
	344	unless eval { $fd->{handle}->isa('IO::Handle') } ;
	345	# If some of handles to redirect-to coincide with handles to
	346	# redirect, we need to use saved variants:
	347	$fd->{handle}->fdopen($saved{fileno $fd->{open_as}} \|\| $fd->{open_as},
	348	$fd->{mode});
	349	}
f55ee38a	350	unless ($^O eq 'MSWin32') {
	351	# Stderr may be redirected below, so we save the err text:
	352	foreach $fd (@$close_in_child) {
	353	fcntl($fd, Fcntl::F_SETFD(), 1) or push @errs, "fcntl $fd: $!"
	354	unless $saved{fileno $fd}; # Do not close what we redirect!
	355	}
a24d8dfd	356	}
	357
	358	unless (@errs) {
	359	$pid = eval { system 1, @_ }; # 1 == P_NOWAIT
	360	push @errs, "IO::Pipe: Can't spawn-NOWAIT: $!" if !$pid \|\| $pid < 0;
	361	}
	362
	363	foreach $fd (@$fds) {
	364	$fd->{handle}->fdopen($fd->{tmp_copy}, $fd->{mode});
	365	$fd->{tmp_copy}->close or croak "Can't close: $!";
	366	}
	367	croak join "\n", @errs if @errs;
	368	return $pid;
	369	}
	370
	371	1; # so require is happy