[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
#
# $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: $!";
}

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;
    $dad_rdr = qualify $dad_rdr, $package;
    $dad_err = qualify $dad_err, $package;

    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 && $dup_err
		&& fileno($dad_err) == fileno(STDOUT)) {
	    my $tmp = gensym;
	    xopen($tmp, ">&$dad_err");
	    $dad_err = $tmp;
	}

	if ($dup_wtr) {
	    xopen \*STDIN,  "<&$dad_wtr" if fileno(STDIN) != fileno($dad_wtr);
	} else {
	    xclose $dad_wtr;
	    xopen \*STDIN,  "<&=" . fileno $kid_rdr;
	}
	if ($dup_rdr) {
	    xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != fileno($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, ">&" . fileno $dad_err
		    if fileno(STDERR) != fileno($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
4375e838	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
a0d0e21e	87	#
	88	# $Id: open3.pl,v 1.1 1993/11/23 06:26:15 marc Exp $
	89	#
	90	# usage: $pid = open3('wtr', 'rdr', 'err' 'some cmd and args', 'optarg', ...);
	91	#
	92	# spawn the given $cmd and connect rdr for
	93	# reading, wtr for writing, and err for errors.
	94	# if err is '', or the same as rdr, then stdout and
	95	# stderr of the child are on the same fh. returns pid
7e1af8bc	96	# of child (or dies on failure).
a0d0e21e	97
a0d0e21e	98
4633a7c4	99	# if wtr begins with '<&', then wtr will be closed in the parent, and
a0d0e21e	100	# the child will read from it directly. if rdr or err begins with
	101	# '>&', then the child will send output directly to that fd. In both
	102	# cases, there will be a dup() instead of a pipe() made.
	103
	104
	105	# WARNING: this is dangerous, as you may block forever
	106	# unless you are very careful.
	107	#
	108	# $wtr is left unbuffered.
	109	#
	110	# abort program if
	111	# rdr or wtr are null
7e1af8bc	112	# a system call fails
a0d0e21e	113
2675ae2b	114	our $Me = 'open3 (bug)'; # you should never see this, it's always localized
a0d0e21e	115
7e1af8bc	116	# Fatal.pm needs to be fixed WRT prototypes.
	117
	118	sub xfork {
	119	my $pid = fork;
	120	defined $pid or croak "$Me: fork failed: $!";
	121	return $pid;
	122	}
	123
	124	sub xpipe {
	125	pipe $_[0], $_[1] or croak "$Me: pipe($_[0], $_[1]) failed: $!";
	126	}
	127
	128	# I tried using a * prototype character for the filehandle but it still
	129	# disallows a bearword while compiling under strict subs.
a0d0e21e	130
7e1af8bc	131	sub xopen {
	132	open $_[0], $_[1] or croak "$Me: open($_[0], $_[1]) failed: $!";
	133	}
	134
	135	sub xclose {
	136	close $_[0] or croak "$Me: close($_[0]) failed: $!";
	137	}
	138
f55ee38a	139	my $do_spawn = $^O eq 'os2' \|\| $^O eq 'MSWin32';
a24d8dfd	140
7e1af8bc	141	sub _open3 {
	142	local $Me = shift;
	143	my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
	144	my($dup_wtr, $dup_rdr, $dup_err, $kidpid);
	145
2675ae2b	146	# simulate autovivification of filehandles because
	147	# it's too ugly to use @_ throughout to make perl do it for us
	148	# tchrist 5-Mar-00
	149
	150	unless (eval {
	151	$dad_wtr = $_[1] = gensym unless defined $dad_wtr && length $dad_wtr;
	152	$dad_rdr = $_[2] = gensym unless defined $dad_rdr && length $dad_rdr;
	153	1; })
	154	{
	155	# must strip crud for croak to add back, or looks ugly
	156	$@ =~ s/(?<=value attempted) at .*//s;
	157	croak "$Me: $@";
	158	}
	159
	160	$dad_err \|\|= $dad_rdr;
a0d0e21e	161
4633a7c4	162	$dup_wtr = ($dad_wtr =~ s/^[<>]&//);
	163	$dup_rdr = ($dad_rdr =~ s/^[<>]&//);
	164	$dup_err = ($dad_err =~ s/^[<>]&//);
a0d0e21e	165
2675ae2b	166	# force unqualified filehandles into caller's package
7e1af8bc	167	$dad_wtr = qualify $dad_wtr, $package;
	168	$dad_rdr = qualify $dad_rdr, $package;
	169	$dad_err = qualify $dad_err, $package;
	170
8b3e92c6	171	my $kid_rdr = gensym;
	172	my $kid_wtr = gensym;
	173	my $kid_err = gensym;
7e1af8bc	174
	175	xpipe $kid_rdr, $dad_wtr if !$dup_wtr;
	176	xpipe $dad_rdr, $kid_wtr if !$dup_rdr;
	177	xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr;
	178
a24d8dfd	179	$kidpid = $do_spawn ? -1 : xfork;
a24d8dfd	180	if ($kidpid == 0) { # Kid
7e1af8bc	181	# If she wants to dup the kid's stderr onto her stdout I need to
	182	# save a copy of her stdout before I put something else there.
	183	if ($dad_rdr ne $dad_err && $dup_err
	184	&& fileno($dad_err) == fileno(STDOUT)) {
8b3e92c6	185	my $tmp = gensym;
7e1af8bc	186	xopen($tmp, ">&$dad_err");
	187	$dad_err = $tmp;
	188	}
a0d0e21e	189
a0d0e21e	190	if ($dup_wtr) {
8ebc5c01	191	xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != fileno($dad_wtr);
a0d0e21e	192	} else {
8ebc5c01	193	xclose $dad_wtr;
8b3e92c6	194	xopen \*STDIN, "<&=" . fileno $kid_rdr;
a0d0e21e	195	}
a0d0e21e	196	if ($dup_rdr) {
8ebc5c01	197	xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != fileno($dad_rdr);
a0d0e21e	198	} else {
8ebc5c01	199	xclose $dad_rdr;
8b3e92c6	200	xopen \*STDOUT, ">&=" . fileno $kid_wtr;
a0d0e21e	201	}
	202	if ($dad_rdr ne $dad_err) {
	203	if ($dup_err) {
8b3e92c6	204	# I have to use a fileno here because in this one case
	205	# I'm doing a dup but the filehandle might be a reference
	206	# (from the special case above).
	207	xopen \*STDERR, ">&" . fileno $dad_err
8ebc5c01	208	if fileno(STDERR) != fileno($dad_err);
a0d0e21e	209	} else {
8ebc5c01	210	xclose $dad_err;
8b3e92c6	211	xopen \*STDERR, ">&=" . fileno $kid_err;
a0d0e21e	212	}
a0d0e21e	213	} else {
8ebc5c01	214	xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
a0d0e21e	215	}
a0d0e21e	216	local($")=(" ");
2675ae2b	217	exec @cmd # XXX: wrong process to croak from
ad973f30	218	or croak "$Me: exec of @cmd failed";
a24d8dfd	219	} elsif ($do_spawn) {
	220	# All the bookkeeping of coincidence between handles is
	221	# handled in spawn_with_handles.
	222
	223	my @close;
	224	if ($dup_wtr) {
8b3e92c6	225	$kid_rdr = \*{$dad_wtr};
8b3e92c6	226	push @close, $kid_rdr;
a24d8dfd	227	} else {
8b3e92c6	228	push @close, \*{$dad_wtr}, $kid_rdr;
a24d8dfd	229	}
a24d8dfd	230	if ($dup_rdr) {
8b3e92c6	231	$kid_wtr = \*{$dad_rdr};
8b3e92c6	232	push @close, $kid_wtr;
a24d8dfd	233	} else {
8b3e92c6	234	push @close, \*{$dad_rdr}, $kid_wtr;
a24d8dfd	235	}
	236	if ($dad_rdr ne $dad_err) {
	237	if ($dup_err) {
8b3e92c6	238	$kid_err = \*{$dad_err};
8b3e92c6	239	push @close, $kid_err;
a24d8dfd	240	} else {
8b3e92c6	241	push @close, \*{$dad_err}, $kid_err;
a24d8dfd	242	}
	243	} else {
	244	$kid_err = $kid_wtr;
	245	}
	246	require IO::Pipe;
	247	$kidpid = eval {
	248	spawn_with_handles( [ { mode => 'r',
8b3e92c6	249	open_as => $kid_rdr,
a24d8dfd	250	handle => \*STDIN },
a24d8dfd	251	{ mode => 'w',
8b3e92c6	252	open_as => $kid_wtr,
a24d8dfd	253	handle => \*STDOUT },
a24d8dfd	254	{ mode => 'w',
8b3e92c6	255	open_as => $kid_err,
a24d8dfd	256	handle => \*STDERR },
	257	], \@close, @cmd);
	258	};
ad973f30	259	die "$Me: $@" if $@;
a0d0e21e	260	}
a0d0e21e	261
7e1af8bc	262	xclose $kid_rdr if !$dup_wtr;
	263	xclose $kid_wtr if !$dup_rdr;
	264	xclose $kid_err if !$dup_err && $dad_rdr ne $dad_err;
	265	# If the write handle is a dup give it away entirely, close my copy
	266	# of it.
	267	xclose $dad_wtr if $dup_wtr;
a0d0e21e	268
	269	select((select($dad_wtr), $\| = 1)[0]); # unbuffer pipe
	270	$kidpid;
	271	}
7e1af8bc	272
7e1af8bc	273	sub open3 {
a24d8dfd	274	if (@_ < 4) {
	275	local $" = ', ';
	276	croak "open3(@_): not enough arguments";
	277	}
7e1af8bc	278	return _open3 'open3', scalar caller, @_
7e1af8bc	279	}
a0d0e21e	280
a24d8dfd	281	sub spawn_with_handles {
	282	my $fds = shift; # Fields: handle, mode, open_as
	283	my $close_in_child = shift;
	284	my ($fd, $pid, @saved_fh, $saved, %saved, @errs);
	285	require Fcntl;
	286
	287	foreach $fd (@$fds) {
	288	$fd->{tmp_copy} = IO::Handle->new_from_fd($fd->{handle}, $fd->{mode});
	289	$saved{fileno $fd->{handle}} = $fd->{tmp_copy};
	290	}
	291	foreach $fd (@$fds) {
	292	bless $fd->{handle}, 'IO::Handle'
	293	unless eval { $fd->{handle}->isa('IO::Handle') } ;
	294	# If some of handles to redirect-to coincide with handles to
	295	# redirect, we need to use saved variants:
	296	$fd->{handle}->fdopen($saved{fileno $fd->{open_as}} \|\| $fd->{open_as},
	297	$fd->{mode});
	298	}
f55ee38a	299	unless ($^O eq 'MSWin32') {
	300	# Stderr may be redirected below, so we save the err text:
	301	foreach $fd (@$close_in_child) {
	302	fcntl($fd, Fcntl::F_SETFD(), 1) or push @errs, "fcntl $fd: $!"
	303	unless $saved{fileno $fd}; # Do not close what we redirect!
	304	}
a24d8dfd	305	}
	306
	307	unless (@errs) {
	308	$pid = eval { system 1, @_ }; # 1 == P_NOWAIT
	309	push @errs, "IO::Pipe: Can't spawn-NOWAIT: $!" if !$pid \|\| $pid < 0;
	310	}
	311
	312	foreach $fd (@$fds) {
	313	$fd->{handle}->fdopen($fd->{tmp_copy}, $fd->{mode});
	314	$fd->{tmp_copy}->close or croak "Can't close: $!";
	315	}
	316	croak join "\n", @errs if @errs;
	317	return $pid;
	318	}
	319
	320	1; # so require is happy