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