package IPC::Open3;
+
+use strict;
+no strict 'refs'; # because users pass me bareword filehandles
+use vars qw($VERSION @ISA @EXPORT $Fh $Me);
+
require 5.001;
require Exporter;
+
use Carp;
+use Symbol 'qualify';
+
+$VERSION = 1.0101;
+@ISA = qw(Exporter);
+@EXPORT = qw(open3);
=head1 NAME
=head1 SYNOPSIS
- $pid = open3(\*WTRFH, \*RDRFH, \*ERRFH
+ $pid = open3(\*WTRFH, \*RDRFH, \*ERRFH,
'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 '', or the same as RDRFH, then STDOUT and STDERR of the child are
-on the same file handle.
+on the same file handle. The WTRFH will have autoflush turned on.
-If WTRFH begins with "<&", then WTRFH will be closed in the parent, and
+If WTRFH begins with "E<lt>&", then WTRFH will be closed in the parent, and
the child will read from it directly. If RDRFH or ERRFH begins with
-">&", then the child will send output directly to that file handle. In both
-cases, there will be a dup(2) instead of a pipe(2) made.
+"E<gt>&", then the child will send output directly to that file handle.
+In both cases, there will be a dup(2) instead of a pipe(2) made.
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(), which means you'll have to use sysread() instead
of normal stuff.
-All caveats from open2() continue to apply. See L<open2> for details.
+open3() returns the process ID of the child process. It doesn't return on
+failure: it just raises an exception matching C</^open3:/>.
-=cut
+=head1 WARNING
+
+It will not create these file handles for you. You have to do this
+yourself. So don't pass it empty variables expecting them to get filled
+in for you.
+
+Additionally, 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.
-@ISA = qw(Exporter);
-@EXPORT = qw(open3);
+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.
+
+=cut
# &open3: Marc Horowitz <marc@mit.edu>
# derived mostly from &open2 by tom christiansen, <tchrist@convex.com>
# 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 0 on failure.
+# of child (or dies on failure).
# if wtr begins with '<&', then wtr will be closed in the parent, and
#
# abort program if
# rdr or wtr are null
-# pipe or fork or exec fails
+# a system call fails
-$fh = 'FHOPEN000'; # package static in case called more than once
+$Fh = 'FHOPEN000'; # package static in case called more than once
+$Me = 'open3 (bug)'; # you should never see this, it's always localized
-sub open3 {
- my($kidpid);
- my($dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
- my($dup_wtr, $dup_rdr, $dup_err);
+# 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: $!";
+}
- $dad_wtr || croak "open3: wtr should not be null";
- $dad_rdr || croak "open3: rdr should not be null";
+# 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';
+
+sub _open3 {
+ local $Me = shift;
+ my($package, $dad_wtr, $dad_rdr, $dad_err, @cmd) = @_;
+ my($dup_wtr, $dup_rdr, $dup_err, $kidpid);
+
+ $dad_wtr or croak "$Me: wtr should not be null";
+ $dad_rdr or croak "$Me: rdr should not be null";
$dad_err = $dad_rdr if ($dad_err eq '');
$dup_wtr = ($dad_wtr =~ s/^[<>]&//);
$dup_err = ($dad_err =~ s/^[<>]&//);
# force unqualified filehandles into callers' package
- my($package) = caller;
- $dad_wtr =~ s/^[^:]+$/$package\:\:$&/ unless ref $dad_wtr;
- $dad_rdr =~ s/^[^:]+$/$package\:\:$&/ unless ref $dad_rdr;
- $dad_err =~ s/^[^:]+$/$package\:\:$&/ unless ref $dad_err;
+ $dad_wtr = qualify $dad_wtr, $package;
+ $dad_rdr = qualify $dad_rdr, $package;
+ $dad_err = qualify $dad_err, $package;
- my($kid_rdr) = ++$fh;
- my($kid_wtr) = ++$fh;
- my($kid_err) = ++$fh;
+ my $kid_rdr = ++$Fh;
+ my $kid_wtr = ++$Fh;
+ my $kid_err = ++$Fh;
- if (!$dup_wtr) {
- pipe($kid_rdr, $dad_wtr) || croak "open3: pipe 1 (stdin) failed: $!";
- }
- if (!$dup_rdr) {
- pipe($dad_rdr, $kid_wtr) || croak "open3: pipe 2 (stdout) failed: $!";
- }
- if ($dad_err ne $dad_rdr && !$dup_err) {
- pipe($dad_err, $kid_err) || croak "open3: pipe 3 (stderr) failed: $!";
- }
+ 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 $tmp = ++$Fh;
+ xopen($tmp, ">&$dad_err");
+ $dad_err = $tmp;
+ }
- if (($kidpid = fork) < 0) {
- croak "open3: fork failed: $!";
- } elsif ($kidpid == 0) {
if ($dup_wtr) {
- open(STDIN, "<&$dad_wtr") if (fileno(STDIN) != fileno($dad_wtr));
+ xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != fileno($dad_wtr);
} else {
- close($dad_wtr);
- open(STDIN, "<&$kid_rdr");
+ xclose $dad_wtr;
+ xopen \*STDIN, "<&$kid_rdr";
+ xclose $kid_rdr;
}
if ($dup_rdr) {
- open(STDOUT, ">&$dad_rdr") if (fileno(STDOUT) != fileno($dad_rdr));
+ xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != fileno($dad_rdr);
} else {
- close($dad_rdr);
- open(STDOUT, ">&$kid_wtr");
+ xclose $dad_rdr;
+ xopen \*STDOUT, ">&$kid_wtr";
+ xclose $kid_wtr;
}
if ($dad_rdr ne $dad_err) {
if ($dup_err) {
- open(STDERR, ">&$dad_err")
- if (fileno(STDERR) != fileno($dad_err));
+ xopen \*STDERR, ">&$dad_err"
+ if fileno(STDERR) != fileno($dad_err);
} else {
- close($dad_err);
- open(STDERR, ">&$kid_err");
+ xclose $dad_err;
+ xopen \*STDERR, ">&$kid_err";
+ xclose $kid_err;
}
} else {
- open(STDERR, ">&STDOUT") if (fileno(STDERR) != fileno(STDOUT));
+ xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
}
local($")=(" ");
exec @cmd
- or croak "open3: exec of @cmd failed";
- }
+ or croak "$Me: exec of @cmd failed";
+ } elsif ($do_spawn) {
+ # All the bookkeeping of coincidence between handles is
+ # handled in spawn_with_handles.
- close $kid_rdr; close $kid_wtr; close $kid_err;
- if ($dup_wtr) {
- close($dad_wtr);
+ my @close;
+ if ($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;
}
-1; # so require is happy
+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});
+ }
+ # 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
projects / p5sagit/p5-mst-13.2.git / blobdiff