use strict;
no strict 'refs'; # because users pass me bareword filehandles
-use vars qw($VERSION @ISA @EXPORT $Fh $Me);
+our ($VERSION, @ISA, @EXPORT);
-require 5.001;
require Exporter;
use Carp;
-use Symbol 'qualify';
+use Symbol qw(gensym qualify);
-$VERSION = 1.01;
+$VERSION = 1.02;
@ISA = qw(Exporter);
@EXPORT = qw(open3);
=head1 SYNOPSIS
- $pid = open3(\*WTRFH, \*RDRFH, \*ERRFH
+ $pid = open3(\*CHLD_IN, \*CHLD_OUT, \*CHLD_ERR,
+ 'some cmd and args', 'optarg', ...);
+
+ my($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 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.
-
-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
-"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.
+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:/>.
-
-=head1 WARNING
+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.
-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,
+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 the child process, you can't 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 $
#
# rdr or wtr are null
# a system call fails
-$Fh = 'FHOPEN000'; # package static in case called more than once
-$Me = 'open3 (bug)'; # you should never see this, it's always localized
+our $Me = 'open3 (bug)'; # you should never see this, it's always localized
# Fatal.pm needs to be fixed WRT prototypes.
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);
- $dad_wtr or croak "$Me: wtr should not be null";
- $dad_rdr or croak "$Me: rdr should not be null";
- $dad_err = $dad_rdr if ($dad_err eq '');
+ 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 callers' package
- $dad_wtr = qualify $dad_wtr, $package;
- $dad_rdr = qualify $dad_rdr, $package;
- $dad_err = qualify $dad_err, $package;
+ # 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 $kid_rdr = ++$Fh;
- my $kid_wtr = ++$Fh;
- my $kid_err = ++$Fh;
+ 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;
- $kidpid = xfork;
- if ($kidpid == 0) {
+ $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 && $dup_err
- && fileno($dad_err) == fileno(STDOUT)) {
- my $tmp = ++$Fh;
+ && xfileno($dad_err) == fileno(STDOUT)) {
+ my $tmp = gensym;
xopen($tmp, ">&$dad_err");
$dad_err = $tmp;
}
if ($dup_wtr) {
- open(STDIN, "<&$dad_wtr") if (fileno(STDIN) != fileno($dad_wtr));
+ xopen \*STDIN, "<&$dad_wtr" if fileno(STDIN) != xfileno($dad_wtr);
} else {
- close($dad_wtr);
- open(STDIN, "<&$kid_rdr");
+ xclose $dad_wtr;
+ xopen \*STDIN, "<&=" . fileno $kid_rdr;
}
if ($dup_rdr) {
- open(STDOUT, ">&$dad_rdr") if (fileno(STDOUT) != fileno($dad_rdr));
+ xopen \*STDOUT, ">&$dad_rdr" if fileno(STDOUT) != xfileno($dad_rdr);
} else {
- close($dad_rdr);
- open(STDOUT, ">&$kid_wtr");
+ xclose $dad_rdr;
+ xopen \*STDOUT, ">&=" . fileno $kid_wtr;
}
if ($dad_rdr ne $dad_err) {
if ($dup_err) {
- open(STDERR, ">&$dad_err")
- if (fileno(STDERR) != fileno($dad_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 {
- close($dad_err);
- open(STDERR, ">&$kid_err");
+ xclose $dad_err;
+ xopen \*STDERR, ">&=" . fileno $kid_err;
}
} else {
- open(STDERR, ">&STDOUT") if (fileno(STDERR) != fileno(STDOUT));
+ xopen \*STDERR, ">&STDOUT" if fileno(STDERR) != fileno(STDOUT);
}
+ return 0 if ($cmd[0] eq '-');
local($")=(" ");
- exec @cmd
- or croak "open3: exec of @cmd failed";
+ exec @cmd or do {
+ carp "$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;
}
sub open3 {
+ if (@_ < 4) {
+ local $" = ', ';
+ croak "open3(@_): not enough arguments";
+ }
return _open3 'open3', scalar caller, @_
}
-1; # so require is happy
+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
projects / p5sagit/p5-mst-13.2.git / blobdiff