Merge ext/IPC-Open2 into ext/IPC-Open3.

IPC::Open2::open2() is implemented as a thin wrapper around
IPC::Open3::_open3(), and hence is very tightly coupled to it.

2 files changed, 181 insertions, 0 deletions

diff --git a/ext/IPC-Open3/lib/IPC/Open2.pm b/ext/IPC-Open3/lib/IPC/Open2.pm
new file mode 100644
index 0000000000..9e27144571
--- /dev/null
+++ b/ext/IPC-Open3/lib/IPC/Open2.pm
@@ -0,0 +1,120 @@
+package IPC::Open2;
+
+use strict;
+our ($VERSION, @ISA, @EXPORT);
+
+require 5.000;
+require Exporter;
+
+$VERSION	= 1.04;
+@ISA		= qw(Exporter);
+@EXPORT		= qw(open2);
+
+=head1 NAME
+
+IPC::Open2 - open a process for both reading and writing using open2()
+
+=head1 SYNOPSIS
+
+    use IPC::Open2;
+
+    $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'some cmd and args');
+      # or without using the shell
+    $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'some', 'cmd', 'and', 'args');
+
+    # or with handle autovivification
+    my($chld_out, $chld_in);
+    $pid = open2($chld_out, $chld_in, 'some cmd and args');
+      # or without using the shell
+    $pid = open2($chld_out, $chld_in, 'some', 'cmd', 'and', 'args');
+
+    waitpid( $pid, 0 );
+    my $child_exit_status = $? >> 8;
+
+=head1 DESCRIPTION
+
+The open2() function runs the given $cmd and connects $chld_out for
+reading and $chld_in for writing.  It's what you think should work 
+when you try
+
+    $pid = open(HANDLE, "|cmd args|");
+
+The write filehandle will have autoflush turned on.
+
+If $chld_out is a string (that is, a bareword filehandle rather than a glob
+or a reference) and it begins with C<< >& >>, then the child will send output
+directly to that file handle.  If $chld_in is a string that begins with
+C<< <& >>, then $chld_in will be closed in the parent, and the child will
+read from it directly.  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.
+
+open2() returns the process ID of the child process.  It doesn't return on
+failure: it just raises an exception matching C</^open2:/>.  However,
+C<exec> failures in the child are not detected.  You'll have to
+trap SIGPIPE yourself.
+
+open2() 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.
+
+This whole affair is quite 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.
+
+The IO::Pty and Expect modules from CPAN can help with this, as they
+provide a real tty (well, a pseudo-tty, actually), which gets you
+back to line buffering in the invoked command again.
+
+=head1 WARNING 
+
+The order of arguments differs from that of open3().
+
+=head1 SEE ALSO
+
+See L<IPC::Open3> for an alternative that handles STDERR as well.  This
+function is really just a wrapper around open3().
+
+=cut
+
+# &open2: tom christiansen, <tchrist@convex.com>
+#
+# usage: $pid = open2('rdr', 'wtr', 'some cmd and args');
+#    or  $pid = open2('rdr', 'wtr', 'some', 'cmd', 'and', 'args');
+#
+# spawn the given $cmd and connect $rdr for
+# reading and $wtr for writing.  return pid
+# of child, or 0 on failure.  
+# 
+# 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
+
+require IPC::Open3;
+
+sub open2 {
+    local $Carp::CarpLevel = $Carp::CarpLevel + 1;
+    return IPC::Open3::_open3('open2', $_[1], $_[0], '>&STDERR', @_[2 .. $#_]);
+}
+
+1
diff --git a/ext/IPC-Open3/t/IPC-Open2.t b/ext/IPC-Open3/t/IPC-Open2.t
new file mode 100644
index 0000000000..fecb209663
--- /dev/null
+++ b/ext/IPC-Open3/t/IPC-Open2.t
@@ -0,0 +1,61 @@
+#!./perl -w
+
+use Config;
+BEGIN {
+    require Test::More;
+    if (!$Config{'d_fork'}
+       # open2/3 supported on win32 (but not Borland due to CRT bugs)
+       && (($^O ne 'MSWin32' && $^O ne 'NetWare') || $Config{'cc'} =~ /^bcc/i))
+    {
+	Test::More->import(skip_all => 'open2/3 not available with MSWin32+Netware+cc=bcc');
+	exit 0;
+    }
+    # make warnings fatal
+    $SIG{__WARN__} = sub { die @_ };
+}
+
+use strict;
+use IPC::Open2;
+use Test::More tests => 15;
+
+my $perl = $^X;
+
+sub cmd_line {
+	if ($^O eq 'MSWin32' || $^O eq 'NetWare') {
+		return qq/"$_[0]"/;
+	}
+	else {
+		return $_[0];
+	}
+}
+
+STDOUT->autoflush;
+STDERR->autoflush;
+
+my $pid = open2('READ', 'WRITE', $perl, '-e', cmd_line('print scalar <STDIN>'));
+cmp_ok($pid, '>', 1, 'got a sane process ID');
+ok(print WRITE "hi kid\n");
+like(<READ>, qr/^hi kid\r?\n$/);
+ok(close(WRITE), "closing WRITE: $!");
+ok(close(READ), "closing READ: $!");
+my $reaped_pid = waitpid $pid, 0;
+is($reaped_pid, $pid, "Reaped PID matches");
+is($?, 0, '$? should be zero');
+
+{
+    package SKREEEK;
+    my $pid = IPC::Open2::open2('KAZOP', 'WRITE', $perl, '-e',
+				main::cmd_line('print scalar <STDIN>'));
+    main::cmp_ok($pid, '>', 1, 'got a sane process ID');
+    main::ok(print WRITE "hi kid\n");
+    main::like(<KAZOP>, qr/^hi kid\r?\n$/);
+    main::ok(close(WRITE), "closing WRITE: $!");
+    main::ok(close(KAZOP), "closing READ: $!");
+    my $reaped_pid = waitpid $pid, 0;
+    main::is($reaped_pid, $pid, "Reaped PID matches");
+    main::is($?, 0, '$? should be zero');
+}
+
+$pid = eval { open2('READ', '', $perl, '-e', cmd_line('print scalar <STDIN>')) };
+like($@, qr/^open2: Modification of a read-only value attempted at /,
+     'open2 faults read-only parameters correctly') or do {waitpid $pid, 0};