-# 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.
-#
-# $wtr is left unbuffered.
-#
-# abort program if
-# rdr or wtr are null
-# pipe or fork or exec fails
-
-package open2;
-$fh = 'FHOPEN000'; # package static in case called more than once
-
-sub main'open2 {
- local($kidpid);
- local($dad_rdr, $dad_wtr, @cmd) = @_;
-
- $dad_rdr ne '' || die "open2: rdr should not be null";
- $dad_wtr ne '' || die "open2: wtr should not be null";
-
- # force unqualified filehandles into callers' package
- local($package) = caller;
- $dad_rdr =~ s/^[^']+$/$package'$&/;
- $dad_wtr =~ s/^[^']+$/$package'$&/;
-
- local($kid_rdr) = ++$fh;
- local($kid_wtr) = ++$fh;
-
- pipe($dad_rdr, $kid_wtr) || die "open2: pipe 1 failed: $!";
- pipe($kid_rdr, $dad_wtr) || die "open2: pipe 2 failed: $!";