PipeListenerDialer.Close should be called once

PipeListenerDialer.Close will return unix.EINVAL if it is called more
than once. This is to emulate the behavior of other standard listeners.

Also:

  * PipeListenerDialer.Accept will return (nil, unix.EINVAL) if the
    listener is closed. This roughly matches with behavior described in
    accept(2).

  * PipeListenerDialer.Dial will also return (nil, unix.EINVAL) if the
    address passed does not match the one passed to New. It will also
    return (nil, unix.ECONNREFUSED) if the listener is closed. This
    roughly matches the behavior described in connect(2) and unix(7).

  * The custom errors ErrBadAddress and ErrClosed are removed.

1 files changed, 4 insertions, 1 deletions

diff --git a/go.mod b/go.mod
index e6f2ddd..e9bef6d 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module go.awhk.org/pipeln
 
 go 1.15
 
-require github.com/stretchr/testify v1.7.0
+require (
+	github.com/stretchr/testify v1.7.0
+	golang.org/x/sys v0.0.0-20210316092937-0b90fd5c4c48
+)