Initial

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/github.com/containerd/fifo/raw.go

@@ -0,0 +1,114 @@
+// +build go1.12
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package fifo
+
+import (
+	"syscall"
+)
+
+// SyscallConn provides raw access to the fifo's underlying filedescrptor.
+// See syscall.Conn for guarentees provided by this interface.
+func (f *fifo) SyscallConn() (syscall.RawConn, error) {
+	// deterministic check for closed
+	select {
+	case <-f.closed:
+		return nil, ErrClosed
+	default:
+	}
+
+	select {
+	case <-f.closed:
+		return nil, ErrClosed
+	case <-f.opened:
+		return f.file.SyscallConn()
+	default:
+	}
+
+	// Not opened and not closed, this means open is non-blocking AND it's not open yet
+	// Use rawConn to deal with non-blocking open.
+	rc := &rawConn{f: f, ready: make(chan struct{})}
+	go func() {
+		select {
+		case <-f.closed:
+			return
+		case <-f.opened:
+			rc.raw, rc.err = f.file.SyscallConn()
+			close(rc.ready)
+		}
+	}()
+
+	return rc, nil
+}
+
+type rawConn struct {
+	f     *fifo
+	ready chan struct{}
+	raw   syscall.RawConn
+	err   error
+}
+
+func (r *rawConn) Control(f func(fd uintptr)) error {
+	select {
+	case <-r.f.closed:
+		return ErrCtrlClosed
+	case <-r.ready:
+	}
+
+	if r.err != nil {
+		return r.err
+	}
+
+	return r.raw.Control(f)
+}
+
+func (r *rawConn) Read(f func(fd uintptr) (done bool)) error {
+	if r.f.flag&syscall.O_WRONLY > 0 {
+		return ErrRdFrmWRONLY
+	}
+
+	select {
+	case <-r.f.closed:
+		return ErrReadClosed
+	case <-r.ready:
+	}
+
+	if r.err != nil {
+		return r.err
+	}
+
+	return r.raw.Read(f)
+}
+
+func (r *rawConn) Write(f func(fd uintptr) (done bool)) error {
+	if r.f.flag&(syscall.O_WRONLY|syscall.O_RDWR) == 0 {
+		return ErrWrToRDONLY
+	}
+
+	select {
+	case <-r.f.closed:
+		return ErrWriteClosed
+	case <-r.ready:
+	}
+
+	if r.err != nil {
+		return r.err
+	}
+
+	return r.raw.Write(f)
+}