You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: stream_unix.go
    path of file: ./repos/moby/vendor/github.com/containerd/containerd/diff
    
    the code of the file until where you have to start completion: //go:build !windows

/*
   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 l
    
func NewBinaryProcessor(ctx context.Context, imt, rmt string, stream StreamProcessor, name string, args, env []string, payload typeurl.Any) (StreamProcessor, error) {
	cmd := exec.CommandContext(ctx, name, args...)
	cmd.Env = os.Environ()
	cmd.Env = append(cmd.Env, env...)

	var payloadC io.Closer
	if payload != nil {
		pb := protobuf.FromAny(payload)
		data, err := proto.Marshal(pb)
		if err != nil {
			return nil, err
		}
		r, w, err := os.Pipe()
		if err != nil {
			return nil, err
		}
		go func() {
			io.Copy(w, bytes.NewReader(data))
			w.Close()
		}()

		cmd.ExtraFiles = append(cmd.ExtraFiles, r)
		payloadC = r
	}
	cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", mediaTypeEnvVar, imt))
	var (
		stdin  io.Reader
		closer func() error
		err    error
	)
	if f, ok := stream.(RawProcessor); ok {
		stdin = f.File()
		closer = f.File().Close
	} else {
		stdin = stream
	}
	cmd.Stdin = stdin
	r, w, err := os.Pipe()
	if err != nil {
		return nil, err
	}
	cmd.Stdout = w

	stderr := bytes.NewBuffer(nil)
	cmd.Stderr = stderr

	if err := cmd.Start(); err != nil {
		return nil, err
	}
	p := &binaryProcessor{
		cmd:    cmd,
		r:      r,
		mt:     rmt,
		stderr: stderr,
		done:   make(chan struct{}),
	}
	go p.wait()

	// close after start and dup
	w.Close()
	if closer != nil {
		closer()
	}
	if payloadC != nil {
		payloadC.Close()
	}
	return p, nil
}