package vpn

import (

"io"

"os"

"github.com/hashicorp/go-multierror"

"golang.org/x/xerrors"

)

// BidirectionalPipe combines a pair of files that can be used for bidirectional

// communication.

type BidirectionalPipe struct {

read *os.File

write *os.File

}

var _ io.ReadWriteCloser = BidirectionalPipe{}

// NewBidirectionalPipe creates a new BidirectionalPipe from the given file

// descriptors.

func NewBidirectionalPipe(readFd, writeFd uintptr) (BidirectionalPipe, error) {

read := os.NewFile(readFd, "pipe_read")

_, err := read.Stat()

if err != nil {

return BidirectionalPipe{}, xerrors.Errorf("stat pipe_read (fd=%v): %w", readFd, err)

}

write := os.NewFile(writeFd, "pipe_write")

_, err = write.Stat()

if err != nil {

return BidirectionalPipe{}, xerrors.Errorf("stat pipe_write (fd=%v): %w", writeFd, err)

}

return BidirectionalPipe{

read: read,

write: write,

}, nil

}

// Read implements io.Reader. Data is read from the read pipe.

func (b BidirectionalPipe) Read(p []byte) (int, error) {

n, err := b.read.Read(p)

if err != nil {

return n, xerrors.Errorf("read from pipe_read (fd=%v): %w", b.read.Fd(), err)

}

return n, nil

}

// Write implements io.Writer. Data is written to the write pipe.

func (b BidirectionalPipe) Write(p []byte) (n int, err error) {

n, err = b.write.Write(p)

if err != nil {

return n, xerrors.Errorf("write to pipe_write (fd=%v): %w", b.write.Fd(), err)

}

return n, nil

}

// Close implements io.Closer. Both the read and write pipes are closed.

func (b BidirectionalPipe) Close() error {

var err error

rErr := b.read.Close()

if rErr != nil {

err = multierror.Append(err, xerrors.Errorf("close pipe_read (fd=%v): %w", b.read.Fd(), rErr))

}

wErr := b.write.Close()

if err != nil {

err = multierror.Append(err, xerrors.Errorf("close pipe_write (fd=%v): %w", b.write.Fd(), wErr))

}

return err

}