fifo: add new fifo package for named pipes (#4665)

* fifo: add new fifo package for named pipes

client/lib/fifo/doc.go

@@ -0,0 +1,8 @@
+/*
+Package fifo implements functions to create and open a fifo for inter-process
+communication in an OS agnostic way. A few assumptions should be made when
+using this package. First, New() must always be called before Open(). Second
+Open() returns an io.ReadWriteCloser that is only connected with the
+io.ReadWriteCloser returned from New().
+*/
+package fifo

client/lib/fifo/fifo_test.go

@@ -0,0 +1,117 @@
+package fifo
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/hashicorp/nomad/helper/uuid"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFIFO(t *testing.T) {
+	require := require.New(t)
+	var path string
+
+	if runtime.GOOS == "windows" {
+		path = "//./pipe/fifo"
+	} else {
+		dir, err := ioutil.TempDir("", "")
+		require.NoError(err)
+		defer os.RemoveAll(dir)
+
+		path = filepath.Join(dir, "fifo")
+	}
+
+	reader, err := New(path)
+	require.NoError(err)
+
+	toWrite := [][]byte{
+		[]byte("abc\n"),
+		[]byte(""),
+		[]byte("def\n"),
+		[]byte("nomad"),
+		[]byte("\n"),
+	}
+
+	var readBuf bytes.Buffer
+	var wait sync.WaitGroup
+	wait.Add(1)
+	go func() {
+		defer wait.Done()
+		io.Copy(&readBuf, reader)
+	}()
+
+	writer, err := Open(path)
+	require.NoError(err)
+	for _, b := range toWrite {
+		n, err := writer.Write(b)
+		require.NoError(err)
+		require.Equal(n, len(b))
+	}
+	require.NoError(writer.Close())
+	time.Sleep(500 * time.Millisecond)
+	require.NoError(reader.Close())
+
+	wait.Wait()
+
+	expected := "abc\ndef\nnomad\n"
+	require.Equal(expected, readBuf.String())
+
+	require.NoError(Remove(path))
+}
+
+func TestWriteClose(t *testing.T) {
+	require := require.New(t)
+	var path string
+
+	if runtime.GOOS == "windows" {
+		path = "//./pipe/" + uuid.Generate()[:4]
+	} else {
+		dir, err := ioutil.TempDir("", "")
+		require.NoError(err)
+		defer os.RemoveAll(dir)
+
+		path = filepath.Join(dir, "fifo")
+	}
+
+	reader, err := New(path)
+	require.NoError(err)
+
+	var readBuf bytes.Buffer
+	var wait sync.WaitGroup
+	wait.Add(1)
+	go func() {
+		defer wait.Done()
+		io.Copy(&readBuf, reader)
+	}()
+
+	writer, err := Open(path)
+	require.NoError(err)
+
+	var count int
+	wait.Add(1)
+	go func() {
+		defer wait.Done()
+		for count = 0; count < int(^uint16(0)); count++ {
+			_, err := writer.Write([]byte(","))
+			if err != nil && IsClosedErr(err) {
+				break
+			}
+			require.NoError(err)
+			time.Sleep(5 * time.Millisecond)
+		}
+	}()
+
+	time.Sleep(500 * time.Millisecond)
+	require.NoError(writer.Close())
+	wait.Wait()
+
+	require.Equal(count, len(readBuf.String()))
+}

client/lib/fifo/fifo_unix.go

@@ -0,0 +1,36 @@
+// +build !windows
+
+package fifo
+
+import (
+	"context"
+	"io"
+	"os"
+	"syscall"
+
+	cfifo "github.com/containerd/fifo"
+)
+
+// New creates a fifo at the given path and returns an io.ReadWriteCloser for it
+// The fifo must not already exist
+func New(path string) (io.ReadWriteCloser, error) {
+	return cfifo.OpenFifo(context.Background(), path, syscall.O_RDONLY|syscall.O_CREAT|syscall.O_NONBLOCK, 0600)
+}
+
+// Open opens a fifo that already exists and returns an io.ReadWriteCloser for it
+func Open(path string) (io.ReadWriteCloser, error) {
+	return cfifo.OpenFifo(context.Background(), path, syscall.O_WRONLY|syscall.O_NONBLOCK, 0600)
+}
+
+// Remove a fifo that already exists at a given path
+func Remove(path string) error {
+	return os.Remove(path)
+}
+
+func IsClosedErr(err error) bool {
+	err2, ok := err.(*os.PathError)
+	if ok {
+		return err2.Err == os.ErrClosed
+	}
+	return false
+}

client/lib/fifo/fifo_windows.go

@@ -0,0 +1,105 @@
+package fifo
+
+import (
+	"io"
+	"net"
+	"os"
+	"sync"
+	"time"
+
+	winio "github.com/Microsoft/go-winio"
+)
+
+// PipeBufferSize is the size of the input and output buffers for the windows
+// named pipe
+const PipeBufferSize = int32(^uint16(0))
+
+type winFIFO struct {
+	listener net.Listener
+	conn     net.Conn
+	connLock sync.Mutex
+}
+
+func (f *winFIFO) Read(p []byte) (n int, err error) {
+	f.connLock.Lock()
+	defer f.connLock.Unlock()
+	if f.conn == nil {
+		c, err := f.listener.Accept()
+		if err != nil {
+			return 0, err
+		}
+
+		f.conn = c
+	}
+
+	// If the connection is closed then we need to close the listener
+	// to emulate unix fifo behavior
+	n, err = f.conn.Read(p)
+	if err == io.EOF {
+		f.listener.Close()
+	}
+	return n, err
+}
+
+func (f *winFIFO) Write(p []byte) (n int, err error) {
+	f.connLock.Lock()
+	defer f.connLock.Unlock()
+	if f.conn == nil {
+		c, err := f.listener.Accept()
+		if err != nil {
+			return 0, err
+		}
+
+		f.conn = c
+	}
+
+	// If the connection is closed then we need to close the listener
+	// to emulate unix fifo behavior
+	n, err = f.conn.Write(p)
+	if err == io.EOF {
+		f.listener.Close()
+	}
+	return n, err
+
+}
+
+func (f *winFIFO) Close() error {
+	return f.listener.Close()
+}
+
+// New creates a fifo at the given path and returns an io.ReadWriteCloser for it. The fifo
+// must not already exist
+func New(path string) (io.ReadWriteCloser, error) {
+	l, err := winio.ListenPipe(path, &winio.PipeConfig{
+		InputBufferSize:  PipeBufferSize,
+		OutputBufferSize: PipeBufferSize,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return &winFIFO{
+		listener: l,
+	}, nil
+}
+
+// OpenWriter opens a fifo that already exists and returns an io.ReadWriteCloser for it
+func Open(path string) (io.ReadWriteCloser, error) {
+	return winio.DialPipe(path, nil)
+}
+
+// Remove a fifo that already exists at a given path
+func Remove(path string) error {
+	dur := 500 * time.Millisecond
+	conn, err := winio.DialPipe(path, &dur)
+	if err == nil {
+		return conn.Close()
+	}
+
+	os.Remove(path)
+	return nil
+}
+
+func IsClosedErr(err error) bool {
+	return err == winio.ErrFileClosed
+}

vendor/github.com/Microsoft/go-winio/backup.go

@@ -68,10 +68,20 @@ func NewBackupStreamReader(r io.Reader) *BackupStreamReader {
 	return &BackupStreamReader{r, 0}
 }
 
-// Next returns the next backup stream and prepares for calls to Write(). It skips the remainder of the current stream if
+// Next returns the next backup stream and prepares for calls to Read(). It skips the remainder of the current stream if
 // it was not completely read.
 func (r *BackupStreamReader) Next() (*BackupHeader, error) {
 	if r.bytesLeft > 0 {
+		if s, ok := r.r.(io.Seeker); ok {
+			// Make sure Seek on io.SeekCurrent sometimes succeeds
+			// before trying the actual seek.
+			if _, err := s.Seek(0, io.SeekCurrent); err == nil {
+				if _, err = s.Seek(r.bytesLeft, io.SeekCurrent); err != nil {
+					return nil, err
+				}
+				r.bytesLeft = 0
+			}
+		}
 		if _, err := io.Copy(ioutil.Discard, r); err != nil {
 			return nil, err
 		}
@@ -220,7 +230,7 @@ type BackupFileWriter struct {
 	ctx             uintptr
 }
 
-// NewBackupFileWrtier returns a new BackupFileWriter from a file handle. If includeSecurity is true,
+// NewBackupFileWriter returns a new BackupFileWriter from a file handle. If includeSecurity is true,
 // Write() will attempt to restore the security descriptor from the stream.
 func NewBackupFileWriter(f *os.File, includeSecurity bool) *BackupFileWriter {
 	w := &BackupFileWriter{f, includeSecurity, 0}

vendor/github.com/Microsoft/go-winio/ea.go

@@ -0,0 +1,137 @@
+package winio
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+)
+
+type fileFullEaInformation struct {
+	NextEntryOffset uint32
+	Flags           uint8
+	NameLength      uint8
+	ValueLength     uint16
+}
+
+var (
+	fileFullEaInformationSize = binary.Size(&fileFullEaInformation{})
+
+	errInvalidEaBuffer = errors.New("invalid extended attribute buffer")
+	errEaNameTooLarge  = errors.New("extended attribute name too large")
+	errEaValueTooLarge = errors.New("extended attribute value too large")
+)
+
+// ExtendedAttribute represents a single Windows EA.
+type ExtendedAttribute struct {
+	Name  string
+	Value []byte
+	Flags uint8
+}
+
+func parseEa(b []byte) (ea ExtendedAttribute, nb []byte, err error) {
+	var info fileFullEaInformation
+	err = binary.Read(bytes.NewReader(b), binary.LittleEndian, &info)
+	if err != nil {
+		err = errInvalidEaBuffer
+		return
+	}
+
+	nameOffset := fileFullEaInformationSize
+	nameLen := int(info.NameLength)
+	valueOffset := nameOffset + int(info.NameLength) + 1
+	valueLen := int(info.ValueLength)
+	nextOffset := int(info.NextEntryOffset)
+	if valueLen+valueOffset > len(b) || nextOffset < 0 || nextOffset > len(b) {
+		err = errInvalidEaBuffer
+		return
+	}
+
+	ea.Name = string(b[nameOffset : nameOffset+nameLen])
+	ea.Value = b[valueOffset : valueOffset+valueLen]
+	ea.Flags = info.Flags
+	if info.NextEntryOffset != 0 {
+		nb = b[info.NextEntryOffset:]
+	}
+	return
+}
+
+// DecodeExtendedAttributes decodes a list of EAs from a FILE_FULL_EA_INFORMATION
+// buffer retrieved from BackupRead, ZwQueryEaFile, etc.
+func DecodeExtendedAttributes(b []byte) (eas []ExtendedAttribute, err error) {
+	for len(b) != 0 {
+		ea, nb, err := parseEa(b)
+		if err != nil {
+			return nil, err
+		}
+
+		eas = append(eas, ea)
+		b = nb
+	}
+	return
+}
+
+func writeEa(buf *bytes.Buffer, ea *ExtendedAttribute, last bool) error {
+	if int(uint8(len(ea.Name))) != len(ea.Name) {
+		return errEaNameTooLarge
+	}
+	if int(uint16(len(ea.Value))) != len(ea.Value) {
+		return errEaValueTooLarge
+	}
+	entrySize := uint32(fileFullEaInformationSize + len(ea.Name) + 1 + len(ea.Value))
+	withPadding := (entrySize + 3) &^ 3
+	nextOffset := uint32(0)
+	if !last {
+		nextOffset = withPadding
+	}
+	info := fileFullEaInformation{
+		NextEntryOffset: nextOffset,
+		Flags:           ea.Flags,
+		NameLength:      uint8(len(ea.Name)),
+		ValueLength:     uint16(len(ea.Value)),
+	}
+
+	err := binary.Write(buf, binary.LittleEndian, &info)
+	if err != nil {
+		return err
+	}
+
+	_, err = buf.Write([]byte(ea.Name))
+	if err != nil {
+		return err
+	}
+
+	err = buf.WriteByte(0)
+	if err != nil {
+		return err
+	}
+
+	_, err = buf.Write(ea.Value)
+	if err != nil {
+		return err
+	}
+
+	_, err = buf.Write([]byte{0, 0, 0}[0 : withPadding-entrySize])
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// EncodeExtendedAttributes encodes a list of EAs into a FILE_FULL_EA_INFORMATION
+// buffer for use with BackupWrite, ZwSetEaFile, etc.
+func EncodeExtendedAttributes(eas []ExtendedAttribute) ([]byte, error) {
+	var buf bytes.Buffer
+	for i := range eas {
+		last := false
+		if i == len(eas)-1 {
+			last = true
+		}
+
+		err := writeEa(&buf, &eas[i], last)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return buf.Bytes(), nil
+}

vendor/github.com/Microsoft/go-winio/file.go

@@ -16,13 +16,19 @@ import (
 //sys createIoCompletionPort(file syscall.Handle, port syscall.Handle, key uintptr, threadCount uint32) (newport syscall.Handle, err error) = CreateIoCompletionPort
 //sys getQueuedCompletionStatus(port syscall.Handle, bytes *uint32, key *uintptr, o **ioOperation, timeout uint32) (err error) = GetQueuedCompletionStatus
 //sys setFileCompletionNotificationModes(h syscall.Handle, flags uint8) (err error) = SetFileCompletionNotificationModes
-//sys timeBeginPeriod(period uint32) (n int32) = winmm.timeBeginPeriod
 
 type atomicBool int32
 
 func (b *atomicBool) isSet() bool { return atomic.LoadInt32((*int32)(b)) != 0 }
 func (b *atomicBool) setFalse()   { atomic.StoreInt32((*int32)(b), 0) }
 func (b *atomicBool) setTrue()    { atomic.StoreInt32((*int32)(b), 1) }
+func (b *atomicBool) swap(new bool) bool {
+	var newInt int32
+	if new {
+		newInt = 1
+	}
+	return atomic.SwapInt32((*int32)(b), newInt) == 1
+}
 
 const (
 	cFILE_SKIP_COMPLETION_PORT_ON_SUCCESS = 1
@@ -71,7 +77,8 @@ func initIo() {
 type win32File struct {
 	handle        syscall.Handle
 	wg            sync.WaitGroup
-	closing       bool
+	wgLock        sync.RWMutex
+	closing       atomicBool
 	readDeadline  deadlineHandler
 	writeDeadline deadlineHandler
 }
@@ -107,14 +114,18 @@ func MakeOpenFile(h syscall.Handle) (io.ReadWriteCloser, error) {
 
 // closeHandle closes the resources associated with a Win32 handle
 func (f *win32File) closeHandle() {
-	if !f.closing {
+	f.wgLock.Lock()
+	// Atomically set that we are closing, releasing the resources only once.
+	if !f.closing.swap(true) {
+		f.wgLock.Unlock()
 		// cancel all IO and wait for it to complete
-		f.closing = true
 		cancelIoEx(f.handle, nil)
 		f.wg.Wait()
 		// at this point, no new IO can start
 		syscall.Close(f.handle)
 		f.handle = 0
+	} else {
+		f.wgLock.Unlock()
 	}
 }
 
@@ -127,10 +138,13 @@ func (f *win32File) Close() error {
 // prepareIo prepares for a new IO operation.
 // The caller must call f.wg.Done() when the IO is finished, prior to Close() returning.
 func (f *win32File) prepareIo() (*ioOperation, error) {
-	f.wg.Add(1)
-	if f.closing {
+	f.wgLock.RLock()
+	if f.closing.isSet() {
+		f.wgLock.RUnlock()
 		return nil, ErrFileClosed
 	}
+	f.wg.Add(1)
+	f.wgLock.RUnlock()
 	c := &ioOperation{}
 	c.ch = make(chan ioResult)
 	return c, nil
@@ -138,8 +152,6 @@ func (f *win32File) prepareIo() (*ioOperation, error) {
 
 // ioCompletionProcessor processes completed async IOs forever
 func ioCompletionProcessor(h syscall.Handle) {
-	// Set the timer resolution to 1. This fixes a performance regression in golang 1.6.
-	timeBeginPeriod(1)
 	for {
 		var bytes uint32
 		var key uintptr
@@ -159,7 +171,7 @@ func (f *win32File) asyncIo(c *ioOperation, d *deadlineHandler, bytes uint32, er
 		return int(bytes), err
 	}
 
-	if f.closing {
+	if f.closing.isSet() {
 		cancelIoEx(f.handle, &c.o)
 	}
 
@@ -175,7 +187,7 @@ func (f *win32File) asyncIo(c *ioOperation, d *deadlineHandler, bytes uint32, er
 	case r = <-c.ch:
 		err = r.err
 		if err == syscall.ERROR_OPERATION_ABORTED {
-			if f.closing {
+			if f.closing.isSet() {
 				err = ErrFileClosed
 			}
 		}

vendor/github.com/Microsoft/go-winio/fileinfo.go

@@ -20,7 +20,8 @@ const (
 // FileBasicInfo contains file access time and file attributes information.
 type FileBasicInfo struct {
 	CreationTime, LastAccessTime, LastWriteTime, ChangeTime syscall.Filetime
-	FileAttributes                                          uintptr // includes padding
+	FileAttributes                                          uint32
+	pad                                                     uint32 // padding
 }
 
 // GetFileBasicInfo retrieves times and attributes for a file.

vendor/github.com/Microsoft/go-winio/pipe.go

@@ -15,13 +15,13 @@ import (
 //sys connectNamedPipe(pipe syscall.Handle, o *syscall.Overlapped) (err error) = ConnectNamedPipe
 //sys createNamedPipe(name string, flags uint32, pipeMode uint32, maxInstances uint32, outSize uint32, inSize uint32, defaultTimeout uint32, sa *syscall.SecurityAttributes) (handle syscall.Handle, err error)  [failretval==syscall.InvalidHandle] = CreateNamedPipeW
 //sys createFile(name string, access uint32, mode uint32, sa *syscall.SecurityAttributes, createmode uint32, attrs uint32, templatefile syscall.Handle) (handle syscall.Handle, err error) [failretval==syscall.InvalidHandle] = CreateFileW
-//sys waitNamedPipe(name string, timeout uint32) (err error) = WaitNamedPipeW
 //sys getNamedPipeInfo(pipe syscall.Handle, flags *uint32, outSize *uint32, inSize *uint32, maxInstances *uint32) (err error) = GetNamedPipeInfo
 //sys getNamedPipeHandleState(pipe syscall.Handle, state *uint32, curInstances *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32, userName *uint16, maxUserNameSize uint32) (err error) = GetNamedPipeHandleStateW
 //sys localAlloc(uFlags uint32, length uint32) (ptr uintptr) = LocalAlloc
 
 const (
 	cERROR_PIPE_BUSY      = syscall.Errno(231)
+	cERROR_NO_DATA        = syscall.Errno(232)
 	cERROR_PIPE_CONNECTED = syscall.Errno(535)
 	cERROR_SEM_TIMEOUT    = syscall.Errno(121)
 
@@ -120,6 +120,11 @@ func (f *win32MessageBytePipe) Read(b []byte) (int, error) {
 		// zero-byte message, ensure that all future Read() calls
 		// also return EOF.
 		f.readEOF = true
+	} else if err == syscall.ERROR_MORE_DATA {
+		// ERROR_MORE_DATA indicates that the pipe's read mode is message mode
+		// and the message still has more bytes. Treat this as a success, since
+		// this package presents all named pipes as byte streams.
+		err = nil
 	}
 	return n, err
 }
@@ -133,12 +138,14 @@ func (s pipeAddress) String() string {
 }
 
 // DialPipe connects to a named pipe by path, timing out if the connection
-// takes longer than the specified duration. If timeout is nil, then the timeout
-// is the default timeout established by the pipe server.
+// takes longer than the specified duration. If timeout is nil, then we use
+// a default timeout of 5 seconds.  (We do not use WaitNamedPipe.)
 func DialPipe(path string, timeout *time.Duration) (net.Conn, error) {
 	var absTimeout time.Time
 	if timeout != nil {
 		absTimeout = time.Now().Add(*timeout)
+	} else {
+		absTimeout = time.Now().Add(time.Second * 2)
 	}
 	var err error
 	var h syscall.Handle
@@ -147,22 +154,13 @@ func DialPipe(path string, timeout *time.Duration) (net.Conn, error) {
 		if err != cERROR_PIPE_BUSY {
 			break
 		}
-		now := time.Now()
-		var ms uint32
-		if absTimeout.IsZero() {
-			ms = cNMPWAIT_USE_DEFAULT_WAIT
-		} else if now.After(absTimeout) {
-			ms = cNMPWAIT_NOWAIT
-		} else {
-			ms = uint32(absTimeout.Sub(now).Nanoseconds() / 1000 / 1000)
-		}
-		err = waitNamedPipe(path, ms)
-		if err != nil {
-			if err == cERROR_SEM_TIMEOUT {
-				return nil, ErrTimeout
-			}
-			break
+		if time.Now().After(absTimeout) {
+			return nil, ErrTimeout
 		}
+
+		// Wait 10 msec and try again. This is a rather simplistic
+		// view, as we always try each 10 milliseconds.
+		time.Sleep(time.Millisecond * 10)
 	}
 	if err != nil {
 		return nil, &os.PathError{Op: "open", Path: path, Err: err}
@@ -174,16 +172,6 @@ func DialPipe(path string, timeout *time.Duration) (net.Conn, error) {
 		return nil, err
 	}
 
-	var state uint32
-	err = getNamedPipeHandleState(h, &state, nil, nil, nil, nil, 0)
-	if err != nil {
-		return nil, err
-	}
-
-	if state&cPIPE_READMODE_MESSAGE != 0 {
-		return nil, &os.PathError{Op: "open", Path: path, Err: errors.New("message readmode pipes not supported")}
-	}
-
 	f, err := makeWin32File(h)
 	if err != nil {
 		syscall.Close(h)
@@ -254,6 +242,36 @@ func (l *win32PipeListener) makeServerPipe() (*win32File, error) {
 	return f, nil
 }
 
+func (l *win32PipeListener) makeConnectedServerPipe() (*win32File, error) {
+	p, err := l.makeServerPipe()
+	if err != nil {
+		return nil, err
+	}
+
+	// Wait for the client to connect.
+	ch := make(chan error)
+	go func(p *win32File) {
+		ch <- connectPipe(p)
+	}(p)
+
+	select {
+	case err = <-ch:
+		if err != nil {
+			p.Close()
+			p = nil
+		}
+	case <-l.closeCh:
+		// Abort the connect request by closing the handle.
+		p.Close()
+		p = nil
+		err = <-ch
+		if err == nil || err == ErrFileClosed {
+			err = ErrPipeListenerClosed
+		}
+	}
+	return p, err
+}
+
 func (l *win32PipeListener) listenerRoutine() {
 	closed := false
 	for !closed {
@@ -261,31 +279,20 @@ func (l *win32PipeListener) listenerRoutine() {
 		case <-l.closeCh:
 			closed = true
 		case responseCh := <-l.acceptCh:
-			p, err := l.makeServerPipe()
-			if err == nil {
-				// Wait for the client to connect.
-				ch := make(chan error)
-				go func() {
-					ch <- connectPipe(p)
-				}()
-				select {
-				case err = <-ch:
-					if err != nil {
-						p.Close()
-						p = nil
-					}
-				case <-l.closeCh:
-					// Abort the connect request by closing the handle.
-					p.Close()
-					p = nil
-					err = <-ch
-					if err == nil || err == ErrFileClosed {
-						err = ErrPipeListenerClosed
-					}
-					closed = true
+			var (
+				p   *win32File
+				err error
+			)
+			for {
+				p, err = l.makeConnectedServerPipe()
+				// If the connection was immediately closed by the client, try
+				// again.
+				if err != cERROR_NO_DATA {
+					break
 				}
 			}
 			responseCh <- acceptResponse{p, err}
+			closed = err == ErrPipeListenerClosed
 		}
 	}
 	syscall.Close(l.firstHandle)
@@ -334,13 +341,23 @@ func ListenPipe(path string, c *PipeConfig) (net.Listener, error) {
 	if err != nil {
 		return nil, err
 	}
-	// Immediately open and then close a client handle so that the named pipe is
-	// created but not currently accepting connections.
+	// Create a client handle and connect it.  This results in the pipe
+	// instance always existing, so that clients see ERROR_PIPE_BUSY
+	// rather than ERROR_FILE_NOT_FOUND.  This ties the first instance
+	// up so that no other instances can be used.  This would have been
+	// cleaner if the Win32 API matched CreateFile with ConnectNamedPipe
+	// instead of CreateNamedPipe.  (Apparently created named pipes are
+	// considered to be in listening state regardless of whether any
+	// active calls to ConnectNamedPipe are outstanding.)
 	h2, err := createFile(path, 0, 0, nil, syscall.OPEN_EXISTING, cSECURITY_SQOS_PRESENT|cSECURITY_ANONYMOUS, 0)
 	if err != nil {
 		syscall.Close(h)
 		return nil, err
 	}
+	// Close the client handle. The server side of the instance will
+	// still be busy, leading to ERROR_PIPE_BUSY instead of
+	// ERROR_NOT_FOUND, as long as we don't close the server handle,
+	// or disconnect the client with DisconnectNamedPipe.
 	syscall.Close(h2)
 	l := &win32PipeListener{
 		firstHandle:        h,

vendor/github.com/Microsoft/go-winio/zsyscall_windows.go

@@ -38,14 +38,12 @@ func errnoErr(e syscall.Errno) error {
 
 var (
 	modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
-	modwinmm    = windows.NewLazySystemDLL("winmm.dll")
 	modadvapi32 = windows.NewLazySystemDLL("advapi32.dll")
 
 	procCancelIoEx                                           = modkernel32.NewProc("CancelIoEx")
 	procCreateIoCompletionPort                               = modkernel32.NewProc("CreateIoCompletionPort")
 	procGetQueuedCompletionStatus                            = modkernel32.NewProc("GetQueuedCompletionStatus")
 	procSetFileCompletionNotificationModes                   = modkernel32.NewProc("SetFileCompletionNotificationModes")
-	proctimeBeginPeriod                                      = modwinmm.NewProc("timeBeginPeriod")
 	procConnectNamedPipe                                     = modkernel32.NewProc("ConnectNamedPipe")
 	procCreateNamedPipeW                                     = modkernel32.NewProc("CreateNamedPipeW")
 	procCreateFileW                                          = modkernel32.NewProc("CreateFileW")
@@ -122,12 +120,6 @@ func setFileCompletionNotificationModes(h syscall.Handle, flags uint8) (err erro
 	return
 }
 
-func timeBeginPeriod(period uint32) (n int32) {
-	r0, _, _ := syscall.Syscall(proctimeBeginPeriod.Addr(), 1, uintptr(period), 0, 0)
-	n = int32(r0)
-	return
-}
-
 func connectNamedPipe(pipe syscall.Handle, o *syscall.Overlapped) (err error) {
 	r1, _, e1 := syscall.Syscall(procConnectNamedPipe.Addr(), 2, uintptr(pipe), uintptr(unsafe.Pointer(o)), 0)
 	if r1 == 0 {

vendor/github.com/containerd/fifo/LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   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.

vendor/github.com/containerd/fifo/Makefile

@@ -0,0 +1,27 @@
+#   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.
+
+.PHONY: fmt vet test deps
+
+test: deps
+	go test -v ./...
+
+deps:
+	go get -d -t ./...
+
+fmt:
+	gofmt -s -l .
+
+vet:
+	go vet ./...

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

@@ -0,0 +1,236 @@
+/*
+   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 (
+	"io"
+	"os"
+	"runtime"
+	"sync"
+	"syscall"
+
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+)
+
+type fifo struct {
+	flag        int
+	opened      chan struct{}
+	closed      chan struct{}
+	closing     chan struct{}
+	err         error
+	file        *os.File
+	closingOnce sync.Once // close has been called
+	closedOnce  sync.Once // fifo is closed
+	handle      *handle
+}
+
+var leakCheckWg *sync.WaitGroup
+
+// OpenFifo opens a fifo. Returns io.ReadWriteCloser.
+// Context can be used to cancel this function until open(2) has not returned.
+// Accepted flags:
+// - syscall.O_CREAT - create new fifo if one doesn't exist
+// - syscall.O_RDONLY - open fifo only from reader side
+// - syscall.O_WRONLY - open fifo only from writer side
+// - syscall.O_RDWR - open fifo from both sides, never block on syscall level
+// - syscall.O_NONBLOCK - return io.ReadWriteCloser even if other side of the
+//     fifo isn't open. read/write will be connected after the actual fifo is
+//     open or after fifo is closed.
+func OpenFifo(ctx context.Context, fn string, flag int, perm os.FileMode) (io.ReadWriteCloser, error) {
+	if _, err := os.Stat(fn); err != nil {
+		if os.IsNotExist(err) && flag&syscall.O_CREAT != 0 {
+			if err := mkfifo(fn, uint32(perm&os.ModePerm)); err != nil && !os.IsExist(err) {
+				return nil, errors.Wrapf(err, "error creating fifo %v", fn)
+			}
+		} else {
+			return nil, err
+		}
+	}
+
+	block := flag&syscall.O_NONBLOCK == 0 || flag&syscall.O_RDWR != 0
+
+	flag &= ^syscall.O_CREAT
+	flag &= ^syscall.O_NONBLOCK
+
+	h, err := getHandle(fn)
+	if err != nil {
+		return nil, err
+	}
+
+	f := &fifo{
+		handle:  h,
+		flag:    flag,
+		opened:  make(chan struct{}),
+		closed:  make(chan struct{}),
+		closing: make(chan struct{}),
+	}
+
+	wg := leakCheckWg
+	if wg != nil {
+		wg.Add(2)
+	}
+
+	go func() {
+		if wg != nil {
+			defer wg.Done()
+		}
+		select {
+		case <-ctx.Done():
+			select {
+			case <-f.opened:
+			default:
+				f.Close()
+			}
+		case <-f.opened:
+		case <-f.closed:
+		}
+	}()
+	go func() {
+		if wg != nil {
+			defer wg.Done()
+		}
+		var file *os.File
+		fn, err := h.Path()
+		if err == nil {
+			file, err = os.OpenFile(fn, flag, 0)
+		}
+		select {
+		case <-f.closing:
+			if err == nil {
+				select {
+				case <-ctx.Done():
+					err = ctx.Err()
+				default:
+					err = errors.Errorf("fifo %v was closed before opening", h.Name())
+				}
+				if file != nil {
+					file.Close()
+				}
+			}
+		default:
+		}
+		if err != nil {
+			f.closedOnce.Do(func() {
+				f.err = err
+				close(f.closed)
+			})
+			return
+		}
+		f.file = file
+		close(f.opened)
+	}()
+	if block {
+		select {
+		case <-f.opened:
+		case <-f.closed:
+			return nil, f.err
+		}
+	}
+	return f, nil
+}
+
+// Read from a fifo to a byte array.
+func (f *fifo) Read(b []byte) (int, error) {
+	if f.flag&syscall.O_WRONLY > 0 {
+		return 0, errors.New("reading from write-only fifo")
+	}
+	select {
+	case <-f.opened:
+		return f.file.Read(b)
+	default:
+	}
+	select {
+	case <-f.opened:
+		return f.file.Read(b)
+	case <-f.closed:
+		return 0, errors.New("reading from a closed fifo")
+	}
+}
+
+// Write from byte array to a fifo.
+func (f *fifo) Write(b []byte) (int, error) {
+	if f.flag&(syscall.O_WRONLY|syscall.O_RDWR) == 0 {
+		return 0, errors.New("writing to read-only fifo")
+	}
+	select {
+	case <-f.opened:
+		return f.file.Write(b)
+	default:
+	}
+	select {
+	case <-f.opened:
+		return f.file.Write(b)
+	case <-f.closed:
+		return 0, errors.New("writing to a closed fifo")
+	}
+}
+
+// Close the fifo. Next reads/writes will error. This method can also be used
+// before open(2) has returned and fifo was never opened.
+func (f *fifo) Close() (retErr error) {
+	for {
+		select {
+		case <-f.closed:
+			f.handle.Close()
+			return
+		default:
+			select {
+			case <-f.opened:
+				f.closedOnce.Do(func() {
+					retErr = f.file.Close()
+					f.err = retErr
+					close(f.closed)
+				})
+			default:
+				if f.flag&syscall.O_RDWR != 0 {
+					runtime.Gosched()
+					break
+				}
+				f.closingOnce.Do(func() {
+					close(f.closing)
+				})
+				reverseMode := syscall.O_WRONLY
+				if f.flag&syscall.O_WRONLY > 0 {
+					reverseMode = syscall.O_RDONLY
+				}
+				fn, err := f.handle.Path()
+				// if Close() is called concurrently(shouldn't) it may cause error
+				// because handle is closed
+				select {
+				case <-f.closed:
+				default:
+					if err != nil {
+						// Path has become invalid. We will leak a goroutine.
+						// This case should not happen in linux.
+						f.closedOnce.Do(func() {
+							f.err = err
+							close(f.closed)
+						})
+						<-f.closed
+						break
+					}
+					f, err := os.OpenFile(fn, reverseMode|syscall.O_NONBLOCK, 0)
+					if err == nil {
+						f.Close()
+					}
+					runtime.Gosched()
+				}
+			}
+		}
+	}
+}

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

@@ -0,0 +1,97 @@
+// +build linux
+
+/*
+   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 (
+	"fmt"
+	"os"
+	"sync"
+	"syscall"
+
+	"github.com/pkg/errors"
+)
+
+const O_PATH = 010000000
+
+type handle struct {
+	f         *os.File
+	fd        uintptr
+	dev       uint64
+	ino       uint64
+	closeOnce sync.Once
+	name      string
+}
+
+func getHandle(fn string) (*handle, error) {
+	f, err := os.OpenFile(fn, O_PATH, 0)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to open %v with O_PATH", fn)
+	}
+
+	var (
+		stat syscall.Stat_t
+		fd   = f.Fd()
+	)
+	if err := syscall.Fstat(int(fd), &stat); err != nil {
+		f.Close()
+		return nil, errors.Wrapf(err, "failed to stat handle %v", fd)
+	}
+
+	h := &handle{
+		f:    f,
+		name: fn,
+		dev:  uint64(stat.Dev),
+		ino:  stat.Ino,
+		fd:   fd,
+	}
+
+	// check /proc just in case
+	if _, err := os.Stat(h.procPath()); err != nil {
+		f.Close()
+		return nil, errors.Wrapf(err, "couldn't stat %v", h.procPath())
+	}
+
+	return h, nil
+}
+
+func (h *handle) procPath() string {
+	return fmt.Sprintf("/proc/self/fd/%d", h.fd)
+}
+
+func (h *handle) Name() string {
+	return h.name
+}
+
+func (h *handle) Path() (string, error) {
+	var stat syscall.Stat_t
+	if err := syscall.Stat(h.procPath(), &stat); err != nil {
+		return "", errors.Wrapf(err, "path %v could not be statted", h.procPath())
+	}
+	if uint64(stat.Dev) != h.dev || stat.Ino != h.ino {
+		return "", errors.Errorf("failed to verify handle %v/%v %v/%v", stat.Dev, h.dev, stat.Ino, h.ino)
+	}
+	return h.procPath(), nil
+}
+
+func (h *handle) Close() error {
+	h.closeOnce.Do(func() {
+		h.f.Close()
+	})
+	return nil
+}

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

@@ -0,0 +1,65 @@
+// +build !linux
+
+/*
+   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"
+
+	"github.com/pkg/errors"
+)
+
+type handle struct {
+	fn  string
+	dev uint64
+	ino uint64
+}
+
+func getHandle(fn string) (*handle, error) {
+	var stat syscall.Stat_t
+	if err := syscall.Stat(fn, &stat); err != nil {
+		return nil, errors.Wrapf(err, "failed to stat %v", fn)
+	}
+
+	h := &handle{
+		fn:  fn,
+		dev: uint64(stat.Dev),
+		ino: uint64(stat.Ino),
+	}
+
+	return h, nil
+}
+
+func (h *handle) Path() (string, error) {
+	var stat syscall.Stat_t
+	if err := syscall.Stat(h.fn, &stat); err != nil {
+		return "", errors.Wrapf(err, "path %v could not be statted", h.fn)
+	}
+	if uint64(stat.Dev) != h.dev || uint64(stat.Ino) != h.ino {
+		return "", errors.Errorf("failed to verify handle %v/%v %v/%v for %v", stat.Dev, h.dev, stat.Ino, h.ino, h.fn)
+	}
+	return h.fn, nil
+}
+
+func (h *handle) Name() string {
+	return h.fn
+}
+
+func (h *handle) Close() error {
+	return nil
+}

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

@@ -0,0 +1,25 @@
+// +build !solaris
+
+/*
+   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"
+
+func mkfifo(path string, mode uint32) (err error) {
+	return syscall.Mkfifo(path, mode)
+}

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

@@ -0,0 +1,27 @@
+// +build solaris
+
+/*
+   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 (
+	"golang.org/x/sys/unix"
+)
+
+func mkfifo(path string, mode uint32) (err error) {
+	return unix.Mkfifo(path, mode)
+}

vendor/github.com/containerd/fifo/readme.md

@@ -0,0 +1,32 @@
+### fifo
+
+[![Build Status](https://travis-ci.org/containerd/fifo.svg?branch=master)](https://travis-ci.org/containerd/fifo)
+
+Go package for handling fifos in a sane way.
+
+```
+// OpenFifo opens a fifo. Returns io.ReadWriteCloser.
+// Context can be used to cancel this function until open(2) has not returned.
+// Accepted flags:
+// - syscall.O_CREAT - create new fifo if one doesn't exist
+// - syscall.O_RDONLY - open fifo only from reader side
+// - syscall.O_WRONLY - open fifo only from writer side
+// - syscall.O_RDWR - open fifo from both sides, never block on syscall level
+// - syscall.O_NONBLOCK - return io.ReadWriteCloser even if other side of the
+//     fifo isn't open. read/write will be connected after the actual fifo is
+//     open or after fifo is closed.
+func OpenFifo(ctx context.Context, fn string, flag int, perm os.FileMode) (io.ReadWriteCloser, error)
+
+
+// Read from a fifo to a byte array.
+func (f *fifo) Read(b []byte) (int, error)
+
+
+// Write from byte array to a fifo.
+func (f *fifo) Write(b []byte) (int, error)
+
+
+// Close the fifo. Next reads/writes will error. This method can also be used
+// before open(2) has returned and fifo was never opened.
+func (f *fifo) Close() error
+```

vendor/vendor.json

@@ -7,7 +7,7 @@
 		{"path":"github.com/Azure/go-ansiterm","checksumSHA1":"9NFR6RG8H2fNyKHscGmuGLQhRm4=","revision":"d6e3b3328b783f23731bc4d058875b0371ff8109","revisionTime":"2017-09-29T23:40:23Z","version":"master","versionExact":"master"},
 		{"path":"github.com/Azure/go-ansiterm/winterm","checksumSHA1":"3/UphB+6Hbx5otA4PjFjvObT+L4=","revision":"d6e3b3328b783f23731bc4d058875b0371ff8109","revisionTime":"2017-09-29T23:40:23Z","version":"master","versionExact":"master"},
 		{"path":"github.com/DataDog/datadog-go/statsd","checksumSHA1":"WvApwvvSe3i/3KO8300dyeFmkbI=","revision":"b10af4b12965a1ad08d164f57d14195b4140d8de","revisionTime":"2017-08-09T10:47:06Z"},
-		{"path":"github.com/Microsoft/go-winio","checksumSHA1":"AzjRkOQtVBTwIw4RJLTygFhJs3s=","revision":"f533f7a102197536779ea3a8cb881d639e21ec5a","revisionTime":"2017-05-24T00:36:31Z"},
+		{"path":"github.com/Microsoft/go-winio","checksumSHA1":"PbR6ZKoLeSZl8aXxDQqXih0wSgE=","revision":"97e4973ce50b2ff5f09635a57e2b88a037aae829","revisionTime":"2018-08-23T22:24:21Z"},
 		{"path":"github.com/NVIDIA/gpu-monitoring-tools","checksumSHA1":"kF1vk+8Xvb3nGBiw9+qbUc0SZ4M=","revision":"86f2a9fac6c5b597dc494420005144b8ef7ec9fb","revisionTime":"2018-08-29T22:20:09Z"},
 		{"path":"github.com/NVIDIA/gpu-monitoring-tools/bindings/go/nvml","checksumSHA1":"P8FATSSgpe5A17FyPrGpsX95Xw8=","revision":"86f2a9fac6c5b597dc494420005144b8ef7ec9fb","revisionTime":"2018-08-29T22:20:09Z"},
 		{"path":"github.com/NYTimes/gziphandler","checksumSHA1":"jktW57+vJsziNVPeXMCoujTzdW4=","revision":"97ae7fbaf81620fe97840685304a78a306a39c64","revisionTime":"2017-09-16T00:36:49Z"},
@@ -60,6 +60,7 @@
 		{"path":"github.com/circonus-labs/circonusllhist","checksumSHA1":"VbfeVqeOM+dTNxCmpvmYS0LwQn0=","revision":"7d649b46cdc2cd2ed102d350688a75a4fd7778c6","revisionTime":"2016-11-21T13:51:53Z"},
 		{"path":"github.com/containerd/console","checksumSHA1":"IGtuR58l2zmYRcNf8sPDlCSgovE=","origin":"github.com/opencontainers/runc/vendor/github.com/containerd/console","revision":"459bfaec1fc6c17d8bfb12d0a0f69e7e7271ed2a","revisionTime":"2018-08-23T14:46:37Z"},
 		{"path":"github.com/containerd/continuity/pathdriver","checksumSHA1":"GqIrOttKaO7k6HIaHQLPr3cY7rY=","origin":"github.com/docker/docker/vendor/github.com/containerd/continuity/pathdriver","revision":"320063a2ad06a1d8ada61c94c29dbe44e2d87473","revisionTime":"2018-08-16T08:14:46Z"},
+		{"path":"github.com/containerd/fifo","checksumSHA1":"Ur3lVmFp+HTGUzQU+/ZBolKe8FU=","revision":"3d5202aec260678c48179c56f40e6f38a095738c","revisionTime":"2018-03-07T16:51:37Z"},
 		{"path":"github.com/containernetworking/cni/pkg/types","checksumSHA1":"NeAp/3+Hedu9tnMai+LihERPj84=","revision":"5c3c17164270150467498a32c71436c7cd5501be","revisionTime":"2016-06-02T16:00:07Z"},
 		{"path":"github.com/coreos/go-semver/semver","checksumSHA1":"97BsbXOiZ8+Kr+LIuZkQFtSj7H4=","revision":"1817cd4bea52af76542157eeabd74b057d1a199e","revisionTime":"2017-06-13T09:22:38Z"},
 		{"path":"github.com/coreos/go-systemd/dbus","checksumSHA1":"/zxxFPYjUB7Wowz33r5AhTDvoz0=","origin":"github.com/opencontainers/runc/vendor/github.com/coreos/go-systemd/dbus","revision":"459bfaec1fc6c17d8bfb12d0a0f69e7e7271ed2a","revisionTime":"2018-08-23T14:46:37Z"},