Merge pull request #27405 from tonistiigi/fix-fifo2

Fix issues with fifos blocking on open
Upstream-commit: 32b541e44385206772b30b2a6f241a7c809aa62f
Component: engine

components/engine/vendor/src/github.com/tonistiigi/fifo/LICENSE

@@ -0,0 +1,21 @@
+MIT
+
+Copyright (C) 2016 Tõnis Tiigi <tonistiigi@gmail.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

components/engine/vendor/src/github.com/tonistiigi/fifo/Makefile

@@ -0,0 +1,13 @@
+.PHONY: fmt vet test deps
+
+test: deps
+	go test -v ./...
+
+deps:
+	go get -d -t ./...
+
+fmt:
+	gofmt -s -l .
+
+vet:
+	go vet ./...

components/engine/vendor/src/github.com/tonistiigi/fifo/fifo.go

@@ -0,0 +1,215 @@
+package fifo
+
+import (
+	"context"
+	"io"
+	"os"
+	"runtime"
+	"sync"
+	"syscall"
+
+	"github.com/pkg/errors"
+)
+
+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 := syscall.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():
+			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", fn)
+				}
+				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() error {
+	for {
+		select {
+		case <-f.closed:
+			f.handle.Close()
+			return f.err
+		default:
+			select {
+			case <-f.opened:
+				f.closedOnce.Do(func() {
+					f.err = f.file.Close()
+					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()
+				}
+			}
+		}
+	}
+}

components/engine/vendor/src/github.com/tonistiigi/fifo/handle_linux.go

@@ -0,0 +1,70 @@
+// +build linux
+
+package fifo
+
+import (
+	"fmt"
+	"os"
+	"sync"
+	"syscall"
+
+	"github.com/pkg/errors"
+)
+
+const O_PATH = 010000000
+
+type handle struct {
+	f         *os.File
+	dev       uint64
+	ino       uint64
+	closeOnce sync.Once
+}
+
+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
+	if err := syscall.Fstat(int(f.Fd()), &stat); err != nil {
+		f.Close()
+		return nil, errors.Wrapf(err, "failed to stat handle %v", f.Fd())
+	}
+
+	h := &handle{
+		f:   f,
+		dev: stat.Dev,
+		ino: stat.Ino,
+	}
+
+	// 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.f.Fd())
+}
+
+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 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
+}

components/engine/vendor/src/github.com/tonistiigi/fifo/handle_nolinux.go

@@ -0,0 +1,45 @@
+// +build !linux
+
+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: 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 || 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.fn, nil
+}
+
+func (h *handle) Close() error {
+	return nil
+}

components/engine/vendor/src/github.com/tonistiigi/fifo/readme.md

@@ -0,0 +1,30 @@
+### 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 
+```