1 files changed, 162 insertions, 0 deletions
diff --git a/pkg/shim/proc/io.go b/pkg/shim/proc/io.go
new file mode 100644
index 000000000..34d825fb7
--- /dev/null
+++ b/pkg/shim/proc/io.go
@@ -0,0 +1,162 @@
+// Copyright 2018 The containerd Authors.
+// Copyright 2018 The gVisor 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
+//
+//     https://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 proc
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"sync"
+	"sync/atomic"
+	"syscall"
+
+	"github.com/containerd/containerd/log"
+	"github.com/containerd/fifo"
+	runc "github.com/containerd/go-runc"
+)
+
+// TODO(random-liu): This file can be a util.
+
+var bufPool = sync.Pool{
+	New: func() interface{} {
+		buffer := make([]byte, 32<<10)
+		return &buffer
+	},
+}
+
+func copyPipes(ctx context.Context, rio runc.IO, stdin, stdout, stderr string, wg *sync.WaitGroup) error {
+	var sameFile *countingWriteCloser
+	for _, i := range []struct {
+		name string
+		dest func(wc io.WriteCloser, rc io.Closer)
+	}{
+		{
+			name: stdout,
+			dest: func(wc io.WriteCloser, rc io.Closer) {
+				wg.Add(1)
+				go func() {
+					p := bufPool.Get().(*[]byte)
+					defer bufPool.Put(p)
+					if _, err := io.CopyBuffer(wc, rio.Stdout(), *p); err != nil {
+						log.G(ctx).Warn("error copying stdout")
+					}
+					wg.Done()
+					wc.Close()
+					if rc != nil {
+						rc.Close()
+					}
+				}()
+			},
+		}, {
+			name: stderr,
+			dest: func(wc io.WriteCloser, rc io.Closer) {
+				wg.Add(1)
+				go func() {
+					p := bufPool.Get().(*[]byte)
+					defer bufPool.Put(p)
+					if _, err := io.CopyBuffer(wc, rio.Stderr(), *p); err != nil {
+						log.G(ctx).Warn("error copying stderr")
+					}
+					wg.Done()
+					wc.Close()
+					if rc != nil {
+						rc.Close()
+					}
+				}()
+			},
+		},
+	} {
+		ok, err := isFifo(i.name)
+		if err != nil {
+			return err
+		}
+		var (
+			fw io.WriteCloser
+			fr io.Closer
+		)
+		if ok {
+			if fw, err = fifo.OpenFifo(ctx, i.name, syscall.O_WRONLY, 0); err != nil {
+				return fmt.Errorf("gvisor-containerd-shim: opening %s failed: %s", i.name, err)
+			}
+			if fr, err = fifo.OpenFifo(ctx, i.name, syscall.O_RDONLY, 0); err != nil {
+				return fmt.Errorf("gvisor-containerd-shim: opening %s failed: %s", i.name, err)
+			}
+		} else {
+			if sameFile != nil {
+				sameFile.count++
+				i.dest(sameFile, nil)
+				continue
+			}
+			if fw, err = os.OpenFile(i.name, syscall.O_WRONLY|syscall.O_APPEND, 0); err != nil {
+				return fmt.Errorf("gvisor-containerd-shim: opening %s failed: %s", i.name, err)
+			}
+			if stdout == stderr {
+				sameFile = &countingWriteCloser{
+					WriteCloser: fw,
+					count:       1,
+				}
+			}
+		}
+		i.dest(fw, fr)
+	}
+	if stdin == "" {
+		return nil
+	}
+	f, err := fifo.OpenFifo(context.Background(), stdin, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
+	if err != nil {
+		return fmt.Errorf("gvisor-containerd-shim: opening %s failed: %s", stdin, err)
+	}
+	go func() {
+		p := bufPool.Get().(*[]byte)
+		defer bufPool.Put(p)
+
+		io.CopyBuffer(rio.Stdin(), f, *p)
+		rio.Stdin().Close()
+		f.Close()
+	}()
+	return nil
+}
+
+// countingWriteCloser masks io.Closer() until close has been invoked a certain number of times.
+type countingWriteCloser struct {
+	io.WriteCloser
+	count int64
+}
+
+func (c *countingWriteCloser) Close() error {
+	if atomic.AddInt64(&c.count, -1) > 0 {
+		return nil
+	}
+	return c.WriteCloser.Close()
+}
+
+// isFifo checks if a file is a fifo.
+//
+// If the file does not exist then it returns false.
+func isFifo(path string) (bool, error) {
+	stat, err := os.Stat(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	if stat.Mode()&os.ModeNamedPipe == os.ModeNamedPipe {
+		return true, nil
+	}
+	return false, nil
+}