Move isFifo from process/io to sys/ and make public

Make "IsFifo" a public function for use by other parts of containerd
codebase.

Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>

pkg/process/io.go

@@ -33,6 +33,7 @@ import (
 	"github.com/containerd/containerd/log"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/pkg/stdio"
+	"github.com/containerd/containerd/sys"
 	"github.com/containerd/fifo"
 	runc "github.com/containerd/go-runc"
 	"github.com/pkg/errors"
@@ -174,7 +175,7 @@ func copyPipes(ctx context.Context, rio runc.IO, stdin, stdout, stderr string, w
 			},
 		},
 	} {
-		ok, err := isFifo(i.name)
+		ok, err := sys.IsFifo(i.name)
 		if err != nil {
 			return err
 		}
@@ -240,22 +241,6 @@ func (c *countingWriteCloser) Close() error {
 	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
-}
-
 // NewBinaryIO runs a custom binary process for pluggable shim logging
 func NewBinaryIO(ctx context.Context, id string, uri *url.URL) (runc.IO, error) {
 	ns, err := namespaces.NamespaceRequired(ctx)

sys/filesys.go

@@ -0,0 +1,35 @@
+/*
+   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 sys
+
+import "os"
+
+// IsFifo checks if a file is a (named pipe) 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
+}