1 files changed, 76 insertions, 0 deletions
diff --git a/common/hugio/writers.go b/common/hugio/writers.go
new file mode 100644
index 000000000..82c4dca52
--- /dev/null
+++ b/common/hugio/writers.go
@@ -0,0 +1,76 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// 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 hugio
+
+import (
+	"io"
+	"io/ioutil"
+)
+
+type multiWriteCloser struct {
+	io.Writer
+	closers []io.WriteCloser
+}
+
+func (m multiWriteCloser) Close() error {
+	var err error
+	for _, c := range m.closers {
+		if closeErr := c.Close(); err != nil {
+			err = closeErr
+		}
+	}
+	return err
+}
+
+// NewMultiWriteCloser creates a new io.WriteCloser that duplicates its writes to all the
+// provided writers.
+func NewMultiWriteCloser(writeClosers ...io.WriteCloser) io.WriteCloser {
+	writers := make([]io.Writer, len(writeClosers))
+	for i, w := range writeClosers {
+		writers[i] = w
+	}
+	return multiWriteCloser{Writer: io.MultiWriter(writers...), closers: writeClosers}
+}
+
+// ToWriteCloser creates an io.WriteCloser from the given io.Writer.
+// If it's not already, one will be created with a Close method that does nothing.
+func ToWriteCloser(w io.Writer) io.WriteCloser {
+	if rw, ok := w.(io.WriteCloser); ok {
+		return rw
+	}
+
+	return struct {
+		io.Writer
+		io.Closer
+	}{
+		w,
+		ioutil.NopCloser(nil),
+	}
+}
+
+// ToReadCloser creates an io.ReadCloser from the given io.Reader.
+// If it's not already, one will be created with a Close method that does nothing.
+func ToReadCloser(r io.Reader) io.ReadCloser {
+	if rc, ok := r.(io.ReadCloser); ok {
+		return rc
+	}
+
+	return struct {
+		io.Reader
+		io.Closer
+	}{
+		r,
+		ioutil.NopCloser(nil),
+	}
+}