2 files changed, 107 insertions, 0 deletions
diff --git a/utils/ioutil/common.go b/utils/ioutil/common.go
new file mode 100644
index 0000000..13db692
--- /dev/null
+++ b/utils/ioutil/common.go
@@ -0,0 +1,52 @@
+package ioutil
+
+import (
+	"bufio"
+	"errors"
+	"io"
+)
+
+type readPeeker interface {
+	io.Reader
+	Peek(int) ([]byte, error)
+}
+
+var (
+	ErrEmptyReader = errors.New("reader is empty")
+)
+
+// NonEmptyReader takes a reader and returns it if it is not empty, or
+// `ErrEmptyReader` if it is empty. If there is an error when reading the first
+// byte of the given reader, it will be propagated.
+func NonEmptyReader(r io.Reader) (io.Reader, error) {
+	pr, ok := r.(readPeeker)
+	if !ok {
+		pr = bufio.NewReader(r)
+	}
+
+	_, err := pr.Peek(1)
+	if err == io.EOF {
+		return nil, ErrEmptyReader
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	return pr, nil
+}
+
+type readCloser struct {
+	io.Reader
+	closer io.Closer
+}
+
+func (r *readCloser) Close() error {
+	return r.closer.Close()
+}
+
+// NewReadCloser creates an `io.ReadCloser` with the given `io.Reader` and
+// `io.Closer`.
+func NewReadCloser(r io.Reader, c io.Closer) io.ReadCloser {
+	return &readCloser{Reader: r, closer: c}
+}
diff --git a/utils/ioutil/common_test.go b/utils/ioutil/common_test.go
new file mode 100644
index 0000000..f5017f7
--- /dev/null
+++ b/utils/ioutil/common_test.go
@@ -0,0 +1,55 @@
+package ioutil
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+
+	. "gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type CommonSuite struct{}
+
+var _ = Suite(&CommonSuite{})
+
+type closer struct {
+	called int
+}
+
+func (c *closer) Close() error {
+	c.called++
+	return nil
+}
+
+func (s *CommonSuite) TestNonEmptyReader_Empty(c *C) {
+	var buf bytes.Buffer
+	r, err := NonEmptyReader(&buf)
+	c.Assert(err, Equals, ErrEmptyReader)
+	c.Assert(r, IsNil)
+}
+
+func (s *CommonSuite) TestNonEmptyReader_NonEmpty(c *C) {
+	buf := bytes.NewBuffer([]byte("1"))
+	r, err := NonEmptyReader(buf)
+	c.Assert(err, IsNil)
+	c.Assert(r, NotNil)
+
+	read, err := ioutil.ReadAll(r)
+	c.Assert(err, IsNil)
+	c.Assert(string(read), Equals, "1")
+}
+
+func (s *CommonSuite) TestNewReadCloser(c *C) {
+	buf := bytes.NewBuffer([]byte("1"))
+	closer := &closer{}
+	r := NewReadCloser(buf, closer)
+
+	read, err := ioutil.ReadAll(r)
+	c.Assert(err, IsNil)
+	c.Assert(string(read), Equals, "1")
+
+	c.Assert(r.Close(), IsNil)
+	c.Assert(closer.called, Equals, 1)
+}