fix golint issues in core/iox (#488)

core/iox/read.go

@@ -16,9 +16,11 @@ type (
 		omitPrefix    string
 	}
 
+	// TextReadOption defines the method to customize the text reading functions.
 	TextReadOption func(*textReadOptions)
 )
 
+// DupReadCloser returns two io.ReadCloser that read from the first will be written to the second.
 // The first returned reader needs to be read first, because the content
 // read from it will be written to the underlying buffer of the second reader.
 func DupReadCloser(reader io.ReadCloser) (io.ReadCloser, io.ReadCloser) {
@@ -27,6 +29,7 @@ func DupReadCloser(reader io.ReadCloser) (io.ReadCloser, io.ReadCloser) {
 	return ioutil.NopCloser(tee), ioutil.NopCloser(&buf)
 }
 
+// KeepSpace customizes the reading functions to keep leading and tailing spaces.
 func KeepSpace() TextReadOption {
 	return func(o *textReadOptions) {
 		o.keepSpace = true
@@ -49,6 +52,7 @@ func ReadBytes(reader io.Reader, buf []byte) error {
 	return nil
 }
 
+// ReadText reads content from the given file with leading and tailing spaces trimmed.
 func ReadText(filename string) (string, error) {
 	content, err := ioutil.ReadFile(filename)
 	if err != nil {
@@ -58,6 +62,7 @@ func ReadText(filename string) (string, error) {
 	return strings.TrimSpace(string(content)), nil
 }
 
+// ReadTextLines reads the text lines from given file.
 func ReadTextLines(filename string, opts ...TextReadOption) ([]string, error) {
 	var readOpts textReadOptions
 	for _, opt := range opts {
@@ -90,12 +95,14 @@ func ReadTextLines(filename string, opts ...TextReadOption) ([]string, error) {
 	return lines, scanner.Err()
 }
 
+// WithoutBlank customizes the reading functions to ignore blank lines.
 func WithoutBlank() TextReadOption {
 	return func(o *textReadOptions) {
 		o.withoutBlanks = true
 	}
 }
 
+// OmitWithPrefix customizes the reading functions to ignore the lines with given leading prefix.
 func OmitWithPrefix(prefix string) TextReadOption {
 	return func(o *textReadOptions) {
 		o.omitPrefix = prefix