Add newlines to the JSON stream functions

This makes the JSON streams a _lot_ easier to parse in less well-baked JSON parsers, and no less so in better ones.

Line-based JSON streams are very, very common, where simply chunk-based is not very common at all.

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

utils/streamformatter.go

@@ -14,6 +14,10 @@ func NewStreamFormatter(json bool) *StreamFormatter {
 	return &StreamFormatter{json, false}
 }
 
+const streamNewline = "\r\n"
+
+var streamNewlineBytes = []byte(streamNewline)
+
 func (sf *StreamFormatter) FormatStream(str string) []byte {
 	sf.used = true
 	if sf.json {
@@ -21,7 +25,7 @@ func (sf *StreamFormatter) FormatStream(str string) []byte {
 		if err != nil {
 			return sf.FormatError(err)
 		}
-		return b
+		return append(b, streamNewlineBytes...)
 	}
 	return []byte(str + "\r")
 }
@@ -34,9 +38,9 @@ func (sf *StreamFormatter) FormatStatus(id, format string, a ...interface{}) []b
 		if err != nil {
 			return sf.FormatError(err)
 		}
-		return b
+		return append(b, streamNewlineBytes...)
 	}
-	return []byte(str + "\r\n")
+	return []byte(str + streamNewline)
 }
 
 func (sf *StreamFormatter) FormatError(err error) []byte {
@@ -47,11 +51,11 @@ func (sf *StreamFormatter) FormatError(err error) []byte {
 			jsonError = &JSONError{Message: err.Error()}
 		}
 		if b, err := json.Marshal(&JSONMessage{Error: jsonError, ErrorMessage: err.Error()}); err == nil {
-			return b
+			return append(b, streamNewlineBytes...)
 		}
-		return []byte("{\"error\":\"format error\"}")
+		return []byte("{\"error\":\"format error\"}" + streamNewline)
 	}
-	return []byte("Error: " + err.Error() + "\r\n")
+	return []byte("Error: " + err.Error() + streamNewline)
 }
 
 func (sf *StreamFormatter) FormatProgress(id, action string, progress *JSONProgress) []byte {