ensure valid json

commands.go

@@ -1258,14 +1258,9 @@ func (cli *DockerCli) stream(method, path string, in io.Reader, out io.Writer) e
 	}
 
 	if resp.Header.Get("Content-Type") == "application/json" {
-		type Message struct {
-			Status   string `json:"status,omitempty"`
-			Progress string `json:"progress,omitempty"`
-			Error    string `json:"error,omitempty"`
-		}
 		dec := json.NewDecoder(resp.Body)
 		for {
-			var m Message
+			var m utils.JsonMessage
 			if err := dec.Decode(&m); err == io.EOF {
 				break
 			} else if err != nil {

server.go

@@ -368,7 +368,7 @@ func (srv *Server) pullRepository(out io.Writer, remote, askedTag string, sf *ut
 		success := false
 		for _, ep := range repoData.Endpoints {
 			if err := srv.pullImage(out, img.Id, "https://"+ep+"/v1", repoData.Tokens, sf); err != nil {
-				fmt.Fprintf(out, sf.FormatStatus("Error while retrieving image for tag: %s (%s); checking next endpoint\n"), askedTag, err)
+				fmt.Fprintf(out, sf.FormatStatus("Error while retrieving image for tag: %s (%s); checking next endpoint"), askedTag, err)
 				continue
 			}
 			success = true

utils/utils.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/sha256"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"index/suffixarray"
@@ -557,6 +558,12 @@ func NewWriteFlusher(w io.Writer) *WriteFlusher {
 	return &WriteFlusher{w: w, flusher: flusher}
 }
 
+type JsonMessage struct {
+	Status   string `json:"status,omitempty"`
+	Progress string `json:"progress,omitempty"`
+	Error    string `json:"error,omitempty"`
+}
+
 type StreamFormatter struct {
 	json bool
 	used bool
@@ -569,7 +576,11 @@ func NewStreamFormatter(json bool) *StreamFormatter {
 func (sf *StreamFormatter) FormatStatus(str string) string {
 	sf.used = true
 	if sf.json {
-		return "{\"status\" : \"" + str + "\"}"
+		b, err := json.Marshal(&JsonMessage{Status:str});
+		if err != nil {
+			return sf.FormatError(err)
+		}
+		return string(b)
 	}
 	return str + "\r\n"
 }
@@ -577,7 +588,10 @@ func (sf *StreamFormatter) FormatStatus(str string) string {
 func (sf *StreamFormatter) FormatError(err error) string {
 	sf.used = true
 	if sf.json {
-		return "{\"error\" : \"" + err.Error() + "\"}"
+		if b, err := json.Marshal(&JsonMessage{Error:err.Error()}); err == nil {
+			return string(b)
+		}
+		return "{\"error\":\"format error\"}"
 	}
 	return "Error: " + err.Error() + "\r\n"
 }
@@ -585,7 +599,11 @@ func (sf *StreamFormatter) FormatError(err error) string {
 func (sf *StreamFormatter) FormatProgress(action, str string) string {
 	sf.used = true
 	if sf.json {
-		return "{\"progress\" : \"" + str + "\"}"
+		b, err := json.Marshal(&JsonMessage{Progress:str})
+		if err != nil {
+                        return sf.FormatError(err)
+                }
+		return string(b)
 	}
 	return action + " " + str + "\r"
 }