X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/7db3ceda16742b65d73ebbc05d02351a5e0496bd..b334b065b36357dd08099adad9835f4aa7075337:/sdk/go/httpserver/responsewriter.go

diff --git a/sdk/go/httpserver/responsewriter.go b/sdk/go/httpserver/responsewriter.go
index 26aee65c5c..049a3f1aae 100644
--- a/sdk/go/httpserver/responsewriter.go
+++ b/sdk/go/httpserver/responsewriter.go
@@ -22,7 +22,7 @@ type ResponseWriter interface {
 // error.
 type responseWriter struct {
 	http.ResponseWriter
-	wroteStatus    int   // Last status given to WriteHeader()
+	wroteStatus    int   // First status given to WriteHeader()
 	wroteBodyBytes int   // Bytes successfully written
 	err            error // Last error returned from Write()
 	sniffed        []byte
@@ -40,15 +40,21 @@ func (w *responseWriter) CloseNotify() <-chan bool {
 }
 
 func (w *responseWriter) WriteHeader(s int) {
-	w.wroteStatus = s
+	if w.wroteStatus == 0 {
+		w.wroteStatus = s
+	}
+	// ...else it's too late to change the status seen by the
+	// client -- but we call the wrapped WriteHeader() anyway so
+	// it can log a warning.
 	w.ResponseWriter.WriteHeader(s)
 }
 
 func (w *responseWriter) Write(data []byte) (n int, err error) {
 	if w.wroteStatus == 0 {
 		w.WriteHeader(http.StatusOK)
+	} else if w.wroteStatus >= 400 {
+		w.sniff(data)
 	}
-	w.sniff(data)
 	n, err = w.ResponseWriter.Write(data)
 	w.wroteBodyBytes += n
 	w.err = err