From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Mon, 23 May 2011 01:46:48 +0000 (-0700)
Subject: http: add docs/warning on incorrect use of NewChunkedWriter
X-Git-Tag: weekly.2011-05-22~1
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=ccafd53ed35b64cfe32b191870e0523d1538f00a;p=gostls13.git

http: add docs/warning on incorrect use of NewChunkedWriter

R=golang-dev, adg, r
CC=golang-dev
https://golang.org/cl/4536075
---

diff --git a/src/pkg/http/chunked.go b/src/pkg/http/chunked.go
index bfd68a4408..59121c5a23 100644
--- a/src/pkg/http/chunked.go
+++ b/src/pkg/http/chunked.go
@@ -6,14 +6,24 @@ package http
 
 import (
 	"io"
+	"log"
 	"os"
 	"strconv"
 )
 
 // NewChunkedWriter returns a new writer that translates writes into HTTP
-// "chunked" format before writing them to w.  Closing the returned writer
+// "chunked" format before writing them to w. Closing the returned writer
 // sends the final 0-length chunk that marks the end of the stream.
+//
+// NewChunkedWriter is not needed by normal applications. The http
+// package adds chunking automatically if handlers don't set a
+// Content-Length header. Using NewChunkedWriter inside a handler
+// would result in double chunking or chunking with a Content-Length
+// length, both of which are wrong.
 func NewChunkedWriter(w io.Writer) io.WriteCloser {
+	if _, bad := w.(*response); bad {
+		log.Printf("warning: using NewChunkedWriter in an http.Handler; expect corrupt output")
+	}
 	return &chunkedWriter{w}
 }