net/http: add NoBody, don't return nil from NewRequest on zero bodies

This is an alternate solution to https://golang.org/cl/31445

Instead of making NewRequest return a request with Request.Body == nil
to signal a zero byte body, add a well-known variable that means
explicitly zero.

Too many tests inside Google (and presumably the outside world)
broke.

Change-Id: I78f6ecca8e8aa1e12179c234ccfb6bcf0ee29ba8
Reviewed-on: https://go-review.googlesource.com/31726
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

1 files changed, 2 insertions, 20 deletions

diff --git a/src/net/http/server.go b/src/net/http/server.go
index ad89d0cfbe..c47cc328fc 100644
--- a/src/net/http/server.go
+++ b/src/net/http/server.go
@@ -1776,7 +1776,7 @@ func registerOnHitEOF(rc io.ReadCloser, fn func()) {
 // requestBodyRemains reports whether future calls to Read
 // on rc might yield more data.
 func requestBodyRemains(rc io.ReadCloser) bool {
-	if rc == eofReader {
+	if rc == NoBody {
 		return false
 	}
 	switch v := rc.(type) {
@@ -2702,24 +2702,6 @@ func (globalOptionsHandler) ServeHTTP(w ResponseWriter, r *Request) {
 	}
 }
 
-type eofReaderWithWriteTo struct{}
-
-func (eofReaderWithWriteTo) WriteTo(io.Writer) (int64, error) { return 0, nil }
-func (eofReaderWithWriteTo) Read([]byte) (int, error)         { return 0, io.EOF }
-
-// eofReader is a non-nil io.ReadCloser that always returns EOF.
-// It has a WriteTo method so io.Copy won't need a buffer.
-var eofReader = &struct {
-	eofReaderWithWriteTo
-	io.Closer
-}{
-	eofReaderWithWriteTo{},
-	ioutil.NopCloser(nil),
-}
-
-// Verify that an io.Copy from an eofReader won't require a buffer.
-var _ io.WriterTo = eofReader
-
 // initNPNRequest is an HTTP handler that initializes certain
 // uninitialized fields in its *Request. Such partially-initialized
 // Requests come from NPN protocol handlers.
@@ -2734,7 +2716,7 @@ func (h initNPNRequest) ServeHTTP(rw ResponseWriter, req *Request) {
 		*req.TLS = h.c.ConnectionState()
 	}
 	if req.Body == nil {
-		req.Body = eofReader
+		req.Body = NoBody
 	}
 	if req.RemoteAddr == "" {
 		req.RemoteAddr = h.c.RemoteAddr().String()