crypto/cipher: don't persist errors in StreamWriter.

I messed this up from the beginning. The receiver isn't a pointer so
setting Err is useless. In order to maintain the API, just remove the
superfluous code.

Fixes #4657.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7161043

diff --git a/src/pkg/crypto/cipher/io.go b/src/pkg/crypto/cipher/io.go
index 76048fbf33953684faa83e44103b3110f59add7c..807e8daeaf45a9681b28ef386c075f76c5b4beff 100644 (file)
--- a/src/pkg/crypto/cipher/io.go
+++ b/src/pkg/crypto/cipher/io.go
@@ -28,13 +28,10 @@ func (r StreamReader) Read(dst []byte) (n int, err error) {
 type StreamWriter struct {
        S   Stream
        W   io.Writer
-       Err error
+       Err error // unused
 }
 
 func (w StreamWriter) Write(src []byte) (n int, err error) {
-       if w.Err != nil {
-               return 0, w.Err
-       }
        c := make([]byte, len(src))
        w.S.XORKeyStream(c, src)
        n, err = w.W.Write(c)
@@ -42,7 +39,6 @@ func (w StreamWriter) Write(src []byte) (n int, err error) {
                if err == nil { // should never happen
                        err = io.ErrShortWrite
                }
-               w.Err = err
        }
        return
 }