diff options
Diffstat (limited to 'src/net/http/server.go')
-rw-r--r-- | src/net/http/server.go | 40 |
1 files changed, 10 insertions, 30 deletions
diff --git a/src/net/http/server.go b/src/net/http/server.go index ad99741177d..198102ffd21 100644 --- a/src/net/http/server.go +++ b/src/net/http/server.go @@ -577,37 +577,17 @@ func (w *response) ReadFrom(src io.Reader) (n int64, err error) { return io.CopyBuffer(writerOnly{w}, src, buf) } - // sendfile path: - - // Do not start actually writing response until src is readable. - // If body length is <= sniffLen, sendfile/splice path will do - // little anyway. This small read also satisfies sniffing the - // body in case Content-Type is missing. - nr, er := src.Read(buf[:sniffLen]) - atEOF := errors.Is(er, io.EOF) - n += int64(nr) - - if nr > 0 { - // Write the small amount read normally. - nw, ew := w.Write(buf[:nr]) - if ew != nil { - err = ew - } else if nr != nw { - err = io.ErrShortWrite + // Copy the first sniffLen bytes before switching to ReadFrom. + // This ensures we don't start writing the response before the + // source is available (see golang.org/issue/5660) and provides + // enough bytes to perform Content-Type sniffing when required. + if !w.cw.wroteHeader { + n0, err := io.CopyBuffer(writerOnly{w}, io.LimitReader(src, sniffLen), buf) + n += n0 + if err != nil || n0 < sniffLen { + return n, err } } - if err == nil && er != nil && !atEOF { - err = er - } - - // Do not send StatusOK in the error case where nothing has been written. - if err == nil && !w.wroteHeader { - w.WriteHeader(StatusOK) // nr == 0, no error (or EOF) - } - - if err != nil || atEOF { - return n, err - } w.w.Flush() // get rid of any previous writes w.cw.flush() // make sure Header is written; flush data to rwc @@ -620,7 +600,7 @@ func (w *response) ReadFrom(src io.Reader) (n int64, err error) { return n, err } - n0, err := io.Copy(writerOnly{w}, src) + n0, err := io.CopyBuffer(writerOnly{w}, src, buf) n += n0 return n, err } |