add vendor & update README.md

vendor/github.com/qiniu/x/bytes.v7/seekable/seekable.go

@@ -0,0 +1,63 @@
+// This package provide a method to read and replace http.Request's body.
+package seekable
+
+import (
+	"errors"
+	"io"
+	"io/ioutil"
+	"net/http"
+
+	"qiniupkg.com/x/bytes.v7"
+)
+
+// ---------------------------------------------------
+
+type Seekabler interface {
+	Bytes() []byte
+	Read(val []byte) (n int, err error)
+	SeekToBegin() error
+}
+
+type SeekableCloser interface {
+	Seekabler
+	io.Closer
+}
+
+// ---------------------------------------------------
+
+type readCloser struct {
+	Seekabler
+	io.Closer
+}
+
+var ErrNoBody = errors.New("no body")
+
+func New(req *http.Request) (r SeekableCloser, err error) {
+	if req.Body == nil {
+		return nil, ErrNoBody
+	}
+	var ok bool
+	if r, ok = req.Body.(SeekableCloser); ok {
+		return
+	}
+	b, err2 := ReadAll(req)
+	if err2 != nil {
+		return nil, err2
+	}
+	r = bytes.NewReader(b)
+	req.Body = readCloser{r, req.Body}
+	return
+}
+
+func ReadAll(req *http.Request) (b []byte, err error) {
+	if req.ContentLength > 0 {
+		b = make([]byte, int(req.ContentLength))
+		_, err = io.ReadFull(req.Body, b)
+		return
+	} else if req.ContentLength == 0 {
+		return nil, ErrNoBody
+	}
+	return ioutil.ReadAll(req.Body)
+}
+
+// ---------------------------------------------------