update: limit logBrief http body size (#3498)

Co-authored-by: 常公征 <changgz@yealink.com>

core/iox/tee.go

@@ -0,0 +1,33 @@
+package iox
+
+import "io"
+
+// LimitTeeReader returns a Reader that writes up to n bytes to w what it reads from r.
+// First n bytes reads from r performed through it are matched with
+// corresponding writes to w. There is no internal buffering -
+// the write must complete before the first n bytes read completes.
+// Any error encountered while writing is reported as a read error.
+func LimitTeeReader(r io.Reader, w io.Writer, n int64) io.Reader {
+	return &limitTeeReader{r, w, n}
+}
+
+type limitTeeReader struct {
+	r io.Reader
+	w io.Writer
+	n int64 // limit bytes remaining
+}
+
+func (t *limitTeeReader) Read(p []byte) (n int, err error) {
+	n, err = t.r.Read(p)
+	if n > 0 && t.n > 0 {
+		limit := int64(n)
+		if limit > t.n {
+			limit = t.n
+		}
+		if n, err := t.w.Write(p[:limit]); err != nil {
+			return n, err
+		}
+		t.n -= limit
+	}
+	return
+}