mox!

moxio/limitreader.go

@@ -0,0 +1,27 @@
+package moxio
+
+import (
+	"errors"
+	"io"
+)
+
+var ErrLimit = errors.New("input exceeds maximum size") // Returned by LimitReader.
+
+// LimitReader reads up to Limit bytes, returning an error if more bytes are
+// read. LimitReader can be used to enforce a maximum input length.
+type LimitReader struct {
+	R     io.Reader
+	Limit int64
+}
+
+// Read reads bytes from the underlying reader.
+func (r *LimitReader) Read(buf []byte) (int, error) {
+	n, err := r.R.Read(buf)
+	if n > 0 {
+		r.Limit -= int64(n)
+		if r.Limit < 0 {
+			return 0, ErrLimit
+		}
+	}
+	return n, err
+}