1 files changed, 18 insertions, 0 deletions
diff --git a/src/crypto/rand/rand.go b/src/crypto/rand/rand.go
index fddd1147e6..f2c276008d 100644
--- a/src/crypto/rand/rand.go
+++ b/src/crypto/rand/rand.go
@@ -23,3 +23,21 @@ var Reader io.Reader
 func Read(b []byte) (n int, err error) {
 	return io.ReadFull(Reader, b)
 }
+
+// batched returns a function that calls f to populate a []byte by chunking it
+// into subslices of, at most, readMax bytes.
+func batched(f func([]byte) error, readMax int) func([]byte) error {
+	return func(out []byte) error {
+		for len(out) > 0 {
+			read := len(out)
+			if read > readMax {
+				read = readMax
+			}
+			if err := f(out[:read]); err != nil {
+				return err
+			}
+			out = out[read:]
+		}
+		return nil
+	}
+}