blob: 84b1295a8770600491d2776a428cef13a648a8c5 [file] [log] [blame]
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package randutil contains internal randomness utilities for various
// crypto packages.
package randutil
import (
var (
closedChanOnce sync.Once
closedChan chan struct{}
// MaybeReadByte reads a single byte from r with ~50% probability. This is used
// to ensure that callers do not depend on non-guaranteed behaviour, e.g.
// assuming that rsa.GenerateKey is deterministic w.r.t. a given random stream.
// This does not affect tests that pass a stream of fixed bytes as the random
// source (e.g. a zeroReader).
func MaybeReadByte(r io.Reader) {
closedChanOnce.Do(func() {
closedChan = make(chan struct{})
select {
case <-closedChan:
case <-closedChan:
var buf [1]byte