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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /src/crypto/internal/randutil | |
parent | Initial commit. (diff) | |
download | golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/crypto/internal/randutil')
-rw-r--r-- | src/crypto/internal/randutil/randutil.go | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/src/crypto/internal/randutil/randutil.go b/src/crypto/internal/randutil/randutil.go new file mode 100644 index 0000000..84b1295 --- /dev/null +++ b/src/crypto/internal/randutil/randutil.go @@ -0,0 +1,38 @@ +// 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 ( + "io" + "sync" +) + +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{}) + close(closedChan) + }) + + select { + case <-closedChan: + return + case <-closedChan: + var buf [1]byte + r.Read(buf[:]) + } +} |