1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
base / rand_util_fuchsia.cc [blame]
// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40284755): Remove this and spanify to fix the errors.
#pragma allow_unsafe_buffers
#endif
#include "base/rand_util.h"
#include <zircon/syscalls.h>
#include <atomic>
#include "base/containers/span.h"
#include "base/feature_list.h"
#include "third_party/boringssl/src/include/openssl/rand.h"
namespace base {
namespace internal {
namespace {
// The BoringSSl helpers are duplicated in rand_util_posix.cc and
// rand_util_win.cc.
std::atomic<bool> g_use_boringssl;
BASE_FEATURE(kUseBoringSSLForRandBytes,
"UseBoringSSLForRandBytes",
FEATURE_DISABLED_BY_DEFAULT);
} // namespace
void ConfigureBoringSSLBackedRandBytesFieldTrial() {
g_use_boringssl.store(FeatureList::IsEnabled(kUseBoringSSLForRandBytes),
std::memory_order_relaxed);
}
bool UseBoringSSLForRandBytes() {
return g_use_boringssl.load(std::memory_order_relaxed);
}
} // namespace internal
void RandBytes(span<uint8_t> output) {
if (internal::UseBoringSSLForRandBytes()) {
// BoringSSL's RAND_bytes always returns 1. Any error aborts the program.
(void)RAND_bytes(output.data(), output.size());
return;
}
zx_cprng_draw(output.data(), output.size());
}
namespace internal {
double RandDoubleAvoidAllocation() {
uint64_t number;
zx_cprng_draw(&number, sizeof(number));
// This transformation is explained in rand_util.cc.
return (number >> 11) * 0x1.0p-53;
}
} // namespace internal
} // namespace base