blob: 767497ca7aa799db84699705a2e6d9b6cb52ce4d [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/rand_util.h"
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdint.h>
#include <unistd.h>
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/no_destructor.h"
#include "base/posix/eintr_wrapper.h"
namespace {
// We keep the file descriptor for /dev/urandom around so we don't need to
// reopen it (which is expensive), and since we may not even be able to reopen
// it if we are later put in a sandbox. This class wraps the file descriptor so
// we can use a static-local variable to handle opening it on the first access.
class URandomFd {
#if defined(OS_AIX)
// AIX has no 64-bit support for open falgs such as -
URandomFd() : fd_(HANDLE_EINTR(open("/dev/urandom", O_RDONLY))) {
DPCHECK(fd_ >= 0) << "Cannot open /dev/urandom";
URandomFd() : fd_(HANDLE_EINTR(open("/dev/urandom", O_RDONLY | O_CLOEXEC))) {
DPCHECK(fd_ >= 0) << "Cannot open /dev/urandom";
~URandomFd() { close(fd_); }
int fd() const { return fd_; }
const int fd_;
} // namespace
namespace base {
void RandBytes(void* output, size_t output_length) {
const int urandom_fd = GetUrandomFD();
const bool success =
ReadFromFD(urandom_fd, static_cast<char*>(output), output_length);
int GetUrandomFD() {
static NoDestructor<URandomFd> urandom_fd;
return urandom_fd->fd();
} // namespace base