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// 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/logging.h"
#include "base/posix/eintr_wrapper.h"
namespace {
class URandomFd {
public:
URandomFd() : fd_(open("/dev/urandom", O_RDONLY)) {
DCHECK_GE(fd_, 0) << "Cannot open /dev/urandom: " << errno;
}
~URandomFd() { close(fd_); }
int fd() const { return fd_; }
private:
const int fd_;
};
bool ReadFromFD(int fd, char* buffer, size_t bytes) {
size_t total_read = 0;
while (total_read < bytes) {
ssize_t bytes_read =
HANDLE_EINTR(read(fd, buffer + total_read, bytes - total_read));
if (bytes_read <= 0)
break;
total_read += bytes_read;
}
return total_read == bytes;
}
} // namespace
namespace base {
// NOTE: This function must be cryptographically secure. http://crbug.com/140076
uint64_t RandUint64() {
uint64_t number;
RandBytes(&number, sizeof(number));
return number;
}
void RandBytes(void* output, size_t output_length) {
URandomFd urandom_fd;
const bool success =
ReadFromFD(urandom_fd.fd(), static_cast<char*>(output), output_length);
CHECK(success);
}
} // namespace base
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