blob: a3faba81bc756bea90ef779890863f6a99f5aeef [file] [log] [blame]
// Copyright 2016 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Adapted from base/rand_util_posix.cc
#include "starboard/system.h"
#include "starboard/file.h"
#include "starboard/log.h"
#include "starboard/mutex.h"
#include "starboard/once.h"
namespace {
// We keep the open file descriptor for /dev/urandom around so we don't need to
// reopen it (which is expensive).
class URandomFile {
public:
URandomFile() {
file_ =
SbFileOpen("/dev/urandom", kSbFileOpenOnly | kSbFileRead, NULL, NULL);
SB_DCHECK(SbFileIsValid(file_)) << "Cannot open /dev/urandom";
}
~URandomFile() { SbFileClose(file_); }
SbFile file() const { return file_; }
private:
SbFile file_;
};
// A file that will produce any number of very random bytes.
URandomFile* g_urandom_file = NULL;
// Control to initialize g_urandom_file.
SbOnceControl g_urandom_file_once = SB_ONCE_INITIALIZER;
// Lazily initialize g_urandom_file.
void InitializeRandom() {
SB_DCHECK(g_urandom_file == NULL);
g_urandom_file = new URandomFile();
}
} // namespace
void SbSystemGetRandomData(void* out_buffer, int buffer_size) {
SB_DCHECK(out_buffer);
char* buffer = reinterpret_cast<char*>(out_buffer);
int remaining = buffer_size;
bool once_result = SbOnce(&g_urandom_file_once, &InitializeRandom);
SB_DCHECK(once_result);
SbFile file = g_urandom_file->file();
do {
// This is unsynchronized access to the File that could happen from multiple
// threads. It doesn't appear that there is any locking in the Chromium
// POSIX implementation that is very similar.
int result = SbFileRead(file, buffer, remaining);
if (result <= 0)
break;
remaining -= result;
buffer += result;
} while (remaining);
SB_CHECK(remaining == 0);
}