You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
90 lines
2.5 KiB
90 lines
2.5 KiB
4 months ago
|
//
|
||
|
|
// Copyright (C) 2014 The Android Open Source Project
|
||
|
|
//
|
||
|
|
// 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.
|
||
|
|
//
|
||
|
|
|
||
|
|
#include "update_engine/update_manager/real_random_provider.h"
|
||
|
|
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
|
||
|
|
#include <string>
|
||
|
|
|
||
|
|
#include <base/files/file_path.h>
|
||
|
|
#include <base/files/scoped_file.h>
|
||
|
|
#include <base/strings/stringprintf.h>
|
||
|
|
|
||
|
|
#include "update_engine/update_manager/variable.h"
|
||
|
|
|
||
|
|
using std::string;
|
||
|
|
|
||
|
|
namespace {
|
||
|
|
|
||
|
|
// The device providing randomness.
|
||
|
|
const char* kRandomDevice = "/dev/urandom";
|
||
|
|
|
||
|
|
} // namespace
|
||
|
|
|
||
|
|
namespace chromeos_update_manager {
|
||
|
|
|
||
|
|
// A random seed variable.
|
||
|
|
class RandomSeedVariable : public Variable<uint64_t> {
|
||
|
|
public:
|
||
|
|
// RandomSeedVariable is initialized as kVariableModeConst to let the
|
||
|
|
// EvaluationContext cache the value between different evaluations of the same
|
||
|
|
// policy request.
|
||
|
|
RandomSeedVariable(const string& name, FILE* fp)
|
||
|
|
: Variable<uint64_t>(name, kVariableModeConst), fp_(fp) {}
|
||
|
|
~RandomSeedVariable() override {}
|
||
|
|
|
||
|
|
protected:
|
||
|
|
const uint64_t* GetValue(base::TimeDelta /* timeout */,
|
||
|
|
string* errmsg) override {
|
||
|
|
uint64_t result;
|
||
|
|
// Aliasing via char pointer abides by the C/C++ strict-aliasing rules.
|
||
|
|
char* const buf = reinterpret_cast<char*>(&result);
|
||
|
|
unsigned int buf_rd = 0;
|
||
|
|
|
||
|
|
while (buf_rd < sizeof(result)) {
|
||
|
|
int rd = fread(buf + buf_rd, 1, sizeof(result) - buf_rd, fp_.get());
|
||
|
|
if (rd == 0 || ferror(fp_.get())) {
|
||
|
|
// Either EOF on fp or read failed.
|
||
|
|
if (errmsg) {
|
||
|
|
*errmsg = base::StringPrintf(
|
||
|
|
"Error reading from the random device: %s", kRandomDevice);
|
||
|
|
}
|
||
|
|
return nullptr;
|
||
|
|
}
|
||
|
|
buf_rd += rd;
|
||
|
|
}
|
||
|
|
|
||
|
|
return new uint64_t(result);
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
base::ScopedFILE fp_;
|
||
|
|
|
||
|
|
DISALLOW_COPY_AND_ASSIGN(RandomSeedVariable);
|
||
|
|
};
|
||
|
|
|
||
|
|
bool RealRandomProvider::Init(void) {
|
||
|
|
FILE* fp = fopen(kRandomDevice, "r");
|
||
|
|
if (!fp)
|
||
|
|
return false;
|
||
|
|
var_seed_.reset(new RandomSeedVariable("seed", fp));
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace chromeos_update_manager
|