| // Copyright (c) 2014 The Chromium OS 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 <stdio.h> |
| #include <unistd.h> |
| |
| #include <base/file_path.h> |
| #include <base/file_util.h> |
| |
| #include "policy_manager/random_provider.h" |
| #include "policy_manager/random_vars.h" |
| |
| using std::string; |
| |
| namespace { |
| |
| // The device providing randomness. |
| const char* kRandomDevice = "/dev/urandom"; |
| |
| } // namespace |
| |
| namespace chromeos_policy_manager { |
| |
| // The random variable class implementation. |
| class RandomVariable : public Variable<uint64> { |
| public: |
| RandomVariable(FILE* fp) : fp_(fp) {} |
| virtual ~RandomVariable() {} |
| |
| protected: |
| virtual const uint64* GetValue(base::TimeDelta /* timeout */, |
| string* errmsg) { |
| uint8 buf[sizeof(uint64)]; |
| unsigned int buf_rd = 0; |
| |
| while (buf_rd < sizeof(uint64)) { |
| int rd = fread(buf + buf_rd, 1, sizeof(uint64) - buf_rd, fp_.get()); |
| if (rd == 0 || ferror(fp_.get())) { |
| // Either EOF on fp or read failed. |
| if (errmsg) |
| *errmsg = string("Error reading from the random device: ") |
| + kRandomDevice; |
| return NULL; |
| } |
| buf_rd += rd; |
| } |
| // Convert the result to a uint64. |
| uint64 result = 0; |
| for (unsigned int i = 0; i < sizeof(uint64); ++i) |
| result = (result << 8) | buf[i]; |
| |
| return new uint64(result); |
| } |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(RandomVariable); |
| |
| file_util::ScopedFILE fp_; |
| }; |
| |
| |
| // RandomProvider implementation. |
| |
| RandomProvider::~RandomProvider(void) { |
| if (var_random_seed) { |
| delete var_random_seed; |
| var_random_seed = NULL; |
| } |
| } |
| |
| bool RandomProvider::DoInit(void) { |
| FILE* fp = fopen(kRandomDevice, "r"); |
| if (!fp) |
| return false; |
| var_random_seed = new RandomVariable(fp); |
| return true; |
| } |
| |
| } // namespace chromeos_policy_manager |