| 1 | /* |
| 2 | * Copyright (C) 2023 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: LGPL-2.1-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #ifndef LTTNG_RANDOM_H |
| 9 | #define LTTNG_RANDOM_H |
| 10 | |
| 11 | #include "exception.hpp" |
| 12 | |
| 13 | #include <cstddef> |
| 14 | #include <string> |
| 15 | |
| 16 | namespace lttng { |
| 17 | namespace random { |
| 18 | |
| 19 | using seed_t = unsigned int; |
| 20 | |
| 21 | class production_error : public ::lttng::runtime_error { |
| 22 | public: |
| 23 | explicit production_error(const std::string& msg, |
| 24 | const char *file_name, |
| 25 | const char *function_name, |
| 26 | unsigned int line_number); |
| 27 | }; |
| 28 | |
| 29 | /* |
| 30 | * Get a seed from a reliable source of randomness without blocking, raising |
| 31 | * an exception on failure. |
| 32 | */ |
| 33 | seed_t produce_true_random_seed(); |
| 34 | |
| 35 | /* |
| 36 | * Get a random seed making a best-effort to use a true randomness source, |
| 37 | * but falling back to a pseudo-random seed based on the time and various system |
| 38 | * configuration values on failure. |
| 39 | * |
| 40 | * Note that this function attempts to use the urandom device, which will block |
| 41 | * in the unlikely event that its pool is uninitialized, on platforms that don't |
| 42 | * provide getrandom(). |
| 43 | */ |
| 44 | seed_t produce_best_effort_random_seed(); |
| 45 | |
| 46 | } /* namespace random */ |
| 47 | } /* namespace lttng */ |
| 48 | |
| 49 | #endif /* LTTNG_RANDOM_H */ |