| 1 | /* |
| 2 | * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: LGPL-2.1-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #ifndef LTTNG_MAKE_UNIQUE_WRAPPER_H |
| 9 | #define LTTNG_MAKE_UNIQUE_WRAPPER_H |
| 10 | |
| 11 | #include <common/macros.hpp> |
| 12 | |
| 13 | #include <memory> |
| 14 | |
| 15 | namespace lttng { |
| 16 | |
| 17 | /* |
| 18 | * make_unique_wrapper is intended to facilitate the use of std::unique_ptr |
| 19 | * to wrap C-style APIs that don't provide RAII resource management facilities. |
| 20 | * |
| 21 | * Usage example: |
| 22 | * |
| 23 | * // API |
| 24 | * struct my_c_struct { |
| 25 | * // ... |
| 26 | * }; |
| 27 | * |
| 28 | * struct my_c_struct *create_my_c_struct(void); |
| 29 | * void destroy_my_c_struct(struct my_c_struct *value); |
| 30 | * |
| 31 | * // Creating a unique_ptr to my_c_struct. |
| 32 | * auto safe_c_struct = |
| 33 | * lttng::make_unique_wrapper<my_c_struct, destroy_my_c_struct>( |
| 34 | * create_my_c_struct()); |
| 35 | * |
| 36 | * Note that this facility is intended for use in the scope of a function. |
| 37 | * If you need to return this unique_ptr instance, you should consider writting |
| 38 | * a proper, idiomatic, wrapper. |
| 39 | */ |
| 40 | |
| 41 | namespace memory { |
| 42 | template <typename WrappedType, void (*DeleterFunction)(WrappedType *)> |
| 43 | struct create_deleter_class { |
| 44 | struct deleter { |
| 45 | void operator()(WrappedType *instance) const |
| 46 | { |
| 47 | DeleterFunction(instance); |
| 48 | } |
| 49 | }; |
| 50 | |
| 51 | std::unique_ptr<WrappedType, deleter> operator()(WrappedType *instance) const |
| 52 | { |
| 53 | return std::unique_ptr<WrappedType, deleter>(instance); |
| 54 | } |
| 55 | }; |
| 56 | } /* namespace memory */ |
| 57 | |
| 58 | /* |
| 59 | * 'free' is a utility function for use with make_unique_wrapper. It makes it easier to |
| 60 | * wrap raw pointers that have to be deleted with `free`. Using libc's 'free' as |
| 61 | * a make_unique_wrapper template argument will result in an error as 'WrappedType *' will |
| 62 | * not match free's 'void *' argument. |
| 63 | */ |
| 64 | template <class Type> |
| 65 | void free(Type *ptr) |
| 66 | { |
| 67 | std::free(ptr); |
| 68 | } |
| 69 | |
| 70 | template <typename WrappedType, void (*DeleterFunc)(WrappedType *)> |
| 71 | std::unique_ptr<WrappedType, |
| 72 | typename memory::create_deleter_class<WrappedType, DeleterFunc>::deleter> |
| 73 | make_unique_wrapper(WrappedType *instance = nullptr) |
| 74 | { |
| 75 | const memory::create_deleter_class<WrappedType, DeleterFunc> unique_deleter; |
| 76 | |
| 77 | return unique_deleter(instance); |
| 78 | } |
| 79 | |
| 80 | } /* namespace lttng */ |
| 81 | |
| 82 | #endif /* LTTNG_MAKE_UNIQUE_WRAPPER_H */ |