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b0b92aeb PA |
1 | /* Poison symbols at compile time. |
2 | ||
3 | Copyright (C) 2017 Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
19 | ||
20 | #ifndef COMMON_POISON_H | |
21 | #define COMMON_POISON_H | |
22 | ||
23 | #include "traits.h" | |
24 | ||
25 | /* Poison memset of non-POD types. The idea is catching invalid | |
26 | initialization of non-POD structs that is easy to be introduced as | |
27 | side effect of refactoring. For example, say this: | |
28 | ||
29 | struct S { VEC(foo_s) *m_data; }; | |
30 | ||
31 | is converted to this at some point: | |
32 | ||
33 | struct S { | |
34 | S() { m_data.reserve (10); } | |
35 | std::vector<foo> m_data; | |
36 | }; | |
37 | ||
38 | and old code was initializing S objects like this: | |
39 | ||
40 | struct S s; | |
41 | memset (&s, 0, sizeof (S)); // whoops, now wipes vector. | |
42 | ||
43 | Declaring memset as deleted for non-POD types makes the memset above | |
44 | be a compile-time error. */ | |
45 | ||
46 | /* Helper for SFINAE. True if "T *" is memsettable. I.e., if T is | |
47 | either void, or POD. */ | |
48 | template<typename T> | |
49 | struct IsMemsettable | |
50 | : gdb::Or<std::is_void<T>, | |
51 | std::is_pod<T>> | |
52 | {}; | |
53 | ||
54 | template <typename T, | |
55 | typename = gdb::Requires<gdb::Not<IsMemsettable<T>>>> | |
56 | void *memset (T *s, int c, size_t n) = delete; | |
57 | ||
58 | /* Similarly, poison memcpy and memmove of non trivially-copyable | |
59 | types, which is undefined. */ | |
60 | ||
61 | /* True if "T *" is relocatable. I.e., copyable with memcpy/memmove. | |
62 | I.e., T is either trivially copyable, or void. */ | |
63 | template<typename T> | |
64 | struct IsRelocatable | |
65 | : gdb::Or<std::is_void<T>, | |
66 | std::is_trivially_copyable<T>> | |
67 | {}; | |
68 | ||
69 | /* True if both source and destination are relocatable. */ | |
70 | ||
71 | template <typename D, typename S> | |
72 | using BothAreRelocatable | |
73 | = gdb::And<IsRelocatable<D>, IsRelocatable<S>>; | |
74 | ||
75 | template <typename D, typename S, | |
76 | typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>> | |
77 | void *memcpy (D *dest, const S *src, size_t n) = delete; | |
78 | ||
79 | template <typename D, typename S, | |
80 | typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>> | |
81 | void *memmove (D *dest, const S *src, size_t n) = delete; | |
82 | ||
83 | #endif /* COMMON_POISON_H */ |