gdbsupport/poison.h

   1 /* Poison symbols at compile time.
   2
   3    Copyright (C) 2017-2024 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 #include "obstack.h"
  25
  26 /* Poison memset of non-POD types.  The idea is catching invalid
  27    initialization of non-POD structs that is easy to be introduced as
  28    side effect of refactoring.  For example, say this:
  29
  30  struct S { VEC(foo_s) *m_data; };
  31
  32 is converted to this at some point:
  33
  34  struct S {
  35    S() { m_data.reserve (10); }
  36    std::vector<foo> m_data;
  37  };
  38
  39 and old code was initializing S objects like this:
  40
  41  struct S s;
  42  memset (&s, 0, sizeof (S)); // whoops, now wipes vector.
  43
  44 Declaring memset as deleted for non-POD types makes the memset above
  45 be a compile-time error.  */
  46
  47 /* Helper for SFINAE.  True if "T *" is memsettable.  I.e., if T is
  48    either void, or POD.  */
  49 template<typename T>
  50 struct IsMemsettable
  51   : gdb::Or<std::is_void<T>,
  52             gdb::And<std::is_standard_layout<T>, std::is_trivial<T>>>
  53 {};
  54
  55 template <typename T,
  56           typename = gdb::Requires<gdb::Not<IsMemsettable<T>>>>
  57 void *memset (T *s, int c, size_t n) = delete;
  58
  59 /* Similarly, poison memcpy and memmove of non trivially-copyable
  60    types, which is undefined.  */
  61
  62 /* True if "T *" is relocatable.  I.e., copyable with memcpy/memmove.
  63    I.e., T is either trivially copyable, or void.  */
  64 template<typename T>
  65 struct IsRelocatable
  66   : gdb::Or<std::is_void<T>,
  67             std::is_trivially_copyable<T>>
  68 {};
  69
  70 /* True if both source and destination are relocatable.  */
  71
  72 template <typename D, typename S>
  73 using BothAreRelocatable
  74   = gdb::And<IsRelocatable<D>, IsRelocatable<S>>;
  75
  76 template <typename D, typename S,
  77           typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
  78 void *memcpy (D *dest, const S *src, size_t n) = delete;
  79
  80 template <typename D, typename S,
  81           typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
  82 void *memmove (D *dest, const S *src, size_t n) = delete;
  83
  84 /* Poison XNEW and friends to catch usages of malloc-style allocations on
  85    objects that require new/delete.  */
  86
  87 template<typename T>
  88 using IsMallocable = std::is_trivially_constructible<T>;
  89
  90 template<typename T>
  91 using IsFreeable = gdb::Or<std::is_trivially_destructible<T>, std::is_void<T>>;
  92
  93 template <typename T, typename = gdb::Requires<gdb::Not<IsFreeable<T>>>>
  94 void free (T *ptr) = delete;
  95
  96 template<typename T>
  97 static T *
  98 xnew ()
  99 {
 100   static_assert (IsMallocable<T>::value, "Trying to use XNEW with a non-POD \
 101 data type.  Use operator new instead.");
 102   return XNEW (T);
 103 }
 104
 105 #undef XNEW
 106 #define XNEW(T) xnew<T>()
 107
 108 template<typename T>
 109 static T *
 110 xcnew ()
 111 {
 112   static_assert (IsMallocable<T>::value, "Trying to use XCNEW with a non-POD \
 113 data type.  Use operator new instead.");
 114   return XCNEW (T);
 115 }
 116
 117 #undef XCNEW
 118 #define XCNEW(T) xcnew<T>()
 119
 120 template<typename T>
 121 static void
 122 xdelete (T *p)
 123 {
 124   static_assert (IsFreeable<T>::value, "Trying to use XDELETE with a non-POD \
 125 data type.  Use operator delete instead.");
 126   XDELETE (p);
 127 }
 128
 129 #undef XDELETE
 130 #define XDELETE(P) xdelete (P)
 131
 132 template<typename T>
 133 static T *
 134 xnewvec (size_t n)
 135 {
 136   static_assert (IsMallocable<T>::value, "Trying to use XNEWVEC with a \
 137 non-POD data type.  Use operator new[] (or std::vector) instead.");
 138   return XNEWVEC (T, n);
 139 }
 140
 141 #undef XNEWVEC
 142 #define XNEWVEC(T, N) xnewvec<T> (N)
 143
 144 template<typename T>
 145 static T *
 146 xcnewvec (size_t n)
 147 {
 148   static_assert (IsMallocable<T>::value, "Trying to use XCNEWVEC with a \
 149 non-POD data type.  Use operator new[] (or std::vector) instead.");
 150   return XCNEWVEC (T, n);
 151 }
 152
 153 #undef XCNEWVEC
 154 #define XCNEWVEC(T, N) xcnewvec<T> (N)
 155
 156 template<typename T>
 157 static T *
 158 xresizevec (T *p, size_t n)
 159 {
 160   static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVEC with a \
 161 non-POD data type.");
 162   return XRESIZEVEC (T, p, n);
 163 }
 164
 165 #undef XRESIZEVEC
 166 #define XRESIZEVEC(T, P, N) xresizevec<T> (P, N)
 167
 168 template<typename T>
 169 static void
 170 xdeletevec (T *p)
 171 {
 172   static_assert (IsFreeable<T>::value, "Trying to use XDELETEVEC with a \
 173 non-POD data type.  Use operator delete[] (or std::vector) instead.");
 174   XDELETEVEC (p);
 175 }
 176
 177 #undef XDELETEVEC
 178 #define XDELETEVEC(P) xdeletevec (P)
 179
 180 template<typename T>
 181 static T *
 182 xnewvar (size_t s)
 183 {
 184   static_assert (IsMallocable<T>::value, "Trying to use XNEWVAR with a \
 185 non-POD data type.");
 186   return XNEWVAR (T, s);;
 187 }
 188
 189 #undef XNEWVAR
 190 #define XNEWVAR(T, S) xnewvar<T> (S)
 191
 192 template<typename T>
 193 static T *
 194 xcnewvar (size_t s)
 195 {
 196   static_assert (IsMallocable<T>::value, "Trying to use XCNEWVAR with a \
 197 non-POD data type.");
 198   return XCNEWVAR (T, s);
 199 }
 200
 201 #undef XCNEWVAR
 202 #define XCNEWVAR(T, S) xcnewvar<T> (S)
 203
 204 template<typename T>
 205 static T *
 206 xresizevar (T *p, size_t s)
 207 {
 208   static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVAR with a \
 209 non-POD data type.");
 210   return XRESIZEVAR (T, p, s);
 211 }
 212
 213 #undef XRESIZEVAR
 214 #define XRESIZEVAR(T, P, S) xresizevar<T> (P, S)
 215
 216 template<typename T>
 217 static T *
 218 xobnew (obstack *ob)
 219 {
 220   static_assert (IsMallocable<T>::value, "Trying to use XOBNEW with a \
 221 non-POD data type.");
 222   return XOBNEW (ob, T);
 223 }
 224
 225 #undef XOBNEW
 226 #define XOBNEW(O, T) xobnew<T> (O)
 227
 228 template<typename T>
 229 static T *
 230 xobnewvec (obstack *ob, size_t n)
 231 {
 232   static_assert (IsMallocable<T>::value, "Trying to use XOBNEWVEC with a \
 233 non-POD data type.");
 234   return XOBNEWVEC (ob, T, n);
 235 }
 236
 237 #undef XOBNEWVEC
 238 #define XOBNEWVEC(O, T, N) xobnewvec<T> (O, N)
 239
 240 #endif /* COMMON_POISON_H */