gdbsupport/poison.h

   1 /* Poison symbols at compile time.
   2
   3    Copyright (C) 2017-2020 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             std::is_pod<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 #if HAVE_IS_TRIVIALLY_COPYABLE
  60
  61 /* Similarly, poison memcpy and memmove of non trivially-copyable
  62    types, which is undefined.  */
  63
  64 /* True if "T *" is relocatable.  I.e., copyable with memcpy/memmove.
  65    I.e., T is either trivially copyable, or void.  */
  66 template<typename T>
  67 struct IsRelocatable
  68   : gdb::Or<std::is_void<T>,
  69             std::is_trivially_copyable<T>>
  70 {};
  71
  72 /* True if both source and destination are relocatable.  */
  73
  74 template <typename D, typename S>
  75 using BothAreRelocatable
  76   = gdb::And<IsRelocatable<D>, IsRelocatable<S>>;
  77
  78 template <typename D, typename S,
  79           typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
  80 void *memcpy (D *dest, const S *src, size_t n) = delete;
  81
  82 template <typename D, typename S,
  83           typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
  84 void *memmove (D *dest, const S *src, size_t n) = delete;
  85
  86 #endif /* HAVE_IS_TRIVIALLY_COPYABLE */
  87
  88 /* Poison XNEW and friends to catch usages of malloc-style allocations on
  89    objects that require new/delete.  */
  90
  91 template<typename T>
  92 #if HAVE_IS_TRIVIALLY_CONSTRUCTIBLE
  93 using IsMallocable = std::is_trivially_constructible<T>;
  94 #else
  95 using IsMallocable = std::true_type;
  96 #endif
  97
  98 template<typename T>
  99 using IsFreeable = gdb::Or<std::is_trivially_destructible<T>, std::is_void<T>>;
 100
 101 template <typename T, typename = gdb::Requires<gdb::Not<IsFreeable<T>>>>
 102 void free (T *ptr) = delete;
 103
 104 template<typename T>
 105 static T *
 106 xnew ()
 107 {
 108   static_assert (IsMallocable<T>::value, "Trying to use XNEW with a non-POD \
 109 data type.  Use operator new instead.");
 110   return XNEW (T);
 111 }
 112
 113 #undef XNEW
 114 #define XNEW(T) xnew<T>()
 115
 116 template<typename T>
 117 static T *
 118 xcnew ()
 119 {
 120   static_assert (IsMallocable<T>::value, "Trying to use XCNEW with a non-POD \
 121 data type.  Use operator new instead.");
 122   return XCNEW (T);
 123 }
 124
 125 #undef XCNEW
 126 #define XCNEW(T) xcnew<T>()
 127
 128 template<typename T>
 129 static void
 130 xdelete (T *p)
 131 {
 132   static_assert (IsFreeable<T>::value, "Trying to use XDELETE with a non-POD \
 133 data type.  Use operator delete instead.");
 134   XDELETE (p);
 135 }
 136
 137 #undef XDELETE
 138 #define XDELETE(P) xdelete (P)
 139
 140 template<typename T>
 141 static T *
 142 xnewvec (size_t n)
 143 {
 144   static_assert (IsMallocable<T>::value, "Trying to use XNEWVEC with a \
 145 non-POD data type.  Use operator new[] (or std::vector) instead.");
 146   return XNEWVEC (T, n);
 147 }
 148
 149 #undef XNEWVEC
 150 #define XNEWVEC(T, N) xnewvec<T> (N)
 151
 152 template<typename T>
 153 static T *
 154 xcnewvec (size_t n)
 155 {
 156   static_assert (IsMallocable<T>::value, "Trying to use XCNEWVEC with a \
 157 non-POD data type.  Use operator new[] (or std::vector) instead.");
 158   return XCNEWVEC (T, n);
 159 }
 160
 161 #undef XCNEWVEC
 162 #define XCNEWVEC(T, N) xcnewvec<T> (N)
 163
 164 template<typename T>
 165 static T *
 166 xresizevec (T *p, size_t n)
 167 {
 168   static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVEC with a \
 169 non-POD data type.");
 170   return XRESIZEVEC (T, p, n);
 171 }
 172
 173 #undef XRESIZEVEC
 174 #define XRESIZEVEC(T, P, N) xresizevec<T> (P, N)
 175
 176 template<typename T>
 177 static void
 178 xdeletevec (T *p)
 179 {
 180   static_assert (IsFreeable<T>::value, "Trying to use XDELETEVEC with a \
 181 non-POD data type.  Use operator delete[] (or std::vector) instead.");
 182   XDELETEVEC (p);
 183 }
 184
 185 #undef XDELETEVEC
 186 #define XDELETEVEC(P) xdeletevec (P)
 187
 188 template<typename T>
 189 static T *
 190 xnewvar (size_t s)
 191 {
 192   static_assert (IsMallocable<T>::value, "Trying to use XNEWVAR with a \
 193 non-POD data type.");
 194   return XNEWVAR (T, s);;
 195 }
 196
 197 #undef XNEWVAR
 198 #define XNEWVAR(T, S) xnewvar<T> (S)
 199
 200 template<typename T>
 201 static T *
 202 xcnewvar (size_t s)
 203 {
 204   static_assert (IsMallocable<T>::value, "Trying to use XCNEWVAR with a \
 205 non-POD data type.");
 206   return XCNEWVAR (T, s);
 207 }
 208
 209 #undef XCNEWVAR
 210 #define XCNEWVAR(T, S) xcnewvar<T> (S)
 211
 212 template<typename T>
 213 static T *
 214 xresizevar (T *p, size_t s)
 215 {
 216   static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVAR with a \
 217 non-POD data type.");
 218   return XRESIZEVAR (T, p, s);
 219 }
 220
 221 #undef XRESIZEVAR
 222 #define XRESIZEVAR(T, P, S) xresizevar<T> (P, S)
 223
 224 template<typename T>
 225 static T *
 226 xobnew (obstack *ob)
 227 {
 228   static_assert (IsMallocable<T>::value, "Trying to use XOBNEW with a \
 229 non-POD data type.");
 230   return XOBNEW (ob, T);
 231 }
 232
 233 #undef XOBNEW
 234 #define XOBNEW(O, T) xobnew<T> (O)
 235
 236 template<typename T>
 237 static T *
 238 xobnewvec (obstack *ob, size_t n)
 239 {
 240   static_assert (IsMallocable<T>::value, "Trying to use XOBNEWVEC with a \
 241 non-POD data type.");
 242   return XOBNEWVEC (ob, T, n);
 243 }
 244
 245 #undef XOBNEWVEC
 246 #define XOBNEWVEC(O, T, N) xobnewvec<T> (O, N)
 247
 248 #endif /* COMMON_POISON_H */