gdb/common/poison.h

   1 /* Poison symbols at compile time.
   2
   3    Copyright (C) 2017-2018 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 #if HAVE_IS_TRIVIALLY_COPYABLE
  59
  60 /* Similarly, poison memcpy and memmove of non trivially-copyable
  61    types, which is undefined.  */
  62
  63 /* True if "T *" is relocatable.  I.e., copyable with memcpy/memmove.
  64    I.e., T is either trivially copyable, or void.  */
  65 template<typename T>
  66 struct IsRelocatable
  67   : gdb::Or<std::is_void<T>,
  68             std::is_trivially_copyable<T>>
  69 {};
  70
  71 /* True if both source and destination are relocatable.  */
  72
  73 template <typename D, typename S>
  74 using BothAreRelocatable
  75   = gdb::And<IsRelocatable<D>, IsRelocatable<S>>;
  76
  77 template <typename D, typename S,
  78           typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
  79 void *memcpy (D *dest, const S *src, size_t n) = delete;
  80
  81 template <typename D, typename S,
  82           typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
  83 void *memmove (D *dest, const S *src, size_t n) = delete;
  84
  85 #endif /* HAVE_IS_TRIVIALLY_COPYABLE */
  86
  87 /* Poison XNEW and friends to catch usages of malloc-style allocations on
  88    objects that require new/delete.  */
  89
  90 template<typename T>
  91 using IsMallocable = std::is_pod<T>;
  92
  93 template<typename T>
  94 using IsFreeable = gdb::Or<std::is_trivially_destructible<T>, std::is_void<T>>;
  95
  96 template <typename T, typename = gdb::Requires<gdb::Not<IsFreeable<T>>>>
  97 void free (T *ptr) = delete;
  98
  99 template<typename T>
 100 static T *
 101 xnew ()
 102 {
 103   static_assert (IsMallocable<T>::value, "Trying to use XNEW with a non-POD \
 104 data type.  Use operator new instead.");
 105   return XNEW (T);
 106 }
 107
 108 #undef XNEW
 109 #define XNEW(T) xnew<T>()
 110
 111 template<typename T>
 112 static T *
 113 xcnew ()
 114 {
 115   static_assert (IsMallocable<T>::value, "Trying to use XCNEW with a non-POD \
 116 data type.  Use operator new instead.");
 117   return XCNEW (T);
 118 }
 119
 120 #undef XCNEW
 121 #define XCNEW(T) xcnew<T>()
 122
 123 template<typename T>
 124 static void
 125 xdelete (T *p)
 126 {
 127   static_assert (IsFreeable<T>::value, "Trying to use XDELETE with a non-POD \
 128 data type.  Use operator delete instead.");
 129   XDELETE (p);
 130 }
 131
 132 #undef XDELETE
 133 #define XDELETE(P) xdelete (P)
 134
 135 template<typename T>
 136 static T *
 137 xnewvec (size_t n)
 138 {
 139   static_assert (IsMallocable<T>::value, "Trying to use XNEWVEC with a \
 140 non-POD data type.  Use operator new[] (or std::vector) instead.");
 141   return XNEWVEC (T, n);
 142 }
 143
 144 #undef XNEWVEC
 145 #define XNEWVEC(T, N) xnewvec<T> (N)
 146
 147 template<typename T>
 148 static T *
 149 xcnewvec (size_t n)
 150 {
 151   static_assert (IsMallocable<T>::value, "Trying to use XCNEWVEC with a \
 152 non-POD data type.  Use operator new[] (or std::vector) instead.");
 153   return XCNEWVEC (T, n);
 154 }
 155
 156 #undef XCNEWVEC
 157 #define XCNEWVEC(T, N) xcnewvec<T> (N)
 158
 159 template<typename T>
 160 static T *
 161 xresizevec (T *p, size_t n)
 162 {
 163   static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVEC with a \
 164 non-POD data type.");
 165   return XRESIZEVEC (T, p, n);
 166 }
 167
 168 #undef XRESIZEVEC
 169 #define XRESIZEVEC(T, P, N) xresizevec<T> (P, N)
 170
 171 template<typename T>
 172 static void
 173 xdeletevec (T *p)
 174 {
 175   static_assert (IsFreeable<T>::value, "Trying to use XDELETEVEC with a \
 176 non-POD data type.  Use operator delete[] (or std::vector) instead.");
 177   XDELETEVEC (p);
 178 }
 179
 180 #undef XDELETEVEC
 181 #define XDELETEVEC(P) xdeletevec (P)
 182
 183 template<typename T>
 184 static T *
 185 xnewvar (size_t s)
 186 {
 187   static_assert (IsMallocable<T>::value, "Trying to use XNEWVAR with a \
 188 non-POD data type.");
 189   return XNEWVAR (T, s);;
 190 }
 191
 192 #undef XNEWVAR
 193 #define XNEWVAR(T, S) xnewvar<T> (S)
 194
 195 template<typename T>
 196 static T *
 197 xcnewvar (size_t s)
 198 {
 199   static_assert (IsMallocable<T>::value, "Trying to use XCNEWVAR with a \
 200 non-POD data type.");
 201   return XCNEWVAR (T, s);
 202 }
 203
 204 #undef XCNEWVAR
 205 #define XCNEWVAR(T, S) xcnewvar<T> (S)
 206
 207 template<typename T>
 208 static T *
 209 xresizevar (T *p, size_t s)
 210 {
 211   static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVAR with a \
 212 non-POD data type.");
 213   return XRESIZEVAR (T, p, s);
 214 }
 215
 216 #undef XRESIZEVAR
 217 #define XRESIZEVAR(T, P, S) xresizevar<T> (P, S)
 218
 219 #endif /* COMMON_POISON_H */