gdbsupport/new-op.cc

   1 /* Replace operator new/new[], for GDB, the GNU debugger.
   2
   3    Copyright (C) 2016-2024 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 /* GCC does not understand __has_feature.  */
  21 #if !defined(__has_feature)
  22 # define __has_feature(x) 0
  23 #endif
  24
  25 #if !__has_feature(address_sanitizer) && !defined(__SANITIZE_ADDRESS__)
  26 #include "host-defs.h"
  27 #include <new>
  28
  29 /* These are declared in <new> starting C++14, but removing them
  30    caused a build failure with clang.  See PR build/31141.  */
  31 extern void operator delete (void *p, std::size_t) noexcept;
  32 extern void operator delete[] (void *p, std::size_t) noexcept;
  33
  34 /* Override operator new / operator new[], in order to internal_error
  35    on allocation failure and thus query the user for abort/core
  36    dump/continue, just like xmalloc does.  We don't do this from a
  37    new-handler function instead (std::set_new_handler) because we want
  38    to catch allocation errors from within global constructors too.
  39
  40    Skip overriding if building with -fsanitize=address though.
  41    Address sanitizer wants to override operator new/delete too in
  42    order to detect malloc+delete and new+free mismatches.  Our
  43    versions would mask out ASan's, with the result of losing that
  44    useful mismatch detection.
  45
  46    Note that C++ implementations could either have their throw
  47    versions call the nothrow versions (libstdc++), or the other way
  48    around (clang/libc++).  For that reason, we replace both throw and
  49    nothrow variants and call malloc directly.  */
  50
  51 void *
  52 operator new (std::size_t sz)
  53 {
  54   /* malloc (0) is unpredictable; avoid it.  */
  55   if (sz == 0)
  56     sz = 1;
  57
  58   void *p = malloc (sz);        /* ARI: malloc */
  59   if (p == NULL)
  60     {
  61       /* If the user decides to continue debugging, throw a
  62          gdb_quit_bad_alloc exception instead of a regular QUIT
  63          gdb_exception.  The former extends both std::bad_alloc and a
  64          QUIT gdb_exception.  This is necessary because operator new
  65          can only ever throw std::bad_alloc, or something that extends
  66          it.  */
  67       try
  68         {
  69           malloc_failure (sz);
  70         }
  71       catch (gdb_exception &ex)
  72         {
  73           throw gdb_quit_bad_alloc (std::move (ex));
  74         }
  75     }
  76   return p;
  77 }
  78
  79 void *
  80 operator new (std::size_t sz, const std::nothrow_t&) noexcept
  81 {
  82   /* malloc (0) is unpredictable; avoid it.  */
  83   if (sz == 0)
  84     sz = 1;
  85   return malloc (sz);           /* ARI: malloc */
  86 }
  87
  88 void *
  89 operator new[] (std::size_t sz)
  90 {
  91    return ::operator new (sz);
  92 }
  93
  94 void*
  95 operator new[] (std::size_t sz, const std::nothrow_t&) noexcept
  96 {
  97   return ::operator new (sz, std::nothrow);
  98 }
  99
 100 /* Define also operators delete as one can LD_PRELOAD=libasan.so.*
 101    without recompiling the program with -fsanitize=address and then one would
 102    get false positive alloc-dealloc-mismatch (malloc vs operator delete [])
 103    errors from AddressSanitizers.  */
 104
 105 void
 106 operator delete (void *p) noexcept
 107 {
 108   free (p);
 109 }
 110
 111 void
 112 operator delete (void *p, const std::nothrow_t&) noexcept
 113 {
 114   return ::operator delete (p);
 115 }
 116
 117 void
 118 operator delete (void *p, std::size_t) noexcept
 119 {
 120   return ::operator delete (p, std::nothrow);
 121 }
 122
 123 void
 124 operator delete[] (void *p) noexcept
 125 {
 126   return ::operator delete (p);
 127 }
 128
 129 void
 130 operator delete[] (void *p, const std::nothrow_t&) noexcept
 131 {
 132   return ::operator delete (p, std::nothrow);
 133 }
 134
 135 void
 136 operator delete[] (void *p, std::size_t) noexcept
 137 {
 138   return ::operator delete[] (p, std::nothrow);
 139 }
 140
 141 #endif