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