libcxxabi/src/cxa_default_handlers.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //
   8 // This file implements the default terminate_handler, unexpected_handler and
   9 // new_handler.
  10 //===----------------------------------------------------------------------===//
  11
  12 #include <exception>
  13 #include <memory>
  14 #include <stdlib.h>
  15 #include "abort_message.h"
  16 #include "cxxabi.h"
  17 #include "cxa_handlers.h"
  18 #include "cxa_exception.h"
  19 #include "private_typeinfo.h"
  20 #include "include/atomic_support.h" // from libc++
  21
  22 #if !defined(LIBCXXABI_SILENT_TERMINATE)
  23
  24 static constinit const char* cause = "uncaught";
  25
  26 #ifndef _LIBCXXABI_NO_EXCEPTIONS
  27 // Demangle the given string, or return the string as-is in case of an error.
  28 static std::unique_ptr<char const, void (*)(char const*)> demangle(char const* str)
  29 {
  30 #if !defined(LIBCXXABI_NON_DEMANGLING_TERMINATE)
  31     if (const char* result = __cxxabiv1::__cxa_demangle(str, nullptr, nullptr, nullptr))
  32         return {result, [](char const* p) { std::free(const_cast<char*>(p)); }};
  33 #endif
  34     return {str, [](char const*) { /* nothing to free */ }};
  35 }
  36
  37 __attribute__((noreturn))
  38 static void demangling_terminate_handler()
  39 {
  40     using namespace __cxxabiv1;
  41     __cxa_eh_globals* globals = __cxa_get_globals_fast();
  42
  43     // If there is no uncaught exception, just note that we're terminating
  44     if (!globals)
  45         abort_message("terminating");
  46
  47     __cxa_exception* exception_header = globals->caughtExceptions;
  48     if (!exception_header)
  49         abort_message("terminating");
  50
  51     _Unwind_Exception* unwind_exception =
  52         reinterpret_cast<_Unwind_Exception*>(exception_header + 1) - 1;
  53
  54     // If we're terminating due to a foreign exception
  55     if (!__isOurExceptionClass(unwind_exception))
  56         abort_message("terminating due to %s foreign exception", cause);
  57
  58     void* thrown_object =
  59         __getExceptionClass(unwind_exception) == kOurDependentExceptionClass ?
  60             ((__cxa_dependent_exception*)exception_header)->primaryException :
  61             exception_header + 1;
  62     const __shim_type_info* thrown_type =
  63         static_cast<const __shim_type_info*>(exception_header->exceptionType);
  64     auto name = demangle(thrown_type->name());
  65     // If the uncaught exception can be caught with std::exception&
  66     const __shim_type_info* catch_type =
  67         static_cast<const __shim_type_info*>(&typeid(std::exception));
  68     if (catch_type->can_catch(thrown_type, thrown_object))
  69     {
  70         // Include the what() message from the exception
  71         const std::exception* e = static_cast<const std::exception*>(thrown_object);
  72         abort_message("terminating due to %s exception of type %s: %s", cause, name.get(), e->what());
  73     }
  74     else
  75     {
  76         // Else just note that we're terminating due to an exception
  77         abort_message("terminating due to %s exception of type %s", cause, name.get());
  78     }
  79 }
  80 #else // !_LIBCXXABI_NO_EXCEPTIONS
  81 __attribute__((noreturn))
  82 static void demangling_terminate_handler()
  83 {
  84     abort_message("terminating");
  85 }
  86 #endif // !_LIBCXXABI_NO_EXCEPTIONS
  87
  88 __attribute__((noreturn))
  89 static void demangling_unexpected_handler()
  90 {
  91     cause = "unexpected";
  92     std::terminate();
  93 }
  94
  95 static constexpr std::terminate_handler default_terminate_handler = demangling_terminate_handler;
  96 static constexpr std::terminate_handler default_unexpected_handler = demangling_unexpected_handler;
  97 #else // !LIBCXXABI_SILENT_TERMINATE
  98 static constexpr std::terminate_handler default_terminate_handler = ::abort;
  99 static constexpr std::terminate_handler default_unexpected_handler = std::terminate;
 100 #endif // !LIBCXXABI_SILENT_TERMINATE
 101
 102 //
 103 // Global variables that hold the pointers to the current handler
 104 //
 105 _LIBCXXABI_DATA_VIS
 106 constinit std::terminate_handler __cxa_terminate_handler = default_terminate_handler;
 107
 108 _LIBCXXABI_DATA_VIS
 109 constinit std::unexpected_handler __cxa_unexpected_handler = default_unexpected_handler;
 110
 111 _LIBCXXABI_DATA_VIS
 112 constinit std::new_handler __cxa_new_handler = nullptr;
 113
 114 namespace std
 115 {
 116
 117 unexpected_handler
 118 set_unexpected(unexpected_handler func) noexcept
 119 {
 120     if (func == 0)
 121         func = default_unexpected_handler;
 122     return __libcpp_atomic_exchange(&__cxa_unexpected_handler, func,
 123                                     _AO_Acq_Rel);
 124 }
 125
 126 terminate_handler
 127 set_terminate(terminate_handler func) noexcept
 128 {
 129     if (func == 0)
 130         func = default_terminate_handler;
 131     return __libcpp_atomic_exchange(&__cxa_terminate_handler, func,
 132                                     _AO_Acq_Rel);
 133 }
 134
 135 new_handler
 136 set_new_handler(new_handler handler) noexcept
 137 {
 138     return __libcpp_atomic_exchange(&__cxa_new_handler, handler, _AO_Acq_Rel);
 139 }
 140
 141 }