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 }
142