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.
demangle(char const * str)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))
demangling_terminate_handler()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))
demangling_terminate_handler()82 static void demangling_terminate_handler()
83 {
84 abort_message("terminating");
85 }
86 #endif // !_LIBCXXABI_NO_EXCEPTIONS
87
88 __attribute__((noreturn))
demangling_unexpected_handler()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
set_unexpected(unexpected_handler func)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
set_terminate(terminate_handler func)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
set_new_handler(new_handler 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