1 //===------------------------- cxa_default_handlers.cpp -------------------===//
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 and unexpected_handler.
9 //===----------------------------------------------------------------------===//
10 
11 #include <exception>
12 #include <stdlib.h>
13 #include "abort_message.h"
14 #include "cxxabi.h"
15 #include "cxa_handlers.h"
16 #include "cxa_exception.h"
17 #include "private_typeinfo.h"
18 #include "include/atomic_support.h"
19 
20 #if !defined(LIBCXXABI_SILENT_TERMINATE)
21 
22 _LIBCPP_SAFE_STATIC
23 static const char* cause = "uncaught";
24 
25 __attribute__((noreturn))
26 static void demangling_terminate_handler()
27 {
28 #ifndef _LIBCXXABI_NO_EXCEPTIONS
29     // If there might be an uncaught exception
30     using namespace __cxxabiv1;
31     __cxa_eh_globals* globals = __cxa_get_globals_fast();
32     if (globals)
33     {
34         __cxa_exception* exception_header = globals->caughtExceptions;
35         // If there is an uncaught exception
36         if (exception_header)
37         {
38             _Unwind_Exception* unwind_exception =
39                 reinterpret_cast<_Unwind_Exception*>(exception_header + 1) - 1;
40             if (__isOurExceptionClass(unwind_exception))
41             {
42                 void* thrown_object =
43                     __getExceptionClass(unwind_exception) == kOurDependentExceptionClass ?
44                         ((__cxa_dependent_exception*)exception_header)->primaryException :
45                         exception_header + 1;
46                 const __shim_type_info* thrown_type =
47                     static_cast<const __shim_type_info*>(exception_header->exceptionType);
48 #if !defined(LIBCXXABI_NON_DEMANGLING_TERMINATE)
49                 // Try to get demangled name of thrown_type
50                 int status;
51                 char buf[1024];
52                 size_t len = sizeof(buf);
53                 const char* name = __cxa_demangle(thrown_type->name(), buf, &len, &status);
54                 if (status != 0)
55                     name = thrown_type->name();
56 #else
57                 const char* name = thrown_type->name();
58 #endif
59                 // If the uncaught exception can be caught with std::exception&
60                 const __shim_type_info* catch_type =
61                     static_cast<const __shim_type_info*>(&typeid(std::exception));
62                 if (catch_type->can_catch(thrown_type, thrown_object))
63                 {
64                     // Include the what() message from the exception
65                     const std::exception* e = static_cast<const std::exception*>(thrown_object);
66                     abort_message("terminating with %s exception of type %s: %s",
67                                   cause, name, e->what());
68                 }
69                 else
70                     // Else just note that we're terminating with an exception
71                     abort_message("terminating with %s exception of type %s",
72                                    cause, name);
73             }
74             else
75                 // Else we're terminating with a foreign exception
76                 abort_message("terminating with %s foreign exception", cause);
77         }
78     }
79 #endif
80     // Else just note that we're terminating
81     abort_message("terminating");
82 }
83 
84 __attribute__((noreturn))
85 static void demangling_unexpected_handler()
86 {
87     cause = "unexpected";
88     std::terminate();
89 }
90 
91 static constexpr std::terminate_handler default_terminate_handler = demangling_terminate_handler;
92 static constexpr std::terminate_handler default_unexpected_handler = demangling_unexpected_handler;
93 #else
94 static constexpr std::terminate_handler default_terminate_handler = ::abort;
95 static constexpr std::terminate_handler default_unexpected_handler = std::terminate;
96 #endif
97 
98 //
99 // Global variables that hold the pointers to the current handler
100 //
101 _LIBCXXABI_DATA_VIS
102 _LIBCPP_SAFE_STATIC std::terminate_handler __cxa_terminate_handler = default_terminate_handler;
103 
104 _LIBCXXABI_DATA_VIS
105 _LIBCPP_SAFE_STATIC std::unexpected_handler __cxa_unexpected_handler = default_unexpected_handler;
106 
107 namespace std
108 {
109 
110 unexpected_handler
111 set_unexpected(unexpected_handler func) noexcept
112 {
113     if (func == 0)
114         func = default_unexpected_handler;
115     return __libcpp_atomic_exchange(&__cxa_unexpected_handler, func,
116                                     _AO_Acq_Rel);
117 }
118 
119 terminate_handler
120 set_terminate(terminate_handler func) noexcept
121 {
122     if (func == 0)
123         func = default_terminate_handler;
124     return __libcpp_atomic_exchange(&__cxa_terminate_handler, func,
125                                     _AO_Acq_Rel);
126 }
127 
128 }
129