1 //===------------------------- cxa_default_handlers.cpp -------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //
9 // This file implements the default terminate_handler and unexpected_handler.
10 //===----------------------------------------------------------------------===//
11
12 #include <stdexcept>
13 #include <new>
14 #include <exception>
15 #include "abort_message.h"
16 #include "config.h" // For __sync_swap
17 #include "cxxabi.h"
18 #include "cxa_handlers.hpp"
19 #include "cxa_exception.hpp"
20 #include "private_typeinfo.h"
21
22 static const char* cause = "uncaught";
23
24 __attribute__((noreturn))
default_terminate_handler()25 static void default_terminate_handler()
26 {
27 // If there might be an uncaught exception
28 using namespace __cxxabiv1;
29 __cxa_eh_globals* globals = __cxa_get_globals_fast();
30 if (globals)
31 {
32 __cxa_exception* exception_header = globals->caughtExceptions;
33 // If there is an uncaught exception
34 if (exception_header)
35 {
36 _Unwind_Exception* unwind_exception =
37 reinterpret_cast<_Unwind_Exception*>(exception_header + 1) - 1;
38 bool native_exception =
39 (unwind_exception->exception_class & get_vendor_and_language) ==
40 (kOurExceptionClass & get_vendor_and_language);
41 if (native_exception)
42 {
43 void* thrown_object =
44 unwind_exception->exception_class == kOurDependentExceptionClass ?
45 ((__cxa_dependent_exception*)exception_header)->primaryException :
46 exception_header + 1;
47 const __shim_type_info* thrown_type =
48 static_cast<const __shim_type_info*>(exception_header->exceptionType);
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 // If the uncaught exception can be caught with std::exception&
57 const __shim_type_info* catch_type =
58 static_cast<const __shim_type_info*>(&typeid(std::exception));
59 if (catch_type->can_catch(thrown_type, thrown_object))
60 {
61 // Include the what() message from the exception
62 const std::exception* e = static_cast<const std::exception*>(thrown_object);
63 abort_message("terminating with %s exception of type %s: %s",
64 cause, name, e->what());
65 }
66 else
67 // Else just note that we're terminating with an exception
68 abort_message("terminating with %s exception of type %s",
69 cause, name);
70 }
71 else
72 // Else we're terminating with a foreign exception
73 abort_message("terminating with %s foreign exception", cause);
74 }
75 }
76 // Else just note that we're terminating
77 abort_message("terminating");
78 }
79
80 __attribute__((noreturn))
default_unexpected_handler()81 static void default_unexpected_handler()
82 {
83 cause = "unexpected";
84 std::terminate();
85 }
86
87
88 //
89 // Global variables that hold the pointers to the current handler
90 //
91 std::terminate_handler __cxa_terminate_handler = default_terminate_handler;
92 std::unexpected_handler __cxa_unexpected_handler = default_unexpected_handler;
93
94 // In the future these will become:
95 // TODO(ajwong): Can this actually be true? Is std::atomic part of libc++? If so, do we have a
96 // layering violation?
97 //
98 // std::atomic<std::terminate_handler> __cxa_terminate_handler(default_terminate_handler);
99 // std::atomic<std::unexpected_handler> __cxa_unexpected_handler(default_unexpected_handler);
100
101 namespace std
102 {
103
104 unexpected_handler
set_unexpected(unexpected_handler func)105 set_unexpected(unexpected_handler func) _NOEXCEPT
106 {
107 if (func == 0)
108 func = default_unexpected_handler;
109 return __sync_swap(&__cxa_unexpected_handler, func);
110 // Using of C++11 atomics this should be rewritten
111 // return __cxa_unexpected_handler.exchange(func, memory_order_acq_rel);
112 }
113
114 terminate_handler
set_terminate(terminate_handler func)115 set_terminate(terminate_handler func) _NOEXCEPT
116 {
117 if (func == 0)
118 func = default_terminate_handler;
119 return __sync_swap(&__cxa_terminate_handler, func);
120 // Using of C++11 atomics this should be rewritten
121 // return __cxa_terminate_handler.exchange(func, memory_order_acq_rel);
122 }
123
124 }
125