2 * Copyright 2015 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include <folly/experimental/exception_tracer/ExceptionTracerLib.h>
23 #include <folly/Portability.h>
24 #include <folly/SharedMutex.h>
25 #include <folly/Synchronized.h>
27 namespace __cxxabiv1 {
30 FOLLY_NORETURN void __cxa_throw(void* thrownException,
32 void (*destructor)(void*));
33 void* __cxa_begin_catch(void* excObj) throw();
34 FOLLY_NORETURN void __cxa_rethrow(void);
35 void __cxa_rethrow(void);
36 void __cxa_end_catch(void);
39 } // namespace __cxxabiv1
41 using namespace folly::exception_tracer;
45 template <typename Function>
46 class CallbackHolder {
48 void registerCallback(Function f) {
49 SYNCHRONIZED(callbacks_) { callbacks_.push_back(std::move(f)); }
52 // always inline to enforce kInternalFramesNumber
53 template <typename... Args>
54 FOLLY_ALWAYS_INLINE void invoke(Args... args) {
55 SYNCHRONIZED_CONST(callbacks_) {
56 for (auto& cb : callbacks_) {
63 folly::Synchronized<std::vector<Function>> callbacks_;
69 namespace exception_tracer {
71 #define DECLARE_CALLBACK(NAME) \
72 CallbackHolder<NAME##Type>& get##NAME##Callbacks() { \
73 static CallbackHolder<NAME##Type> Callbacks; \
76 void register##NAME##Callback(NAME##Type callback) { \
77 get##NAME##Callbacks().registerCallback(callback); \
80 DECLARE_CALLBACK(CxaThrow);
81 DECLARE_CALLBACK(CxaBeginCatch);
82 DECLARE_CALLBACK(CxaRethrow);
83 DECLARE_CALLBACK(CxaEndCatch);
84 DECLARE_CALLBACK(RethrowException);
89 namespace __cxxabiv1 {
91 void __cxa_throw(void* thrownException,
93 void (*destructor)(void*)) {
94 static auto orig_cxa_throw =
95 reinterpret_cast<decltype(&__cxa_throw)>(dlsym(RTLD_NEXT, "__cxa_throw"));
96 getCxaThrowCallbacks().invoke(thrownException, type, destructor);
97 orig_cxa_throw(thrownException, type, destructor);
98 __builtin_unreachable(); // orig_cxa_throw never returns
101 void __cxa_rethrow() {
102 // __cxa_rethrow leaves the current exception on the caught stack,
103 // and __cxa_begin_catch recognizes that case. We could do the same, but
104 // we'll implement something simpler (and slower): we pop the exception from
105 // the caught stack, and push it back onto the active stack; this way, our
106 // implementation of __cxa_begin_catch doesn't have to do anything special.
107 static auto orig_cxa_rethrow = reinterpret_cast<decltype(&__cxa_rethrow)>(
108 dlsym(RTLD_NEXT, "__cxa_rethrow"));
109 getCxaRethrowCallbacks().invoke();
111 __builtin_unreachable(); // orig_cxa_rethrow never returns
114 void* __cxa_begin_catch(void* excObj) throw() {
115 // excObj is a pointer to the unwindHeader in __cxa_exception
116 static auto orig_cxa_begin_catch =
117 reinterpret_cast<decltype(&__cxa_begin_catch)>(
118 dlsym(RTLD_NEXT, "__cxa_begin_catch"));
119 getCxaBeginCatchCallbacks().invoke(excObj);
120 return orig_cxa_begin_catch(excObj);
123 void __cxa_end_catch() {
124 static auto orig_cxa_end_catch = reinterpret_cast<decltype(&__cxa_end_catch)>(
125 dlsym(RTLD_NEXT, "__cxa_end_catch"));
126 getCxaEndCatchCallbacks().invoke();
127 orig_cxa_end_catch();
130 } // namespace __cxxabiv1
134 void rethrow_exception(std::exception_ptr ep) {
135 // Mangled name for std::rethrow_exception
136 // TODO(tudorb): Dicey, as it relies on the fact that std::exception_ptr
137 // is typedef'ed to a type in namespace __exception_ptr
138 static auto orig_rethrow_exception =
139 reinterpret_cast<decltype(&rethrow_exception)>(
141 "_ZSt17rethrow_exceptionNSt15__exception_ptr13exception_ptrE"));
142 getRethrowExceptionCallbacks().invoke(ep);
143 orig_rethrow_exception(ep);
144 __builtin_unreachable(); // orig_rethrow_exception never returns