1 | /* |
2 | * Copyright 2016-present Facebook, Inc. |
3 | * |
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 |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
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. |
15 | */ |
16 | |
17 | #include <exception> |
18 | |
19 | #include <folly/experimental/exception_tracer/ExceptionAbi.h> |
20 | #include <folly/experimental/exception_tracer/ExceptionTracer.h> |
21 | #include <folly/experimental/exception_tracer/ExceptionTracerLib.h> |
22 | #include <folly/experimental/exception_tracer/StackTrace.h> |
23 | #include <folly/experimental/symbolizer/Symbolizer.h> |
24 | |
25 | using namespace folly::exception_tracer; |
26 | |
27 | namespace { |
28 | |
29 | // If we somehow ended up in an invalid state, we don't want to print any stack |
30 | // trace at all because in could be bogus |
31 | FOLLY_TLS bool invalid; |
32 | |
33 | FOLLY_TLS StackTraceStack activeExceptions; |
34 | FOLLY_TLS StackTraceStack caughtExceptions; |
35 | |
36 | } // namespace |
37 | |
38 | // This function is exported and may be found via dlsym(RTLD_NEXT, ...) |
39 | extern "C" StackTraceStack* getExceptionStackTraceStack() { |
40 | return invalid ? nullptr : &caughtExceptions; |
41 | } |
42 | |
43 | namespace { |
44 | |
45 | void addActiveException() { |
46 | // Capture stack trace |
47 | if (!invalid) { |
48 | if (!activeExceptions.pushCurrent()) { |
49 | activeExceptions.clear(); |
50 | caughtExceptions.clear(); |
51 | invalid = true; |
52 | } |
53 | } |
54 | } |
55 | |
56 | void moveTopException(StackTraceStack& from, StackTraceStack& to) { |
57 | if (invalid) { |
58 | return; |
59 | } |
60 | if (!to.moveTopFrom(from)) { |
61 | from.clear(); |
62 | to.clear(); |
63 | invalid = true; |
64 | } |
65 | } |
66 | |
67 | struct Initializer { |
68 | Initializer() { |
69 | registerCxaThrowCallback( |
70 | [](void*, std::type_info*, void (*)(void*)) noexcept { |
71 | addActiveException(); |
72 | }); |
73 | |
74 | registerCxaBeginCatchCallback([](void*) noexcept { |
75 | moveTopException(activeExceptions, caughtExceptions); |
76 | }); |
77 | |
78 | registerCxaRethrowCallback([]() noexcept { |
79 | moveTopException(caughtExceptions, activeExceptions); |
80 | }); |
81 | |
82 | registerCxaEndCatchCallback([]() noexcept { |
83 | if (invalid) { |
84 | return; |
85 | } |
86 | |
87 | __cxxabiv1::__cxa_exception* top = |
88 | __cxxabiv1::__cxa_get_globals_fast()->caughtExceptions; |
89 | // This is gcc specific and not specified in the ABI: |
90 | // abs(handlerCount) is the number of active handlers, it's negative |
91 | // for rethrown exceptions and positive (always 1) for regular |
92 | // exceptions. |
93 | // In the rethrow case, we've already popped the exception off the |
94 | // caught stack, so we don't do anything here. |
95 | // For Lua interop, we see the handlerCount = 0 |
96 | if ((top->handlerCount == 1) || (top->handlerCount == 0)) { |
97 | if (!caughtExceptions.pop()) { |
98 | activeExceptions.clear(); |
99 | invalid = true; |
100 | } |
101 | } |
102 | }); |
103 | |
104 | registerRethrowExceptionCallback( |
105 | [](std::exception_ptr) noexcept { addActiveException(); }); |
106 | |
107 | try { |
108 | ::folly::exception_tracer::installHandlers(); |
109 | } catch (...) { |
110 | } |
111 | } |
112 | }; |
113 | |
114 | Initializer initializer; |
115 | |
116 | } // namespace |
117 | |