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- /*
- * Copyright 2016-present Facebook, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- #include <exception>
- #include <folly/experimental/exception_tracer/ExceptionAbi.h>
- #include <folly/experimental/exception_tracer/ExceptionTracer.h>
- #include <folly/experimental/exception_tracer/ExceptionTracerLib.h>
- #include <folly/experimental/exception_tracer/StackTrace.h>
- #include <folly/experimental/symbolizer/Symbolizer.h>
- using namespace folly::exception_tracer;
- namespace {
- // If we somehow ended up in an invalid state, we don't want to print any stack
- // trace at all because in could be bogus
- FOLLY_TLS bool invalid;
- FOLLY_TLS StackTraceStack activeExceptions;
- FOLLY_TLS StackTraceStack caughtExceptions;
- } // namespace
- // This function is exported and may be found via dlsym(RTLD_NEXT, ...)
- extern "C" StackTraceStack* getExceptionStackTraceStack() {
- return invalid ? nullptr : &caughtExceptions;
- }
- namespace {
- void addActiveException() {
- // Capture stack trace
- if (!invalid) {
- if (!activeExceptions.pushCurrent()) {
- activeExceptions.clear();
- caughtExceptions.clear();
- invalid = true;
- }
- }
- }
- void moveTopException(StackTraceStack& from, StackTraceStack& to) {
- if (invalid) {
- return;
- }
- if (!to.moveTopFrom(from)) {
- from.clear();
- to.clear();
- invalid = true;
- }
- }
- struct Initializer {
- Initializer() {
- registerCxaThrowCallback(
- [](void*, std::type_info*, void (*)(void*)) noexcept {
- addActiveException();
- });
- registerCxaBeginCatchCallback([](void*) noexcept {
- moveTopException(activeExceptions, caughtExceptions);
- });
- registerCxaRethrowCallback([]() noexcept {
- moveTopException(caughtExceptions, activeExceptions);
- });
- registerCxaEndCatchCallback([]() noexcept {
- if (invalid) {
- return;
- }
- __cxxabiv1::__cxa_exception* top =
- __cxxabiv1::__cxa_get_globals_fast()->caughtExceptions;
- // This is gcc specific and not specified in the ABI:
- // abs(handlerCount) is the number of active handlers, it's negative
- // for rethrown exceptions and positive (always 1) for regular
- // exceptions.
- // In the rethrow case, we've already popped the exception off the
- // caught stack, so we don't do anything here.
- // For Lua interop, we see the handlerCount = 0
- if ((top->handlerCount == 1) || (top->handlerCount == 0)) {
- if (!caughtExceptions.pop()) {
- activeExceptions.clear();
- invalid = true;
- }
- }
- });
- registerRethrowExceptionCallback(
- [](std::exception_ptr) noexcept { addActiveException(); });
- try {
- ::folly::exception_tracer::installHandlers();
- } catch (...) {
- }
- }
- };
- Initializer initializer;
- } // namespace
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