| // Copyright 2018 The Abseil Authors. |
| // |
| // 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 |
| // |
| // https://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. |
| // |
| // ----------------------------------------------------------------------------- |
| // File: failure_signal_handler.h |
| // ----------------------------------------------------------------------------- |
| // |
| // This file configures the Abseil *failure signal handler* to capture and dump |
| // useful debugging information (such as a stacktrace) upon program failure. |
| // |
| // To use the failure signal handler, call `absl::InstallFailureSignalHandler()` |
| // very early in your program, usually in the first few lines of main(): |
| // |
| // int main(int argc, char** argv) { |
| // // Initialize the symbolizer to get a human-readable stack trace |
| // absl::InitializeSymbolizer(argv[0]); |
| // |
| // absl::FailureSignalHandlerOptions options; |
| // absl::InstallFailureSignalHandler(options); |
| // DoSomethingInteresting(); |
| // return 0; |
| // } |
| // |
| // Any program that raises a fatal signal (such as `SIGSEGV`, `SIGILL`, |
| // `SIGFPE`, `SIGABRT`, `SIGTERM`, `SIGBUG`, and `SIGTRAP`) will call the |
| // installed failure signal handler and provide debugging information to stderr. |
| // |
| // Note that you should *not* install the Abseil failure signal handler more |
| // than once. You may, of course, have another (non-Abseil) failure signal |
| // handler installed (which would be triggered if Abseil's failure signal |
| // handler sets `call_previous_handler` to `true`). |
| |
| #ifndef ABSL_DEBUGGING_FAILURE_SIGNAL_HANDLER_H_ |
| #define ABSL_DEBUGGING_FAILURE_SIGNAL_HANDLER_H_ |
| |
| namespace absl { |
| |
| // FailureSignalHandlerOptions |
| // |
| // Struct for holding `absl::InstallFailureSignalHandler()` configuration |
| // options. |
| struct FailureSignalHandlerOptions { |
| // If true, try to symbolize the stacktrace emitted on failure, provided that |
| // you have initialized a symbolizer for that purpose. (See symbolize.h for |
| // more information.) |
| bool symbolize_stacktrace = true; |
| |
| // If true, try to run signal handlers on an alternate stack (if supported on |
| // the given platform). An alternate stack is useful for program crashes due |
| // to a stack overflow; by running on a alternate stack, the signal handler |
| // may run even when normal stack space has been exausted. The downside of |
| // using an alternate stack is that extra memory for the alternate stack needs |
| // to be pre-allocated. |
| bool use_alternate_stack = true; |
| |
| // If positive, indicates the number of seconds after which the failure signal |
| // handler is invoked to abort the program. Setting such an alarm is useful in |
| // cases where the failure signal handler itself may become hung or |
| // deadlocked. |
| int alarm_on_failure_secs = 3; |
| |
| // If true, call the previously registered signal handler for the signal that |
| // was received (if one was registered) after the existing signal handler |
| // runs. This mechanism can be used to chain signal handlers together. |
| // |
| // If false, the signal is raised to the default handler for that signal |
| // (which normally terminates the program). |
| // |
| // IMPORTANT: If true, the chained fatal signal handlers must not try to |
| // recover from the fatal signal. Instead, they should terminate the program |
| // via some mechanism, like raising the default handler for the signal, or by |
| // calling `_exit()`. Note that the failure signal handler may put parts of |
| // the Abseil library into a state from which they cannot recover. |
| bool call_previous_handler = false; |
| |
| // If non-null, indicates a pointer to a callback function that will be called |
| // upon failure, with a std::string argument containing failure data. This function |
| // may be used as a hook to write failure data to a secondary location, such |
| // as a log file. This function may also be called with null data, as a hint |
| // to flush any buffered data before the program may be terminated. Consider |
| // flushing any buffered data in all calls to this function. |
| // |
| // Since this function runs within a signal handler, it should be |
| // async-signal-safe if possible. |
| // See http://man7.org/linux/man-pages/man7/signal-safety.7.html |
| void (*writerfn)(const char*) = nullptr; |
| }; |
| |
| // InstallFailureSignalHandler() |
| // |
| // Installs a signal handler for the common failure signals `SIGSEGV`, `SIGILL`, |
| // `SIGFPE`, `SIGABRT`, `SIGTERM`, `SIGBUG`, and `SIGTRAP` (provided they exist |
| // on the given platform). The failure signal handler dumps program failure data |
| // useful for debugging in an unspecified format to stderr. This data may |
| // include the program counter, a stacktrace, and register information on some |
| // systems; do not rely on an exact format for the output, as it is subject to |
| // change. |
| void InstallFailureSignalHandler(const FailureSignalHandlerOptions& options); |
| |
| namespace debugging_internal { |
| const char* FailureSignalToString(int signo); |
| } // namespace debugging_internal |
| |
| } // namespace absl |
| |
| #endif // ABSL_DEBUGGING_FAILURE_SIGNAL_HANDLER_H_ |