| // 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`). | |
| namespace absl { | |
| ABSL_NAMESPACE_BEGIN | |
| // 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 exhausted. 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 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 will 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 | |
| ABSL_NAMESPACE_END | |
| } // namespace absl | |