Support for custom signal callbacks.

CInterface/Core.cpp

@@ -1,4 +1,9 @@
 #include "Core.hpp"
+#include "../src/SignalHandling.hpp"
 
 std::string ExceptionHandler::_ArbutilsLastException = "";
 export const char* Arbutils_C_GetLastException() { return ExceptionHandler::GetLastException(); }
+
+static ArbUt::SignalHandling sh;
+export void Arbutils_C_SetSignalCallback(void (*callback)(const char*)) { sh = ArbUt::SignalHandling(callback); }
+export void Arbutils_C_RaiseSignal() { raise(SIGSEGV); }

src/Exception.hpp

@@ -41,18 +41,27 @@ namespace ArbUt {
         [[nodiscard]] std::string GetStacktrace([[maybe_unused]] size_t depth = 6,
                                                 [[maybe_unused]] bool include_addr = true) const {
 #if !WINDOWS
-            if (_stack.size() == 0) {
+            return BuildStacktraceFromStack(_stack, depth, include_addr);
+#else
+            return "Stack trace not available on Windows.";
+#endif
+        }
+
+#if !WINDOWS
+        static std::string BuildStacktraceFromStack(const backward::StackTrace& stack, size_t depth = 6,
+                                                    bool include_addr = true) {
+            if (stack.size() == 0) {
                 return "No stack trace could be retrieved.";
             }
             backward::TraceResolver tr;
             backward::SnippetFactory snippetFactory;
-            tr.load_stacktrace(_stack);
+            tr.load_stacktrace(stack);
             std::stringstream ss;
             ss << "Stacktrace with depth " << depth << ": " << std::endl;
             bool foundExceptionClass = false;
             size_t framesAppended = 0;
-            for (size_t i = 0; i < _stack.size() && framesAppended <= depth; ++i) {
-                backward::ResolvedTrace trace = tr.resolve(_stack[i]);
+            for (size_t i = 0; i < stack.size() && framesAppended <= depth; ++i) {
+                backward::ResolvedTrace trace = tr.resolve(stack[i]);
                 if (trace.source.filename.empty()) {
                     AppendNoSourceStack(ss, trace, include_addr);
                     if (foundExceptionClass) {
@@ -74,12 +83,8 @@ namespace ArbUt {
                 }
             }
             return ss.str();
-#else
-            return "Stack trace not available on Windows.";
-#endif
         }
 
-#if !WINDOWS
     private:
         static void AppendNoSourceStack(std::stringstream& ss, const backward::ResolvedTrace& trace,
                                         bool include_addr) {

src/SignalHandling.cpp

@@ -0,0 +1,3 @@
+#include "SignalHandling.hpp"
+
+void(*ArbUt::SignalHandling::_callback)(const char*) = nullptr;

src/SignalHandling.hpp

@@ -0,0 +1,334 @@
+#ifndef ARBUTILS_SIGNALHANDLING_HPP
+#define ARBUTILS_SIGNALHANDLING_HPP
+#if PRETTYTRACES
+#define BACKWARD_HAS_DW 1
+#endif
+#include "../extern/backward.hpp"
+#include "Exception.hpp"
+
+// Sourced from https://github.com/bombela/backward-cpp/blob/master/backward.hpp#L3849
+// Modified to allow for custom callbacks.
+
+namespace ArbUt {
+
+#if defined(BACKWARD_SYSTEM_LINUX) || defined(BACKWARD_SYSTEM_DARWIN)
+
+    class SignalHandling {
+    public:
+        static std::vector<int> make_default_signals() {
+            const int posix_signals[] = {
+                // Signals for which the default action is "Core".
+                SIGABRT, // Abort signal from abort(3)
+                SIGBUS,  // Bus error (bad memory access)
+                SIGFPE,  // Floating point exception
+                SIGILL,  // Illegal Instruction
+                SIGIOT,  // IOT trap. A synonym for SIGABRT
+                SIGQUIT, // Quit from keyboard
+                SIGSEGV, // Invalid memory reference
+                SIGSYS,  // Bad argument to routine (SVr4)
+                SIGTRAP, // Trace/breakpoint trap
+                SIGXCPU, // CPU time limit exceeded (4.2BSD)
+                SIGXFSZ, // File size limit exceeded (4.2BSD)
+#if defined(BACKWARD_SYSTEM_DARWIN)
+                SIGEMT, // emulation instruction executed
+#endif
+            };
+            return std::vector<int>(posix_signals, posix_signals + sizeof posix_signals / sizeof posix_signals[0]);
+        }
+
+        SignalHandling(void(callback)(const char*) = nullptr,
+                       const std::vector<int>& posix_signals = make_default_signals())
+            : _loaded(false){
+            bool success = true;
+
+            const size_t stack_size = 1024 * 1024 * 8;
+            _stack_content.reset(static_cast<char*>(malloc(stack_size)));
+            if (_stack_content) {
+                stack_t ss;
+                ss.ss_sp = _stack_content.get();
+                ss.ss_size = stack_size;
+                ss.ss_flags = 0;
+                if (sigaltstack(&ss, nullptr) < 0) {
+                    success = false;
+                }
+            } else {
+                success = false;
+            }
+            _callback = callback;
+
+            for (size_t i = 0; i < posix_signals.size(); ++i) {
+                struct sigaction action;
+                memset(&action, 0, sizeof action);
+                action.sa_flags = static_cast<int>(SA_SIGINFO | SA_ONSTACK | SA_NODEFER | SA_RESETHAND);
+                sigfillset(&action.sa_mask);
+                sigdelset(&action.sa_mask, posix_signals[i]);
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdisabled-macro-expansion"
+#endif
+                action.sa_sigaction = &sig_handler;
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+
+                int r = sigaction(posix_signals[i], &action, nullptr);
+                if (r < 0)
+                    success = false;
+            }
+
+            _loaded = success;
+        }
+
+        bool loaded() const { return _loaded; }
+
+        static void handleSignal(int, siginfo_t* info, void* _ctx) {
+            ucontext_t* uctx = static_cast<ucontext_t*>(_ctx);
+
+            backward::StackTrace st;
+            void* error_addr = nullptr;
+#ifdef REG_RIP // x86_64
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext.gregs[REG_RIP]);
+#elif defined(REG_EIP) // x86_32
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext.gregs[REG_EIP]);
+#elif defined(__arm__)
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext.arm_pc);
+#elif defined(__aarch64__)
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext.pc);
+#elif defined(__mips__)
+            error_addr = reinterpret_cast<void*>(reinterpret_cast<struct sigcontext*>(&uctx->uc_mcontext)->sc_pc);
+#elif defined(__ppc__) || defined(__powerpc) || defined(__powerpc__) || defined(__POWERPC__)
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext.regs->nip);
+#elif defined(__s390x__)
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext.psw.addr);
+#elif defined(__APPLE__) && defined(__x86_64__)
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext->__ss.__rip);
+#elif defined(__APPLE__)
+            error_addr = reinterpret_cast<void*>(uctx->uc_mcontext->__ss.__eip);
+#else
+#warning ":/ sorry, ain't know no nothing none not of your architecture!"
+#endif
+            if (error_addr) {
+                st.load_from(error_addr, 32);
+            } else {
+                st.load_here(32);
+            }
+
+            if (_callback != nullptr) {
+                auto str = Exception::BuildStacktraceFromStack(st);
+                _callback(str.c_str());
+            }
+
+#if _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
+            psiginfo(info, nullptr);
+#else
+            (void)info;
+#endif
+        }
+
+    private:
+        backward::details::handle<char*> _stack_content;
+        bool _loaded;
+        static void(*_callback)(const char*);
+
+#ifdef __GNUC__
+        __attribute__((noreturn))
+#endif
+        static void
+        sig_handler(int signo, siginfo_t* info, void* _ctx) {
+            handleSignal(signo, info, _ctx);
+
+            // try to forward the signal.
+            raise(info->si_signo);
+
+            // terminate the process immediately.
+            puts("watf? exit");
+            _exit(EXIT_FAILURE);
+        }
+    };
+
+#endif // BACKWARD_SYSTEM_LINUX || BACKWARD_SYSTEM_DARWIN
+
+#ifdef BACKWARD_SYSTEM_WINDOWS
+
+    class SignalHandling {
+    public:
+        SignalHandling(const std::vector<int>& = std::vector<int>())
+            : reporter_thread_([]() {
+                  /* We handle crashes in a utility thread:
+                    backward structures and some Windows functions called here
+                    need stack space, which we do not have when we encounter a
+                    stack overflow.
+                    To support reporting stack traces during a stack overflow,
+                    we create a utility thread at startup, which waits until a
+                    crash happens or the program exits normally. */
+
+                  {
+                      std::unique_lock<std::mutex> lk(mtx());
+                      cv().wait(lk, [] { return crashed() != crash_status::running; });
+                  }
+                  if (crashed() == crash_status::crashed) {
+                      handle_stacktrace(skip_recs());
+                  }
+                  {
+                      std::unique_lock<std::mutex> lk(mtx());
+                      crashed() = crash_status::ending;
+                  }
+                  cv().notify_one();
+              }) {
+            SetUnhandledExceptionFilter(crash_handler);
+
+            signal(SIGABRT, signal_handler);
+            _set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT);
+
+            set_terminate(&terminator);
+            set_unexpected(&terminator);
+            _set_purecall_handler(&terminator);
+            _set_invalid_parameter_handler(&invalid_parameter_handler);
+        }
+        bool loaded() const { return true; }
+
+        ~SignalHandling() {
+            {
+                std::unique_lock<std::mutex> lk(mtx());
+                crashed() = crash_status::normal_exit;
+            }
+
+            cv().notify_one();
+
+            reporter_thread_.join();
+        }
+
+    private:
+        static CONTEXT* ctx() {
+            static CONTEXT data;
+            return &data;
+        }
+
+        enum class crash_status { running, crashed, normal_exit, ending };
+
+        static crash_status& crashed() {
+            static crash_status data;
+            return data;
+        }
+
+        static std::mutex& mtx() {
+            static std::mutex data;
+            return data;
+        }
+
+        static std::condition_variable& cv() {
+            static std::condition_variable data;
+            return data;
+        }
+
+        static HANDLE& thread_handle() {
+            static HANDLE handle;
+            return handle;
+        }
+
+        std::thread reporter_thread_;
+
+        // TODO: how not to hardcode these?
+        static const constexpr int signal_skip_recs =
+#ifdef __clang__
+            // With clang, RtlCaptureContext also captures the stack frame of the
+            // current function Below that, there ar 3 internal Windows functions
+            4
+#else
+            // With MSVC cl, RtlCaptureContext misses the stack frame of the current
+            // function The first entries during StackWalk are the 3 internal Windows
+            // functions
+            3
+#endif
+            ;
+
+        static int& skip_recs() {
+            static int data;
+            return data;
+        }
+
+        static inline void terminator() {
+            crash_handler(signal_skip_recs);
+            abort();
+        }
+
+        static inline void signal_handler(int) {
+            crash_handler(signal_skip_recs);
+            abort();
+        }
+
+        static inline void __cdecl invalid_parameter_handler(const wchar_t*, const wchar_t*, const wchar_t*,
+                                                             unsigned int, uintptr_t) {
+            crash_handler(signal_skip_recs);
+            abort();
+        }
+
+        NOINLINE static LONG WINAPI crash_handler(EXCEPTION_POINTERS* info) {
+            // The exception info supplies a trace from exactly where the issue was,
+            // no need to skip records
+            crash_handler(0, info->ContextRecord);
+            return EXCEPTION_CONTINUE_SEARCH;
+        }
+
+        NOINLINE static void crash_handler(int skip, CONTEXT* ct = nullptr) {
+
+            if (ct == nullptr) {
+                RtlCaptureContext(ctx());
+            } else {
+                memcpy(ctx(), ct, sizeof(CONTEXT));
+            }
+            DuplicateHandle(GetCurrentProcess(), GetCurrentThread(), GetCurrentProcess(), &thread_handle(), 0, FALSE,
+                            DUPLICATE_SAME_ACCESS);
+
+            skip_recs() = skip;
+
+            {
+                std::unique_lock<std::mutex> lk(mtx());
+                crashed() = crash_status::crashed;
+            }
+
+            cv().notify_one();
+
+            {
+                std::unique_lock<std::mutex> lk(mtx());
+                cv().wait(lk, [] { return crashed() != crash_status::crashed; });
+            }
+        }
+
+        static void handle_stacktrace(int skip_frames = 0) {
+            // printer creates the TraceResolver, which can supply us a machine type
+            // for stack walking. Without this, StackTrace can only guess using some
+            // macros.
+            // StackTrace also requires that the PDBs are already loaded, which is done
+            // in the constructor of TraceResolver
+            Printer printer;
+
+            StackTrace st;
+            st.set_machine_type(printer.resolver().machine_type());
+            st.set_context(ctx());
+            st.set_thread_handle(thread_handle());
+            st.load_here(32 + skip_frames);
+            st.skip_n_firsts(skip_frames);
+
+            printer.address = true;
+            printer.print(st, std::cerr);
+        }
+    };
+
+#endif // BACKWARD_SYSTEM_WINDOWS
+
+#ifdef BACKWARD_SYSTEM_UNKNOWN
+
+    class SignalHandling {
+    public:
+        SignalHandling(const std::vector<int>& = std::vector<int>()) {}
+        bool init() { return false; }
+        bool loaded() { return false; }
+    };
+
+#endif // BACKWARD_SYSTEM_UNKNOWN
+
+    void SetSignalCallback(void(*callback)(const char*));
+}
+
+#endif // ARBUTILS_SIGNALHANDLING_HPP