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authorLexi Winter <lexi@le-fay.org>2025-06-29 19:25:29 +0100
committerLexi Winter <lexi@le-fay.org>2025-06-29 19:25:29 +0100
commitbc524d70253a4ab2fe40c3ca3e5666e267c0a4d1 (patch)
tree1e629e7b46b1d9972a973bc93fd100bcebd395be /src/catch2/internal/catch_fatal_condition_handler.cpp
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+
+// Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.txt or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+/** \file
+ * This file provides platform specific implementations of FatalConditionHandler
+ *
+ * This means that there is a lot of conditional compilation, and platform
+ * specific code. Currently, Catch2 supports a dummy handler (if no
+ * handler is desired), and 2 platform specific handlers:
+ * * Windows' SEH
+ * * POSIX signals
+ *
+ * Consequently, various pieces of code below are compiled if either of
+ * the platform specific handlers is enabled, or if none of them are
+ * enabled. It is assumed that both cannot be enabled at the same time,
+ * and doing so should cause a compilation error.
+ *
+ * If another platform specific handler is added, the compile guards
+ * below will need to be updated taking these assumptions into account.
+ */
+
+#include <catch2/internal/catch_fatal_condition_handler.hpp>
+
+#include <catch2/internal/catch_compiler_capabilities.hpp>
+#include <catch2/internal/catch_context.hpp>
+#include <catch2/internal/catch_enforce.hpp>
+#include <catch2/interfaces/catch_interfaces_capture.hpp>
+#include <catch2/internal/catch_windows_h_proxy.hpp>
+#include <catch2/internal/catch_stdstreams.hpp>
+
+#include <algorithm>
+
+#if !defined( CATCH_CONFIG_WINDOWS_SEH ) && !defined( CATCH_CONFIG_POSIX_SIGNALS )
+
+namespace Catch {
+
+ // If neither SEH nor signal handling is required, the handler impls
+ // do not have to do anything, and can be empty.
+ void FatalConditionHandler::engage_platform() {}
+ void FatalConditionHandler::disengage_platform() noexcept {}
+ FatalConditionHandler::FatalConditionHandler() = default;
+ FatalConditionHandler::~FatalConditionHandler() = default;
+
+} // end namespace Catch
+
+#endif // !CATCH_CONFIG_WINDOWS_SEH && !CATCH_CONFIG_POSIX_SIGNALS
+
+#if defined( CATCH_CONFIG_WINDOWS_SEH ) && defined( CATCH_CONFIG_POSIX_SIGNALS )
+#error "Inconsistent configuration: Windows' SEH handling and POSIX signals cannot be enabled at the same time"
+#endif // CATCH_CONFIG_WINDOWS_SEH && CATCH_CONFIG_POSIX_SIGNALS
+
+#if defined( CATCH_CONFIG_WINDOWS_SEH ) || defined( CATCH_CONFIG_POSIX_SIGNALS )
+
+namespace {
+ //! Signals fatal error message to the run context
+ void reportFatal( char const * const message ) {
+ Catch::getCurrentContext().getResultCapture()->handleFatalErrorCondition( message );
+ }
+
+ //! Minimal size Catch2 needs for its own fatal error handling.
+ //! Picked empirically, so it might not be sufficient on all
+ //! platforms, and for all configurations.
+ constexpr std::size_t minStackSizeForErrors = 32 * 1024;
+} // end unnamed namespace
+
+#endif // CATCH_CONFIG_WINDOWS_SEH || CATCH_CONFIG_POSIX_SIGNALS
+
+#if defined( CATCH_CONFIG_WINDOWS_SEH )
+
+namespace Catch {
+
+ struct SignalDefs { DWORD id; const char* name; };
+
+ // There is no 1-1 mapping between signals and windows exceptions.
+ // Windows can easily distinguish between SO and SigSegV,
+ // but SigInt, SigTerm, etc are handled differently.
+ static SignalDefs signalDefs[] = {
+ { EXCEPTION_ILLEGAL_INSTRUCTION, "SIGILL - Illegal instruction signal" },
+ { EXCEPTION_STACK_OVERFLOW, "SIGSEGV - Stack overflow" },
+ { EXCEPTION_ACCESS_VIOLATION, "SIGSEGV - Segmentation violation signal" },
+ { EXCEPTION_INT_DIVIDE_BY_ZERO, "Divide by zero error" },
+ };
+
+ static LONG CALLBACK topLevelExceptionFilter(PEXCEPTION_POINTERS ExceptionInfo) {
+ for (auto const& def : signalDefs) {
+ if (ExceptionInfo->ExceptionRecord->ExceptionCode == def.id) {
+ reportFatal(def.name);
+ }
+ }
+ // If its not an exception we care about, pass it along.
+ // This stops us from eating debugger breaks etc.
+ return EXCEPTION_CONTINUE_SEARCH;
+ }
+
+ // Since we do not support multiple instantiations, we put these
+ // into global variables and rely on cleaning them up in outlined
+ // constructors/destructors
+ static LPTOP_LEVEL_EXCEPTION_FILTER previousTopLevelExceptionFilter = nullptr;
+
+
+ // For MSVC, we reserve part of the stack memory for handling
+ // memory overflow structured exception.
+ FatalConditionHandler::FatalConditionHandler() {
+ ULONG guaranteeSize = static_cast<ULONG>(minStackSizeForErrors);
+ if (!SetThreadStackGuarantee(&guaranteeSize)) {
+ // We do not want to fully error out, because needing
+ // the stack reserve should be rare enough anyway.
+ Catch::cerr()
+ << "Failed to reserve piece of stack."
+ << " Stack overflows will not be reported successfully.";
+ }
+ }
+
+ // We do not attempt to unset the stack guarantee, because
+ // Windows does not support lowering the stack size guarantee.
+ FatalConditionHandler::~FatalConditionHandler() = default;
+
+
+ void FatalConditionHandler::engage_platform() {
+ // Register as a the top level exception filter.
+ previousTopLevelExceptionFilter = SetUnhandledExceptionFilter(topLevelExceptionFilter);
+ }
+
+ void FatalConditionHandler::disengage_platform() noexcept {
+ if (SetUnhandledExceptionFilter(previousTopLevelExceptionFilter) != topLevelExceptionFilter) {
+ Catch::cerr()
+ << "Unexpected SEH unhandled exception filter on disengage."
+ << " The filter was restored, but might be rolled back unexpectedly.";
+ }
+ previousTopLevelExceptionFilter = nullptr;
+ }
+
+} // end namespace Catch
+
+#endif // CATCH_CONFIG_WINDOWS_SEH
+
+#if defined( CATCH_CONFIG_POSIX_SIGNALS )
+
+#include <signal.h>
+
+namespace Catch {
+
+ struct SignalDefs {
+ int id;
+ const char* name;
+ };
+
+ static SignalDefs signalDefs[] = {
+ { SIGINT, "SIGINT - Terminal interrupt signal" },
+ { SIGILL, "SIGILL - Illegal instruction signal" },
+ { SIGFPE, "SIGFPE - Floating point error signal" },
+ { SIGSEGV, "SIGSEGV - Segmentation violation signal" },
+ { SIGTERM, "SIGTERM - Termination request signal" },
+ { SIGABRT, "SIGABRT - Abort (abnormal termination) signal" }
+ };
+
+// Older GCCs trigger -Wmissing-field-initializers for T foo = {}
+// which is zero initialization, but not explicit. We want to avoid
+// that.
+#if defined(__GNUC__)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
+ static char* altStackMem = nullptr;
+ static std::size_t altStackSize = 0;
+ static stack_t oldSigStack{};
+ static struct sigaction oldSigActions[sizeof(signalDefs) / sizeof(SignalDefs)]{};
+
+ static void restorePreviousSignalHandlers() noexcept {
+ // We set signal handlers back to the previous ones. Hopefully
+ // nobody overwrote them in the meantime, and doesn't expect
+ // their signal handlers to live past ours given that they
+ // installed them after ours..
+ for (std::size_t i = 0; i < sizeof(signalDefs) / sizeof(SignalDefs); ++i) {
+ sigaction(signalDefs[i].id, &oldSigActions[i], nullptr);
+ }
+ // Return the old stack
+ sigaltstack(&oldSigStack, nullptr);
+ }
+
+ static void handleSignal( int sig ) {
+ char const * name = "<unknown signal>";
+ for (auto const& def : signalDefs) {
+ if (sig == def.id) {
+ name = def.name;
+ break;
+ }
+ }
+ // We need to restore previous signal handlers and let them do
+ // their thing, so that the users can have the debugger break
+ // when a signal is raised, and so on.
+ restorePreviousSignalHandlers();
+ reportFatal( name );
+ raise( sig );
+ }
+
+ FatalConditionHandler::FatalConditionHandler() {
+ assert(!altStackMem && "Cannot initialize POSIX signal handler when one already exists");
+ if (altStackSize == 0) {
+ altStackSize = std::max(static_cast<size_t>(SIGSTKSZ), minStackSizeForErrors);
+ }
+ altStackMem = new char[altStackSize]();
+ }
+
+ FatalConditionHandler::~FatalConditionHandler() {
+ delete[] altStackMem;
+ // We signal that another instance can be constructed by zeroing
+ // out the pointer.
+ altStackMem = nullptr;
+ }
+
+ void FatalConditionHandler::engage_platform() {
+ stack_t sigStack;
+ sigStack.ss_sp = altStackMem;
+ sigStack.ss_size = altStackSize;
+ sigStack.ss_flags = 0;
+ sigaltstack(&sigStack, &oldSigStack);
+ struct sigaction sa = { };
+
+ sa.sa_handler = handleSignal;
+ sa.sa_flags = SA_ONSTACK;
+ for (std::size_t i = 0; i < sizeof(signalDefs)/sizeof(SignalDefs); ++i) {
+ sigaction(signalDefs[i].id, &sa, &oldSigActions[i]);
+ }
+ }
+
+#if defined(__GNUC__)
+# pragma GCC diagnostic pop
+#endif
+
+
+ void FatalConditionHandler::disengage_platform() noexcept {
+ restorePreviousSignalHandlers();
+ }
+
+} // end namespace Catch
+
+#endif // CATCH_CONFIG_POSIX_SIGNALS