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authorGravatar Abseil Team <absl-team@google.com>2018-04-26 06:47:58 -0700
committerGravatar Derek Mauro <dmauro@google.com>2018-04-26 11:05:43 -0400
commit28f5b890702139effabf3576f20e1a4db4a90a80 (patch)
treea063698e44f3bb6ad708fcf290a05d1af3ea9aa6 /absl/debugging/failure_signal_handler.cc
parentea0e750e52ee223db34a242f9a7229ac04a0f473 (diff)
- 81cdce434ff1bd8fa54c832a11dda59af46e79cc Adds a failure signal handler to Abseil. by Derek Mauro <dmauro@google.com>
- 40a973dd1b159e7455dd5fc06ac2d3f494d72c3e Remove test fixture requirement for ExceptionSafetyTester... by Abseil Team <absl-team@google.com> GitOrigin-RevId: 81cdce434ff1bd8fa54c832a11dda59af46e79cc Change-Id: Ia9fca98e38f229b68f7ec45600dee1bbd5dcff33
Diffstat (limited to 'absl/debugging/failure_signal_handler.cc')
-rw-r--r--absl/debugging/failure_signal_handler.cc351
1 files changed, 351 insertions, 0 deletions
diff --git a/absl/debugging/failure_signal_handler.cc b/absl/debugging/failure_signal_handler.cc
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--- /dev/null
+++ b/absl/debugging/failure_signal_handler.cc
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+//
+// 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
+//
+// 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 "absl/debugging/failure_signal_handler.h"
+
+#include "absl/base/config.h"
+
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <unistd.h>
+#endif
+
+#ifdef ABSL_HAVE_MMAP
+#include <sys/mman.h>
+#endif
+
+#include <algorithm>
+#include <atomic>
+#include <cerrno>
+#include <csignal>
+#include <cstring>
+#include <ctime>
+
+#include "absl/base/attributes.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/internal/sysinfo.h"
+#include "absl/debugging/internal/examine_stack.h"
+#include "absl/debugging/stacktrace.h"
+
+#ifndef _WIN32
+#define ABSL_HAVE_SIGACTION
+#endif
+
+namespace absl {
+
+ABSL_CONST_INIT static FailureSignalHandlerOptions fsh_options;
+
+// Resets the signal handler for signo to the default action for that
+// signal, then raises the signal.
+static void RaiseToDefaultHandler(int signo) {
+ signal(signo, SIG_DFL);
+ raise(signo);
+}
+
+struct FailureSignalData {
+ const int signo;
+ const char* const as_string;
+#ifdef ABSL_HAVE_SIGACTION
+ struct sigaction previous_action;
+ // StructSigaction is used to silence -Wmissing-field-initializers.
+ using StructSigaction = struct sigaction;
+ #define FSD_PREVIOUS_INIT FailureSignalData::StructSigaction()
+#else
+ void (*previous_handler)(int);
+ #define FSD_PREVIOUS_INIT SIG_DFL
+#endif
+};
+
+ABSL_CONST_INIT static FailureSignalData failure_signal_data[] = {
+ {SIGSEGV, "SIGSEGV", FSD_PREVIOUS_INIT},
+ {SIGILL, "SIGILL", FSD_PREVIOUS_INIT},
+ {SIGFPE, "SIGFPE", FSD_PREVIOUS_INIT},
+ {SIGABRT, "SIGABRT", FSD_PREVIOUS_INIT},
+ {SIGTERM, "SIGTERM", FSD_PREVIOUS_INIT},
+#ifndef _WIN32
+ {SIGBUS, "SIGBUS", FSD_PREVIOUS_INIT},
+ {SIGTRAP, "SIGTRAP", FSD_PREVIOUS_INIT},
+#endif
+};
+
+#undef FSD_PREVIOUS_INIT
+
+static void RaiseToPreviousHandler(int signo) {
+ // Search for the previous handler.
+ for (const auto& it : failure_signal_data) {
+ if (it.signo == signo) {
+#ifdef ABSL_HAVE_SIGACTION
+ sigaction(signo, &it.previous_action, nullptr);
+#else
+ signal(signo, it.previous_handler);
+#endif
+ raise(signo);
+ return;
+ }
+ }
+
+ // Not found, use the default handler.
+ RaiseToDefaultHandler(signo);
+}
+
+namespace debugging_internal {
+
+const char* FailureSignalToString(int signo) {
+ for (const auto& it : failure_signal_data) {
+ if (it.signo == signo) {
+ return it.as_string;
+ }
+ }
+ return "";
+}
+
+} // namespace debugging_internal
+
+#ifndef _WIN32
+
+static bool SetupAlternateStackOnce() {
+ const size_t page_mask = getpagesize() - 1;
+ size_t stack_size = (std::max(SIGSTKSZ, 65536) + page_mask) & ~page_mask;
+#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
+ defined(THREAD_SANITIZER)
+ // Account for sanitizer instrumentation requiring additional stack space.
+ stack_size *= 5;
+#endif
+
+ stack_t sigstk;
+ memset(&sigstk, 0, sizeof(sigstk));
+ sigstk.ss_size = stack_size;
+
+#ifdef ABSL_HAVE_MMAP
+#ifndef MAP_STACK
+#define MAP_STACK 0
+#endif
+ sigstk.ss_sp = mmap(nullptr, sigstk.ss_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+ if (sigstk.ss_sp == MAP_FAILED) {
+ ABSL_RAW_LOG(FATAL, "mmap() for alternate signal stack failed");
+ }
+#else
+ sigstk.ss_sp = malloc(sigstk.ss_size);
+ if (sigstk.ss_sp == nullptr) {
+ ABSL_RAW_LOG(FATAL, "malloc() for alternate signal stack failed");
+ }
+#endif
+
+ if (sigaltstack(&sigstk, nullptr) != 0) {
+ ABSL_RAW_LOG(FATAL, "sigaltstack() failed with errno=%d", errno);
+ }
+ return true;
+}
+
+#endif
+
+// Sets up an alternate stack for signal handlers once.
+// Returns the appropriate flag for sig_action.sa_flags
+// if the system supports using an alternate stack.
+static int MaybeSetupAlternateStack() {
+#ifndef _WIN32
+ ABSL_ATTRIBUTE_UNUSED static const bool kOnce = SetupAlternateStackOnce();
+ return SA_ONSTACK;
+#endif
+ return 0;
+}
+
+#ifdef ABSL_HAVE_SIGACTION
+
+static void InstallOneFailureHandler(FailureSignalData* data,
+ void (*handler)(int, siginfo_t*, void*)) {
+ struct sigaction act;
+ memset(&act, 0, sizeof(act));
+ sigemptyset(&act.sa_mask);
+ act.sa_flags |= SA_SIGINFO;
+ // SA_NODEFER is required to handle SIGABRT from
+ // ImmediateAbortSignalHandler().
+ act.sa_flags |= SA_NODEFER;
+ if (fsh_options.use_alternate_stack) {
+ act.sa_flags |= MaybeSetupAlternateStack();
+ }
+ act.sa_sigaction = handler;
+ ABSL_RAW_CHECK(sigaction(data->signo, &act, &data->previous_action) == 0,
+ "sigaction() failed");
+}
+
+#else
+
+static void InstallOneFailureHandler(FailureSignalData* data,
+ void (*handler)(int)) {
+ data->previous_handler = signal(data->signo, handler);
+ ABSL_RAW_CHECK(data->previous_handler != SIG_ERR, "signal() failed");
+}
+
+#endif
+
+static void WriteToStderr(const char* data) {
+ int old_errno = errno;
+ absl::raw_logging_internal::SafeWriteToStderr(data, strlen(data));
+ errno = old_errno;
+}
+
+static void WriteSignalMessage(int signo, void (*writerfn)(const char*)) {
+ char buf[64];
+ const char* const signal_string =
+ debugging_internal::FailureSignalToString(signo);
+ if (signal_string != nullptr && signal_string[0] != '\0') {
+ snprintf(buf, sizeof(buf), "*** %s received at time=%ld ***\n",
+ signal_string,
+ static_cast<long>(time(nullptr))); // NOLINT(runtime/int)
+ } else {
+ snprintf(buf, sizeof(buf), "*** Signal %d received at time=%ld ***\n",
+ signo, static_cast<long>(time(nullptr))); // NOLINT(runtime/int)
+ }
+ writerfn(buf);
+}
+
+// `void*` might not be big enough to store `void(*)(const char*)`.
+struct WriterFnStruct {
+ void (*writerfn)(const char*);
+};
+
+// Many of the absl::debugging_internal::Dump* functions in
+// examine_stack.h take a writer function pointer that has a void* arg
+// for historical reasons. failure_signal_handler_writer only takes a
+// data pointer. This function converts between these types.
+static void WriterFnWrapper(const char* data, void* arg) {
+ static_cast<WriterFnStruct*>(arg)->writerfn(data);
+}
+
+// Convenient wrapper around DumpPCAndFrameSizesAndStackTrace() for signal
+// handlers. "noinline" so that GetStackFrames() skips the top-most stack
+// frame for this function.
+ABSL_ATTRIBUTE_NOINLINE static void WriteStackTrace(
+ void* ucontext, bool symbolize_stacktrace,
+ void (*writerfn)(const char*, void*), void* writerfn_arg) {
+ constexpr int kNumStackFrames = 32;
+ void* stack[kNumStackFrames];
+ int frame_sizes[kNumStackFrames];
+ int min_dropped_frames;
+ int depth = absl::GetStackFramesWithContext(
+ stack, frame_sizes, kNumStackFrames,
+ 1, // Do not include this function in stack trace.
+ ucontext, &min_dropped_frames);
+ absl::debugging_internal::DumpPCAndFrameSizesAndStackTrace(
+ absl::debugging_internal::GetProgramCounter(ucontext), stack, frame_sizes,
+ depth, min_dropped_frames, symbolize_stacktrace, writerfn, writerfn_arg);
+}
+
+// Called by FailureSignalHandler() to write the failure info. It is
+// called once with writerfn set to WriteToStderr() and then possibly
+// with writerfn set to the user provided function.
+static void WriteFailureInfo(int signo, void* ucontext,
+ void (*writerfn)(const char*)) {
+ WriterFnStruct writerfn_struct{writerfn};
+ WriteSignalMessage(signo, writerfn);
+ WriteStackTrace(ucontext, fsh_options.symbolize_stacktrace, WriterFnWrapper,
+ &writerfn_struct);
+}
+
+// absl::SleepFor() can't be used here since AbslInternalSleepFor()
+// may be overridden to do something that isn't async-signal-safe on
+// some platforms.
+static void PortableSleepForSeconds(int seconds) {
+#ifdef _WIN32
+ Sleep(seconds * 1000);
+#else
+ struct timespec sleep_time;
+ sleep_time.tv_sec = seconds;
+ sleep_time.tv_nsec = 0;
+ while (nanosleep(&sleep_time, &sleep_time) != 0 && errno == EINTR) {}
+#endif
+}
+
+#ifdef ABSL_HAVE_ALARM
+// FailureSignalHandler() installs this as a signal handler for
+// SIGALRM, then sets an alarm to be delivered to the program after a
+// set amount of time. If FailureSignalHandler() hangs for more than
+// the alarm timeout, ImmediateAbortSignalHandler() will abort the
+// program.
+static void ImmediateAbortSignalHandler(int) {
+ RaiseToDefaultHandler(SIGABRT);
+}
+#endif
+
+// absl::base_internal::GetTID() returns pid_t on most platforms, but
+// returns absl::base_internal::pid_t on Windows.
+using GetTidType = decltype(absl::base_internal::GetTID());
+ABSL_CONST_INIT static std::atomic<GetTidType> failed_tid(0);
+
+#ifndef ABSL_HAVE_SIGACTION
+static void FailureSignalHandler(int signo) {
+ void* ucontext = nullptr;
+#else
+static void FailureSignalHandler(int signo, siginfo_t*,
+ void* ucontext) {
+#endif
+
+ const GetTidType this_tid = absl::base_internal::GetTID();
+ GetTidType previous_failed_tid = 0;
+ if (!failed_tid.compare_exchange_strong(
+ previous_failed_tid, static_cast<intptr_t>(this_tid),
+ std::memory_order_acq_rel, std::memory_order_relaxed)) {
+ ABSL_RAW_LOG(
+ ERROR,
+ "Signal %d raised at PC=%p while already in FailureSignalHandler()",
+ signo, absl::debugging_internal::GetProgramCounter(ucontext));
+ if (this_tid != previous_failed_tid) {
+ // Another thread is already in FailureSignalHandler(), so wait
+ // a bit for it to finish. If the other thread doesn't kill us,
+ // we do so after sleeping.
+ PortableSleepForSeconds(3);
+ RaiseToDefaultHandler(signo);
+ // The recursively raised signal may be blocked until we return.
+ return;
+ }
+ }
+
+#ifdef ABSL_HAVE_ALARM
+ // Set an alarm to abort the program in case this code hangs or deadlocks.
+ if (fsh_options.alarm_on_failure_secs > 0) {
+ alarm(0); // Cancel any existing alarms.
+ signal(SIGALRM, ImmediateAbortSignalHandler);
+ alarm(fsh_options.alarm_on_failure_secs);
+ }
+#endif
+
+ // First write to stderr.
+ WriteFailureInfo(signo, ucontext, WriteToStderr);
+
+ // Riskier code (because it is less likely to be async-signal-safe)
+ // goes after this point.
+ if (fsh_options.writerfn != nullptr) {
+ WriteFailureInfo(signo, ucontext, fsh_options.writerfn);
+ }
+
+ if (fsh_options.call_previous_handler) {
+ RaiseToPreviousHandler(signo);
+ } else {
+ RaiseToDefaultHandler(signo);
+ }
+}
+
+void InstallFailureSignalHandler(const FailureSignalHandlerOptions& options) {
+ fsh_options = options;
+ for (auto& it : failure_signal_data) {
+ InstallOneFailureHandler(&it, FailureSignalHandler);
+ }
+}
+
+} // namespace absl