mirror of
https://github.com/oxen-io/lokinet.git
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362 lines
11 KiB
C++
362 lines
11 KiB
C++
//
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// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#include "absl/debugging/failure_signal_handler.h"
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#include "absl/base/config.h"
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#ifdef _WIN32
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#include <windows.h>
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#else
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#include <unistd.h>
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#endif
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#ifdef ABSL_HAVE_MMAP
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#include <sys/mman.h>
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#endif
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#include <algorithm>
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#include <atomic>
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#include <cerrno>
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#include <csignal>
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#include <cstdio>
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#include <cstring>
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#include <ctime>
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#include "absl/base/attributes.h"
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#include "absl/base/internal/raw_logging.h"
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#include "absl/base/internal/sysinfo.h"
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#include "absl/debugging/internal/examine_stack.h"
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#include "absl/debugging/stacktrace.h"
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#ifndef _WIN32
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#define ABSL_HAVE_SIGACTION
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#endif
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namespace absl {
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inline namespace lts_2018_12_18 {
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ABSL_CONST_INIT static FailureSignalHandlerOptions fsh_options;
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// Resets the signal handler for signo to the default action for that
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// signal, then raises the signal.
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static void RaiseToDefaultHandler(int signo) {
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signal(signo, SIG_DFL);
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raise(signo);
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}
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struct FailureSignalData {
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const int signo;
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const char* const as_string;
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#ifdef ABSL_HAVE_SIGACTION
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struct sigaction previous_action;
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// StructSigaction is used to silence -Wmissing-field-initializers.
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using StructSigaction = struct sigaction;
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#define FSD_PREVIOUS_INIT FailureSignalData::StructSigaction()
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#else
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void (*previous_handler)(int);
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#define FSD_PREVIOUS_INIT SIG_DFL
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#endif
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};
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ABSL_CONST_INIT static FailureSignalData failure_signal_data[] = {
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{SIGSEGV, "SIGSEGV", FSD_PREVIOUS_INIT},
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{SIGILL, "SIGILL", FSD_PREVIOUS_INIT},
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{SIGFPE, "SIGFPE", FSD_PREVIOUS_INIT},
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{SIGABRT, "SIGABRT", FSD_PREVIOUS_INIT},
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{SIGTERM, "SIGTERM", FSD_PREVIOUS_INIT},
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#ifndef _WIN32
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{SIGBUS, "SIGBUS", FSD_PREVIOUS_INIT},
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{SIGTRAP, "SIGTRAP", FSD_PREVIOUS_INIT},
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#endif
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};
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#undef FSD_PREVIOUS_INIT
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static void RaiseToPreviousHandler(int signo) {
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// Search for the previous handler.
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for (const auto& it : failure_signal_data) {
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if (it.signo == signo) {
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#ifdef ABSL_HAVE_SIGACTION
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sigaction(signo, &it.previous_action, nullptr);
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#else
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signal(signo, it.previous_handler);
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#endif
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raise(signo);
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return;
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}
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}
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// Not found, use the default handler.
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RaiseToDefaultHandler(signo);
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}
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namespace debugging_internal {
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const char* FailureSignalToString(int signo) {
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for (const auto& it : failure_signal_data) {
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if (it.signo == signo) {
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return it.as_string;
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}
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}
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return "";
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}
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} // namespace debugging_internal
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#ifndef _WIN32
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static bool SetupAlternateStackOnce() {
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#if defined(__wasm__) || defined (__asjms__)
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const size_t page_mask = getpagesize() - 1;
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#else
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const size_t page_mask = sysconf(_SC_PAGESIZE) - 1;
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#endif
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size_t stack_size = (std::max((unsigned)SIGSTKSZ, (unsigned)65536) + page_mask) & ~page_mask;
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#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
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defined(THREAD_SANITIZER)
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// Account for sanitizer instrumentation requiring additional stack space.
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stack_size *= 5;
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#endif
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stack_t sigstk;
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memset(&sigstk, 0, sizeof(sigstk));
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sigstk.ss_size = stack_size;
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#ifdef ABSL_HAVE_MMAP
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#ifndef MAP_STACK
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#define MAP_STACK 0
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#endif
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#if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
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#define MAP_ANONYMOUS MAP_ANON
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#endif
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sigstk.ss_sp = mmap(nullptr, sigstk.ss_size, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
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if (sigstk.ss_sp == MAP_FAILED) {
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ABSL_RAW_LOG(FATAL, "mmap() for alternate signal stack failed");
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}
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#else
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sigstk.ss_sp = malloc(sigstk.ss_size);
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if (sigstk.ss_sp == nullptr) {
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ABSL_RAW_LOG(FATAL, "malloc() for alternate signal stack failed");
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}
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#endif
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if (sigaltstack(&sigstk, nullptr) != 0) {
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ABSL_RAW_LOG(FATAL, "sigaltstack() failed with errno=%d", errno);
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}
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return true;
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}
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#endif
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#ifdef ABSL_HAVE_SIGACTION
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// Sets up an alternate stack for signal handlers once.
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// Returns the appropriate flag for sig_action.sa_flags
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// if the system supports using an alternate stack.
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static int MaybeSetupAlternateStack() {
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#ifndef _WIN32
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ABSL_ATTRIBUTE_UNUSED static const bool kOnce = SetupAlternateStackOnce();
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return SA_ONSTACK;
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#else
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return 0;
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#endif
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}
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static void InstallOneFailureHandler(FailureSignalData* data,
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void (*handler)(int, siginfo_t*, void*)) {
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struct sigaction act;
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memset(&act, 0, sizeof(act));
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sigemptyset(&act.sa_mask);
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act.sa_flags |= SA_SIGINFO;
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// SA_NODEFER is required to handle SIGABRT from
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// ImmediateAbortSignalHandler().
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act.sa_flags |= SA_NODEFER;
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if (fsh_options.use_alternate_stack) {
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act.sa_flags |= MaybeSetupAlternateStack();
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}
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act.sa_sigaction = handler;
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ABSL_RAW_CHECK(sigaction(data->signo, &act, &data->previous_action) == 0,
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"sigaction() failed");
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}
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#else
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static void InstallOneFailureHandler(FailureSignalData* data,
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void (*handler)(int)) {
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data->previous_handler = signal(data->signo, handler);
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ABSL_RAW_CHECK(data->previous_handler != SIG_ERR, "signal() failed");
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}
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#endif
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static void WriteToStderr(const char* data) {
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int old_errno = errno;
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absl::raw_logging_internal::SafeWriteToStderr(data, strlen(data));
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errno = old_errno;
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}
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static void WriteSignalMessage(int signo, void (*writerfn)(const char*)) {
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char buf[64];
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const char* const signal_string =
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debugging_internal::FailureSignalToString(signo);
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if (signal_string != nullptr && signal_string[0] != '\0') {
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snprintf(buf, sizeof(buf), "*** %s received at time=%ld ***\n",
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signal_string,
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static_cast<long>(time(nullptr))); // NOLINT(runtime/int)
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} else {
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snprintf(buf, sizeof(buf), "*** Signal %d received at time=%ld ***\n",
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signo, static_cast<long>(time(nullptr))); // NOLINT(runtime/int)
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}
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writerfn(buf);
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}
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// `void*` might not be big enough to store `void(*)(const char*)`.
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struct WriterFnStruct {
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void (*writerfn)(const char*);
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};
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// Many of the absl::debugging_internal::Dump* functions in
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// examine_stack.h take a writer function pointer that has a void* arg
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// for historical reasons. failure_signal_handler_writer only takes a
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// data pointer. This function converts between these types.
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static void WriterFnWrapper(const char* data, void* arg) {
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static_cast<WriterFnStruct*>(arg)->writerfn(data);
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}
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// Convenient wrapper around DumpPCAndFrameSizesAndStackTrace() for signal
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// handlers. "noinline" so that GetStackFrames() skips the top-most stack
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// frame for this function.
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ABSL_ATTRIBUTE_NOINLINE static void WriteStackTrace(
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void* ucontext, bool symbolize_stacktrace,
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void (*writerfn)(const char*, void*), void* writerfn_arg) {
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constexpr int kNumStackFrames = 32;
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void* stack[kNumStackFrames];
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int frame_sizes[kNumStackFrames];
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int min_dropped_frames;
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int depth = absl::GetStackFramesWithContext(
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stack, frame_sizes, kNumStackFrames,
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1, // Do not include this function in stack trace.
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ucontext, &min_dropped_frames);
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absl::debugging_internal::DumpPCAndFrameSizesAndStackTrace(
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absl::debugging_internal::GetProgramCounter(ucontext), stack, frame_sizes,
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depth, min_dropped_frames, symbolize_stacktrace, writerfn, writerfn_arg);
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}
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// Called by AbslFailureSignalHandler() to write the failure info. It is
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// called once with writerfn set to WriteToStderr() and then possibly
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// with writerfn set to the user provided function.
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static void WriteFailureInfo(int signo, void* ucontext,
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void (*writerfn)(const char*)) {
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WriterFnStruct writerfn_struct{writerfn};
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WriteSignalMessage(signo, writerfn);
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WriteStackTrace(ucontext, fsh_options.symbolize_stacktrace, WriterFnWrapper,
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&writerfn_struct);
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}
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// absl::SleepFor() can't be used here since AbslInternalSleepFor()
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// may be overridden to do something that isn't async-signal-safe on
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// some platforms.
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static void PortableSleepForSeconds(int seconds) {
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#ifdef _MSC_VER
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Sleep(seconds * 1000);
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#else
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struct timespec sleep_time;
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sleep_time.tv_sec = seconds;
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sleep_time.tv_nsec = 0;
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while (nanosleep(&sleep_time, &sleep_time) != 0 && errno == EINTR) {}
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#endif
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}
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#ifdef ABSL_HAVE_ALARM
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// AbslFailureSignalHandler() installs this as a signal handler for
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// SIGALRM, then sets an alarm to be delivered to the program after a
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// set amount of time. If AbslFailureSignalHandler() hangs for more than
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// the alarm timeout, ImmediateAbortSignalHandler() will abort the
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// program.
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static void ImmediateAbortSignalHandler(int) {
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RaiseToDefaultHandler(SIGABRT);
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}
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#endif
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// absl::base_internal::GetTID() returns pid_t on most platforms, but
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// returns absl::base_internal::pid_t on Windows.
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using GetTidType = decltype(absl::base_internal::GetTID());
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ABSL_CONST_INIT static std::atomic<GetTidType> failed_tid(0);
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#ifndef ABSL_HAVE_SIGACTION
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static void AbslFailureSignalHandler(int signo) {
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void* ucontext = nullptr;
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#else
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static void AbslFailureSignalHandler(int signo, siginfo_t*, void* ucontext) {
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#endif
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const GetTidType this_tid = absl::base_internal::GetTID();
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GetTidType previous_failed_tid = 0;
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if (!failed_tid.compare_exchange_strong(
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previous_failed_tid, static_cast<intptr_t>(this_tid),
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std::memory_order_acq_rel, std::memory_order_relaxed)) {
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ABSL_RAW_LOG(
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ERROR,
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"Signal %d raised at PC=%p while already in AbslFailureSignalHandler()",
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signo, absl::debugging_internal::GetProgramCounter(ucontext));
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if (this_tid != previous_failed_tid) {
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// Another thread is already in AbslFailureSignalHandler(), so wait
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// a bit for it to finish. If the other thread doesn't kill us,
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// we do so after sleeping.
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PortableSleepForSeconds(3);
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RaiseToDefaultHandler(signo);
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// The recursively raised signal may be blocked until we return.
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return;
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}
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}
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#ifdef ABSL_HAVE_ALARM
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// Set an alarm to abort the program in case this code hangs or deadlocks.
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if (fsh_options.alarm_on_failure_secs > 0) {
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alarm(0); // Cancel any existing alarms.
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signal(SIGALRM, ImmediateAbortSignalHandler);
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alarm(fsh_options.alarm_on_failure_secs);
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}
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#endif
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// First write to stderr.
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WriteFailureInfo(signo, ucontext, WriteToStderr);
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// Riskier code (because it is less likely to be async-signal-safe)
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// goes after this point.
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if (fsh_options.writerfn != nullptr) {
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WriteFailureInfo(signo, ucontext, fsh_options.writerfn);
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}
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if (fsh_options.call_previous_handler) {
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RaiseToPreviousHandler(signo);
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} else {
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RaiseToDefaultHandler(signo);
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}
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}
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void InstallFailureSignalHandler(const FailureSignalHandlerOptions& options) {
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fsh_options = options;
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for (auto& it : failure_signal_data) {
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InstallOneFailureHandler(&it, AbslFailureSignalHandler);
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}
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}
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} // inline namespace lts_2018_12_18
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} // namespace absl
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