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/**
* Copyright (C) 2010-2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kControl
#include "mongo/platform/basic.h"
#include "mongo/util/signal_handlers_synchronous.h"
#include <boost/exception/diagnostic_information.hpp>
#include <boost/exception/exception.hpp>
#include <csignal>
#include <exception>
#include <iostream>
#include <memory>
#include <streambuf>
#include <typeinfo>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/string_data.h"
#include "mongo/logger/log_domain.h"
#include "mongo/logger/logger.h"
#include "mongo/platform/compiler.h"
#include "mongo/stdx/thread.h"
#include "mongo/util/concurrency/thread_name.h"
#include "mongo/util/concurrency/threadlocal.h"
#include "mongo/util/debug_util.h"
#include "mongo/util/debugger.h"
#include "mongo/util/exception_filter_win32.h"
#include "mongo/util/exit_code.h"
#include "mongo/util/log.h"
#include "mongo/util/quick_exit.h"
#include "mongo/util/stacktrace.h"
#include "mongo/util/text.h"
namespace mongo {
namespace {
#if defined(_WIN32)
const char* strsignal(int signalNum) {
// should only see SIGABRT on windows
switch (signalNum) {
case SIGABRT:
return "SIGABRT";
default:
return "UNKNOWN";
}
}
void endProcessWithSignal(int signalNum) {
RaiseException(EXIT_ABRUPT, EXCEPTION_NONCONTINUABLE, 0, NULL);
}
#else
void endProcessWithSignal(int signalNum) {
// This works by restoring the system-default handler for the given signal and re-raising it, in
// order to get the system default termination behavior (i.e., dumping core, or just exiting).
struct sigaction defaultedSignals;
memset(&defaultedSignals, 0, sizeof(defaultedSignals));
defaultedSignals.sa_handler = SIG_DFL;
sigemptyset(&defaultedSignals.sa_mask);
invariant(sigaction(signalNum, &defaultedSignals, nullptr) == 0);
raise(signalNum);
}
#endif
// This should only be used with MallocFreeOSteam
class MallocFreeStreambuf : public std::streambuf {
MONGO_DISALLOW_COPYING(MallocFreeStreambuf);
public:
MallocFreeStreambuf() {
setp(_buffer, _buffer + maxLogLineSize);
}
StringData str() const {
return StringData(pbase(), pptr() - pbase());
}
void rewind() {
setp(pbase(), epptr());
}
private:
static const size_t maxLogLineSize = 100 * 1000;
char _buffer[maxLogLineSize];
};
class MallocFreeOStream : public std::ostream {
MONGO_DISALLOW_COPYING(MallocFreeOStream);
public:
MallocFreeOStream() : std::ostream(&_buf) {}
StringData str() const {
return _buf.str();
}
void rewind() {
_buf.rewind();
}
private:
MallocFreeStreambuf _buf;
};
MallocFreeOStream mallocFreeOStream;
/**
* Instances of this type guard the mallocFreeOStream. While locking a mutex isn't guaranteed to
* be signal-safe, this file does it anyway. The assumption is that the main safety risk to
* locking a mutex is that you could deadlock with yourself. That risk is protected against by
* only locking the mutex in fatal functions that log then exit. There is a remaining risk that
* one of these functions recurses (possible if logging segfaults while handing a
* segfault). This is currently acceptable because if things are that broken, there is little we
* can do about it.
*
* If in the future, we decide to be more strict about posix signal safety, we could switch to
* an atomic test-and-set loop, possibly with a mechanism for detecting signals raised while
* handling other signals.
*/
class MallocFreeOStreamGuard {
public:
explicit MallocFreeOStreamGuard() : _lk(_streamMutex, stdx::defer_lock) {
if (terminateDepth++) {
quickExit(EXIT_ABRUPT);
}
_lk.lock();
}
private:
static stdx::mutex _streamMutex;
static MONGO_TRIVIALLY_CONSTRUCTIBLE_THREAD_LOCAL int terminateDepth;
stdx::unique_lock<stdx::mutex> _lk;
};
stdx::mutex MallocFreeOStreamGuard::_streamMutex;
MONGO_TRIVIALLY_CONSTRUCTIBLE_THREAD_LOCAL
int MallocFreeOStreamGuard::terminateDepth = 0;
// must hold MallocFreeOStreamGuard to call
void writeMallocFreeStreamToLog() {
logger::globalLogDomain()
->append(logger::MessageEventEphemeral(Date_t::now(),
logger::LogSeverity::Severe(),
getThreadName(),
mallocFreeOStream.str())
.setIsTruncatable(false))
.transitional_ignore();
mallocFreeOStream.rewind();
}
// must hold MallocFreeOStreamGuard to call
void printSignalAndBacktrace(int signalNum) {
mallocFreeOStream << "Got signal: " << signalNum << " (" << strsignal(signalNum) << ").\n";
printStackTrace(mallocFreeOStream);
writeMallocFreeStreamToLog();
}
// this will be called in certain c++ error cases, for example if there are two active
// exceptions
void myTerminate() {
MallocFreeOStreamGuard lk{};
// In c++11 we can recover the current exception to print it.
if (std::current_exception()) {
mallocFreeOStream << "terminate() called. An exception is active;"
<< " attempting to gather more information";
writeMallocFreeStreamToLog();
const std::type_info* typeInfo = nullptr;
try {
try {
throw;
} catch (const DBException& ex) {
typeInfo = &typeid(ex);
mallocFreeOStream << "DBException::toString(): " << ex.toString() << '\n';
} catch (const std::exception& ex) {
typeInfo = &typeid(ex);
mallocFreeOStream << "std::exception::what(): " << ex.what() << '\n';
} catch (const boost::exception& ex) {
typeInfo = &typeid(ex);
mallocFreeOStream << "boost::diagnostic_information(): "
<< boost::diagnostic_information(ex) << '\n';
} catch (...) {
mallocFreeOStream << "A non-standard exception type was thrown\n";
}
if (typeInfo) {
const std::string name = demangleName(*typeInfo);
mallocFreeOStream << "Actual exception type: " << name << '\n';
}
} catch (...) {
mallocFreeOStream << "Exception while trying to print current exception.\n";
if (typeInfo) {
// It is possible that we failed during demangling. At least try to print the
// mangled name.
mallocFreeOStream << "Actual exception type: " << typeInfo->name() << '\n';
}
}
} else {
mallocFreeOStream << "terminate() called. No exception is active";
}
printStackTrace(mallocFreeOStream);
writeMallocFreeStreamToLog();
breakpoint();
endProcessWithSignal(SIGABRT);
}
void abruptQuit(int signalNum) {
MallocFreeOStreamGuard lk{};
printSignalAndBacktrace(signalNum);
breakpoint();
endProcessWithSignal(signalNum);
}
#if defined(_WIN32)
void myInvalidParameterHandler(const wchar_t* expression,
const wchar_t* function,
const wchar_t* file,
unsigned int line,
uintptr_t pReserved) {
severe() << "Invalid parameter detected in function " << toUtf8String(function)
<< " File: " << toUtf8String(file) << " Line: " << line;
severe() << "Expression: " << toUtf8String(expression);
severe() << "immediate exit due to invalid parameter";
abruptQuit(SIGABRT);
}
void myPureCallHandler() {
severe() << "Pure call handler invoked";
severe() << "immediate exit due to invalid pure call";
abruptQuit(SIGABRT);
}
#else
void abruptQuitWithAddrSignal(int signalNum, siginfo_t* siginfo, void*) {
MallocFreeOStreamGuard lk{};
const char* action = (signalNum == SIGSEGV || signalNum == SIGBUS) ? "access" : "operation";
mallocFreeOStream << "Invalid " << action << " at address: " << siginfo->si_addr;
// Writing out message to log separate from the stack trace so at least that much gets
// logged. This is important because we may get here by jumping to an invalid address which
// could cause unwinding the stack to break.
writeMallocFreeStreamToLog();
printSignalAndBacktrace(signalNum);
breakpoint();
endProcessWithSignal(signalNum);
}
#endif
} // namespace
void setupSynchronousSignalHandlers() {
std::set_terminate(myTerminate);
std::set_new_handler(reportOutOfMemoryErrorAndExit);
#if defined(_WIN32)
invariant(signal(SIGABRT, abruptQuit) != SIG_ERR);
_set_purecall_handler(myPureCallHandler);
_set_invalid_parameter_handler(myInvalidParameterHandler);
setWindowsUnhandledExceptionFilter();
#else
{
struct sigaction ignoredSignals;
memset(&ignoredSignals, 0, sizeof(ignoredSignals));
ignoredSignals.sa_handler = SIG_IGN;
sigemptyset(&ignoredSignals.sa_mask);
invariant(sigaction(SIGHUP, &ignoredSignals, nullptr) == 0);
invariant(sigaction(SIGUSR2, &ignoredSignals, nullptr) == 0);
invariant(sigaction(SIGPIPE, &ignoredSignals, nullptr) == 0);
}
{
struct sigaction plainSignals;
memset(&plainSignals, 0, sizeof(plainSignals));
plainSignals.sa_handler = abruptQuit;
sigemptyset(&plainSignals.sa_mask);
// ^\ is the stronger ^C. Log and quit hard without waiting for cleanup.
invariant(sigaction(SIGQUIT, &plainSignals, nullptr) == 0);
invariant(sigaction(SIGABRT, &plainSignals, nullptr) == 0);
}
{
struct sigaction addrSignals;
memset(&addrSignals, 0, sizeof(addrSignals));
addrSignals.sa_sigaction = abruptQuitWithAddrSignal;
sigemptyset(&addrSignals.sa_mask);
addrSignals.sa_flags = SA_SIGINFO;
invariant(sigaction(SIGSEGV, &addrSignals, nullptr) == 0);
invariant(sigaction(SIGBUS, &addrSignals, nullptr) == 0);
invariant(sigaction(SIGILL, &addrSignals, nullptr) == 0);
invariant(sigaction(SIGFPE, &addrSignals, nullptr) == 0);
}
setupSIGTRAPforGDB();
#endif
}
void reportOutOfMemoryErrorAndExit() {
MallocFreeOStreamGuard lk{};
printStackTrace(mallocFreeOStream << "out of memory.\n");
writeMallocFreeStreamToLog();
quickExit(EXIT_ABRUPT);
}
void clearSignalMask() {
#ifndef _WIN32
// We need to make sure that all signals are unmasked so signals are handled correctly
sigset_t unblockSignalMask;
invariant(sigemptyset(&unblockSignalMask) == 0);
invariant(sigprocmask(SIG_SETMASK, &unblockSignalMask, nullptr) == 0);
#endif
}
} // namespace mongo
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