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// signal_handlers.cpp
/**
* Copyright (C) 2010 10gen 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.
*/
#include "mongo/platform/basic.h"
#include "mongo/util/signal_handlers.h"
#include <boost/thread.hpp>
#include "mongo/db/client.h"
#include "mongo/db/log_process_details.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/exit_code.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"
#include "mongo/util/stacktrace.h"
#if defined(_WIN32)
# include "mongo/util/signal_win32.h"
# include "mongo/util/exception_filter_win32.h"
#else
# include <signal.h>
# include <unistd.h>
#endif
#if defined(_WIN32)
namespace {
const char* strsignal(int signalNum) {
// should only see SIGABRT on windows
switch (signalNum) {
case SIGABRT: return "SIGABRT";
default: return "UNKNOWN";
}
}
}
#endif
namespace mongo {
/*
* WARNING: PLEASE READ BEFORE CHANGING THIS MODULE
*
* All code in this module must be signal-friendly. Before adding any system
* call or other dependency, please make sure that this still holds.
*
* All code in this file follows this pattern:
* Generic code
* #ifdef _WIN32
* Windows code
* #else
* Posix code
* #endif
*
*/
// everything provides this, but only header is instance.h
void exitCleanly(ExitCode exitCode);
namespace {
// 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 = 16*1000;
char _buffer[maxLogLineSize];
};
class MallocFreeOStream : public std::ostream {
MONGO_DISALLOW_COPYING(MallocFreeOStream);
public:
MallocFreeOStream() : ostream(&_buf) {}
StringData str() const { return _buf.str(); }
void rewind() { _buf.rewind(); }
private:
MallocFreeStreambuf _buf;
};
MallocFreeOStream mallocFreeOStream;
// This guards mallocFreeOStream. While locking a pthread_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.
boost::mutex streamMutex;
// must hold streamMutex to call
void writeMallocFreeStreamToLog() {
logger::globalLogDomain()->append(
logger::MessageEventEphemeral(curTimeMillis64(),
logger::LogSeverity::Severe(),
getThreadName(),
mallocFreeOStream.str()));
mallocFreeOStream.rewind();
}
// must hold streamMutex 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() {
boost::mutex::scoped_lock lk(streamMutex);
printStackTrace(mallocFreeOStream << "terminate() called.\n");
writeMallocFreeStreamToLog();
::_exit(EXIT_ABRUPT);
}
// this gets called when new fails to allocate memory
void myNewHandler() {
boost::mutex::scoped_lock lk(streamMutex);
printStackTrace(mallocFreeOStream << "out of memory.\n");
writeMallocFreeStreamToLog();
::_exit(EXIT_ABRUPT);
}
void abruptQuit(int signalNum) {
boost::mutex::scoped_lock lk(streamMutex);
printSignalAndBacktrace(signalNum);
// Don't go through normal shutdown procedure. It may make things worse.
::_exit(EXIT_ABRUPT);
}
#ifdef _WIN32
void consoleTerminate( const char* controlCodeName ) {
Client::initThread( "consoleTerminate" );
log() << "got " << controlCodeName << ", will terminate after current cmd ends" << endl;
exitCleanly( EXIT_KILL );
}
BOOL WINAPI CtrlHandler( DWORD fdwCtrlType ) {
switch( fdwCtrlType ) {
case CTRL_C_EVENT:
log() << "Ctrl-C signal";
consoleTerminate( "CTRL_C_EVENT" );
return TRUE ;
case CTRL_CLOSE_EVENT:
log() << "CTRL_CLOSE_EVENT signal";
consoleTerminate( "CTRL_CLOSE_EVENT" );
return TRUE ;
case CTRL_BREAK_EVENT:
log() << "CTRL_BREAK_EVENT signal";
consoleTerminate( "CTRL_BREAK_EVENT" );
return TRUE;
case CTRL_LOGOFF_EVENT:
// only sent to services, and only in pre-Vista Windows; FALSE means ignore
return FALSE;
case CTRL_SHUTDOWN_EVENT:
log() << "CTRL_SHUTDOWN_EVENT signal";
consoleTerminate( "CTRL_SHUTDOWN_EVENT" );
return TRUE;
default:
return FALSE;
}
}
void eventProcessingThread() {
std::string eventName = getShutdownSignalName(ProcessId::getCurrent().asUInt32());
HANDLE event = CreateEventA(NULL, TRUE, FALSE, eventName.c_str());
if (event == NULL) {
warning() << "eventProcessingThread CreateEvent failed: "
<< errnoWithDescription();
return;
}
ON_BLOCK_EXIT(CloseHandle, event);
int returnCode = WaitForSingleObject(event, INFINITE);
if (returnCode != WAIT_OBJECT_0) {
if (returnCode == WAIT_FAILED) {
warning() << "eventProcessingThread WaitForSingleObject failed: "
<< errnoWithDescription();
return;
}
else {
warning() << "eventProcessingThread WaitForSingleObject failed: "
<< errnoWithDescription(returnCode);
return;
}
}
Client::initThread("eventTerminate");
log() << "shutdown event signaled, will terminate after current cmd ends";
exitCleanly(EXIT_CLEAN);
}
#else
void abruptQuitWithAddrSignal( int signalNum, siginfo_t *siginfo, void * ) {
boost::mutex::scoped_lock lk(streamMutex);
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);
::_exit(EXIT_ABRUPT);
}
// The signals in asyncSignals will be processed by this thread only, in order to
// ensure the db and log mutexes aren't held. Because this is run in a different thread, it does
// not need to be safe to call in signal context.
sigset_t asyncSignals;
void signalProcessingThread() {
Client::initThread( "signalProcessingThread" );
while (true) {
int actualSignal = 0;
int status = sigwait( &asyncSignals, &actualSignal );
fassert(16781, status == 0);
switch (actualSignal) {
case SIGUSR1:
// log rotate signal
fassert(16782, rotateLogs());
logProcessDetailsForLogRotate();
break;
case SIGQUIT:
log() << "Received SIGQUIT; terminating.";
_exit(EXIT_ABRUPT);
default:
// interrupt/terminate signal
log() << "got signal " << actualSignal << " (" << strsignal( actualSignal )
<< "), will terminate after current cmd ends" << endl;
exitCleanly( EXIT_CLEAN );
break;
}
}
}
#endif
} // namespace
void setupSignalHandlers() {
set_terminate( myTerminate );
set_new_handler( myNewHandler );
// SIGABRT is the only signal we want handled by signal handlers on both windows and posix.
invariant( signal(SIGABRT, abruptQuit) != SIG_ERR );
#ifdef _WIN32
_set_purecall_handler( ::abort ); // TODO improve?
setWindowsUnhandledExceptionFilter();
massert(10297,
"Couldn't register Windows Ctrl-C handler",
SetConsoleCtrlHandler(static_cast<PHANDLER_ROUTINE>(CtrlHandler), TRUE));
#else
invariant( signal(SIGHUP , SIG_IGN ) != SIG_ERR );
invariant( signal(SIGUSR2, SIG_IGN ) != SIG_ERR );
invariant( signal(SIGPIPE, SIG_IGN) != SIG_ERR );
struct sigaction addrSignals;
memset( &addrSignals, 0, sizeof( struct sigaction ) );
addrSignals.sa_sigaction = abruptQuitWithAddrSignal;
sigemptyset( &addrSignals.sa_mask );
addrSignals.sa_flags = SA_SIGINFO;
invariant( sigaction(SIGSEGV, &addrSignals, 0) == 0 );
invariant( sigaction(SIGBUS, &addrSignals, 0) == 0 );
invariant( sigaction(SIGILL, &addrSignals, 0) == 0 );
invariant( sigaction(SIGFPE, &addrSignals, 0) == 0 );
setupSIGTRAPforGDB();
// asyncSignals is a global variable listing the signals that should be handled by the
// interrupt thread, once it is started via startSignalProcessingThread().
sigemptyset( &asyncSignals );
sigaddset( &asyncSignals, SIGHUP );
sigaddset( &asyncSignals, SIGINT );
sigaddset( &asyncSignals, SIGTERM );
sigaddset( &asyncSignals, SIGQUIT );
sigaddset( &asyncSignals, SIGUSR1 );
sigaddset( &asyncSignals, SIGXCPU );
#endif
}
void startSignalProcessingThread() {
#ifdef _WIN32
boost::thread(eventProcessingThread).detach();
#else
// Mask signals in the current (only) thread. All new threads will inherit this mask.
invariant( pthread_sigmask( SIG_SETMASK, &asyncSignals, 0 ) == 0 );
// Spawn a thread to capture the signals we just masked off.
boost::thread( signalProcessingThread ).detach();
#endif
}
} // namespace mongo
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