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/*
* Copyright (C) 2008 The Android Open Source Project
*
* 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 "signal_catcher.h"
#include <fcntl.h>
#include <pthread.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <sstream>
#include "arch/instruction_set.h"
#include "base/time_utils.h"
#include "base/unix_file/fd_file.h"
#include "class_linker.h"
#include "gc/heap.h"
#include "os.h"
#include "runtime.h"
#include "scoped_thread_state_change.h"
#include "signal_set.h"
#include "thread.h"
#include "thread_list.h"
#include "utils.h"
namespace art {
static void DumpCmdLine(std::ostream& os) {
#if defined(__linux__)
// Show the original command line, and the current command line too if it's changed.
// On Android, /proc/self/cmdline will have been rewritten to something like "system_server".
// Note: The string "Cmd line:" is chosen to match the format used by debuggerd.
std::string current_cmd_line;
if (ReadFileToString("/proc/self/cmdline", ¤t_cmd_line)) {
current_cmd_line.resize(current_cmd_line.find_last_not_of('\0') + 1); // trim trailing '\0's
std::replace(current_cmd_line.begin(), current_cmd_line.end(), '\0', ' ');
os << "Cmd line: " << current_cmd_line << "\n";
const char* stashed_cmd_line = GetCmdLine();
if (stashed_cmd_line != nullptr && current_cmd_line != stashed_cmd_line
&& strcmp(stashed_cmd_line, "<unset>") != 0) {
os << "Original command line: " << stashed_cmd_line << "\n";
}
}
#else
os << "Cmd line: " << GetCmdLine() << "\n";
#endif
}
SignalCatcher::SignalCatcher(const std::string& stack_trace_file)
: stack_trace_file_(stack_trace_file),
lock_("SignalCatcher lock"),
cond_("SignalCatcher::cond_", lock_),
thread_(nullptr) {
SetHaltFlag(false);
// Create a raw pthread; its start routine will attach to the runtime.
CHECK_PTHREAD_CALL(pthread_create, (&pthread_, nullptr, &Run, this), "signal catcher thread");
Thread* self = Thread::Current();
MutexLock mu(self, lock_);
while (thread_ == nullptr) {
cond_.Wait(self);
}
}
SignalCatcher::~SignalCatcher() {
// Since we know the thread is just sitting around waiting for signals
// to arrive, send it one.
SetHaltFlag(true);
CHECK_PTHREAD_CALL(pthread_kill, (pthread_, SIGQUIT), "signal catcher shutdown");
CHECK_PTHREAD_CALL(pthread_join, (pthread_, nullptr), "signal catcher shutdown");
}
void SignalCatcher::SetHaltFlag(bool new_value) {
MutexLock mu(Thread::Current(), lock_);
halt_ = new_value;
}
bool SignalCatcher::ShouldHalt() {
MutexLock mu(Thread::Current(), lock_);
return halt_;
}
void SignalCatcher::Output(const std::string& s) {
if (stack_trace_file_.empty()) {
LOG(INFO) << s;
return;
}
ScopedThreadStateChange tsc(Thread::Current(), kWaitingForSignalCatcherOutput);
int fd = open(stack_trace_file_.c_str(), O_APPEND | O_CREAT | O_WRONLY, 0666);
if (fd == -1) {
PLOG(ERROR) << "Unable to open stack trace file '" << stack_trace_file_ << "'";
return;
}
std::unique_ptr<File> file(new File(fd, stack_trace_file_, true));
bool success = file->WriteFully(s.data(), s.size());
if (success) {
success = file->FlushCloseOrErase() == 0;
} else {
file->Erase();
}
if (success) {
LOG(INFO) << "Wrote stack traces to '" << stack_trace_file_ << "'";
} else {
PLOG(ERROR) << "Failed to write stack traces to '" << stack_trace_file_ << "'";
}
}
void SignalCatcher::HandleSigQuit() {
Runtime* runtime = Runtime::Current();
std::ostringstream os;
os << "\n"
<< "----- pid " << getpid() << " at " << GetIsoDate() << " -----\n";
DumpCmdLine(os);
// Note: The strings "Build fingerprint:" and "ABI:" are chosen to match the format used by
// debuggerd. This allows, for example, the stack tool to work.
std::string fingerprint = runtime->GetFingerprint();
os << "Build fingerprint: '" << (fingerprint.empty() ? "unknown" : fingerprint) << "'\n";
os << "ABI: '" << GetInstructionSetString(runtime->GetInstructionSet()) << "'\n";
os << "Build type: " << (kIsDebugBuild ? "debug" : "optimized") << "\n";
runtime->DumpForSigQuit(os);
if ((false)) {
std::string maps;
if (ReadFileToString("/proc/self/maps", &maps)) {
os << "/proc/self/maps:\n" << maps;
}
}
os << "----- end " << getpid() << " -----\n";
Output(os.str());
}
void SignalCatcher::HandleSigUsr1() {
LOG(INFO) << "SIGUSR1 forcing GC (no HPROF)";
Runtime::Current()->GetHeap()->CollectGarbage(false);
}
int SignalCatcher::WaitForSignal(Thread* self, SignalSet& signals) {
ScopedThreadStateChange tsc(self, kWaitingInMainSignalCatcherLoop);
// Signals for sigwait() must be blocked but not ignored. We
// block signals like SIGQUIT for all threads, so the condition
// is met. When the signal hits, we wake up, without any signal
// handlers being invoked.
int signal_number = signals.Wait();
if (!ShouldHalt()) {
// Let the user know we got the signal, just in case the system's too screwed for us to
// actually do what they want us to do...
LOG(INFO) << *self << ": reacting to signal " << signal_number;
// If anyone's holding locks (which might prevent us from getting back into state Runnable), say so...
Runtime::Current()->DumpLockHolders(LOG(INFO));
}
return signal_number;
}
void* SignalCatcher::Run(void* arg) {
SignalCatcher* signal_catcher = reinterpret_cast<SignalCatcher*>(arg);
CHECK(signal_catcher != nullptr);
Runtime* runtime = Runtime::Current();
CHECK(runtime->AttachCurrentThread("Signal Catcher", true, runtime->GetSystemThreadGroup(),
!runtime->IsAotCompiler()));
Thread* self = Thread::Current();
DCHECK_NE(self->GetState(), kRunnable);
{
MutexLock mu(self, signal_catcher->lock_);
signal_catcher->thread_ = self;
signal_catcher->cond_.Broadcast(self);
}
// Set up mask with signals we want to handle.
SignalSet signals;
signals.Add(SIGQUIT);
signals.Add(SIGUSR1);
while (true) {
int signal_number = signal_catcher->WaitForSignal(self, signals);
if (signal_catcher->ShouldHalt()) {
runtime->DetachCurrentThread();
return nullptr;
}
switch (signal_number) {
case SIGQUIT:
signal_catcher->HandleSigQuit();
break;
case SIGUSR1:
signal_catcher->HandleSigUsr1();
break;
default:
LOG(ERROR) << "Unexpected signal %d" << signal_number;
break;
}
}
}
} // namespace art
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