// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "tools/android/forwarder2/daemon.h"
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <cstdlib>
#include <cstring>
#include <memory>
#include <string>
#include <utility>
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "tools/android/forwarder2/common.h"
#include "tools/android/forwarder2/socket.h"
namespace forwarder2 {
namespace {
const int kBufferSize = 256;
// Timeout constant used for polling when connecting to the daemon's Unix Domain
// Socket and also when waiting for its death when it is killed.
const int kNumTries = 100;
const int kIdleTimeMSec = 20;
void InitLoggingForDaemon(const std::string& log_file) {
logging::LoggingSettings settings;
settings.logging_dest = log_file.empty() ? logging::LOG_TO_SYSTEM_DEBUG_LOG |
logging::LOG_TO_STDERR
: logging::LOG_TO_FILE;
settings.log_file_path = log_file.c_str();
settings.lock_log = logging::DONT_LOCK_LOG_FILE;
CHECK(logging::InitLogging(settings));
}
bool RunServerAcceptLoop(const std::string& welcome_message,
Socket* server_socket,
Daemon::ServerDelegate* server_delegate) {
bool failed = false;
for (;;) {
std::unique_ptr<Socket> client_socket(new Socket());
if (!server_socket->Accept(client_socket.get())) {
if (server_socket->DidReceiveEvent())
break;
PError("Accept()");
failed = true;
break;
}
if (!client_socket->Write(welcome_message.c_str(),
welcome_message.length() + 1)) {
PError("Write()");
failed = true;
continue;
}
server_delegate->OnClientConnected(std::move(client_socket));
}
return !failed;
}
void SigChildHandler(int signal_number) {
DCHECK_EQ(signal_number, SIGCHLD);
int status;
pid_t child_pid = waitpid(-1 /* any child */, &status, WNOHANG);
if (child_pid < 0) {
PError("waitpid");
return;
}
if (child_pid == 0)
return;
if (WIFEXITED(status) && WEXITSTATUS(status) == 0)
return;
// Avoid using StringAppendF() since it's unsafe in a signal handler due to
// its use of LOG().
FixedSizeStringBuilder<256> string_builder;
string_builder.Append("Daemon (pid=%d) died unexpectedly with ", child_pid);
if (WIFEXITED(status))
string_builder.Append("status %d.", WEXITSTATUS(status));
else if (WIFSIGNALED(status))
string_builder.Append("signal %d.", WTERMSIG(status));
else
string_builder.Append("unknown reason.");
SIGNAL_SAFE_LOG(ERROR, string_builder.buffer());
}
std::unique_ptr<Socket> ConnectToUnixDomainSocket(
const std::string& socket_name,
int tries_count,
int idle_time_msec,
const std::string& expected_welcome_message) {
for (int i = 0; i < tries_count; ++i) {
std::unique_ptr<Socket> socket(new Socket());
if (!socket->ConnectUnix(socket_name)) {
if (idle_time_msec)
usleep(idle_time_msec * 1000);
continue;
}
char buf[kBufferSize];
DCHECK(expected_welcome_message.length() + 1 <= sizeof(buf));
memset(buf, 0, sizeof(buf));
if (socket->Read(buf, expected_welcome_message.length() + 1) < 0) {
perror("read");
continue;
}
if (expected_welcome_message != buf) {
LOG(ERROR) << "Unexpected message read from daemon: " << buf;
break;
}
return socket;
}
return nullptr;
}
} // namespace
Daemon::Daemon(const std::string& log_file_path,
const std::string& identifier,
ClientDelegate* client_delegate,
ServerDelegate* server_delegate,
GetExitNotifierFDCallback get_exit_fd_callback)
: log_file_path_(log_file_path),
identifier_(identifier),
client_delegate_(client_delegate),
server_delegate_(server_delegate),
get_exit_fd_callback_(get_exit_fd_callback) {
DCHECK(client_delegate_);
DCHECK(server_delegate_);
DCHECK(get_exit_fd_callback_);
}
Daemon::~Daemon() {}
bool Daemon::SpawnIfNeeded() {
const int kSingleTry = 1;
const int kNoIdleTime = 0;
std::unique_ptr<Socket> client_socket = ConnectToUnixDomainSocket(
identifier_, kSingleTry, kNoIdleTime, identifier_);
if (!client_socket) {
switch (fork()) {
case -1:
PError("fork()");
return false;
// Child.
case 0: {
if (setsid() < 0) { // Detach the child process from its parent.
PError("setsid()");
exit(1);
}
InitLoggingForDaemon(log_file_path_);
CloseFD(STDIN_FILENO);
CloseFD(STDOUT_FILENO);
CloseFD(STDERR_FILENO);
const int null_fd = open("/dev/null", O_RDWR);
CHECK_EQ(null_fd, STDIN_FILENO);
CHECK_EQ(dup(null_fd), STDOUT_FILENO);
CHECK_EQ(dup(null_fd), STDERR_FILENO);
Socket command_socket;
if (!command_socket.BindUnix(identifier_)) {
client_socket = ConnectToUnixDomainSocket(identifier_, kSingleTry,
kNoIdleTime, identifier_);
if (client_socket.get()) {
// The daemon was spawned by a concurrent process.
exit(0);
}
PError("bind()");
exit(1);
}
server_delegate_->Init();
command_socket.AddEventFd(get_exit_fd_callback_());
return RunServerAcceptLoop(
identifier_, &command_socket, server_delegate_);
}
default:
break;
}
}
// Parent.
// Install the custom SIGCHLD handler.
sigset_t blocked_signals_set;
if (sigprocmask(0 /* first arg ignored */, NULL, &blocked_signals_set) < 0) {
PError("sigprocmask()");
return false;
}
struct sigaction old_action;
struct sigaction new_action;
memset(&new_action, 0, sizeof(new_action));
new_action.sa_handler = SigChildHandler;
new_action.sa_flags = SA_NOCLDSTOP;
sigemptyset(&new_action.sa_mask);
if (sigaction(SIGCHLD, &new_action, &old_action) < 0) {
PError("sigaction()");
return false;
}
// Connect to the daemon's Unix Domain Socket.
bool failed = false;
if (!client_socket) {
client_socket = ConnectToUnixDomainSocket(
identifier_, kNumTries, kIdleTimeMSec, identifier_);
if (!client_socket) {
LOG(ERROR) << "Could not connect to daemon's Unix Daemon socket";
failed = true;
}
}
if (!failed)
client_delegate_->OnDaemonReady(client_socket.get());
// Restore the previous signal action for SIGCHLD.
if (sigaction(SIGCHLD, &old_action, NULL) < 0) {
PError("sigaction");
failed = true;
}
return !failed;
}
bool Daemon::Kill() {
pid_t daemon_pid = Socket::GetUnixDomainSocketProcessOwner(identifier_);
if (daemon_pid < 0) {
LOG(ERROR) << "No forwarder daemon seems to be running";
return true;
}
if (kill(daemon_pid, SIGTERM) < 0) {
if (errno == ESRCH /* invalid PID */) {
// The daemon exited for some reason (e.g. kill by a process other than
// us) right before the call to kill() above.
LOG(ERROR) << "Could not kill daemon with PID " << daemon_pid;
return true;
}
PError("kill");
return false;
}
for (int i = 0; i < kNumTries; ++i) {
const pid_t previous_pid = daemon_pid;
daemon_pid = Socket::GetUnixDomainSocketProcessOwner(identifier_);
if (daemon_pid < 0)
return true;
// Since we are polling we might not see the 'daemon exited' event if
// another daemon was spawned during our idle period.
if (daemon_pid != previous_pid) {
LOG(WARNING) << "Daemon (pid=" << previous_pid
<< ") was successfully killed but a new daemon (pid="
<< daemon_pid << ") seems to be running now.";
return true;
}
usleep(kIdleTimeMSec * 1000);
}
LOG(ERROR) << "Timed out while killing daemon. "
"It might still be tearing down.";
return false;
}
} // namespace forwarder2
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