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[fix] fix daemon not working on Linux

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This commit is contained in:
dijunkun
2025-11-20 15:35:37 +08:00
parent f3901d09ea
commit e3c2edfb1c
2 changed files with 106 additions and 194 deletions
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271
src/app/daemon.cpp
View File

@@ -21,6 +21,7 @@
#include <sys/wait.h>
#include <unistd.h>
#else
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
@@ -77,21 +78,9 @@ Daemon::Daemon(const std::string& name)
{
}
void Daemon::stop() {
#ifdef _WIN32
running_ = false;
#else
running_ = false;
#endif
}
void Daemon::stop() { running_ = false; }
bool Daemon::isRunning() const {
#ifdef _WIN32
return running_;
#else
return running_;
#endif
}
bool Daemon::isRunning() const { return running_; }
bool Daemon::start(MainLoopFunc loop) {
#ifdef _WIN32
@@ -102,15 +91,77 @@ bool Daemon::start(MainLoopFunc loop) {
running_ = true;
return runWithRestart(loop);
#else
// Linux: Use traditional daemonization
// linux: Daemonize first, then run with restart monitoring
instance_ = this;
runUnix(loop);
return true;
// check if running from terminal before fork
bool from_terminal =
(isatty(STDIN_FILENO) != 0) || (isatty(STDOUT_FILENO) != 0);
// first fork: detach from terminal
pid_t pid = fork();
if (pid < 0) {
std::cerr << "Failed to fork daemon process" << std::endl;
return false;
}
if (pid > 0) _exit(0);
if (setsid() < 0) {
std::cerr << "Failed to create new session" << std::endl;
return false;
}
pid = fork();
if (pid < 0) {
std::cerr << "Failed to fork daemon process (second fork)" << std::endl;
return false;
}
if (pid > 0) _exit(0);
umask(0);
chdir("/");
// redirect file descriptors: keep stdout/stderr if from terminal, else
// redirect to /dev/null
int fd = open("/dev/null", O_RDWR);
if (fd >= 0) {
dup2(fd, STDIN_FILENO);
if (!from_terminal) {
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
}
if (fd > 2) close(fd);
}
// set up signal handlers
signal(SIGTERM, [](int) {
if (instance_) instance_->stop();
});
signal(SIGINT, [](int) {
if (instance_) instance_->stop();
});
// ignore SIGPIPE
signal(SIGPIPE, SIG_IGN);
// set up SIGCHLD handler to reap zombie processes
struct sigaction sa_chld;
sa_chld.sa_handler = [](int) {
// reap zombie processes
while (waitpid(-1, nullptr, WNOHANG) > 0) {
// continue until no more zombie children
}
};
sigemptyset(&sa_chld.sa_mask);
sa_chld.sa_flags = SA_RESTART | SA_NOCLDSTOP;
sigaction(SIGCHLD, &sa_chld, nullptr);
running_ = true;
return runWithRestart(loop);
#endif
}
#ifdef _WIN32
// windows: execute loop and catch C++ exceptions
static int RunLoopCatchCpp(Daemon::MainLoopFunc& loop) {
try {
loop();
@@ -124,12 +175,11 @@ static int RunLoopCatchCpp(Daemon::MainLoopFunc& loop) {
}
}
// windows: Use SEH wrapper function to catch system-level crashes
static int RunLoopWithSEH(Daemon::MainLoopFunc& loop) {
__try {
return RunLoopCatchCpp(loop);
} __except (EXCEPTION_EXECUTE_HANDLER) {
// Catch system-level crashes (access violation, divide by zero, etc.)
// catch system-level crashes (access violation, divide by zero, etc.)
DWORD code = GetExceptionCode();
std::cerr << "System crash detected (SEH exception code: 0x" << std::hex
<< code << std::dec << ")" << std::endl;
@@ -138,9 +188,7 @@ static int RunLoopWithSEH(Daemon::MainLoopFunc& loop) {
}
#endif
// run function with restart logic (infinite restart)
// use child process monitoring: parent process creates child process to run
// main program, monitors child process status, restarts on crash
// run with restart logic: parent monitors child process and restarts on crash
bool Daemon::runWithRestart(MainLoopFunc loop) {
int restart_count = 0;
std::string exe_path = GetExecutablePath();
@@ -148,7 +196,6 @@ bool Daemon::runWithRestart(MainLoopFunc loop) {
std::cerr
<< "Failed to get executable path, falling back to direct execution"
<< std::endl;
// fallback to direct execution
while (isRunning()) {
try {
loop();
@@ -170,7 +217,6 @@ bool Daemon::runWithRestart(MainLoopFunc loop) {
STARTUPINFOA si = {sizeof(si)};
PROCESS_INFORMATION pi = {0};
// build command line arguments (add --child flag)
std::string cmd_line = "\"" + exe_path + "\" --child";
std::vector<char> cmd_line_buf(cmd_line.begin(), cmd_line.end());
cmd_line_buf.push_back('\0');
@@ -197,7 +243,6 @@ bool Daemon::runWithRestart(MainLoopFunc loop) {
continue;
}
// wait for child process to exit
DWORD exit_code = 0;
WaitForSingleObject(pi.hProcess, INFINITE);
GetExitCodeProcess(pi.hProcess, &exit_code);
@@ -205,56 +250,57 @@ bool Daemon::runWithRestart(MainLoopFunc loop) {
CloseHandle(pi.hThread);
if (exit_code == 0) {
// normal exit
break;
} else {
// abnormal exit, restart
break; // normal exit
}
restart_count++;
std::cerr << "Child process exited with code " << exit_code
<< ", restarting... (attempt " << restart_count << ")"
<< std::endl;
std::this_thread::sleep_for(
std::chrono::milliseconds(DAEMON_DEFAULT_RESTART_DELAY_MS));
}
#else
// linux: use fork + exec to create child process
pid_t pid = fork();
if (pid == 0) {
// child process: execute main program, pass --child argument
execl(exe_path.c_str(), exe_path.c_str(), "--child", nullptr);
// if exec fails, exit
_exit(1);
_exit(1); // exec failed
} else if (pid > 0) {
// parent process: wait for child process to exit
int status = 0;
waitpid(pid, &status, 0);
pid_t waited_pid = waitpid(pid, &status, 0);
if (waited_pid < 0) {
restart_count++;
std::cerr << "waitpid failed, errno: " << errno
<< ", restarting... (attempt " << restart_count << ")"
<< std::endl;
std::this_thread::sleep_for(
std::chrono::milliseconds(DAEMON_DEFAULT_RESTART_DELAY_MS));
continue;
}
if (WIFEXITED(status)) {
int exit_code = WEXITSTATUS(status);
if (exit_code == 0) {
// normal exit
break;
} else {
// abnormal exit, restart
break; // normal exit
}
restart_count++;
std::cerr << "Child process exited with code " << exit_code
<< ", restarting... (attempt " << restart_count << ")"
<< std::endl;
std::this_thread::sleep_for(
std::chrono::milliseconds(DAEMON_DEFAULT_RESTART_DELAY_MS));
}
} else if (WIFSIGNALED(status)) {
// child process terminated by signal (crash)
int sig = WTERMSIG(status);
restart_count++;
std::cerr << "Child process crashed with signal " << sig
std::cerr << "Child process crashed with signal " << WTERMSIG(status)
<< ", restarting... (attempt " << restart_count << ")"
<< std::endl;
} else {
restart_count++;
std::cerr << "Child process exited with unknown status, restarting... "
"(attempt "
<< restart_count << ")" << std::endl;
}
std::this_thread::sleep_for(
std::chrono::milliseconds(DAEMON_DEFAULT_RESTART_DELAY_MS));
}
} else {
// fork failed
std::cerr << "Failed to fork child process" << std::endl;
std::this_thread::sleep_for(
std::chrono::milliseconds(DAEMON_DEFAULT_RESTART_DELAY_MS));
@@ -265,132 +311,3 @@ bool Daemon::runWithRestart(MainLoopFunc loop) {
return true;
}
#ifndef _WIN32
void Daemon::runUnix(MainLoopFunc loop) {
struct sigaction sa;
sa.sa_handler = [](int) {};
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sigaction(SIGPIPE, &sa, nullptr);
sigaction(SIGCHLD, &sa, nullptr);
// daemon mode: fork twice, redirect output
pid_t pid = fork();
if (pid > 0) _exit(0);
setsid();
pid = fork();
if (pid > 0) _exit(0);
umask(0);
chdir("/");
int fd = open("/dev/null", O_RDWR);
if (fd >= 0) {
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
if (fd > 2) close(fd);
}
// catch signals for exit
signal(SIGTERM, [](int) { instance_->stop(); });
signal(SIGINT, [](int) { instance_->stop(); });
// catch crash signals, use atomic flags to mark crash
static std::atomic<bool> crash_detected{false};
static std::atomic<bool> should_restart{false};
// use safer signal handling: only set flags, don't call longjmp
struct sigaction sa_crash;
sa_crash.sa_handler = [](int sig) {
const char* sig_name = "Unknown";
switch (sig) {
case SIGSEGV:
sig_name = "SIGSEGV";
break;
case SIGABRT:
sig_name = "SIGABRT";
break;
case SIGFPE:
sig_name = "SIGFPE";
break;
case SIGILL:
sig_name = "SIGILL";
break;
}
std::cerr << "Crash signal detected: " << sig_name
<< ", will restart after process exits" << std::endl;
crash_detected = true;
should_restart = true;
// don't call longjmp, let program exit normally, restart by monitoring
// thread
};
sigemptyset(&sa_crash.sa_mask);
sa_crash.sa_flags = SA_RESETHAND; // handle only once, avoid recursion
sigaction(SIGSEGV, &sa_crash, nullptr);
sigaction(SIGABRT, &sa_crash, nullptr);
sigaction(SIGFPE, &sa_crash, nullptr);
sigaction(SIGILL, &sa_crash, nullptr);
running_ = true;
// run with restart logic (infinite restart)
// run main loop in separate thread, main thread monitors thread status
int restart_count = 0;
while (running_) {
crash_detected = false;
should_restart = false;
std::atomic<bool> loop_completed{false};
std::exception_ptr loop_exception = nullptr;
// run main loop in separate thread
std::thread loop_thread([&loop, &loop_completed, &loop_exception]() {
try {
loop();
loop_completed = true;
} catch (const std::exception& e) {
loop_exception = std::current_exception();
loop_completed = true;
} catch (...) {
loop_exception = std::current_exception();
loop_completed = true;
}
});
// wait for thread to complete
loop_thread.join();
// check exit reason
if (loop_exception) {
restart_count++;
try {
std::rethrow_exception(loop_exception);
} catch (const std::exception& e) {
std::cerr << "Exception caught: " << e.what() << std::endl;
} catch (...) {
std::cerr << "Unknown exception caught" << std::endl;
}
std::cerr << "Restarting... (attempt " << restart_count << ")"
<< std::endl;
std::this_thread::sleep_for(
std::chrono::milliseconds(DAEMON_DEFAULT_RESTART_DELAY_MS));
continue;
}
// check if crash signal detected
if (crash_detected || should_restart) {
restart_count++;
std::cerr << "Crash detected, restarting... (attempt " << restart_count
<< ")" << std::endl;
std::this_thread::sleep_for(
std::chrono::milliseconds(DAEMON_DEFAULT_RESTART_DELAY_MS));
continue;
}
// normal exit
if (loop_completed) {
break;
}
}
}
#endif

5
src/app/daemon.h
View File

@@ -10,7 +10,6 @@
#include <functional>
#include <string>
// default restart delay (milliseconds)
#define DAEMON_DEFAULT_RESTART_DELAY_MS 1000
class Daemon {
@@ -19,13 +18,10 @@ class Daemon {
Daemon(const std::string& name);
// start daemon (restart after 1 second by default)
bool start(MainLoopFunc loop);
// request exit
void stop();
// check if running
bool isRunning() const;
private:
@@ -36,7 +32,6 @@ class Daemon {
bool running_;
#else
static Daemon* instance_;
void runUnix(MainLoopFunc loop);
volatile bool running_;
#endif
};