process.h

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/*
Copyright (c) 2026 MrXie1109
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
 
#pragma once
 
#ifndef __linux__
#error "Unsupported platform - this library is for Linux only"
#endif
 
#include <cstdio>
#include <cstdlib>
#include <fcntl.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
 
namespace console {
    enum class Signal : int {
        Interrupt = SIGINT,  
        Terminate = SIGTERM, 
        Kill      = SIGKILL, 
        Stop      = SIGSTOP, 
        Continue  = SIGCONT, 
        Hangup    = SIGHUP,  
        User1     = SIGUSR1, 
        User2     = SIGUSR2  
    };

    struct ExitStatus {
        int  code;        
        bool signaled;    
        int  signal;      
        bool core_dumped; 

        ExitStatus() :
            code(0), signaled(false), signal(0), core_dumped(false) {}

        bool normal() const { return !signaled; }

        int exit_code() const { return code; }

        int term_signal() const { return signal; }
    };

    struct ProcessInfo {
        pid_t  pid;      
        pid_t  ppid;     
        long   rss_kb;   
        double cpu_time; 
        bool   running;  

        ProcessInfo() :
            pid(0), ppid(0), rss_kb(0), cpu_time(0), running(false) {}
    };

    class Process {
    private:
        pid_t pid_; 

        explicit Process(pid_t pid) : pid_(pid) {}

        static int sys_kill(pid_t pid, int sig) { return ::kill(pid, sig); }
 
    public:
        static Process invalid() { return Process(-1); }

        Process() : pid_(-1) {}

        ~Process() = default;

        Process(const Process &) = delete;

        Process &operator=(const Process &) = delete;

        Process(Process &&other) noexcept : pid_(other.pid_) {
            other.pid_ = -1;
        }

        Process &operator=(Process &&other) noexcept {
            if (this != &other) {
                pid_       = other.pid_;
                other.pid_ = -1;
            }
            return *this;
        }

        pid_t pid() const { return pid_; }

        bool valid() const { return pid_ > 0; }

        static Process fork() {
            pid_t pid = ::fork();
            if (pid == 0) return Process(0);
            if (pid > 0) return Process(pid);
            return Process(-1);
        }

        static Process spawn(int (*fn)(void *), void *arg) {
            pid_t pid = ::fork();
            if (pid == -1) return Process(-1);
            if (pid == 0) {
                int ret = fn(arg);
                std::exit(ret);
            }
            return Process(pid);
        }

        static Process spawn_detach(int (*fn)(void *), void *arg) {
            pid_t pid = ::fork();
            if (pid == -1) return Process(-1);
            if (pid == 0) {
                int ret = fn(arg);
                std::exit(ret);
            }
            return Process(pid);
        }

        static Process self() { return Process(getpid()); }

        static Process parent() { return Process(getppid()); }

        ExitStatus wait() const {
            ExitStatus status;
            int        raw;
            if (waitpid(pid_, &raw, 0) == -1) return status;
            if (WIFEXITED(raw)) {
                status.code     = WEXITSTATUS(raw);
                status.signaled = false;
            } else if (WIFSIGNALED(raw)) {
                status.signaled    = true;
                status.signal      = WTERMSIG(raw);
                status.core_dumped = WCOREDUMP(raw);
            }
            return status;
        }

        bool poll(ExitStatus *status) const {
            int   raw;
            pid_t ret = waitpid(pid_, &raw, WNOHANG);
            if (ret == pid_) {
                if (WIFEXITED(raw)) {
                    status->code     = WEXITSTATUS(raw);
                    status->signaled = false;
                } else if (WIFSIGNALED(raw)) {
                    status->signaled    = true;
                    status->signal      = WTERMSIG(raw);
                    status->core_dumped = WCOREDUMP(raw);
                }
                return true;
            }
            return false;
        }

        static Process wait_any(ExitStatus *status) {
            int   raw;
            pid_t pid = ::wait(&raw);
            if (pid == -1) return Process(-1);
            if (WIFEXITED(raw)) {
                status->code     = WEXITSTATUS(raw);
                status->signaled = false;
            } else if (WIFSIGNALED(raw)) {
                status->signaled    = true;
                status->signal      = WTERMSIG(raw);
                status->core_dumped = WCOREDUMP(raw);
            }
            return Process(pid);
        }

        bool is_alive() const {
            if (pid_ <= 0) return false;
            return sys_kill(pid_, 0) == 0;
        }

        bool send_signal(Signal sig) const {
            return sys_kill(pid_, static_cast<int>(sig)) == 0;
        }

        bool terminate() const { return sys_kill(pid_, SIGTERM) == 0; }

        bool kill() const { return sys_kill(pid_, SIGKILL) == 0; }

        bool stop() const { return sys_kill(pid_, SIGSTOP) == 0; }

        bool resume() const { return sys_kill(pid_, SIGCONT) == 0; }

        ProcessInfo get_info() const {
            ProcessInfo info;
            info.pid     = pid_;
            info.running = is_alive();
            char path[64];
            snprintf(path, sizeof(path), "/proc/%d/stat", pid_);
            FILE *fp = fopen(path, "r");
            if (fp) {
                unsigned long utime, stime;
                int           ppid;
                fscanf(fp,
                    "%d %*s %*c %d %*d %*d %*d %*d %*d %*d %*d %*d %*d %lu %lu",
                    &info.pid,
                    &ppid,
                    &utime,
                    &stime);
                info.ppid     = ppid;
                info.cpu_time = (utime + stime) / (double)sysconf(_SC_CLK_TCK);
                fclose(fp);
            }
            snprintf(path, sizeof(path), "/proc/%d/statm", pid_);
            fp = fopen(path, "r");
            if (fp) {
                long resident;
                if (fscanf(fp, "%*d %ld", &resident) == 1)
                    info.rss_kb = resident * 4;
                fclose(fp);
            }
            return info;
        }

        pid_t ppid() const {
            char path[64];
            snprintf(path, sizeof(path), "/proc/%d/stat", pid_);
            FILE *fp = fopen(path, "r");
            if (!fp) return -1;
            pid_t ppid;
            fscanf(fp, "%*d %*s %*c %d", &ppid);
            fclose(fp);
            return ppid;
        }

        static bool daemonize() {
            pid_t pid = ::fork();
            if (pid < 0) return false;
            if (pid > 0) std::exit(0);
            if (setsid() < 0) return false;
            pid = ::fork();
            if (pid < 0) return false;
            if (pid > 0) std::exit(0);
            chdir("/");
            close(STDIN_FILENO);
            close(STDOUT_FILENO);
            close(STDERR_FILENO);
            open("/dev/null", O_RDONLY);
            open("/dev/null", O_WRONLY);
            open("/dev/null", O_WRONLY);
            return true;
        }
    };
}