#ifdef HAVE_CONFIG_H
# include "SctConfig.h"
#endif

#include "SctVersion.h"
#include "SctConst.h"
#include "SctCommon.h"
#include "ProcCommon.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <fcntl.h>
#include <dirent.h>
#include <unistd.h>
#include <errno.h>
#include <grp.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <pthread.h>
#include <semaphore.h>

#ifdef HAVE_CONF_CAP
#include <sys/prctl.h>
#include <sys/capability.h>
#endif

#define SCTJUDGE_PROC_CHILD_CLOSE_STDIN        0
#define SCTJUDGE_PROC_CHILD_OPEN_STDIN_SINK    1
#define SCTJUDGE_PROC_CHILD_OPEN_STDIN_FILE    2
#define SCTJUDGE_PROC_CHILD_DUP2_STDIN         3
#define SCTJUDGE_PROC_CHILD_CLOSE_STDOUT       4
#define SCTJUDGE_PROC_CHILD_OPEN_STDOUT_SINK   5
#define SCTJUDGE_PROC_CHILD_OPEN_STDOUT_FILE   6
#define SCTJUDGE_PROC_CHILD_DUP2_STDOUT        7
#define SCTJUDGE_PROC_CHILD_CLOSE_STDERR       8
#define SCTJUDGE_PROC_CHILD_REDIR_STDERR       9
#define SCTJUDGE_PROC_CHILD_OPEN_STDERR_FILE  10
#define SCTJUDGE_PROC_CHILD_DUP2_STDERR       11
#define SCTJUDGE_PROC_CHILD_CLOSE_OTHER_FDS   12
#define SCTJUDGE_PROC_CHILD_CHROOT            13
#define SCTJUDGE_PROC_CHILD_SETGID            14
#define SCTJUDGE_PROC_CHILD_SETGROUPS         15
#define SCTJUDGE_PROC_CHILD_SETUID            16
#define SCTJUDGE_PROC_CHILD_RESET_UID         17
#define SCTJUDGE_PROC_CHILD_CAP_SET_PROC      18
#define SCTJUDGE_PROC_CHILD_SETRLIMIT_MEM     19
#define SCTJUDGE_PROC_CHILD_SETRLIMIT_CORE    20
#define SCTJUDGE_PROC_CHILD_SETRLIMIT_CPU     21
#define SCTJUDGE_PROC_CHILD_SETRLIMIT_OUT     22
#define SCTJUDGE_PROC_CHILD_SETRLIMIT_FILE    23
#define SCTJUDGE_PROC_CHILD_SETRLIMIT_PROC    24
#define SCTJUDGE_PROC_CHILD_SETRLIMIT_STACK   25
#define SCTJUDGE_PROC_CHILD_EXEC              26
#define SCTJUDGE_PROC_CHILD_MAX               27


/* 變數用途在 ProcCommon.h 解釋過了 */
pid_t           child_pid;
pthread_mutex_t child_mutex;

_Bool           checktime_exist;
sem_t           checktime_sem;
pthread_t       checktime_thread;
pthread_mutex_t checktime_mutex;

_Bool           monitor_exist;
sem_t           monitor_sem;
pthread_t       monitor_thread;
pthread_mutex_t monitor_mutex;

_Bool           sctproc_tle;
pthread_mutex_t sctproc_tle_mutex;

pthread_mutex_t output_mutex = PTHREAD_MUTEX_INITIALIZER;

/* 內部供 logger 和 err 使用的變數 */
static void (*sctproc_output_debug)(void*, const char*, va_list);
static void (*sctproc_output_normal)(void*, const char*, va_list);
static void (*sctproc_output_err)(void*, const char*, va_list);
static void* sctproc_output_arg;
static int sctproc_verbose;

/* 如果回傳負數表示失敗，就用這個 */
static void sctproc_childonly_fail_if_negative(int fd, int rval, int workname){
    int childonly_mesg[2];
    childonly_mesg[0] = workname;
    childonly_mesg[1] = (rval < 0) ? errno : 0;
    write(fd, &childonly_mesg, sizeof(int) * 2);
    if(rval < 0){
        exit(1);
    }
}

/* 如果回傳 NULL 表示失敗，就用這個 */
static void sctproc_childonly_fail_if_null(int fd, void* rval, int workname){
    int childonly_mesg[2];
    childonly_mesg[0] = workname;
    childonly_mesg[1] = (rval == NULL) ? errno : 0;
    write(fd, &childonly_mesg, sizeof(int) * 2);
    if(rval == NULL){
        exit(2);
    }
}

void sctproc_setdefault(PROCINFO* procinfo){
    procinfo->i_verbose = 1;
    procinfo->i_exec = NULL;
    procinfo->i_argv = NULL;
    procinfo->i_chroot = NULL;
    procinfo->i_infile = NULL;
    procinfo->i_outfile = NULL;
    procinfo->i_errfile = NULL;
    procinfo->i_uid = 65535;
    procinfo->i_gid = 65535;
    procinfo->i_limit_time = 10 * 10000;
    procinfo->i_limit_mem = 64 * 1024 * 1024;
    procinfo->i_limit_core = 0;
    procinfo->i_limit_cpu = 0;
    procinfo->i_limit_out = 0;
    procinfo->i_limit_file = 0;
    procinfo->i_limit_proc = 0;
    procinfo->i_limit_stack = 8 * 1024 * 1024;
    procinfo->i_func_arg = NULL;
    procinfo->i_flag = 
        PROCINFO_FLAG_SECURE_CHECK |
        PROCINFO_FLAG_LIMIT_FILE | 
        PROCINFO_FLAG_LIMIT_PROC |
        PROCINFO_FLAG_LIMIT_CORE;
}

void sctproc_freestring(PROCINFO* procinfo){
    int i;

    if(procinfo->i_exec != NULL){
        free(procinfo->i_exec);
        procinfo->i_exec = NULL;
    }

    if(procinfo->i_argv != NULL){
        for(i=0; i<l4da_getlen(procinfo->i_argv); i++){
            if(l4da_v(procinfo->i_argv, char*, i) != NULL){
                free(l4da_v(procinfo->i_argv, char*, i));
            }
        }
        l4da_free(procinfo->i_argv);
        procinfo->i_argv = NULL;
    }

    if(procinfo->i_chroot != NULL){
        free(procinfo->i_chroot);
        procinfo->i_chroot = NULL;
    }

    if(procinfo->i_infile != NULL){
        free(procinfo->i_infile);
        procinfo->i_infile = NULL;
    }
    if(procinfo->i_outfile != NULL){
        free(procinfo->i_outfile);
        procinfo->i_outfile = NULL;
    }
    if(procinfo->i_errfile != NULL){
        free(procinfo->i_errfile);
        procinfo->i_chroot = NULL;
    }
}

int sctproc_main(PROCINFO* procinfo){

    /* private defines */
#define private_BUFMAX 256
#define private_READLEN ((sizeof(int))*2)

    sctproc_output_debug = procinfo->f_debug;
    sctproc_output_normal = procinfo->f_normal;
    sctproc_output_err = procinfo->f_err;
    sctproc_output_arg = procinfo->i_func_arg;
    sctproc_verbose = procinfo->i_verbose;

    int i;

    int rerr;    /* 接收錯誤碼的地方 */
    char errbuf[private_BUFMAX];  /* 系統錯誤訊息緩衝區 */

    int child_pipe[2]; /* 接收 child process 狀態用的 pipe */
    int child_mesg[2]; /* child process 傳來的訊息，[0]是動作，[1]是 errno */
    int child_status;  /* wait 時回傳的 child process 狀態 */
    _Bool child_terminated;/* child process 終止了沒？ */
    char* child_workstr;   /* 指向 child process 目前狀態訊息的指標 */

    struct timespec exec_begin;
    struct timespec exec_end;

    /* 一些 child process 中專用的變數 */
    int    childonly_fdopt;
    int    childonly_fdcount;
    int    childonly_fdin;
    int    childonly_fdout;
    int    childonly_fderr;
    pid_t  childonly_pid;
    struct rlimit childonly_rlimit;
#ifdef HAVE_CONF_CAP
    cap_t  childonly_cap;
#endif

    /* 列出設定值，僅供偵錯使用 */
    sctproc_logger(2, "%s: 列出 PROCINFO 中的設定值\n", __func__);
    sctproc_logger(2, "%s: i_exec: %s\n", 
        __func__, STRING_NULL(procinfo->i_exec));
    for(i=0; l4da_v(procinfo->i_argv, char*, i) != NULL; i++){
        sctproc_logger(2, "%s: i_argv[%d]: %s\n",
            __func__, i, STRING_NULL(l4da_v(procinfo->i_argv, char*, i)));
    }
    sctproc_logger(2, "%s: i_chroot: %s\n", 
        __func__, STRING_NULL(procinfo->i_chroot));
    sctproc_logger(2, "%s: i_infile: %s\n",
        __func__, STRING_NULL(procinfo->i_infile));
    sctproc_logger(2, "%s: i_outfile: %s\n",
        __func__, STRING_NULL(procinfo->i_outfile));
    sctproc_logger(2, "%s: i_errfile: %s\n",
        __func__, STRING_NULL(procinfo->i_errfile));
    sctproc_logger(2, "%s: i_uid: %u\n", __func__, procinfo->i_uid);
    sctproc_logger(2, "%s: i_gid: %u\n", __func__, procinfo->i_gid);
    sctproc_logger(2, "%s: i_flag: FORCE: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_FORCE));
    sctproc_logger(2, "%s: i_flag: DRYRUN: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_DRYRUN));
    sctproc_logger(2, "%s: i_flag: SECURE_CHECK: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_SECURE_CHECK));
    sctproc_logger(2, "%s: i_flag: REDIR_STDERR: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_REDIR_STDERR));
    sctproc_logger(2, "%s: i_flag: SETUID: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_SETUID));
    sctproc_logger(2, "%s: i_flag: SETGID: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_SETGID));
    sctproc_logger(2, "%s: i_flag: CLOSE_FD: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_CLOSE_FD));
    sctproc_logger(2, "%s: i_flag: LIMIT_MEM: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_LIMIT_MEM));
    sctproc_logger(2, "%s: i_flag: LIMIT_CORE: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_LIMIT_CORE));
    sctproc_logger(2, "%s: i_flag: LIMIT_CPU: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_LIMIT_CPU));
    sctproc_logger(2, "%s: i_flag: LIMIT_OUT: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_LIMIT_OUT));
    sctproc_logger(2, "%s: i_flag: LIMIT_FILE: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_LIMIT_FILE));
    sctproc_logger(2, "%s: i_flag: LIMIT_PROC: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_LIMIT_PROC));
    sctproc_logger(2, "%s: i_flag: LIMIT_STACK: %s\n", __func__,
        DISPLAY_YESNO(procinfo->i_flag, PROCINFO_FLAG_LIMIT_STACK));
    sctproc_logger(2, "%s: i_limit_time: %u\n", 
        __func__, procinfo->i_limit_time);
    sctproc_logger(2, "%s: i_limit_mem: %u\n",
        __func__, procinfo->i_limit_mem);
    sctproc_logger(2, "%s: i_limit_core: %u\n",
        __func__, procinfo->i_limit_core);
    sctproc_logger(2, "%s: i_limit_cpu: %u\n",
        __func__, procinfo->i_limit_cpu);
    sctproc_logger(2, "%s: i_limit_out: %u\n",
        __func__, procinfo->i_limit_out);
    sctproc_logger(2, "%s: i_limit_file: %u\n",
        __func__, procinfo->i_limit_file);
    sctproc_logger(2, "%s: i_limit_proc: %u\n",
        __func__, procinfo->i_limit_proc);
    sctproc_logger(2, "%s: i_limit_stack: %u\n",
        __func__, procinfo->i_limit_stack);

    /* 檢查 UID == 0 的狀況 */
    sctproc_logger(2, "%s: Check for user ID setting\n", __func__);
    if(procinfo->i_uid == 0 && (procinfo->i_flag & PROCINFO_FLAG_SETUID)){
        if(procrealuid == 0){ /* 我們不用 getuid()，因為可能被 swap 過 */
            if(!(procinfo->i_flag & PROCINFO_FLAG_FORCE)){
                sctproc_err("拒絕使用 root 執行受測程式\n");
                return SCTJUDGE_PROC_EXIT_INSECURE;
            }else{
                sctproc_logger(1, 
                    "警告：使用 root 身份執行受測程式，所有限制都可能被忽略\n");
            }
        }else{
            sctproc_err("非超級使用者不能把 UID 設定為 0\n");
            return SCTJUDGE_PROC_EXIT_REJECT;
        }
    }

    /* 檢查安全設定值，如果有要求的話。我們不檢查 chroot 目錄是不是空的，
     * 因為執行檔應該會複製進去 */
    if(procinfo->i_flag & PROCINFO_FLAG_SECURE_CHECK){
        sctproc_logger(2, "%s: Check for security\n", __func__);
        if(procinfo->i_chroot == NULL){
            sctproc_err("您沒有指定 chroot 目錄\n");
            return SCTJUDGE_PROC_EXIT_INSECURE;
        }
        if(!(procinfo->i_flag & PROCINFO_FLAG_SETUID)){
            sctproc_err("您沒有修改執行受測程式時的使用者\n");
            return SCTJUDGE_PROC_EXIT_INSECURE;
        }
        if(!(procinfo->i_flag & PROCINFO_FLAG_SETGID)){
            sctproc_err("您沒有修改執行受測程式時的群組\n");
            return SCTJUDGE_PROC_EXIT_INSECURE;
        }
        if(!(procinfo->i_flag & PROCINFO_FLAG_LIMIT_MEM)){
            sctproc_err("您沒有設定記憶體使用量上限\n");
            return SCTJUDGE_PROC_EXIT_INSECURE;
        }
        if(!(procinfo->i_flag & PROCINFO_FLAG_LIMIT_CORE)){
            sctproc_err("您沒有設定 core 檔案大小上限\n");
            return SCTJUDGE_PROC_EXIT_INSECURE;
        }
        if(!(procinfo->i_flag & PROCINFO_FLAG_LIMIT_PROC)){
            sctproc_err("您沒有設定 process 數量上限\n");
            return SCTJUDGE_PROC_EXIT_INSECURE;
        }
    }
    
    /* 檢查參數，若強制執行就忽略 */
    if(!(procinfo->i_flag & PROCINFO_FLAG_FORCE)){
        sctproc_logger(2, "%s: Validate process configuration\n", __func__);
        if(procinfo->i_exec == NULL){
            sctproc_err("沒有指定受測程式可執行檔名稱\n");
            return SCTJUDGE_PROC_EXIT_INVALID;
        }
        if(procinfo->i_argv == NULL){
            sctproc_err("沒有指定執行程式時的命令列\n");
            return SCTJUDGE_PROC_EXIT_INVALID;
        }
        if(procinfo->i_outfile == NULL){
            sctproc_err("沒有指定輸出檔案\n");
            return SCTJUDGE_PROC_EXIT_INVALID;
        }
        if(procinfo->i_limit_time <= 0){
            sctproc_err("沒有指定執行時間限制\n");
            return SCTJUDGE_PROC_EXIT_INVALID;
        }
        if((procinfo->i_flag & PROCINFO_FLAG_REDIR_STDERR) && 
            (procinfo->i_errfile != NULL)){
            sctproc_err("重新導向 stderr 時，不能指定 stderr 要導向的檔案\n");
            return SCTJUDGE_PROC_EXIT_INVALID;
        }
    }


    /* 產生 child process */
    sctproc_logger(2, "%s: Creating a pipe for status reporting\n", __func__);
    pipe(child_pipe);
    sctproc_logger(2, "%s: Creating a child process\n", __func__);
    child_pid = fork();

    if(child_pid < 0){
        rerr = errno;
        strerror_threadsafe(rerr, errbuf, private_BUFMAX);
        sctproc_logger(2, "%s: fork() = %d\n", __func__, child_pid);
        sctproc_logger(2, "%s: errno = %d (%s)\n", __func__, rerr, errbuf);
        sctproc_err("無法建立新程序：%s\n", errbuf);
        close(child_pipe[0]);
        close(child_pipe[1]);
        return SCTJUDGE_PROC_EXIT_FAILED;

    }else if(child_pid > 0){
        sctproc_logger(2, "%s: fork() = %d\n", __func__, child_pid);
        close(child_pipe[1]);

        /* 持續監測 child process 的狀態 */
        while(read_complete(child_pipe[0], (void*)child_mesg, private_READLEN)
            == private_READLEN){

            strerror_threadsafe(child_mesg[1], errbuf, private_BUFMAX);

            switch(child_mesg[0]){
                case SCTJUDGE_PROC_CHILD_CLOSE_STDIN:
                    sctproc_logger(2, "%s: child: close(%d), "
                        "errno = %d (%s)\n", 
                        __func__, STDIN_FILENO, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "關閉標準輸入");
                    break;

                case SCTJUDGE_PROC_CHILD_OPEN_STDIN_SINK:
                    sctproc_logger(2, "%s: child: open(%s, O_RDONLY), "
                        "errno = %d (%s)\n",
                        __func__, WITH_NULL, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "開啟輸入檔案 "WITH_NULL);
                    break;

                case SCTJUDGE_PROC_CHILD_OPEN_STDIN_FILE:
                    sctproc_logger(2, "%s: child: open(%s, O_RDONLY), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_infile, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "開啟輸入檔案 %s",
                        procinfo->i_infile);
                    break;

                case SCTJUDGE_PROC_CHILD_DUP2_STDIN:
                    sctproc_logger(2, "%s: child: dup2(<input file>, %d), "
                        "errno = %d (%s)\n",
                        __func__, STDIN_FILENO, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "重新導向標準輸入");
                    break;

                case SCTJUDGE_PROC_CHILD_CLOSE_STDOUT:
                    sctproc_logger(2, "%s: child: close(%d), "
                        "errno = %d (%s)\n",
                        __func__, STDOUT_FILENO, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "關閉標準輸出");
                    break;

                case SCTJUDGE_PROC_CHILD_OPEN_STDOUT_SINK:
                    sctproc_logger(2, "%s: child: open(%s, "
                        "O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR), "
                        "errno = %d (%s)\n",
                        __func__, WITH_NULL, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "開啟輸出檔案"WITH_NULL);
                    break;

                case SCTJUDGE_PROC_CHILD_OPEN_STDOUT_FILE:
                    sctproc_logger(2, "%s: child: open(%s, "
                        "O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_outfile, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "開啟輸出檔案 %s",
                        procinfo->i_outfile);
                    break;

                case SCTJUDGE_PROC_CHILD_DUP2_STDOUT:
                    sctproc_logger(2, "%s: child: dup2(<output file>, %d), "
                        "errno = %d (%s)\n",
                        __func__, STDOUT_FILENO, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "重新導向標準輸出");
                    break;

                case SCTJUDGE_PROC_CHILD_CLOSE_STDERR:
                    sctproc_logger(2, "%s: child: close(%d), "
                        "errno = %d (%s)\n",
                        __func__, STDERR_FILENO, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "關閉標準錯誤");
                    break;

                case SCTJUDGE_PROC_CHILD_REDIR_STDERR:
                    sctproc_logger(2, "%s: child: dup2(<output file>, %d), "
                        "errno = %d (%s)\n",
                        __func__, STDERR_FILENO, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "將標準輸出導向標準錯誤");
                    break;

                case SCTJUDGE_PROC_CHILD_OPEN_STDERR_FILE:
                    sctproc_logger(2, "%s: child: open(%s, "
                        "O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_errfile, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "開啟錯誤檔案 %s",
                        procinfo->i_errfile);
                    break;

                case SCTJUDGE_PROC_CHILD_DUP2_STDERR:
                    sctproc_logger(2, "%s: child: dup2(<err file>, %d), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_errfile, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "重新導向標準錯誤");
                    break;

                case SCTJUDGE_PROC_CHILD_CLOSE_OTHER_FDS:
                    sctproc_logger(2, "%s: child: for(i=3; i<getdtablesize();"
                        " i++){ close(i); }, errno = %d (%s)\n", 
                        __func__, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "關閉所有其他已開啟的檔案");
                    break;

                case SCTJUDGE_PROC_CHILD_CHROOT:
                    sctproc_logger(2, "%s: child: chroot(\"%s\"), "
                        "errno = %d (%s)\n", 
                        __func__, procinfo->i_chroot, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "切換根目錄至 %s", 
                        procinfo->i_chroot);
                    break;

                case SCTJUDGE_PROC_CHILD_SETGID:
                    sctproc_logger(2, "%s: child: setgid(%u), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_gid, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定 GID 為 %u",
                        procinfo->i_gid);
                    break;

                case SCTJUDGE_PROC_CHILD_SETGROUPS:
                    sctproc_logger(2, "%s: child: setgroups(1, { %u }), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_gid, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定 supplementary GID 為 "
                        "%u", procinfo->i_gid);
                    break;

                case SCTJUDGE_PROC_CHILD_SETUID:
                case SCTJUDGE_PROC_CHILD_RESET_UID:
                    sctproc_logger(2, "%s: child: setuid(%u), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_uid, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定 UID 為 %d\n", 
                        procinfo->i_uid);
                    break;

                case SCTJUDGE_PROC_CHILD_CAP_SET_PROC:
                    sctproc_logger(2, "%s: child: cap_set_proc(), "
                        "errno = %d (%s)\n",
                        __func__, child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "Drop Linux capabilites");
                    break;

                case SCTJUDGE_PROC_CHILD_SETRLIMIT_MEM:
                    sctproc_logger(2, "%s: child: setrlimit(RLIMIT_AS, "
                        "{ %u, %u }), errno = %d (%s)\n",
                        __func__, procinfo->i_limit_mem, procinfo->i_limit_mem,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定記憶體用量限制");
                    break;

                case SCTJUDGE_PROC_CHILD_SETRLIMIT_CORE:
                    sctproc_logger(2, "%s: child: setrlimit(RLIMIT_CORE, "
                        "{ %u, %u }), errno = %d (%s)\n",
                        __func__, procinfo->i_limit_core, 
                        procinfo->i_limit_core,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定 core dump 大小限制");
                    break;

                case SCTJUDGE_PROC_CHILD_SETRLIMIT_CPU:
                    sctproc_logger(2, "%s: child: setrlimit(RLIMIT_CPU, "
                        "{ %u, %u }), errno = %d (%s)\n",
                        __func__, procinfo->i_limit_cpu, procinfo->i_limit_cpu,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定 CPU 時間限制");
                    break;

                case SCTJUDGE_PROC_CHILD_SETRLIMIT_OUT:
                    sctproc_logger(2, "%s: child: setrlimit(RLIMIT_FSIZE, "
                        "{ %u, %u }), errno = %d (%s)\n",
                        __func__, procinfo->i_limit_out, procinfo->i_limit_out,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定輸出大小限制");
                    break;

                case SCTJUDGE_PROC_CHILD_SETRLIMIT_FILE:
                    sctproc_logger(2, "%s: child: setrlimit(RLIMIT_NOFILE, "
                        "{ %u, %u }), errno = %d (%s)\n",
                        __func__, procinfo->i_limit_file, 
                        procinfo->i_limit_file,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定檔案開啟數量限制");
                    break;

                case SCTJUDGE_PROC_CHILD_SETRLIMIT_PROC:
                    sctproc_logger(2, "%s: child: setrlimit(RLIMIT_NPROC, "
                        "{ %u, %u }), errno = %d (%s)\n",
                        __func__, procinfo->i_limit_proc, 
                        procinfo->i_limit_proc,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定程序數量限制");
                    break;

                case SCTJUDGE_PROC_CHILD_SETRLIMIT_STACK:
                    sctproc_logger(2, "%s: child: setrlimit(RLIMIT_STACK, "
                        "{ %u, %u }), errno = %d (%s)\n",
                        __func__, procinfo->i_limit_stack, 
                        procinfo->i_limit_stack,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "設定 stack 大小限制");
                    break;

                case SCTJUDGE_PROC_CHILD_EXEC:
                    sctproc_logger(2, "%s: child: execv(\"%s\", ...), "
                        "errno = %d (%s)\n",
                        __func__, procinfo->i_exec, procinfo->i_exec,
                        child_mesg[1], errbuf);
                    sprintf_malloc(&child_workstr, "執行受測程式 %s", 
                        procinfo->i_exec);
                    break;

                default:
                    sctproc_logger(2, "%s: child: unknown message\n", __func__);
                    sprintf_malloc(&child_workstr, "不明的訊息");
            }

            if(child_mesg[1]){
                sctproc_err("子程序傳回錯誤：%s：%s\n", child_workstr, errbuf);
                free(child_workstr);
                sctproc_logger(2, "%s: Kill the child process NOW!", __func__);
                kill(child_pid, SIGKILL);
                sctproc_logger(2, "%s: Wait for the child process", __func__);
                waitpid(child_pid, NULL, 0);
                close(child_pipe[0]);
                return SCTJUDGE_PROC_EXIT_FAILED;

            }else{
                free(child_workstr);
            }
        }

        /* exec 成功，正式啟動所有 judge 所需的東西 */
        sctproc_logger(2, "%s: 受測程式已成功執行\n", __func__);
        clock_gettime(CLOCK_REALTIME, &exec_begin);
        sctproc_logger(2, "%s: 現在時間是 (timespec) %d.%ld\n", __func__, 
            exec_begin.tv_sec, exec_begin.tv_nsec);
        close(child_pipe[0]);

        /* 初始化所有同步用的東西 */
        sctproc_logger(2, "%s: Initialize mutexes and semaphores\n", __func__);
        pthread_mutex_init(&checktime_mutex, NULL);
        pthread_mutex_init(&sctproc_tle_mutex, NULL);
        sem_init(&checktime_sem, 0, 0);
        if(procinfo->i_verbose > 0){
            pthread_mutex_init(&monitor_mutex, NULL);
            sem_init(&monitor_sem, 0, 0);
        }

        /* 產生 thread，一樣要有 verbose > 0 才有 monitor */
        sctproc_logger(2, "%s: Create thread: checktime\n", __func__);
        pthread_create(&checktime_thread, NULL, &sctproc_checktime, procinfo);
        pthread_mutex_lock(&checktime_mutex);
        checktime_exist = 1;
        pthread_mutex_unlock(&checktime_mutex);
        if(procinfo->i_verbose > 0){
            sctproc_logger(2, "%s: Create thread: monitor\n", __func__);
            pthread_create(&monitor_thread, NULL, &sctproc_monitor, procinfo);
            pthread_mutex_lock(&monitor_mutex);
            monitor_exist = 1;
            pthread_mutex_unlock(&monitor_mutex);
        }
        
        /* 開始要 wait 了，莫名其妙 stop 的程式我最多只會送
         * SCTJUDGE_PROC_MAX_STOP_TIMES 次 SIGCONT 給你（避免進入無限迴圈）
         * 這種奇怪的程式就等著 SLE 吧 
         * （這個常數定義在 SctConst.h，我想這不是很重要的東西）*/
        for(i=0, child_terminated=0; i<= SCTJUDGE_PROC_MAX_STOP_TIMES; i++){
            wait4(child_pid, &child_status, WUNTRACED, &procinfo->o_rusage);
            if(WIFSTOPPED(child_status) && i!=SCTJUDGE_PROC_MAX_STOP_TIMES){
                sctproc_logger(1, "受測程式因訊號 %d 而暫停，自動傳送 SIGCONT "
                    "(第 %d 次，最多可傳 %d 次)\n", WSTOPSIG(child_status),
                    i+1, SCTJUDGE_PROC_MAX_STOP_TIMES);
                kill(child_pid, SIGCONT);
            }else{
                if(WIFSIGNALED(child_status)){
                    clock_gettime(CLOCK_REALTIME, &exec_end);
                    child_terminated = 1;
                    procinfo->o_signal = WTERMSIG(child_status);
                    if(procinfo->o_signal == SIGXFSZ){
                        procinfo->o_result = PROCINFO_RESULT_OLE;
                    }else{
                        procinfo->o_result = PROCINFO_RESULT_RE;
                    }
                    procinfo->o_procexit = WEXITSTATUS(child_status);
                    break;
                }
                if(WIFEXITED(child_status)){
                    clock_gettime(CLOCK_REALTIME, &exec_end);
                    child_terminated = 1;
                    procinfo->o_result = PROCINFO_RESULT_OK;
                    procinfo->o_procexit = WEXITSTATUS(child_status);
                    break;
                }
                sctproc_logger(2, "%s: The child process is terminated\n",
                    __func__);
            }
        }

        /* 暫停次數超過限制 */
        if(!child_terminated){
            sctproc_logger(2, "%s: Sending SIGKILL\n", __func__);
            kill(child_pid, SIGKILL);
            wait4(child_pid, &child_status, WUNTRACED, &procinfo->o_rusage);
            procinfo->o_result = PROCINFO_RESULT_SLE;
            procinfo->o_procexit = WEXITSTATUS(child_status);
            clock_gettime(CLOCK_REALTIME, &exec_end);
        }


        /* 通知兩個 thread，請他們結束，也等他們結束 */
        pthread_mutex_lock(&checktime_mutex);
        if(checktime_exist){
            checktime_exist = 0;
            pthread_mutex_unlock(&checktime_mutex);
            sctproc_logger(2, "%s: Wait for thread checktime to exit\n",
                __func__);
            sem_post(&checktime_sem);
            pthread_join(checktime_thread, NULL);
        }else{
            pthread_mutex_unlock(&checktime_mutex);
        }

        pthread_mutex_lock(&monitor_mutex);
        if(monitor_exist){
            monitor_exist = 0;
            pthread_mutex_unlock(&monitor_mutex);
            sctproc_logger(2, "%s: Wait for thread monitor to exit\n",
                __func__);
            sem_post(&monitor_sem);
            pthread_join(monitor_thread, NULL);
        }else{
            pthread_mutex_unlock(&monitor_mutex);
        }

        /* 判斷 TLE 和執行時間 */
        difftimespec(&exec_begin, &exec_end, &(procinfo->o_runtime));
        checktimespec(&(procinfo->o_runtime));

        pthread_mutex_lock(&sctproc_tle_mutex);
        if(sctproc_tle){
            procinfo->o_result = PROCINFO_RESULT_TLE;
        }
        pthread_mutex_unlock(&sctproc_tle_mutex);

        if(sctproc_abort){
            procinfo->o_result = PROCINFO_RESULT_AB;
        }

        /* 移除掉所有同步用的東西 */
        sctproc_logger(2, "%s: Destroy mutexes and semaphores\n", __func__);
        pthread_mutex_destroy(&child_mutex);
        pthread_mutex_destroy(&checktime_mutex);
        pthread_mutex_destroy(&monitor_mutex);
        pthread_mutex_destroy(&sctproc_tle_mutex);
        sem_destroy(&checktime_sem);
        sem_destroy(&monitor_sem);

    }else{ 
        /* 這裡是 child process，也是要用到 setuid 的地方 
         * 因為我們在 main() 就已經停用 setuid 了
         * 所以我們必須在這段中需要的地方啟用他
         * 如果是用 Linux capabilites 舊部需要做而外處理
         * 如 */

        close(child_pipe[0]);

        /* close-on-exec 用來關閉這個暫時的資料傳輸通道 */
        childonly_fdopt = fcntl(child_pipe[1], F_GETFD);
        fcntl(child_pipe[1], F_SETFD, childonly_fdopt | FD_CLOEXEC);

        /* 設為獨立的 process group，不過失敗就算了，這不重要 */
        childonly_pid = getpid();
        setpgid(childonly_pid, childonly_pid);

        /* 重設所有 signal handler
         * XXX 我猜 signal 最大值是 31，還有其他更好的寫法嗎？ */
        for(i=1; i<=31; i++){
            signal(i, SIG_DFL);
        }


        /* 開啟或關閉輸入檔案 */
        if(procinfo->i_infile == NULL &&
            (procinfo->i_flag & PROCINFO_FLAG_CLOSE_FD)){
            sctproc_childonly_fail_if_negative(child_pipe[1],
                close(STDIN_FILENO),
                SCTJUDGE_PROC_CHILD_CLOSE_STDIN);
        }else{
            if(procinfo->i_infile == NULL){
                sctproc_childonly_fail_if_negative(child_pipe[1],
                    childonly_fdin = open(WITH_NULL, O_RDONLY),
                    SCTJUDGE_PROC_CHILD_OPEN_STDIN_SINK);
            }else{
                sctproc_childonly_fail_if_negative(child_pipe[1],
                    childonly_fdin = open(procinfo->i_infile, O_RDONLY),
                    SCTJUDGE_PROC_CHILD_OPEN_STDIN_FILE);
            }
            sctproc_childonly_fail_if_negative(child_pipe[1],
                dup2(childonly_fdin, STDIN_FILENO),
                SCTJUDGE_PROC_CHILD_DUP2_STDIN);
        }

        /* 開啟或關閉輸出檔案 */
        childonly_fdout = -1;
        if(procinfo->i_outfile == NULL &&
            (procinfo->i_flag & PROCINFO_FLAG_CLOSE_FD)){
            sctproc_childonly_fail_if_negative(child_pipe[1],
                close(STDOUT_FILENO),
                SCTJUDGE_PROC_CHILD_CLOSE_STDOUT);
        }else{
            if(procinfo->i_outfile == NULL){
                sctproc_childonly_fail_if_negative(child_pipe[1],
                    childonly_fdout = open(WITH_NULL, 
                        O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR),
                    SCTJUDGE_PROC_CHILD_OPEN_STDOUT_SINK);
            }else{
                sctproc_childonly_fail_if_negative(child_pipe[1],
                    childonly_fdout = open(procinfo->i_outfile,
                        O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR),
                    SCTJUDGE_PROC_CHILD_OPEN_STDOUT_FILE);
            }
            sctproc_childonly_fail_if_negative(child_pipe[1],
                dup2(childonly_fdout, STDOUT_FILENO),
                SCTJUDGE_PROC_CHILD_DUP2_STDOUT);
        }

        /* 開啟或關閉標準錯誤檔案 */
        if(procinfo->i_errfile == NULL){
            if(procinfo->i_flag & PROCINFO_FLAG_CLOSE_FD){
                sctproc_childonly_fail_if_negative(child_pipe[1],
                    close(STDERR_FILENO),
                    SCTJUDGE_PROC_CHILD_CLOSE_STDERR);
            }
            if(procinfo->i_flag & PROCINFO_FLAG_REDIR_STDERR && 
                    childonly_fdout >= 0){
                sctproc_childonly_fail_if_negative(child_pipe[1],
                    dup2(childonly_fdout, STDERR_FILENO),
                    SCTJUDGE_PROC_CHILD_REDIR_STDERR);
            }
        }else{
            sctproc_childonly_fail_if_negative(child_pipe[1],
                childonly_fderr = open(procinfo->i_errfile,
                    O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR),
                SCTJUDGE_PROC_CHILD_OPEN_STDERR_FILE);
            sctproc_childonly_fail_if_negative(child_pipe[1],
                dup2(childonly_fderr, STDERR_FILENO),
                SCTJUDGE_PROC_CHILD_DUP2_STDERR);
        }

        /* 很暴力地把所有不該留著的 fd 關掉 */
        childonly_fdcount = getdtablesize();
        for(i=3; i<childonly_fdcount; i++){
            close(i);
        }
        child_mesg[0] = SCTJUDGE_PROC_CHILD_CLOSE_OTHER_FDS;
        child_mesg[1] = 0;
        write(child_pipe[1], &child_mesg, sizeof(int) * 2);

        /* 接下來的操作可能需要提升的權限 */
#ifndef HAVE_CONF_CAP
        enable_setuid();
#endif

        /* 進行 chroot */
        if(procinfo->i_chroot != NULL){
            sctproc_childonly_fail_if_negative(child_pipe[1],
                chroot(procinfo->i_chroot),
                SCTJUDGE_PROC_CHILD_CHROOT);
            chdir("/");
        }

#ifdef HAVE_CONF_CAP
        /* 確保修改身份的時候 capabilities 仍然留著
         * 等一下再自己把 capabilities 丟掉 */
        prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);
#endif      

        /* 我要 setgid 嗎？ */
        if(procinfo->i_flag & PROCINFO_FLAG_SETGID){
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setgid(procinfo->i_gid),
                SCTJUDGE_PROC_CHILD_SETGID);
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setgroups(1, &(procinfo->i_gid)),
                SCTJUDGE_PROC_CHILD_SETGROUPS);
        }
        
        /* 我要 setuid 嗎？ */
        if(procinfo->i_flag & PROCINFO_FLAG_SETGID){
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setuid(procinfo->i_uid),
                SCTJUDGE_PROC_CHILD_SETUID);
        }
        else{
            /* 即使不要求 setuid，也不能讓受測程式拿到 setuid root */
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setuid(procrealuid),
                SCTJUDGE_PROC_CHILD_RESET_UID);
        }


#ifdef HAVE_CONF_CAP
        /* 丟掉所有 Linux capabilities */
        childonly_cap = cap_init();
        cap_clear_flag(childonly_cap, CAP_EFFECTIVE);
        cap_clear_flag(childonly_cap, CAP_INHERITABLE);
        cap_clear_flag(childonly_cap, CAP_PERMITTED);
        sctproc_childonly_fail_if_negative(child_pipe[1],
            cap_set_proc(childonly_cap),
            SCTJUDGE_PROC_CHILD_CAP_SET_PROC);
        /* 需要 drop bound 嗎？再考慮看看 */
#endif

        /* 至此所有特殊權力都已丟棄 */

        
        /* 開始設定資源限制 */

        /* -- MEM -- */
        if(procinfo->i_flag & PROCINFO_FLAG_LIMIT_MEM){
            childonly_rlimit.rlim_cur = procinfo->i_limit_mem;
            childonly_rlimit.rlim_max = procinfo->i_limit_mem;
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setrlimit(RLIMIT_AS, &childonly_rlimit),
                SCTJUDGE_PROC_CHILD_SETRLIMIT_MEM);
        }

        /* -- CORE -- */
        if(procinfo->i_flag & PROCINFO_FLAG_LIMIT_CORE){
            childonly_rlimit.rlim_cur = procinfo->i_limit_core;
            childonly_rlimit.rlim_max = procinfo->i_limit_core;
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setrlimit(RLIMIT_CORE, &childonly_rlimit),
                SCTJUDGE_PROC_CHILD_SETRLIMIT_CORE);
        }

        /* -- CPU -- */
        if(procinfo->i_flag & PROCINFO_FLAG_LIMIT_CPU){
            childonly_rlimit.rlim_cur = procinfo->i_limit_cpu;
            childonly_rlimit.rlim_max = procinfo->i_limit_cpu;
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setrlimit(RLIMIT_CPU, &childonly_rlimit),
                SCTJUDGE_PROC_CHILD_SETRLIMIT_CPU);
        }

        /* -- OUT -- */
        if(procinfo->i_flag & PROCINFO_FLAG_LIMIT_OUT){
            childonly_rlimit.rlim_cur = procinfo->i_limit_out;
            childonly_rlimit.rlim_max = procinfo->i_limit_out;
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setrlimit(RLIMIT_FSIZE, &childonly_rlimit),
                SCTJUDGE_PROC_CHILD_SETRLIMIT_FILE);
        }

        /* -- FILE -- */
        if(procinfo->i_flag & PROCINFO_FLAG_LIMIT_FILE){
            childonly_rlimit.rlim_cur = procinfo->i_limit_file;
            childonly_rlimit.rlim_max = procinfo->i_limit_file;
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setrlimit(
#ifdef RLIMIT_NOFILE
                    RLIMIT_NOFILE
#else
                    RLIMIT_OFILE
#endif
                    , &childonly_rlimit),
                SCTJUDGE_PROC_CHILD_SETRLIMIT_FILE);
        }

        /* -- PROC -- */
        if(procinfo->i_flag & PROCINFO_FLAG_LIMIT_PROC){
            childonly_rlimit.rlim_cur = procinfo->i_limit_proc;
            childonly_rlimit.rlim_max = procinfo->i_limit_proc;
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setrlimit(RLIMIT_NPROC, &childonly_rlimit),
                SCTJUDGE_PROC_CHILD_SETRLIMIT_PROC);
        }

        /* -- STACK -- */
        if(procinfo->i_flag & PROCINFO_FLAG_LIMIT_STACK){
            childonly_rlimit.rlim_cur = procinfo->i_limit_stack;
            childonly_rlimit.rlim_max = procinfo->i_limit_stack;
            sctproc_childonly_fail_if_negative(child_pipe[1],
                setrlimit(RLIMIT_STACK, &childonly_rlimit),
                SCTJUDGE_PROC_CHILD_SETRLIMIT_STACK);
        }
    
        /* 一切都完成了，現在要 exec 了！ */
        sctproc_childonly_fail_if_negative(child_pipe[1],
            execv(procinfo->i_exec, l4da_data(procinfo->i_argv)),
            SCTJUDGE_PROC_CHILD_EXEC);
    }


    return SCTJUDGE_PROC_EXIT_SUCCESS;

    /* drop private defines */
#undef private_BUFMAX
#undef private_READLEN

}

void sctproc_logger(int level, const char* format, ...){
    va_list ap;
    va_start(ap, format);
    if(sctproc_verbose >= level){
        pthread_mutex_lock(&output_mutex);
        if(level >= 2){
            (*sctproc_output_debug)(sctproc_output_arg, format, ap);
        }else{
            (*sctproc_output_normal)(sctproc_output_arg, format, ap);
        }
        pthread_mutex_unlock(&output_mutex);
    }
    va_end(ap);
}

void sctproc_err(const char* format, ...){
    va_list ap;
    va_start(ap, format);
    pthread_mutex_lock(&output_mutex);
    (*sctproc_output_err)(sctproc_output_arg, format, ap);
    pthread_mutex_unlock(&output_mutex);
    va_end(ap);
}

#if 0
static const char* childmsg_text[SCTCHILD_MSGMAX] = {
    "開啟輸入檔案",
    "重新導向標準輸入",
    "開啟輸出檔案",
    "重新導向標準輸出",
    "開啟用於導向標準錯誤的檔案",
    "重新導向標準錯誤",
    "關閉所有不使用的檔案",
    "設定記憶體限制",
    "設定輸出限制",
    "設定禁止開啟其他檔案",
    "設定禁止產生新程序",
    "執行 chroot",
    "修改 real 和 effective UID",
    "修改 real 和 effective GID",
    "修改 supplementary GIDs",
    "丟棄所有 Linux capabilities",
    "執行受測程式"
};

static void sctjudge_makechild_cleanup_p1(void){
    pthread_mutex_lock(&tkill_mx);
    if(tkill_yes){
        tkill_yes = 0;
        pthread_mutex_unlock(&tkill_mx);
        sem_post(&tlethr);
    }else{
        pthread_mutex_unlock(&tkill_mx);
    }

    pthread_mutex_lock(&tdisplay_mx);
    if(tdisplay_yes){
        tdisplay_yes = 0;
        pthread_mutex_unlock(&tdisplay_mx);
        sem_post(&dispthr);
    }else{
        pthread_mutex_unlock(&tdisplay_mx);
    }

}
    
static void sctjudge_makechild_cleanup_p2(mcopt, oldperm, copiedexe)
    const struct makechildopt* mcopt;
    const mode_t oldperm;
    char* copiedexe;
{
    if(oldperm != -1 && mcopt->chrootdir != NULL){
        if(mcopt->flags & SCTMC_VERBOSE){
            printf("恢復 %s 的權限\n", mcopt->chrootdir);
        }
        chmod(mcopt->chrootdir, oldperm);
    }
    if(copiedexe != NULL && mcopt->chrootdir != NULL && 
            !(mcopt->flags & SCTMC_NOCOPY)){
        if(mcopt->flags & SCTMC_VERBOSE){
            printf("移除 %s......\n", copiedexe);
        }
        unlink(copiedexe);
        free(copiedexe);
    }
}

static void sctjudge_makechild_cleanup(mcopt, oldperm, copiedexe)
    const struct makechildopt* mcopt;
    const mode_t oldperm;
    char* copiedexe;
{
    sctjudge_makechild_cleanup_p1();
    sctjudge_makechild_cleanup_p2(mcopt, oldperm, copiedexe);
}

static int copyfilebyname(const char* src, const char* destdir
        , char** srcsn, char** destfn){
    /* strerror 並不 thread safe，因此必須確定只有一個 thread 會用到 */
    /* 為了確保安全，要求目的地目錄必須是空的 */
    DIR* dirp;
    if((dirp=opendir(destdir)) == NULL){
        fprintf(stderr, "無法開啟目錄 %s：%s\n", destdir, strerror(errno));
        return -1;
    }
    struct dirent* entryp;
    while((entryp=readdir(dirp)) != NULL){
        if(entryp->d_name[0] != '.' || 
            (entryp->d_name[1] != '.' && entryp->d_name[1] != '\0')){
            fprintf(stderr, "拒絕複製檔案：目錄 %s 不是空的\n", destdir);
            return -1;
        }
    }
    int fd, fd2;
    if((fd=open(src, O_RDONLY)) < 0){
        fprintf(stderr, "無法讀取檔案 %s：%s\n", src, strerror(errno));
        return -1;
    }
    const int bufsize = 4096;
    void* buf = malloc(bufsize);
    char* srcshortname;
    char* tmp;
    if((tmp=strrchr(src, '/')) == NULL){
        srcshortname = (char*)src;
    }else{
        srcshortname = tmp + 1;
    }
    *srcsn = srcshortname;
    char* destfilename = (char*)
        malloc(strlen(srcshortname) + strlen(destdir) + 1);
    sprintf(destfilename, "%s/%s", destdir, srcshortname);
    *destfn = destfilename;
    /* 新檔案權限是 0755，umask 亂弄的我可不管 */
    if((fd2=open(destfilename, O_CREAT | O_WRONLY | O_EXCL, 
                S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH)) < 0){
        fprintf(stderr, "無法建立檔案 %s：%s\n", 
                destfilename, strerror(errno));
        free(buf);
        return -1;
    }
    int readcount;
    while((readcount = read(fd, buf, bufsize)) > 0){
        write(fd2, buf, readcount);
    }
    close(fd);
    close(fd2);
    free(buf);
    return 0;
}

static void sctjudge_list_settings(const struct makechildopt* mcopt){
    printf("\t受測程式可執行檔名稱：%s", mcopt->executable);
    if(mcopt->flags & SCTMC_NOCOPY && mcopt->chrootdir != NULL){
        printf(" (相對於 %s)\n"
            "\t受測程式執行時的根目錄：%s\n"
            "\t執行前複製檔案：否\n"
            , mcopt->chrootdir, mcopt->chrootdir);
    }else{
        putchar('\n');
        if(mcopt->chrootdir != NULL){
            printf("\t受測程式執行時的根目錄：%s\n"
                "\t執行前複製檔案：是\n"
                , mcopt->chrootdir);
        }else{
            puts("\t受測程式執行時的根目錄：/\n"
            "\t執行前複製檔案：否");
        }
    }
    printf("\t輸入檔案：%s\n"
        "\t輸出檔案：%s"
        , mcopt->inputfile, mcopt->outputfile);
    if(mcopt->flags & SCTMC_REDIR_STDERR){
        puts(" (重新導向標準輸出和標準錯誤)");
    }else{
        puts(" (重新導向標準輸出)");
    }
    printf("\t執行時間限制：%d 毫秒\n", mcopt->exectime);
    fputs("\t記憶體使用量限制：", stdout);
    if(mcopt->memlimit > 0){
        printf("%d 位元組\n", mcopt->memlimit);
    }else{
        puts("無限制");
    }
    fputs("\t輸出限制：", stdout);
    if(mcopt->outlimit > 0){
        printf("%d 位元組\n", mcopt->outlimit);
    }else{
        puts("無限制");
    }
    if(mcopt->flags & SCTMC_SETUID){
        printf("\t設定受測程式執行時的 UID 為 %u\n", mcopt->uid);
    }else{
        puts("\t執行受測程式時維持原有的 real UID 和 effective UID");
    }
    if(mcopt->flags & SCTMC_SETGID){
        printf("\t設定受測程式執行時的 GID 為 %u\n", mcopt->gid);
    }else{
        puts("\t執行受測程式時維持原有的 real GID、effective GID "
                "和 supplementary GID");
    }
}

static int read_size(int fd, void* buf, size_t count){
    /* 一定要讀到 count 位元組的資料才會回傳，所以只要回傳 < count
     * 就表示已經讀到 EOF 了 */
    char* bufp = (char*)buf;
    size_t curcount = 0;
    int rval;
    do{
        rval = read(fd, bufp, count - curcount);
        if(rval < 0){
            return rval;
        }else if(rval == 0){
            return curcount;
        }else{
            bufp += rval;
            curcount += rval;
        }
    }while(curcount < count);
    return count;
}

void* sctjudge_makechild(void* arg){
    /* 首先等所有 thread 都啟動完成再開始動作 */
    sem_wait(&mcthr);

    /* 宣告變數囉！ */
    int i;

    /* 函式參數與回傳值，Judge 結果就當作回傳值 */
    struct makechildopt mcopt = *(struct makechildopt*)arg;
    struct makechildrval* toreturn = 
        (struct makechildrval*)malloc(sizeof(struct makechildrval));
    memset(toreturn, 0, sizeof(struct makechildrval));

    /* 可執行檔名稱儲存區 */
    char* execshortname = NULL; /* 可以說就是 basename，chroot+copy 才會用 */
    char* execdestname = NULL; /* 複製出來的暫時執行檔，chroot+copy 才會用 */
    /* 這幾個變數用來儲存 Judge 結果，如果沒有啟用 verbose 
     * 且一切正常，那這些是唯一會輸出的東西了，目的是輸出容
     * 易被其他程式分析 */

    /* 要 chroot 的目錄的相關資訊 */
    struct stat chrdirinfo;      /* 取得原始的 mode 用的 */
    mode_t chrdir_oldmode = -1;  /* 這樣我們才能在結束時 chmod 回去 */

    /* 子程序的 PID，因為不會變，所以複製一份下來就不用去全域變數拿的 */
    pid_t pidcopy;

    /* 和子程序溝通用的 */
    int childpipe[2];
    int childmsg[2]; /* 每個訊息的大小都是 sizeof(int)*2 
                        [0]=發生事情的名稱 [1]=errno */
    int readsize = sizeof(int) * 2;

    /* 計時用的 */
    struct timespec execstart, execfinish;

    /* 子程序結束狀態 */
    int childexitstat;
    char childterminated = 0;

    /* 子程序才用的到的變數 */
    int fdinput, fdoutput, fderr, childressize;
    const int fdtablesize = getdtablesize();
    struct rlimit childres;

    /* 變數宣告完了 */

    if(mcopt.flags & SCTMC_VERBOSE){
        puts("列出設定值：");
        sctjudge_list_settings(&mcopt);
        fflush(stdout);
    }
    if(mcopt.flags & SCTMC_DRYRUN){
        abort_makechild(SCTMCRVAL_SUCCESS);
    }
    
    /* 我們要開始做正事了 */
    /* 由此開始，我是唯一會用到 strerror() 的 thread
     * 所以說應該沒有問題 */
    if(mcopt.chrootdir != NULL && !(mcopt.flags & SCTMC_NOCOPY)){
        /* 必須要複製可執行檔 */
        if(mcopt.flags & SCTMC_VERBOSE){
            puts("開始複製可執行檔......");
        }
        if(copyfilebyname(mcopt.executable, mcopt.chrootdir, &execshortname
                    , &execdestname) < 0){
            abort_makechild(SCTMCRVAL_PREPARE);
        }
    }
    /* 再來是 chroot 的問題，避免受測程式亂開目錄之類的，
     * 所以把權限設成 0555，不過如果沒有變更 uid 和 gid ，
     * 受測程式還是可以 chmod 回來 */
    if(mcopt.chrootdir != NULL){
        if(mcopt.flags & SCTMC_VERBOSE){
            puts("取得用於 chroot 的目錄相關資訊");
        }
        if(stat(mcopt.chrootdir, &chrdirinfo) < 0){
            fprintf(stderr, "無法取得目錄 %s 的相關資訊：%s\n", 
                mcopt.chrootdir, strerror(errno));
            abort_makechild(SCTMCRVAL_PREPARE);
        }else{
            if((chrdirinfo.st_mode & S_IFMT) == S_IFDIR){
                chrdir_oldmode = chrdirinfo.st_mode &
                    (S_ISUID |S_ISGID |S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO);
            }else{
                fprintf(stderr, "%s 並不是目錄\n", mcopt.chrootdir);
                abort_makechild(SCTMCRVAL_PREPARE);
            }
        }
        if(mcopt.flags & SCTMC_VERBOSE){
            puts("嘗試變更此目錄的權限");
        }
        if(chmod(mcopt.chrootdir, 
            S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH) < 0){
            fprintf(stderr, "無法變更目錄 %s 的權限\n", mcopt.chrootdir);
            abort_makechild(SCTMCRVAL_PREPARE);
        }
    }

    fflush(stdout);
#ifndef HAVE_CONF_CAP
    enable_setuid();
#endif
    /* 建立用來和 chlid process 溝通的 pipe */
    pipe(childpipe);
    pthread_mutex_lock(&pidmutex);
#ifdef HAVE_WORKING_FORK
    pidchild = fork();
#else
#error "This program requires a working fork function."
#endif
    if(pidchild < 0){
#ifndef HAVE_CONF_CAP
        disable_setuid();
#endif
        pthread_mutex_unlock(&pidmutex);
        fprintf(stderr, "子程序建立失敗：%s\n", strerror(errno));
        abort_makechild(SCTMCRVAL_FORK);
    }
    else if(pidchild > 0){
        /* 我們原本的 thread */
        /* 從這裡開始，我們需要 setuid 來 kill 子程序，
         * 所以說不要執行 disable_setuid() */
        pidcopy = pidchild;
        pthread_mutex_unlock(&pidmutex);
        close(childpipe[1]);
        /* 從 pipe 接收 child process 狀態，每次固定要讀 sizeof(int)*2 */
        while(read_size(childpipe[0], (void*)childmsg, readsize) == readsize){
            if(childmsg[0] < 0 || childmsg[0] >= SCTCHILD_MSGMAX){
                /* 會發生嗎？除非被亂七八糟 ptrace 吧 
                 * 這時候先砍掉子程序再說 */
                kill(pidcopy, SIGKILL);
                close(childpipe[0]);
                abort_makechild(SCTMCRVAL_INVALID);
            }else{
                if(childmsg[1]){
                    fprintf(stderr, "子程序[%d]發生錯誤：%s：%s\n",
                            pidcopy, childmsg_text[childmsg[0]], 
                            strerror(childmsg[1]));
                    kill(pidcopy, SIGKILL);
                    close(childpipe[0]);
                    abort_makechild(SCTMCRVAL_CHILDFAIL);
                }else{
                    if(mcopt.flags & SCTMC_VERBOSE){
                        printf("子程序[%d]：%s\n", pidcopy, 
                                childmsg_text[childmsg[0]]);
                    }
                }
            }
        }
        clock_gettime(CLOCK_REALTIME, &execstart);
        close(childpipe[0]);

        /* 現在我們確定受測程式已經在執行了，所以需要記錄一下時間
         * 通知其他 thread */
        sem_post(&tlethr);
        sem_post(&dispthr);

        /* 開始要 wait 了，莫名其妙 stop 的程式我最多只會送
         * 5 次 SIGCONT 給你（避免進入無限迴圈） 
         * 這種奇怪的程式就等著 SLE 吧 */
        for(i=0; i<=5; i++){
            wait4(pidcopy, &childexitstat, WUNTRACED, &toreturn->judge_rusage);
            if(WIFSTOPPED(childexitstat) && i!=5){
                if(mcopt.flags & SCTMC_VERBOSE){
                    printf("\n子程序因訊號 %d 而暫停，自動傳送 SIGCONT "
                            "(第 %d 次)\n",
                        WSTOPSIG(childexitstat), i+1);
                }
                kill(pidcopy, SIGCONT);
            }else{
                if(WIFSIGNALED(childexitstat)){
                    clock_gettime(CLOCK_REALTIME, &execfinish);
                    childterminated = 1;
                    toreturn->judge_signal = WTERMSIG(childexitstat);
                    if(toreturn->judge_signal == SIGXFSZ){
                        toreturn->judge_result = SCTRES_OLE;
                    }else{
                        toreturn->judge_result = SCTRES_RE;
                    }
                    toreturn->judge_exitcode = WEXITSTATUS(childexitstat);
                    break;
                }
                if(WIFEXITED(childexitstat)){
                    clock_gettime(CLOCK_REALTIME, &execfinish);
                    childterminated = 1;
                    toreturn->judge_result = SCTRES_OK;
                    toreturn->judge_exitcode = WEXITSTATUS(childexitstat);
                    break;
                }
            }
        }
        if(!childterminated){
            kill(pidcopy, SIGKILL);
            wait4(pidcopy, &childexitstat, WUNTRACED, &toreturn->judge_rusage);
            toreturn->judge_result = SCTRES_SLE;
            toreturn->judge_exitcode = WEXITSTATUS(childexitstat);
            clock_gettime(CLOCK_REALTIME, &execfinish);
        }
        pthread_mutex_lock(&judge_tle_mx);
        if(judge_tle && toreturn->judge_result == SCTRES_RE){
            toreturn->judge_result = SCTRES_TLE;
        }
        pthread_mutex_unlock(&judge_tle_mx);
        difftimespec(&execstart, &execfinish, &toreturn->judge_time);
        if(break_flag){
            toreturn->judge_result = SCTRES_AB;
        }
        sctjudge_makechild_cleanup_p1();
        if(mcopt.flags & SCTMC_VERBOSE){
            /* XXX 有更好的方法洗掉文字嗎？ */
            fputs("\r                                                       \r"
                    , stdout);
        }
    }else{
        /* 子程序 
         * 由此開始要很小心，因為我們是在 thread 裡面 fork (?) */
        close(childpipe[0]);
        /* close-on-exec 用來關閉這個暫時的資料傳輸通道 */
        fcntl(childpipe[1], F_SETFD, fcntl(childpipe[1],F_GETFD) | FD_CLOEXEC);

        /* 設為獨立的 process group，不過失敗就算了，這不重要 */
        setpgid(getpid(), getpid());

        /* 重設所有 signal handler
         * XXX 我猜 signal 最大值是 32，還有其他更好的寫法嗎？ */
        for(i=1; i<=32; i++){
            signal(i, SIG_DFL);
        }

#ifndef HAVE_CONF_CAP
        disable_setuid();
#endif

        fdinput = open(mcopt.inputfile, O_RDONLY);
        if(fdinput < 0){
            SCTCHILD_WRITE_FAILMSG(SCTCHILD_OPEN_INPUT);
            exit(1);
        }else{
            SCTCHILD_WRITE_SUCCMSG(SCTCHILD_OPEN_INPUT);
        }
        if(dup2(fdinput, STDIN_FILENO) < 0){
            SCTCHILD_WRITE_FAILMSG(SCTCHILD_DUP2_INPUT);
            exit(1);
        }else{
            SCTCHILD_WRITE_SUCCMSG(SCTCHILD_DUP2_INPUT);
        }

        /* 注意：開啟輸出檔會直接覆寫現存檔案！ */
        fdoutput = open(mcopt.outputfile, O_WRONLY | O_CREAT | O_TRUNC,
                S_IRUSR | S_IWUSR);
        if(fdoutput < 0){
            SCTCHILD_WRITE_FAILMSG(SCTCHILD_OPEN_OUTPUT);
            exit(1);
        }else{
            SCTCHILD_WRITE_SUCCMSG(SCTCHILD_OPEN_OUTPUT);
        }
        if(dup2(fdoutput, STDOUT_FILENO) < 0){
            SCTCHILD_WRITE_FAILMSG(SCTCHILD_DUP2_OUTPUT);
            exit(1);
        }else{
            SCTCHILD_WRITE_SUCCMSG(SCTCHILD_DUP2_OUTPUT);
        }

#ifndef HAVE_CONF_CAP
        enable_setuid();
#endif
        fchown(fdoutput, procrealuid, -1);

        /* 再來就是 stderr 了 */
        if(mcopt.flags & SCTMC_REDIR_STDERR){
            if(dup2(fdoutput, STDERR_FILENO) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_DUP2_STDERR);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_DUP2_STDERR);
            }
        }else{
            fderr = open(WITH_NULL, O_RDONLY);
            if(fderr < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_OPEN_STDERR);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_OPEN_STDERR);
            }
            if(dup2(fderr, STDERR_FILENO) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_DUP2_STDERR);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_DUP2_STDERR);
            }
        }

        /* 很暴力地把所有不該留著的 fd 關掉 */
        for(i=3; i<fdtablesize; i++){
            if(i != childpipe[1]){
                close(i);
            }
        }
        SCTCHILD_WRITE_SUCCMSG(SCTCHILD_CLOSE_OTHERFD);

        /* 有人要求我要 chroot 嗎？ */
        if(mcopt.chrootdir != NULL){
            if(chroot(mcopt.chrootdir) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_CHROOT);
                exit(1);
            }else{
                chdir("/");
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_CHROOT);
            }
        }


#ifdef HAVE_CONF_CAP
        /* 確保修改身份的時候 capabilities 仍然留著
         * 等一下再自己把 capabilities 丟掉 */
        prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);
#endif      

        /* 我要 setgid 嗎？ */
        if(mcopt.flags & SCTMC_SETGID){
            if(setregid(mcopt.gid, mcopt.gid) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_SETGID);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_SETGID);
            }
            if(setgroups(1, &mcopt.gid) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_SETGROUPS);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_SETGROUPS);
            }
        }

        /* 我要 setuid 嗎？ */
        if(mcopt.flags & SCTMC_SETUID){
            if(setreuid(mcopt.uid, mcopt.uid) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_SETUID);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_SETUID);
            }
        }
#ifndef HAVE_CONF_CAP
        else{
            /* 確保 setuid 可執行檔所造成的 effective UID 改變不會傳給子程序 */
            setuid(procrealuid);
        }
#endif

        /* 開始設定資源限制 */
        if(mcopt.memlimit > 0){
            childressize = mcopt.memlimit;
            childres.rlim_cur = childressize;
            childres.rlim_max = childressize;
            if(setrlimit(RLIMIT_AS, &childres) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_SETRLIMIT_VM);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_SETRLIMIT_VM);
            }
        }

        if(mcopt.outlimit > 0){
            childressize = mcopt.outlimit;
            childres.rlim_cur = childressize;
            childres.rlim_max = childressize;
            if(setrlimit(RLIMIT_FSIZE, &childres) < 0){
                SCTCHILD_WRITE_FAILMSG(SCTCHILD_SETRLIMIT_FSIZE);
                exit(1);
            }else{
                SCTCHILD_WRITE_SUCCMSG(SCTCHILD_SETRLIMIT_FSIZE);
            }
        }

        /* 從現在開始，不准再開檔案了 */
        childres.rlim_cur = 0;
        childres.rlim_max = 0;
        if(setrlimit(
#ifdef RLIMIT_NOFILE
                    RLIMIT_NOFILE
#else
                    RLIMIT_OFILE
#endif
                    , &childres) < 0){
            SCTCHILD_WRITE_FAILMSG(SCTCHILD_SETRLIMIT_OPENFILE);
            exit(1);
        }else{
            SCTCHILD_WRITE_SUCCMSG(SCTCHILD_SETRLIMIT_OPENFILE);
        }

        /* 從現在開始，不可以再產生新程序了 */
        if(setrlimit(RLIMIT_NPROC, &childres) < 0){
            SCTCHILD_WRITE_FAILMSG(SCTCHILD_SETRLIMIT_PROC);
            exit(1);
        }else{
            SCTCHILD_WRITE_SUCCMSG(SCTCHILD_SETRLIMIT_PROC);
        }
        

        /* 非 Linux 系統就到此結束了，可以 exec 了 */

#ifdef HAVE_CONF_CAP
        /* 正在丟掉 capabilities */
        cap_t nocap = cap_init();
        cap_clear_flag(nocap, CAP_EFFECTIVE);
        cap_clear_flag(nocap, CAP_INHERITABLE);
        cap_clear_flag(nocap, CAP_PERMITTED);
        if(cap_set_proc(nocap) < 0){
            SCTCHILD_WRITE_FAILMSG(SCTCHILD_CAPSET);
            exit(1);
        }else{
            SCTCHILD_WRITE_SUCCMSG(SCTCHILD_CAPSET);
        }
        /* 需要 drop bound 嗎？再考慮看看 */
#endif

        if(mcopt.chrootdir == NULL){
            execl(mcopt.executable, mcopt.executable, NULL);
        }else{
            if(mcopt.flags & SCTMC_NOCOPY){
                execl(mcopt.executable, mcopt.executable, NULL);
            }else{
                execl(execshortname, execshortname, NULL);
            }
        }

        SCTCHILD_WRITE_FAILMSG(SCTCHILD_EXEC);
        exit(2);
    }
    /* Judge 完成，準備離開 */
    fflush(stdout);
    sctjudge_makechild_cleanup_p2(&mcopt, chrdir_oldmode, execdestname);
    fflush(stdout);
    (toreturn->mc_exitcode) = SCTMCRVAL_SUCCESS;
    return (void*)toreturn;
}
#endif