Random sleep execlp bad address on program 检查程序执行时间

Question

我正在尝试使用 fork() 制作一个简单的程序来执行命令或程序，看看它是否在我通过参数引入的时间限制内完成，如下所示：

输入：

    ./timechecker 3 ls ps ls

所以我所知道的是我在最后用 NULL 正确地完成了 execlp 但我不知道为什么我从睡眠 execlp 中得到随机结果有时它说地址错误并且它在我的输出中说与运行关联的程序已被迫完成，但它的发生与我使用的时间无关。示例输出：

execlp sleep: Bad address                   //The ls execlp
  PID TTY          TIME CMD                //The ls execlp without sleep error
execlp sleep: Bad address                  //The ps execlp
  225 pts/3    00:00:00 a.out              //The ps without sleep error
  231 pts/3    00:00:00 ps
  232 pts/3    00:00:00 a.out <defunct>
  PID TTY          TIME CMD
  225 pts/3    00:00:00 a.out
  233 pts/3    00:00:00 ps
  234 pts/3    00:00:00 a.out
Total time: 0 
1 programs have been forced to finish taking more than 1000 seg and 2 programs have been finished under the time limit

代码：

        #include <sys/types.h>
        #include <unistd.h>
        #include <stdio.h>
        #include <time.h>
        #include <sys/wait.h>
        #include <stdlib.h>
        #include <string.h>
        #include <signal.h>
        #define error(a){perror(a);exit(1);}
        
        int main(int argc, char *argv[]) //argv1 timeLimit argv2..argv11 commands
        {
        
            if (argc > 12 || argc < 3)
            {
                error("Incorrect number of arguments");
            }
            
            int timeLimit = atoi(argv[1]);
        
            if(timeLimit < 0)
            {
                error("The time limit must be 0 or greater")
            }
            
            int programs = argc - 2;
            int forced = 0;
            int finished = 0;
            char program[100] = "";
        
            int i = 0, pid, pid_clock, pid_dev = 0, estatus;
        
            time_t t1, t2;
        
            t1 = time(NULL);
        
            while(i<programs) //i<nb_tests
            {
                pid = 0;
                pid_clock = 0;
                estatus = -1;
                t2 = time(NULL);
                pid = fork();
                switch(pid)
                {
                    case -1:
                        error("fork")
                    case 0:
                        strcpy(program, argv[i]);
                        execlp(program, program, NULL);
                        error("execlp programm");
                    default:
                        pid_clock = fork();
                        switch(pid_clock)
                        {
                            case -1:
                                error("fork")
                            case 0:
                                execlp("sleep", "sleep", timeLimit, NULL); //The problem
                                error("execlp sleep");
                            default:
                                pid_dev = wait(NULL);
                                if(pid_dev == pid_clock)
                                {
                                    kill(pid, SIGKILL);
                                    wait(NULL);
                                    estatus = 0;
                                    break;
                                }
                                else if(pid_dev == pid)
                                {
                                    kill(pid_clock, SIGKILL);
                                    wait(NULL);
                                    estatus = 1;
                                    break;
                                }
                                else 
                                {
                                    printf("%d\n", pid_dev);
                                    estatus = -1;
                                    break;
                                }
                        }
                }
                t2 = time(NULL) - t2;
                
                if(estatus == 0)
                {
                    forced++;
                }
                else if(estatus == 1)
                {
                    finished++;
                }
                i++;
            }
        
            t1 = time(NULL) - t1;
        
            printf("Total time: %li \n", t1);
            printf("%d programs have been forced to finish taking more than %d seg and %d programs have been finished under the time limit\n",forced, timeLimit, finished);
        
            return 0;
        }

Answer 1

用于exec 函数的命令的参数是 字符串 的列表。实际上，它们是执行程序中的字符串数组 argv。

您传递一个整数值作为 sleep 命令的参数，而不是字符串。这会导致 未定义的行为 并且很可能会崩溃。

Random sleep execlp bad address on program 检查程序执行时间

Random sleep execlp bad address on program to check the execution time of programs

c

linux

time

fork

exec