Student Test Code for CSL-2025 (Exercise 7 - Q5 for Dr. Asadi and Exercise 2 - Q4 for Dr. Jahangir)

tester.c

/* * STUDENT TESTER
 * This simulates the hardware blindly. 
 * Use this to verify your logic locally.
 */
#define _GNU_SOURCE
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/user.h>
#include <sys/uio.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// 0=Open, 1=Obstacle, 2=Target
const int HIDDEN_MAP[] = {0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 2}; 
const int MAP_SIZE = 11;

void read_mem(pid_t child, unsigned long addr, char *buf, size_t len) {
    struct iovec local = {buf, len};
    struct iovec remote = {(void *)addr, len};
    process_vm_readv(child, &local, 1, &remote, 1, 0);
}

int main(int argc, char *argv[]) {
    if (argc < 2) { printf("Usage: %s <program>\n", argv[0]); return 1; }

    pid_t child = fork();
    if (child == 0) {
        ptrace(PTRACE_TRACEME, 0, NULL, NULL);
        execl(argv[1], argv[1], NULL);
        exit(1);
    } else {
        int status, pos = 0;
        struct user_regs_struct regs;
        wait(&status);
        ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_EXITKILL);

        printf("[HARDWARE] Robot System Booting...\n");

        while (1) {
            ptrace(PTRACE_SYSEMU, child, 0, 0);
            wait(&status);

            if (WIFEXITED(status) || WIFSIGNALED(status)) break;

            ptrace(PTRACE_GETREGS, child, 0, &regs);
            
            if (regs.orig_rax == 100) { // SYS_SCAN
                int val = (pos + 1 < MAP_SIZE) ? HIDDEN_MAP[pos + 1] : 0;
                regs.rax = val;
            } 
            else if (regs.orig_rax == 101) { // SYS_MOVE

                int act = regs.rdi;
                int next = (pos + 1 < MAP_SIZE) ? HIDDEN_MAP[pos + 1] : -1;
                
                if (act == 0) { // Walk
                    if (next == 0 || next == 2) {
                        pos++;
                    } else {
                        printf("\n[HARDWARE] CRITICAL: COLLISION DETECTED.\n");
                        goto CRASH;
                    }
                } else if (act == 1) { // Jump
                    if (next == 1) {
                        pos += 2; 
                    } else {
                        printf("\n[HARDWARE] CRITICAL: ILLEGAL MANEUVER (JUMP ON FLAT).\n");
                        goto CRASH;
                    }
                }
                regs.rax = 0;
            } 
            else if (regs.orig_rax == 102) { // SYS_LOG
                char buf[20] = {0};
                read_mem(child, regs.rdi, buf, regs.rsi < 19 ? regs.rsi : 19);

                if (HIDDEN_MAP[pos] == 2 && strncmp(buf, "MISSION OK", 10) == 0) {
                    printf("\n[BASE STATION] Signal Received: \"%s\"\n", buf);
                    printf("[HARDWARE] MISSION SUCCESSFUL.\n");
                    kill(child, SIGKILL); return 0;
                } 
                else if (strncmp(buf, "LOW", 3) == 0) {
                    printf("\n[BASE STATION] Signal Received: \"%s\"\n", buf);
                    printf("[HARDWARE] SHUTDOWN CONFIRMED (Battery Depleted).\n");
                    kill(child, SIGKILL); return 0;
                }
                else {
                    printf("\n[BASE STATION] Corrupted Packet or Wrong Coordinates.\n");
                    goto CRASH;
                }
            }
            else if (regs.orig_rax == 60) {
                printf("[HARDWARE] Manual Shutdown.\n");
                break;
            }
            
            ptrace(PTRACE_SETREGS, child, 0, &regs);
        }
    }
    return 0;

CRASH:
    printf("[HARDWARE] SYSTEM HALTED.\n");
    kill(child, SIGKILL);
    return 1;
}

همچنین اگر به هر دلیلی مشکلی در اجرای برنامه‌ی ربات بوجود اومد، می‌شود با تغییر خط ‍execl به این شکل از مشکل با خبر شد:

if (execl(argv[1], argv[1], NULL) == -1) {
    perror("[HARDWARE] Failed to execute program");
}