BuckeyeCTF 2021 Staff

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct Course {
    char name[0x20];
    char instructor[0x20];
    int is_staff;
};

static void find_instructor(struct Course *courses, int course_count);
static void find_course(struct Course *courses, int course_count);
static void handle_option(int choice, struct Course *courses, int course_count);

#define NUM_COURSES 50

int main(int argc, char** argv) {
    struct Course courses[NUM_COURSES];

    setvbuf(stdout, NULL, _IONBF, 0); // turn off buffered output

    FILE *fin = fopen("sp22.txt", "r");
    if (!fin) {
        printf("Failed to open sp22.txt\n");
        return 0;
    }

    // Read in courses and instructors
    int course_count = 0;
    while (course_count < NUM_COURSES) {
        char *s = fgets(courses[course_count].name, 0x20, fin);
        if (!s) break;
        s[strcspn(s, "\n")] = 0; // remove newline
        
        s = fgets(courses[course_count].instructor, 0x20, fin);
        if (!s) break;
        s[strcspn(s, "\n")] = 0; // remove newline
        
        courses[course_count].is_staff = 1; // always hide instructors from students until the week before classes
        course_count++;
    }

    while (1) {
        printf("What would you like to do?\n1. Search for a course\n2. Search for an instructor\n> ");
        int choice;
        if (scanf("%d", &choice) != 1) break;
        getc(stdin); // get newline
        handle_option(choice, courses, course_count);
    }
}

static void handle_option(int choice, struct Course *courses, int course_count) {
    switch (choice) {
        case 1:
            find_course(courses, course_count);
            break;
        case 2:
            find_instructor(courses, course_count);
            break;
        default:
            printf("bad choice\n");
            break;
    }
}

static void find_instructor(struct Course *courses, int course_count) {
    char instructor[0x20];
    char course[0x20];

    printf("What instructor would you like to look up?\n> ");
    char *s = fgets(instructor, 0x20, stdin);
    if (!s) return;
    s[strcspn(s, "\n")] = 0; // remove newline

    if (strcmp(instructor, "Staff") == 0) {
        printf("There were %d results, please be more specific in your search.\n", course_count);
    } else {
        int i;
        for (i=0; i<course_count; i++) {
            if (strcmp(instructor, courses[i].instructor) == 0) {
                strncpy(course, courses[i].name, 0x20);
                break;
            }
        }
        if (i == course_count) {
            printf("We couldn't find your instructor.\n");
            return;
        }
    }

    printf("Professor %s will teach %s, but we'll probably change our minds the week before classes start.\n", instructor, course);
} 

static void find_course(struct Course *courses, int course_count) {
    char course[0x20];
    char instructor[0x20];

    printf("What course would you like to look up?\n> ");
    char *s = fgets(course, 0x20, stdin);
    if (!s) return;
    s[strcspn(s, "\n")] = 0; // remove newline

    int i;
    for (i=0; i<course_count; i++) {
        if (strcmp(course, courses[i].name) == 0) {
            strncpy(instructor, courses[i].instructor, 0x20);
            break;
        }
    }

    if (i == course_count) {
        printf("Sorry, we couldn't find your course.\n");
        return;
    }

    if (courses[i].is_staff) {
        printf("This course will be taught by: Staff\n");
    } else {
        printf("This course will be taught by: %s\n", instructor);
    }
}

static void find_instructor(struct Course *courses, int course_count) {
    char instructor[0x20];
    char course[0x20];
    // ...
}
static void find_course(struct Course *courses, int course_count) {
    char course[0x20];
    char instructor[0x20];
    // ...
}

 if (courses[i].is_staff) {
        printf("This course will be taught by: Staff\n");
 }