#include <stdio.h>
// #include <libunwind.h>
#include <unistd.h>
#include <pthread.h>

// void customFunction1(int n);
void *customFunction1(void *n);
void customFunction2(int n);
void customFunction3(int n);

// Call this function to get a backtrace.
// void backtrace() {
//   unw_cursor_t cursor;
//   unw_context_t context;

//   // Initialize cursor to current frame for local unwinding.
//   unw_getcontext(&context);
//   unw_init_local(&cursor, &context);

//   // Unwind frames one by one, going up the frame stack.
//   while (unw_step(&cursor) > 0) {
//     unw_word_t offset, pc;
//     unw_get_reg(&cursor, UNW_REG_IP, &pc);
//     if (pc == 0) {
//       break;
//     }
//     printf("0x%lx:", pc);

//     char sym[256];
//     if (unw_get_proc_name(&cursor, sym, sizeof(sym), &offset) == 0) {
//       printf(" (%s+0x%lx)\n", sym, offset);
//     } else {
//       printf(" -- error: unable to obtain symbol name for this frame\n");
//     }
//   }
// }

void *customFunction1(void *n) {
    int num = *((int *)n);
    if(num <= 0) {
        printf("End of recursion\n");
        printf("pid: %d\n", getpid());
        while (1) {
            sleep(1);
        } // never return, keep stack
        // return NULL;
    } else {
        printf("Calling customFunction2\n");
        customFunction2(num-1);
    }
    return NULL;
}

void customFunction2(int n) {
    printf("Calling customFunction2\n");
    if(n <= 0) {
        printf("End of recursion\n");
        printf("pid: %d\n", getpid());
        while (1) {
            sleep(1);
        } // never return, keep stack
        // return NULL;
    }
    customFunction3(n-1);
}

void customFunction3(int n) {
    printf("Calling customFunction3\n");
    if(n <= 0) {
        printf("End of recursion\n");
        printf("pid: %d\n", getpid());
        while (1) {
            sleep(1);
        } // never return, keep stack
        // return NULL;
    }
    customFunction2(n-1);
}

int main() {
    int num1 = 4;
    int num2 = 5;
    int num3 = 6;

    pthread_t thread_id1, thread_id2, thread_id3;

    pthread_create(&thread_id1, NULL, customFunction1, &num1);
    pthread_create(&thread_id2, NULL, customFunction1, &num2);
    pthread_create(&thread_id3, NULL, customFunction1, &num3);

    pthread_join(thread_id1, NULL);
    pthread_join(thread_id2, NULL);
    pthread_join(thread_id3, NULL);
    return 0;
}