11.4.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <pthread.h>

void cleanup(void *arg)
{
    printf("cleanup: %s\n", (char *)arg);
}

void thr_fn1(void *arg)
{
    printf("thread 1 start\n");
    pthread_cleanup_push(cleanup, "thread 1 first handler");
    pthread_cleanup_push(cleanup, "thread 1 second handler");
    printf("thread 1 push complete\n");
    
    if (arg) {
        return ((void *)1);
    }

    pthread_cleanup_pop(0);
    pthread_cleanup_pop(0);

    return ((void *)1);
}

void thr_fn2(void *arg)
{
    printf("thread 2 start\n");
    
    pthread_cleanup_push(cleanup, "thread 2 first handler");
    pthread_cleanup_push(cleanup, "thread 2 second handler");
    printf("thread 2 push complete\n");
    
    if (arg) {
        pthread_exit((void *)2);
    }

    pthread_cleanup_pop(0);
    pthread_cleanup_pop(0);
    
    pthread_exit((void *)2);
}

int main(void)
{
    int         err;
    pthread_t   tid1, tid2;
    void        *tret;

    err = pthread_create(&tid1, NULL, thr_fn1, (void *)1);
    if (0 != err) {
        printf("can't create thread 1: %s\n", strerror(err));
        exit(-1);
    }
    
    err = pthread_create(&tid2, NULL, thr_fn2, (void *)1);
    if (0 != err) {
        printf("can't create thread 2: %s\n", strerror(err));
        exit(-1);
    }

    err = pthread_join(tid1, &tret);
    if (0 != err) {
        printf("can't join with thread 1: %s\n", strerror(err));
        exit(-1);
    }
    printf("thread 1 exit code %d\n", (int)tret);
    
    err = pthread_join(tid2, &tret);
    if (0 != err) {
        printf("can't join with thread 2: %s\n", strerror(err));
        exit(-1);
    }
    printf("thread 2 exit code %d\n", (int)tret);
    
    return 0;
}