根据这些问题修改以上代码

针对上述提到的问题，我们可以改进代码如下：

1. 添加适当的错误处理：当`fork`、`semop`或其他系统调用失败时，记录错误信息并退出程序，以便于调试。

2. 对于父子进程之间的交互，为了确保任务按预期顺序执行，可以引入一些互斥锁或队列来保证流程控制。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <signal.h>

#define MAX_THREADS 3
#define NUM_FRUITS 5
#define SEMAPHORE_NAME "fruits"

typedef struct {
    int id;
    bool hasFruit;
    pthread_mutex_t mutex;
    sem_t *sem;
} ThreadData;

void* put_fruit(void* arg) {
    ThreadData* data = (ThreadData*)arg;
    while (!data->hasFruit) {
        pthread_mutex_lock(&data->mutex);
        if (rand() % NUM_FRUITS == 0) {
            sem_post(data->sem); // 释放信号量，表示有水果
            data->hasFruit = true;
        }
        pthread_mutex_unlock(&data->mutex);
        sleep(rand() % 3); // 模拟放水果时间
    }
}

void* eat_fruit(void* arg) {
    ThreadData* data = (ThreadData*)arg;
    while (data->hasFruit) {
        pthread_mutex_lock(&data->mutex);
        if (data->hasFruit) {
            printf("Eating fruit...\n");
            sem_wait(data->sem); // 请求信号量，表示等待水果
            data->hasFruit = false;
        } else {
            printf("No fruit available.\n");
        }
        pthread_mutex_unlock(&data->mutex);
        sleep(rand() % 5); // 模拟吃水果时间
    }
}

int main(int argc, char *argv[]) {
    int sem_id;
    ThreadData threads[MAX_THREADS];

    if ((sem_id = sem_open(SEMAPHORE_NAME, O_CREAT, 0666, NUM_FRUITS)) == SEM_FAILED) {
        perror("sem_open");
        exit(EXIT_FAILURE);
    }

    for (int i = 0; i < MAX_THREADS; i++) {
        threads[i].id = i;
        threads[i].hasFruit = false;
        threads[i].sem = &sem_id;
        pthread_mutex_init(&threads[i].mutex, NULL);
    }

    for (int i = 0; i < MAX_THREADS; i++) {
        switch (i) {
            case 0: put_fruit_thread = pthread_create(&threads[i].thread, NULL, put_fruit, &threads[i]); break;
            case 1: eat_fruit_thread = pthread_create(&threads[i].thread, NULL, eat_fruit, &threads[i]); break;
            default: break; // No need to create more than two threads
        }

        if (put_fruit_thread == NULL || eat_fruit_thread == NULL) {
            perror("pthread_create");
            exit(EXIT_FAILURE);
        }
    }

    for (int i = 0; i < MAX_THREADS; i++) {
        if (pthread_join(threads[i].thread, NULL) != 0) {
            perror("pthread_join");
            exit(EXIT_FAILURE);
        }
    }

    sem_close(sem_id);

    return 0;
}

在这个版本中，我们使用了互斥锁`pthread_mutex_t`来保护共享数据，并在`put_fruit`和`eat_fruit`线程之间同步。同时，我们也改进了信号量的使用，不再直接修改其值，而是通过`sem_post`和`sem_wait`来增加或减少信号量计数。这使得进程间的交互更为安全和有序。