linux 共享内存 互斥锁

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <pthread.h>

#define SHM_SIZE 1024

int shmid;
char *shmaddr;
pthread_mutex_t mutex;

void* process(void* arg) {
    int id = *(int*)arg;
    pthread_mutex_lock(&mutex);
    sprintf(shmaddr, "Data from process %d", id);
    printf("Process %d wrote to shared memory\n", id);
    pthread_mutex_unlock(&mutex);
    return NULL;
}

int main() {
    key_t key = ftok("/tmp/shmfile", 65);
    shmid = shmget(key, SHM_SIZE, 0666 | IPC_CREAT);
    shmaddr = shmat(shmid, NULL, 0);

    pthread_t threads[5];
    int thread_ids[5] = {1, 2, 3, 4, 5};

    pthread_mutex_init(&mutex, NULL);

    for(int i = 0; i < 5; i++) {
        pthread_create(&threads[i], NULL, process, &thread_ids[i]);
    }

    for(int i = 0; i < 5; i++) {
        pthread_join(threads[i], NULL);
    }

    printf("Final data in shared memory: %s\n", shmaddr);

    pthread_mutex_destroy(&mutex);
    shmdt(shmaddr);
    shmctl(shmid, IPC_RMID, NULL);

    return 0;
}