map_shared

#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <iostream>

int main() {
    int shm_fd = shm_open("/my_shared_memory", O_CREAT | O_RDWR, 0666);
    if (shm_fd == -1) {
        perror("Failed to create shared memory object");
        return 1;
    }

    if (ftruncate(shm_fd, sizeof(int)) == -1) {
        perror("Failed to set size of shared memory object");
        close(shm_fd);
        return 1;
    }

    int* shared_data = (int*)mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
    if (shared_data == MAP_FAILED) {
        perror("Failed to map shared memory");
        close(shm_fd);
        return 1;
    }

    *shared_data = 42; // 写入数据

    // ... 其他进程可以读取 *shared_data 的值 ...

    if (munmap(shared_data, sizeof(int)) == -1) {
        perror("Failed to unmap shared memory");
    }
    close(shm_fd);
    shm_unlink("/my_shared_memory");

    return 0;
}