共享内存控制程序示例

原码如下：

#include
#include
#include
#include
#include

#define ARRAY_SIZE 4000
#define MALLOC_SIZE 10000
#define SHM_SIZE 10000
#define SHM_MODE (SHM_R | SHM_W)
char array[ARRAY_SIZE];

void printf_shmpemid(struct shmid_ds *buf)
{
    printf(" struct ipc_perm:\n");
    printf(" uid=%d:\n", buf->shm_perm.uid);
    printf(" gid=%d:\n", buf->shm_perm.gid);
    printf(" cuid=%d:\n", buf->shm_perm.cuid);
    printf(" cgid=%d:\n", buf->shm_perm.cgid);
    return;
}
int main(void)
{
    int shmid;
    char *ptr, *shmptr;
    struct shmid_ds shmds;
    printf("array[] from %x to %x\n",
        (unsigned int)&array[0], (unsigned int)&array[ARRAY_SIZE]);
    printf("stack around %x \n", (unsigned int)&shmid);
    if (NULL == (ptr = malloc(MALLOC_SIZE))) {
        fprintf(stderr, "malloc error\n");
        exit(1);
    }

    if ((shmid = shmget(IPC_PRIVATE, SHM_SIZE, SHM_MODE)) <0) {
        fprintf(stderr, "shmget error!\n");
        exit(1);
    }

    if ((shmptr = shmat(shmid, 0, 0)) == (void *) -1) {
        fprintf(stderr, "shmat error!\n");
        exit(1);
    }

    if (shmctl(shmid, IPC_STAT, &shmds) == -1) {
        fprintf(stderr, "GET shmid_ds ERROR!\n");
        exit(1);
    }
    printf_shmpemid(&shmds);
    if (shmctl(shmid, IPC_RMID, 0) < 0) {
        fprintf(stderr, "shmctl error\n");
        exit(1);
    }
    exit(0);
}