Question

以下代码展示了两个进程（服务器和客户端）之间的共享内存这段代码在两个程序之间传输字符，但是我想在这段代码中的两个程序之间传输NSData 我怎么能这样做？

     shm_server.c

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>

#define SHMSZ     27

int main()
{
    char c;
    int shmid;
    key_t key;
    char *shm, *s;

    /*
     * We'll name our shared memory segment
     * "5678".
     */
    key = 5678;

    /*
     * Create the segment.
     */
    if ((shmid = shmget(key, SHMSZ, IPC_CREAT | 0666)) < 0) {
        perror("shmget");
        exit(1);
    }

    /*
     * Now we attach the segment to our data space.
     */
    if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {
        perror("shmat");
        exit(1);
    }

    /*
     * Now put some things into the memory for the
     * other process to read.
     */
    s = shm;

    for (c = 'a'; c <= 'z'; c++)
        *s++ = c;
    *s = NULL;

    /*
     * Finally, we wait until the other process 
     * changes the first character of our memory
     * to '*', indicating that it has read what 
     * we put there.
     */
    while (*shm != '*')
        sleep(1);

    exit(0);
}

shm_client.c

/*
 * shm-client - client program to demonstrate shared memory.
 */
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>

#define SHMSZ     27

int main()
{
    int shmid;
    key_t key;
    char *shm, *s;

    /*
     * We need to get the segment named
     * "5678", created by the server.
     */
    key = 5678;

    /*
     * Locate the segment.
     */
    if ((shmid = shmget(key, SHMSZ, 0666)) < 0) {
        perror("shmget");
        exit(1);
    }

    /*
     * Now we attach the segment to our data space.
     */
    if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {
        perror("shmat");
        exit(1);
    }

    /*
     * Now read what the server put in the memory.
     */
    for (s = shm; *s != NULL; s++)
        putchar(*s);
    putchar('\n');

    /*
     * Finally, change the first character of the 
     * segment to '*', indicating we have read 
     * the segment.
     */
    *shm = '*';

    exit(0);
}

提前致谢

Answer 1

最好使用Distributed Objects。

Answer 2

您需要序列化数据，将其放入共享内存，然后反序列化，就像您通过网络发送数据一样。 This example有点无效，因为它序列化为文本格式，但它应该运行得很好。

用于在Objective C中传输数据（NSData）的共享内存

2 个答案: