IPC之共享存儲區
用共享存儲區進行進程間通信主要有以下步驟組成
1. Create shared memory?
int shmget(key_t key, int size, int shmflg);?
if ((shm_id = shmget (mykey, sizeof (struct sharedbuf), 0600 | IFLAGS)) < 0)
??? perror ("shmget");
2. Attach shared memory?
char *buf = shmat (shm_id, 0, 0);
?
3. Read / Write shared memory?
sharedbuf->size = size_;?
memcpy(sharedbuf->buf, mybuf, size_);?
memcpy(mybuf, sharedbuf->buf, sharedbuf->size);?
?
3. Detach shared memory (optional)?
shmdt (buf);
?
4. Remove shared memory?
if (shmctl (shm_id, IPC_RMID, (struct shmid_ds *)0) < 0)?
??? perror ("shmctl");
一個測試過的實例
#include <stdio.h>
#include <sys/types.h>
#include <sys/shm.h>
#include <sys/ipc.h>
#define SHM_MODE (SHM_R | SHM_W)
#define SHM_SIZE 2048
int main()
{
?int segment_id, segment_size;
?char *shared_memory;
?pid_t pid;
?
?if((segment_id = shmget(IPC_PRIVATE, SHM_SIZE, SHM_MODE)) < 0)/*獲得共享內存標識符*/
??perror("shmget error!\n");
?if((shared_memory = shmat(segment_id, 0, 0)) == (void *)-1)/*進程和共享內存段相連接*/
??perror("shmat error!\n");
?printf("test1 send a message to share memory.\n");
?sprintf(shared_memory, "Hello test2\n");
?shmdt(shared_memory);/*脫離鏈接*/
?pid = fork();
?if(pid < 0)
??perror("Creating process error!\n");
?else if(pid > 0)
?{
??wait(NULL); /*父進程等待子進程結束*/
??shmctl(segment_id, IPC_RMID, 0);/*子進程結束，父進程將共享內存刪除*/
??exit(0);
?}
?else
?{???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
??if((shared_memory = shmat(segment_id, 0, 0)) == (void*)-1)/*子進程和共享內存連接*/
???perror("shmat error!\n");
??printf("test2 get a message form share memory:%s",shared_memory);
??shmdt(shared_memory);
?}
}?????
相關參考：http://blog.csdn.net/Apollo_zhc/archive/2006/06/01/768694.aspx