进程间通信-共享内存-互斥锁同步（一）

代码参考网上其他人的，分三个文件

sm_common.h

#ifndef __SM_COMMON_H__
#define __SM_COMMON_H__
 
#include <pthread.h>
 
#define SM_BUF_SIZE 1024
#define SM_ID 0x1122
 
struct sm_msg
{
	int flag;//标志位，0代表在写，1表示在读
	pthread_mutex_t sm_mutex;//互斥锁
	char buf[SM_BUF_SIZE];//存放的数据
};
 
 
#endif

sm_server.c

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

#include "sm_common.h"

int main(void)
{
	int shm_id = -1;
	int ret = -1;
	int key = -1;
	int running = 1;
	struct sm_msg *msg = NULL;
	void *shared_memory = NULL;
	pthread_mutexattr_t attr;
 
	pthread_mutexattr_init(&attr);//init mutex lock
	pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);//set mutex lock ,other procecc can use

	shm_id = shmget((key_t)SM_ID, sizeof(struct sm_msg), 0666|IPC_CREAT);
	if(shm_id <