进程间通信系列 之 共享内存简单实例

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场景：

    两个进程，A进程创建共享内存并读取数据；B进程连接共享内存写入数据。输入 end 结束进程。

应用实例：

头文件：shm_com.h

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

#define	TEXT_SZ	2048

struct	shared_use_st{
int	written_by_you;
char	some_text[TEXT_SZ];
};

消费者程序：shm_customer.h

#include "shm_com.h"

int main(int argc,char **argv)
{
int	running = 1;
void *shared_memory = (void *)0;
struct	shared_use_st *shared_stuff;
int	shmid;

srand((unsigned int)getpid());

shmid = shmget((key_t)1234,sizeof(struct shared_use_st),0666|IPC_CREAT);
if(shmid == -1){
fprintf(stderr,"shmget failed\n");
exit(-1);
}

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

shared_stuff = (struct shared_use_st *)shared_memory;
shared_stuff->written_by_you = 0;
while(running){
if(shared_stuff->written_by_you){
printf("You wrote: %s",shared_stuff->some_text);
sleep(rand()%4);
shared_stuff->written_by_you = 0;
if(strncmp(shared_stuff->some_text,"end",3) == 0){
running = 0;
}
}
}

if(shmdt(shared_memory) == -1){
fprintf(stderr,"shmdt failed!\n");
exit(-1);
}

if(shmctl(shmid,IPC_RMID,0) == -1){
fprintf(stderr,"shmctl(IPC_RMID) failed!\n");
exit(-1);
}

exit(0);
}

生产者程序：shm_producer.c

#include "shm_com.h"

int main(int argc,char **argv)
{
int	running = 1;
void *shared_memory = (void *)0;
struct	shared_use_st *shared_stuff;
char	buffer[TEXT_SZ];
int	shmid;

shmid = shmget((key_t)1234,sizeof(struct shared_use_st),0666|IPC_CREAT);
if(shmid == -1){
fprintf(stderr,"Shmget failed!\n");
exit(-1);
}

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

printf("Memory attached at %X\n",(int)shared_memory);

shared_stuff = (struct shared_use_st *)shared_memory;
while(running){
while(shared_stuff->written_by_you == 1){
sleep(1);
printf("Waiting for client...\n");
}
printf("Enter some text: ");
fgets(buffer,TEXT_SZ,stdin);

strncpy(shared_stuff->some_text,buffer,TEXT_SZ);
shared_stuff->written_by_you = 1;

if(strncmp(buffer,"end",3) == 0){
running = 0;
}
}

if(shmdt(shared_memory) == -1){
fprintf(stderr,"Shmdt failed\n");
exit(-1);
}

exit(0);
}

 

转自：http://blog.csdn.net/nowdoit/article/details/7094745