linux 进程通信之共享内存机制C++代码实例
欢迎转载请注明出处：海漩涡
http://blog.csdn.net/tanhuifang520
linux 进程通信之共享内存机制C++代码实例
一、使用说明
只需包含share_memory.h
使用类通过名称和内存大小参数与其他进程共同使用一段内存
二、代码实例
1、通用类实现
share_memory.h
#ifndef __SHAREMEMORY_H__
#define __SHAREMEMORY_H__
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;
class CShareMemory
{
public:
CShareMemory(const char *name, u32 size);
~CShareMemory();
int PutToShareMem(const u8 *buffer, u32 length);
int GetFromShareMem(u8 *buffer, u32 length);
private:
void *CreateShareMemory(const char *name, u32 size);
void SemLock ( void )
{
sem_wait ( m_sem );
};
void SemUnLock ( void )
{
sem_post ( m_sem );
};
sem_t *m_sem;
u8 *m_shareMemory;
u32 m_memSize;
};
#endif
share_memory.cpp
#include "hd_share_mem.h"
CShareMemory::CShareMemory(const char *name, u32 size):m_memSize(size)
{
m_sem = sem_open(name, O_CREAT, 0X666, 1);
if(SEM_FAILED == m_sem)
{
printf("sem_open error");
}
sem_unlink(name);
SemLock();
m_shareMemory = (u8 *)CreateShareMemory(name, m_memSize);
SemUnLock();
}
/*
* brief: 写入数据到共享内存
* param1: buffer 写入数据buf
* param2: length 写入数据长度
* return: 返回写入数据的长度
**/
int CShareMemory::PutToShareMem(const u8 *buffer, u32 length)
{
if(m_memSize < length)
{
printf("Input length[%u] exceeds memory length[%u] error", length, m_memSize);
return -1;
}
SemLock();
memcpy(m_shareMemory, buffer, length);
SemUnLock();
return length;
}
/*
* brief: 从共享内存读取数据
* param1: buffer 读取数据buf
* param2: length 读取数据长度
* return: 返回读取数据的长度
**/
int CShareMemory::GetFromShareMem(u8 *buffer, u32 length)
{
if(m_memSize < length) // 获取数据越界
{
length = m_memSize;
}
SemLock();
memcpy(buffer, m_shareMemory, length);
SemUnLock();
return length;
}
/*
* brief: 创建共享内存
* param1: name
* size: 创建内存大小
**/
void * CShareMemory::CreateShareMemory(const char *name, u32 size)
{
int fd, shmid;
void *memory;
struct shmid_ds buf;
char filename[32];
snprintf(filename, 32, "/tmp/.%s", name);
if((fd = open(filename, O_RDWR|O_CREAT|O_EXCL)) > 0)
{
close(fd);
}
shmid = shmget(ftok(filename, 'g'), size, IPC_CREAT);
if (-1 == shmid)
{
perror("shmget err");
return NULL;
}
//printf("shmid:%d \n", shmid);
memory = shmat(shmid, NULL, 0);
if ((void *)-1 == memory)
{
perror("shmget err");
return NULL;
}
shmctl(shmid, IPC_STAT, &buf);
if (buf.shm_nattch == 1)
{
memset(memory, 0, size);
}
return memory;
}
CShareMemory::~CShareMemory()
{
shmdt(m_shareMemory);
sem_close(m_sem);
}
2、使用类例子
（1）进程1
main_1.cpp
#include "hd_share_mem.h"
int main()
{
u8 buffer[] = {0x11, 0x12, 0x13, 0x14, 0x15};
u32 length = sizeof(buffer);
CShareMemory csm("txh", 1024);
while(1)
{
for(int i=0; i<5; i++)
{
buffer[i]++;
}
csm.PutToShareMem(buffer,5);
usleep(100000);
}
return 0;
}
（2）进程2
main_2.cpp
#include "hd_share_mem.h"
int main()
{
char buffer1[] = {0x11, 0x12, 0x13, 0x14, 0x15};
unsigned char buffer[5] = {0};
unsigned int length = sizeof(buffer);
CShareMemory csm("txh", 1024);
while(1)
{
csm.GetFromShareMem(buffer,length);
for(int i=0; i
三、编译运行
g++ share_mem.cpp main_1.cpp -lpthread -o main1
g++ share_mem.cpp main_1.cpp -lpthread -o main2
打开两个终端运行分别运行main1和mian2：注运行时加sudo获取root权限
即实现了两个进程间的共享内存通信
欢迎转载请注明出处：海漩涡
http://blog.csdn.net/tanhuifang520