标签：通信 进程间通信 systemv shmget shmdt
#include <sys/ipc.h>
#include <sys/shm.h>
int shmget( key_t key, //代表共享内存唯一性的key值
size_t size, //共享内存的大小
int shmflg); //共享内存的属性设置
//返回值：>0 (成功，返回共享内存的标识符) -1(失败，错误信息见errno)#include <sys/types.h>
#include <sys/shm.h>
void *shmat(int shmid, //共享内存的标识符
const void *shmaddr, //设置共享内存在进程中的地址，一般置为0由系统分配
int shmflg); //共享内存的操作标志，一般置为0，表示进程有读写权限
//返回值：非(void*)-1（成功，返回映射的地址值）、(void*)-1（连接失败，失败信息见errno）#include <sys/types.h> #include <sys/shm.h> int shmdt(const void *shmaddr); //连接的地址值 //返回值：0（断开成功）、-1（断开连接失败，失败信息见errno）
#include <sys/ipc.h> #include <sys/shm.h>
int shmctl(int shmid, //共享内存标识符
int cmd, //操作命令
struct shmid_ds *buf); //命令对应的参数struct shmid_ds {
struct ipc_perm shm_perm; /* Ownership and permissions */
size_t shm_segsz; /* Size of segment (bytes) */
time_t shm_atime; /* Last attach time */
time_t shm_dtime; /* Last detach time */
time_t shm_ctime; /* Last change time */
pid_t shm_cpid; /* PID of creator */
pid_t shm_lpid; /* PID of last shmat()/shmdt() */
shmatt_t shm_nattch; /* No. of current attaches */
...
};struct ipc_perm {
key_t key; /* Key supplied to shmget() */
uid_t uid; /* Effective UID of owner */
gid_t gid; /* Effective GID of owner */
uid_t cuid; /* Effective UID of creator */
gid_t cgid; /* Effective GID of creator */
unsigned short mode; /* Permissions + SHM_DEST and SHM_LOCKED flags */
unsigned short seq; /* Sequence number */
};/*************************************************************************
> File Name: testshmw.c
> Author: qiaozp
> Mail: qiaozongpeng@163.com
> Created Time: 2014-9-22 10:58:30
> Step: 1 创建共享内存 shmget
2 连接共享内存 shmat
3 操作共享内存
4 断开共享内存 shmdt
************************************************************************/
#include <sys/ipc.h>
#include <sys/shm.h>
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <errno.h>
using namespace std;
#define BUFF_LEN 1024
typedef struct
{
bool isOkToRead;
char data[BUFF_LEN];
}Sbuff;
int main()
{
int shmid = 0;
void* shm = NULL;
//1 创建key值为1234的共享内存
if((shmid = shmget((key_t)1234, (size_t)sizeof(Sbuff) , 0666 | IPC_CREAT)) == -1)
{
cout << "创建共享内存错误，错误信息:" << strerror(errno) << endl;
return -1;
}
//2 连接共享内存
if((shm = shmat(shmid, 0, 0)) == (void*)-1)
{
cout << "连接共享内存错误，错误信息:" << strerror(errno) << endl;
return -1;
}
//3 直接对内存进行操作
Sbuff* buff = (Sbuff*)shm;
while(1)
{
if(buff->isOkToRead)
{
sleep(1);
continue;
}
cout << "请输入写入共享内存的数据:";
scanf("%s", buff->data);
buff->isOkToRead = true;
if(strncasecmp(buff->data, "end", 3) == 0)
{
cout << "收到end命令，断开和共享内存的连接" << endl;
//4 断开共享内存
shmdt(shm);
break;
}
}
return 0;
}
/*************************************************************************
> File Name: testshmr.c
> Author: qiaozp
> Mail: qiaozongpeng@163.com
> Created Time: 2014-9-22 10:58:14
> Step: 1 创建共享内存 shmget
2 连接共享内存 shmat
3 操作共享内存
4 断开共享内存 shmdt
************************************************************************/
#include <sys/ipc.h>
#include <sys/shm.h>
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <errno.h>
using namespace std;
#define BUFF_LEN 1024
typedef struct
{
bool isOkToRead;
char data[BUFF_LEN];
}Sbuff;
int main()
{
int shmid = 0;
void* shm = NULL;
//1 创建共享内存
if((shmid = shmget((key_t)1234, (size_t)sizeof(Sbuff) , 0666 | IPC_CREAT)) == -1)
{
cout << "创建共享内存错误，错误信息:" << strerror(errno) << endl;
return -1;
}
//2 连接共享内存
if((shm = shmat(shmid, 0, 0)) == (void*)-1)
{
cout << "连接共享内存错误，错误信息:" << strerror(errno) << endl;
return -1;
}
//3 操作共享内存
Sbuff* buff = (Sbuff*)shm;
buff->isOkToRead = false;
while(1)
{
if(!buff->isOkToRead)
{
sleep(1);
continue;
}
cout << "共享内存中现在的数据为:" << buff->data << endl;
buff->isOkToRead = false;
if(strncasecmp(buff->data, "end", 3) == 0)
{
cout << "收到end命令，断开和共享内存的连接" << endl;
//4 断开共享内存
shmdt(shm);
break;
}
}
//5 删除共享内存
if(shmctl(shmid, IPC_RMID, 0) == -1)
{
cout << "删除共享内存失败，失败信息:" << strerror(errno) << endl;
return -1;
}
return 0;
}
标签：通信 进程间通信 systemv shmget shmdt
原文地址：http://blog.csdn.net/juncily/article/details/39476197
