shm2.c

本文件介绍了unix内核的c源代码

#include <sys/shm.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <stdio.h>
#include <sys/stat.h>
/*VERIFYERR(a, b)是定义宏，当a成立是，它打印失败信息，否则打印成功信息。*/
#define VERIFYERR(a, b)  \
	if (a) \
	{\
		fprintf(stderr, "%s failed.\n", b);  \
		return;\
	}\
	else \
		fprintf(stderr, "%s success.\n", b);  
void main()
{
	int shmid;
	char *pmat = NULL;
	char buf[1024];
	int no;

	/* 打开信号量 */	
	VERIFYERR((shmid = shmget(0x1234, 10*1024, 0666|IPC_CREAT)) == -1, "Open(Create) Shm");
	/* 映射共享内存，地址存储与pmat处 */
	VERIFYERR((pmat = (char *)shmat(shmid, 0, 0)) == 0, "Link Shm");
	/* 输入读取的内存块号 */
	printf("Please Input No.(0~9):");
	scanf("%d", &no);
	VERIFYERR(no < 0 || no > 9, "Input No.");
	/* 读取共享内存的数据 */
	memcpy(buf, pmat+no*1024, 1024);
	printf("Data:[%s]\n", buf);
	/* 释放共享内存映射 */
	shmdt(pmat);
}