map_sigbus2.c

来自「关于进程间通信的代码集锦2」· C语言 代码 · 共 38 行

#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
typedef struct{
	char name[4];
	int age;
}people;

int main(int argc,char** argv)
{
	int fd,i;
	int pagesize,offset;
	people* p_map;	
	
	pagesize=sysconf(_SC_PAGESIZE);
	printf("pagesize is %d\n",pagesize);
	fd=open(argv[1],O_CREAT|O_RDWR,00777);
	lseek(fd,pagesize*2-100,SEEK_SET);	
	write(fd,"",1);
//	offset=0;
	offset=pagesize;
	p_map=(people*)mmap(NULL,pagesize*3,PROT_READ|PROT_WRITE,MAP_SHARED,fd,offset);
	close(fd);
	for(i=1;i<10;i++)
	{
		(*(p_map+pagesize/sizeof(people)*i-2)).age=100;
		printf("access page %d over\n",i);
		(*(p_map+pagesize/sizeof(people)*i-1)).age=100;
		printf("access page %d edge over now begin to access page %d\n",i,i+1);
		(*(p_map+pagesize/sizeof(people)*i)).age=100;
		printf("access page %d over\n",i+1);
	}
	munmap(p_map,sizeof(people)*10);

	return 0;
}