实例9-17.c

Linux下C语言编程例子

#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
typedef struct{
	char name[4];
	int  age;
}people;
main(int argc, char** argv)
{
	int i;
	people *p_map;
	char temp;
	p_map=(people*)mmap(NULL,sizeof(people)*10,PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANONYMOUS,-1,0);
	if(fork() == 0)
	{
		sleep(2);
		for(i = 0;i<5;i++)
			printf("child read: the %d people's age is %d\n",i+1,(*(p_map+i)).age);
		(*p_map).age = 100;
		munmap(p_map,sizeof(people)*10); //实际上，进程终止时，会自动解除映射。
		exit();
	}
	temp = 'a';
	for(i = 0;i<5;i++)
	{
		temp += 1;
		memcpy((*(p_map+i)).name, &temp,2);
		(*(p_map+i)).age=20+i;
	}

	sleep(5);
	printf( "parent read: the first people,s age is %d\n",(*p_map).age );
	printf("umap\n");
	munmap( p_map,sizeof(people)*10 );
	printf( "umap ok\n" );
}