tshm.c

unix环境高级编程一书源代码 本书全面介绍了UNIX系统的程序设计界面—系统调用界面和标准C库提供的许多函数。 本书的前15章着重于理论知识的阐述

#include	<sys/types.h>
#include	<sys/ipc.h>
#include	<sys/shm.h>
#include	"ourhdr.h"

#define	ARRAY_SIZE	 40000
#define	MALLOC_SIZE	100000
#define	SHM_SIZE	100000
#define	SHM_MODE	(SHM_R | SHM_W)	/* user read/write */

char	array[ARRAY_SIZE];	/* uninitialized data = bss */

int
main(void)
{
	int		shmid;
	char	*ptr, *shmptr;

	printf("array[] from %x to %x\n", &array[0], &array[ARRAY_SIZE]);
	printf("stack around %x\n", &shmid);

	if ( (ptr = malloc(MALLOC_SIZE)) == NULL)
		err_sys("malloc error");
	printf("malloced from %x to %x\n", ptr, ptr+MALLOC_SIZE);

	if ( (shmid = shmget(IPC_PRIVATE, SHM_SIZE, SHM_MODE)) < 0)
		err_sys("shmget error");
	if ( (shmptr = shmat(shmid, 0, 0)) == (void *) -1)
		err_sys("shmat error");
	printf("shared memory attached from %x to %x\n",
				shmptr, shmptr+SHM_SIZE);
	if (shmctl(shmid, IPC_RMID, 0) < 0)
		err_sys("shmctl error");

	exit(0);
}