getshm.c

来自「多用户银行系统」· C语言 代码 · 共 126 行

#include "../include/structs.h"
#include "../include/stddef.h"
#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include <sys/ipc.h>
#include <unistd.h>
#include <sys/shm.h> 
#include <sys/sem.h>

union semun{
	int val;
	struct semid_ds *buf;
	unsigned short int *array;
};
void * getSHM();
int main(int argc,char**argv){
	SHM *shm;
	int shm_id;
	int i;
	int key;
	int p;
	char *name = "/dev/shm/myshm2";
	int sem_id;
	union semun options;
	struct sembuf lock_it;
	//shm = (SHM*)malloc(sizeof(SHM));
	key = ftok(name,0);
	//i = (int *)malloc(sizeof(int));
	if(key == -1){
		perror("ftok error\n");
	}
	printf("111111");
	shm_id = shmget(key,1024,IPC_CREAT);	
	sem_id = semget(key,1,IPC_CREAT|0666);
	printf("sem_id=%d\n",sem_id);
	printf("shm_id=%d\n",shm_id);
	printf("1111111111\n");
	if(-1 == sem_id ){
		printf("create semaphore error\n");
		exit(-1);
	}

	options.val = 0;
	
	printf("111111111111\n");

	semctl(sem_id,0,SETVAL,options);
	i = semctl(sem_id,0,GETVAL,0);
	printf("%d\n",i);
	lock_it.sem_num = 0;
	lock_it.sem_op = -1;
	lock_it.sem_flg = IPC_NOWAIT;
	
	printf("xiu gai hou de %d\n",i);
//	shm_id = shmget(key,1024,IPC_CREAT|0666);
	if(shm_id == -1){
		perror("shmget error\n");
		return;
	}
	printf("3333333333333\n");
	/*p = getSHM();
	printf("aaaa%d\n",p);
	shm = p;
	shm->inta  = 20; 
	printf("%d\n",shm);
	printf("%d\n",shm->inta);
	//(SHM*)getSHM();
	*/
	shm = (SHM*)getSHM();
	
/*	lock_it.sem_num = 0;
	lock_it.sem_op = +1;
	lock_it.sem_flg = IPC_NOWAIT;
	semop(sem_id,&lock_it,1);
*/	
	i = semctl(sem_id,0,GETVAL,0);
	printf("de dao hou xiu gai = %d\n",i); 
	//shm -> inta = 20;
	//printf("%d\n",shm->inta);
	shm->inta = 20;
	printf("%d\n",shm->inta);
}

void * getSHM(){
	//int *i;
	void *p;
	//i = (int *)malloc(sizeof(int));
	int shm_id;
	int sem_id;
	union semun options;
	struct sembuf lock_it;
	int key;
	char *name = "/dev/shm/myshm2";
	//SHM * p;
	key = ftok(name,0);
	shm_id = shmget(key,0,0);
	sem_id = semget(key,0,0);
	
	semctl(sem_id,0,SETVAL,options);
	//*i = semctl(sem_id,0,GETVAL,0);
	p = shmat(shm_id,NULL,0);
	*((int *)p) = semctl(sem_id,0,GETVAL,0);
	printf("%d\n",*((int *)p));
	//i = (int *)malloc(sizeof(int));
	while(1){
		if(*((int *)p)==0){
		//	p = i+sizeof(int);
		//	p = (SHM*)malloc(sizeof(SHM));	
		//	printf("%d\n",i);
		//	return (p);	
			//*i = 1;
			p = p+sizeof(int);
			*((int*)p) = 1;
			printf("%d\n",p);
			return ((void *)p);
		}
		else{
			p = p+sizeof(int)+sizeof(SHM);
			continue;
			
		}
	}
}