#include <sys/types.h>#include <sys/sem.h>#include <sys/ipc.h>#include <unistd.h>#include <stdlib.h>#include <sys/stat.h>#include <fcntl.h>#include <stdio.h>#include "sem_func.h"#define FILE_NAME "buffer"int file_creat;void read_data_base(){	int fd;	int number;		if((fd = open(FILE_NAME,O_RDONLY)) < 0) {		perror("open file fail\n");		exit(1);	}	if(read(fd,&number,sizeof(int)) < 0) {		perror("read error\n");		exit(1);	}	close(fd);	printf("reader:%d	%d\n",getpid(),number);	srand(time(0));	sleep(rand()%3+1);}int main(){	int semid_rc,semid_mutex,semid_db;	int val;	union semun arg;	init(&semid_rc,0,LOCKFILE_RC);	init(&semid_db,1,LOCKFILE_DB);	init(&semid_mutex,1,LOCKFILE_MUTEX);	while(1) {		V(&semid_mutex);		P(&semid_rc);		val = semctl(semid_rc,0,GETVAL,arg);		if(val == 1)			V(&semid_db);		P(&semid_mutex);		/*do work here*/		read_data_base();		V(&semid_mutex);		V(&semid_rc);		val = semctl(semid_rc,0,GETVAL,arg);		if(val == 0)			P(semid_db);		P(semid_mutex);	}	return 0;}