disk.c

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include "disk.h"
#include "data.h"

/*
 *	This function reads an entire page from address specified by blockNumber to pageNumber.
 */
int readFromDisk(int pageNumber, int blockNumber) {
	int fd;
	fd = open(DISK_NAME, O_RDONLY, 0666);
	if (fd < 0) {
		printf("Unable to Open Disk File\n");
		return -1;
	}
	lseek(fd, sizeof(PAGE) * blockNumber, SEEK_SET);
	read(fd, &page[pageNumber], sizeof(PAGE));
	close(fd);
}

/*
 *	This function writes an entire page to blocknumber from pageNumber.
 */
int writeToDisk(int pageNumber, int blockNumber) {
	int fd;
	fd = open(DISK_NAME, O_WRONLY, 0777);
	if (fd < 0) {
		printf("Unable to Open Disk File\n");
		return -1;
	}
	lseek(fd, sizeof(PAGE) * blockNumber, SEEK_SET);
	write(fd, &page[pageNumber], sizeof(PAGE));
	close(fd);
}