126 lines
2.4 KiB
C
126 lines
2.4 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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#include "disk.h"
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/******************************************************************************/
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static int active = 0; /* is the virtual disk open (active) */
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static int handle; /* file handle to virtual disk */
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/******************************************************************************/
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int make_disk(char *name)
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{
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int f, cnt;
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char buf[BLOCK_SIZE];
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if (!name) {
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fprintf(stderr, "make_disk: invalid file name\n");
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return -1;
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}
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if ((f = open(name, O_WRONLY | O_CREAT | O_TRUNC, 0644)) < 0) {
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perror("make_disk: cannot open file");
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return -1;
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}
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memset(buf, 0, BLOCK_SIZE);
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for (cnt = 0; cnt < DISK_BLOCKS; ++cnt)
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write(f, buf, BLOCK_SIZE);
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close(f);
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return 0;
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}
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int open_disk(char *name)
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{
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int f;
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if (!name) {
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fprintf(stderr, "open_disk: invalid file name\n");
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return -1;
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}
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if (active) {
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fprintf(stderr, "open_disk: disk is already open\n");
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return -1;
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}
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if ((f = open(name, O_RDWR, 0644)) < 0) {
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perror("open_disk: cannot open file");
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return -1;
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}
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handle = f;
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active = 1;
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return 0;
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}
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int close_disk()
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{
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if (!active) {
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fprintf(stderr, "close_disk: no open disk\n");
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return -1;
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}
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close(handle);
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active = handle = 0;
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return 0;
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}
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int block_write(int block, char *buf)
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{
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if (!active) {
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fprintf(stderr, "block_write: disk not active\n");
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return -1;
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}
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if ((block < 0) || (block >= DISK_BLOCKS)) {
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fprintf(stderr, "block_write: block index out of bounds\n");
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return -1;
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}
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if (lseek(handle, block * BLOCK_SIZE, SEEK_SET) < 0) {
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perror("block_write: failed to lseek");
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return -1;
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}
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if (write(handle, buf, BLOCK_SIZE) < 0) {
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perror("block_write: failed to write");
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return -1;
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}
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return 0;
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}
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int block_read(int block, char *buf)
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{
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if (!active) {
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fprintf(stderr, "block_read: disk not active\n");
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return -1;
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}
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if ((block < 0) || (block >= DISK_BLOCKS)) {
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fprintf(stderr, "block_read: block index out of bounds\n");
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return -1;
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}
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if (lseek(handle, block * BLOCK_SIZE, SEEK_SET) < 0) {
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perror("block_read: failed to lseek");
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return -1;
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}
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if (read(handle, buf, BLOCK_SIZE) < 0) {
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perror("block_read: failed to read");
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return -1;
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}
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return 0;
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}
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