#include <stdio.h>#include <time.h>#include "msdos.h"extern int dir_start, dir_len, clus_size, dir_entries, fat_error, clus_size;extern unsigned int num_clus, end_fat, last_fat;extern long dir_chain[MAX_DIR_SECS];extern unsigned char *dir_buf;/* * Make a subdirectory grow in length.  Only subdirectories (not root) * may grow.  Returns a 0 on success, 1 on failure (disk full), or -1 * on error. */intdir_grow(fat)unsigned int fat;{	int i, num, buflen, new;	long sector;	char *memset(), *realloc();	unsigned char *offset, tbuf[MAX_CLUSTER];	unsigned int next, last, next_fat(), fat_decode();	void perror(), exit(), disk_write(), disk_read();	last = next_fat(0);	if (last == 1)		return(1);	/* CONSTCOND */	while (1) {		next = fat_decode(fat);		if (next == 1) {			fprintf(stderr, "dir_grow: FAT problem\n");			fat_error++;			return(-1);		}					/* end of cluster chain */		if (next >= last_fat)			break;		fat = next;	}					/* mark the end of the chain */	fat_encode(fat, last);	fat_encode(last, end_fat);					/* zero the buffer */	buflen = clus_size * MSECTOR_SIZE;	memset((char *) tbuf, '\0', buflen);					/* write the cluster */	sector = (long) (last - 2) * clus_size + dir_start + dir_len;	disk_write(sector, tbuf, buflen);					/* fix up the globals.... */	num = dir_entries / 16;	dir_entries += clus_size * 16;	for (i = 0; i < clus_size; i++)		dir_chain[num + i] = sector + i;					/* fix up dir_buf.... */	new = num + clus_size;	dir_buf = (unsigned char *) realloc((char *) dir_buf, (unsigned int) new * MSECTOR_SIZE);	if (dir_buf == NULL) {		perror("dir_grow: realloc");		exit(1);	}	offset = dir_buf + (num * MSECTOR_SIZE);	disk_read(dir_chain[num], offset, clus_size * MSECTOR_SIZE);	return(0);}/* * Returns next free cluster or 1 if none are available. */unsigned intnext_fat(last)unsigned int last;{	register unsigned int i;	unsigned int fat_decode();	for (i = last + 1; i < num_clus + 2; i++) {		if (!fat_decode(i))			return(i);	}	return(1);}