www.pudn.com > minix.instalation.cd-rom-2.0.rar > FAT.CPP

/*  
	FIPS - the First nondestructive Interactive Partition Splitting program  
  
	Module fat.cpp  
  
	RCS - Header:  
	$Header: c:/daten/fips/source/main/RCS/fat.cpp 1.4 1995/01/19 00:00:51 schaefer Exp schaefer $  
  
	Copyright (C) 1993 Arno Schaefer  
  
	This program is free software; you can redistribute it and/or modify  
	it under the terms of the GNU General Public License as published by  
	the Free Software Foundation; either version 2 of the License, or  
	(at your option) any later version.  
  
	This program is distributed in the hope that it will be useful,  
	but WITHOUT ANY WARRANTY; without even the implied warranty of  
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the  
	GNU General Public License for more details.  
  
	You should have received a copy of the GNU General Public License  
	along with this program; if not, write to the Free Software  
	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
  
  
	Report problems and direct all questions to:  
  
	schaefer@rbg.informatik.th-darmstadt.de  
*/  
  
#include   
  
#include "logdr_st.h"  
#include "global.h"  
#include "fat.h"  
#include "input.h"  
  
  
fat::fat (class logical_drive *logical_drive,int number)  
{  
	fat::logical_drive = logical_drive;  
	fat::number = number;  
	buffer = new sector;  
	start_sector = (number == 1) ? logical_drive->info().start_fat1 : logical_drive->info().start_fat2;  
	sector_in_buffer = -1;  
}  
  
  
dword fat16::next_cluster (dword cluster_number)  
{  
	dword sector = cluster_number / 256;  
	int offset = (cluster_number % 256) * 2;  
  
	if (sector != sector_in_buffer)  
	{  
		read_sector (sector);  
	}  
  
	return ((dword) buffer->data[offset] | ((dword) buffer->data[offset + 1] << 8));  
}  
  
  
void fat::read_sector (dword sector)  
{  
	if (logical_drive->read_sector (sector + start_sector,buffer))  
		if (number == 1)  
			error ("Error reading FAT 1");  
		else  
			error ("Error reading FAT 2");  
  
	sector_in_buffer = sector;  
}  
  
  
void fat16::check_against (class fat16 *fat2)  
{  
	printx ("Checking FAT ... ");  
  
	for (int i=0;ibpb().sectors_per_fat;i++)  
	{  
		read_sector (i);  
		fat2->read_sector (i);  
  
		for (int j=0;j<512;j++) if (buffer->data[j] != fat2->buffer->data[j])  
			error ("FAT copies differ: FAT 1 -> %02Xh, FAT 2 -> %02Xh in sector %u, byte %u",buffer->data[j],fat2->buffer->data[j],i,j);  
  
		if (i == 0)  
		{  
			if (buffer->data[0] != 0xf8)  
			{  
				warning (false, "Wrong media descriptor byte in FAT: %02Xh",buffer->data[0]);  
  
				printx ("Continue (y/n)? ");  
				if (ask_yes_no () == 'n') exit (-1);  
			}  
  
			if ((buffer->data[1] != 0xff) || (buffer->data[2] != 0xff) || (buffer->data[3] != 0xff))  
				warning (true, "Wrong FAT entries 1 & 2: %02X %02X %02X %02X",buffer->data[0],buffer->data[1],buffer->data[2],buffer->data[3]);  
		}  
	}  
	printx ("OK\n");  
}  
  
  
void fat16::check_empty (dword new_start_sector)  
{  
	dword first_cluster = (new_start_sector - logical_drive->info().start_data) / logical_drive->bpb().sectors_per_cluster + 2;  
  
	dword last_cluster = logical_drive->info().no_of_clusters + 1;  
  
	if (last_cluster > ((dword) 256 * logical_drive->bpb().sectors_per_fat - 1)) last_cluster = (dword) 256 * logical_drive->bpb().sectors_per_fat - 1;  
  
	printx ("First Cluster: %lu\nLast Cluster: %lu\n\n",first_cluster,last_cluster);  
	printx ("Testing if empty ... ");  
  
	for (dword i=first_cluster;i <= last_cluster;i++)  
	{  
		dword fat_entry = next_cluster (i);  
  
		if (fat_entry != 0) if (fat_entry != 0xfff7)  
		{  
			if (fat_entry == 0xffff)  
			{  
				error ("New partition not empty: cluster %lu ( FAT entry:  )",i);  
			}  
			else  
			{  
				error ("New partition not empty: cluster %lu ( FAT entry: %lu )",i,fat_entry);  
			}  
		}  
	}  
	  
	printx ("OK\n");  
}  
  
  
dword fat16::min_free_cluster (void)  
{  
	dword first_cluster = 2;  
  
	dword last_cluster = logical_drive->info().no_of_clusters + 1;  
  
	if (last_cluster > ((dword) 256 * logical_drive->bpb().sectors_per_fat - 1)) last_cluster = (dword) 256 * logical_drive->bpb().sectors_per_fat - 1;  
  
	printx ("Searching for free space ... ");  
  
	dword i;  
  
	for (i=last_cluster;i >= first_cluster;i--)  
	{  
		dword fat_entry = next_cluster (i);  
  
		if (fat_entry != 0) if (fat_entry != 0xfff7)  
		{  
			i++;  
			break;  
		}  
	}  
	printx ("OK\n\n");  
	return (i);  
}