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/*
* Copyright (C) 2009,2010 Matthias Treydte <mt@waldheinz.de>
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package de.waldheinz.fs.fat;
import de.waldheinz.fs.BlockDevice;
import java.io.IOException;
/**
* Contains the FAT32 specific parts of the boot sector.
*
* @author Matthias Treydte <matthias.treydte at meetwise.com>
*/
final class Fat32BootSector extends BootSector {
/**
* The offset to the entry specifying the first cluster of the FAT32
* root directory.
*/
public final static int ROOT_DIR_FIRST_CLUSTER_OFFSET = 0x2c;
/**
* The offset to the 4 bytes specifying the sectors per FAT value.
*/
public static final int SECTORS_PER_FAT_OFFSET = 0x24;
/**
* Offset to the file system type label.
*/
public static final int FILE_SYSTEM_TYPE_OFFSET = 0x52;
public static final int VERSION_OFFSET = 0x2a;
public static final int VERSION = 0;
public static final int FS_INFO_SECTOR_OFFSET = 0x30;
public static final int BOOT_SECTOR_COPY_OFFSET = 0x32;
public static final int EXTENDED_BOOT_SIGNATURE_OFFSET = 0x42;
/*
* TODO: make this constructor private
*/
public Fat32BootSector(BlockDevice device) throws IOException {
super(device);
}
@Override
public void init() throws IOException {
super.init();
set16(VERSION_OFFSET, VERSION);
setBootSectorCopySector(6); /* as suggested by M$ */
}
/**
* Returns the first cluster in the FAT that contains the root directory.
*
* @return the root directory's first cluster
*/
public long getRootDirFirstCluster() {
return get32(ROOT_DIR_FIRST_CLUSTER_OFFSET);
}
/**
* Sets the first cluster of the root directory.
*
* @param value the root directory's first cluster
*/
public void setRootDirFirstCluster(long value) {
if (getRootDirFirstCluster() == value) return;
set32(ROOT_DIR_FIRST_CLUSTER_OFFSET, value);
}
/**
* Sets the sectur number that contains a copy of the boot sector.
*
* @param sectNr the sector that contains a boot sector copy
*/
public void setBootSectorCopySector(int sectNr) {
if (getBootSectorCopySector() == sectNr) return;
if (sectNr < 0) throw new IllegalArgumentException(
"boot sector copy sector must be >= 0");
set16(BOOT_SECTOR_COPY_OFFSET, sectNr);
}
/**
* Returns the sector that contains a copy of the boot sector, or 0 if
* there is no copy.
*
* @return the sector number of the boot sector copy
*/
public int getBootSectorCopySector() {
return get16(BOOT_SECTOR_COPY_OFFSET);
}
/**
* Sets the 11-byte volume label stored at offset 0x47.
*
* @param label the new volume label, may be {@code null}
*/
public void setVolumeLabel(String label) {
for (int i=0; i < 11; i++) {
final byte c =
(label == null) ? 0 :
(label.length() > i) ? (byte) label.charAt(i) : 0x20;
set8(0x47 + i, c);
}
}
public int getFsInfoSectorNr() {
return get16(FS_INFO_SECTOR_OFFSET);
}
public void setFsInfoSectorNr(int offset) {
if (getFsInfoSectorNr() == offset) return;
set16(FS_INFO_SECTOR_OFFSET, offset);
}
@Override
public void setSectorsPerFat(long v) {
if (getSectorsPerFat() == v) return;
set32(SECTORS_PER_FAT_OFFSET, v);
}
@Override
public long getSectorsPerFat() {
return get32(SECTORS_PER_FAT_OFFSET);
}
@Override
public FatType getFatType() {
return FatType.FAT32;
}
@Override
public void setSectorCount(long count) {
super.setNrTotalSectors(count);
}
@Override
public long getSectorCount() {
return super.getNrTotalSectors();
}
/**
* This is always 0 for FAT32.
*
* @return always 0
*/
@Override
public int getRootDirEntryCount() {
return 0;
}
public void setFileSystemId(int id) {
super.set32(0x43, id);
}
public int getFileSystemId() {
return (int) super.get32(0x43);
}
/**
* Writes a copy of this boot sector to the specified device, if a copy
* is requested.
*
* @param device the device to write the boot sector copy to
* @throws IOException on write error
* @see #getBootSectorCopySector()
*/
public void writeCopy(BlockDevice device) throws IOException {
if (getBootSectorCopySector() > 0) {
final long offset = getBootSectorCopySector() * SIZE;
buffer.rewind();
buffer.limit(buffer.capacity());
device.write(offset, buffer);
}
}
@Override
public int getFileSystemTypeLabelOffset() {
return FILE_SYSTEM_TYPE_OFFSET;
}
@Override
public int getExtendedBootSignatureOffset() {
return EXTENDED_BOOT_SIGNATURE_OFFSET;
}
}
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