de.waldheinz.fs
Interface BlockDevice

All Known Implementing Classes:

FileDisk, RamDisk

public interface BlockDevice

This is the abstraction used for a device that can hold a FileSystem.

Author:

Ewout Prangsma <epr at jnode.org>, Matthias Treydte <waldheinz at gmail.com>

Method Summary

void	close() Closes this BlockDevice.
void	flush() Flushes data in caches to the actual storage.
int	getSectorSize() Returns the size of a sector on this device.
long	getSize() Gets the total length of this device in bytes.
boolean	isClosed() Checks if this device was already closed.
boolean	isReadOnly() Checks if this BlockDevice is read-only.
void	read(long devOffset, ByteBuffer dest) Read a block of data from this device.
void	write(long devOffset, ByteBuffer src) Writes a block of data to this device.

Method Detail

getSize

long getSize()
             throws IOException

Gets the total length of this device in bytes.

Returns:

the total number of bytes on this device

Throws:

IOException - on error getting the size of this device

read

void read(long devOffset,
          ByteBuffer dest)
          throws IOException

Read a block of data from this device.

Parameters:

devOffset - the byte offset where to read the data from

dest - the destination buffer where to store the data read

Throws:

IOException - on read error

write

void write(long devOffset,
           ByteBuffer src)
           throws ReadOnlyException,
                  IOException,
                  IllegalArgumentException

Writes a block of data to this device.

Parameters:

devOffset - the byte offset where to store the data

src - the source ByteBuffer to write to the device

Throws:

ReadOnlyException - if this BlockDevice is read-only

IOException - on write error

IllegalArgumentException - if the devOffset is negative or the write would go beyond the end of the device

See Also:

isReadOnly()

flush

void flush()
           throws IOException

Flushes data in caches to the actual storage.

Throws:

IOException - on write error

getSectorSize

int getSectorSize()
                  throws IOException

Returns the size of a sector on this device.

Returns:

the sector size in bytes

Throws:

IOException - on error determining the sector size

close

void close()
           throws IOException

Closes this BlockDevice. No methods of this device may be accesses after this method was called.

Throws:

IOException - on error closing this device

See Also:

isClosed()

isClosed

boolean isClosed()

Checks if this device was already closed. No methods may be called on a closed device (except this method).

Returns:

if this device is closed

isReadOnly

boolean isReadOnly()

Checks if this BlockDevice is read-only.

Returns:

if this BlockDevice is read-only