moss.drivers
Class MRamdisk

java.lang.Object
  moss.drivers.MRamdisk

All Implemented Interfaces:

MFileOps

public class MRamdisk
extends java.lang.Object
implements MFileOps

this implements a "ramdisk" block device

Field Summary

Fields inherited from interface moss.fs.MFileOps

F_GETFL, F_OK, F_SETFL, LSEEK_BEG, LSEEK_CUR, LSEEK_END, O_CLOEXEC, O_NONBLOCK, OPEN_CREAT, OPEN_READ, OPEN_TRUNC, OPEN_WRITE, R_OK, W_OK, X_OK

Constructor Summary

MRamdisk()
constructor -- initialises the ramdisk

Method Summary

int	close(MFile handle) called when closing the ramdisk (it remains intact, however, unless garbage-collected)
int	fcntl(MFile handle, int op, int arg) file-handle control
int	lseek(MFile handle, int offset, int whence) seeks to a specific block in the ramdisk.
int	open(MFile handle, int flags) called when opening the ramdisk; stores reference to self in the file-handle
int	read(MFile handle, byte[] buffer, int count) called to read a block from the ramdisk (at the current offset)
int	write(MFile handle, byte[] buffer, int count) called to write data to the ramdisk (at the current offset)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MRamdisk

public MRamdisk()

constructor -- initialises the ramdisk

Method Detail

open

public int open(MFile handle,
                int flags)

called when opening the ramdisk; stores reference to self in the file-handle

Specified by:

open in interface MFileOps

Parameters:

handle - file-handle

flags - open flags (ignored)

Returns:

0 on success or < 0 on error

close

public int close(MFile handle)

called when closing the ramdisk (it remains intact, however, unless garbage-collected)

Specified by:

close in interface MFileOps

Parameters:

handle - file-handle

Returns:

0 on success or < 0 on error

lseek

public int lseek(MFile handle,
                 int offset,
                 int whence)

seeks to a specific block in the ramdisk. Seeking to the "end-of-file" is allowed (not much use, though)

Specified by:

lseek in interface MFileOps

Parameters:

handle - file-handle

offset - block offset

whence - where to seek from (LSEEK_{BEG,CUR,END})

Returns:

new absolute block offset, or < 0 indicating error

read

public int read(MFile handle,
                byte[] buffer,
                int count)

called to read a block from the ramdisk (at the current offset)

Specified by:

read in interface MFileOps

Parameters:

handle - file-handle

buffer - buffer where data will be stored

count - maximum number of bytes to read

Returns:

number of bytes read, 0 on end-of-file, or < 0 on error

write

public int write(MFile handle,
                 byte[] buffer,
                 int count)

called to write data to the ramdisk (at the current offset)

Specified by:

write in interface MFileOps

Parameters:

handle - file handle

buffer - data to write

count - number of bytes to write

Returns:

number of bytes written or < 0 on error

fcntl

public int fcntl(MFile handle,
                 int op,
                 int arg)

Description copied from interface: MFileOps

file-handle control

Specified by:

fcntl in interface MFileOps

Parameters:

handle - file-handle

op - operation to perform

arg - argument to operation (if applicable)

Returns:

>= 0 on success, or < 0 indicating failure