142 lines
4.2 KiB
Java
142 lines
4.2 KiB
Java
// PART OF THE MACHINE SIMULATION. DO NOT CHANGE.
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package nachos.machine;
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import java.io.EOFException;
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/**
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* A file that supports reading, writing, and seeking.
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*/
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public class OpenFile {
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/**
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* Allocate a new <tt>OpenFile</tt> object with the specified name on the
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* specified file system.
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*
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* @param fileSystem the file system to which this file belongs.
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* @param name the name of the file, on that file system.
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*/
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public OpenFile(FileSystem fileSystem, String name) {
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this.fileSystem = fileSystem;
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this.name = name;
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}
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/**
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* Allocate a new unnamed <tt>OpenFile</tt> that is not associated with any
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* file system.
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*/
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public OpenFile() {
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this(null, "unnamed");
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}
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/**
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* Get the file system to which this file belongs.
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*
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* @return the file system to which this file belongs.
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*/
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public FileSystem getFileSystem() {
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return fileSystem;
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}
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/**
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* Get the name of this open file.
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*
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* @return the name of this open file.
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*/
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public String getName() {
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return name;
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}
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/**
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* Read this file starting at the specified position and return the number
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* of bytes successfully read. If no bytes were read because of a fatal
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* error, returns -1
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*
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* @param pos the offset in the file at which to start reading.
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* @param buf the buffer to store the bytes in.
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* @param offset the offset in the buffer to start storing bytes.
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* @param length the number of bytes to read.
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* @return the actual number of bytes successfully read, or -1 on failure.
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*/
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public int read(int pos, byte[] buf, int offset, int length) {
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return -1;
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}
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/**
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* Write this file starting at the specified position and return the number
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* of bytes successfully written. If no bytes were written because of a
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* fatal error, returns -1.
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*
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* @param pos the offset in the file at which to start writing.
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* @param buf the buffer to get the bytes from.
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* @param offset the offset in the buffer to start getting.
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* @param length the number of bytes to write.
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* @return the actual number of bytes successfully written, or -1 on
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* failure.
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*/
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public int write(int pos, byte[] buf, int offset, int length) {
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return -1;
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}
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/**
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* Get the length of this file.
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*
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* @return the length of this file, or -1 if this file has no length.
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*/
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public int length() {
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return -1;
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}
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/**
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* Close this file and release any associated system resources.
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*/
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public void close() {
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}
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/**
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* Set the value of the current file pointer.
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*/
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public void seek(int pos) {
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}
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/**
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* Get the value of the current file pointer, or -1 if this file has no
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* pointer.
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*/
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public int tell() {
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return -1;
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}
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/**
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* Read this file starting at the current file pointer and return the
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* number of bytes successfully read. Advances the file pointer by this
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* amount. If no bytes could be* read because of a fatal error, returns -1.
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*
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* @param buf the buffer to store the bytes in.
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* @param offset the offset in the buffer to start storing bytes.
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* @param length the number of bytes to read.
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* @return the actual number of bytes successfully read, or -1 on failure.
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*/
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public int read(byte[] buf, int offset, int length) {
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return -1;
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}
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/**
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* Write this file starting at the current file pointer and return the
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* number of bytes successfully written. Advances the file pointer by this
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* amount. If no bytes could be written because of a fatal error, returns
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* -1.
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*
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* @param buf the buffer to get the bytes from.
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* @param offset the offset in the buffer to start getting.
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* @param length the number of bytes to write.
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* @return the actual number of bytes successfully written, or -1 on
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* failure.
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*/
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public int write(byte[] buf, int offset, int length) {
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return -1;
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}
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private FileSystem fileSystem;
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private String name;
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}
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