OperatingSystemEmulator/FakeFileSystem.java at main · CreatorOfCryptids/OperatingSystemEmulator · GitHub

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importjava.io.RandomAccessFile;
importjava.util.Optional;

publicclassFakeFileSystemimplementsDevice{

privateRandomAccessFilefiles[];

/**
 * Constructor.
 */
FakeFileSystem(){
files = newRandomAccessFile[Device.DEVICE_COUNT];
 }

/**
 * Opens the desired File.
 *
 * @param device The desired file's name.
 */
publicOptional<Integer> open(Strings) {

intfid = -1;
s = s.trim(); // Trim any uneeded whitespace.

// Look for an open entry
for(inti=0; i<Device.DEVICE_COUNT; i++){
if(files[i] == null){ // If we find one, store the entry.
fid = i;
break;
 }
 }

// Get rid of any leading/tailing whitespace.

dbMes("OPEN: fid = " + fid + " String = \"" + s + "\"");

if(fid == -1){
// If we didn't find an open entry, return failure.
dbMes("ERROR: No availible entry.");
returnOptional.empty();
 }
elseif (s != null && s.equals("") == false){
// If the string is valid, open the file and return the fid.
try{
files[fid] = newRandomAccessFile(s, "rw"); //Trim any whitespace from the string.
dbMes("FID: " + fid);
returnOptional.of(fid);
 }
catch (Exceptione){
dbMes("Open(): ERROR: " + e.getMessage());
returnOptional.empty();
 }
 }
else
returnOptional.empty();
 }

/**
 * Reads from the desired File.
 *
 * @param id The FID of the desired File.
 * @param size The amount of data to be read.
 */
publicOptional<byte[]> read(intid, intsize) {
byte[] retval = newbyte[size];

dbMes("Read()");

try{
files[id].read(retval);
dbMes("Read: \"" + newString(retval) + "\"");
returnOptional.of(retval);
 }
catch (Exceptione){
dbMes("Read(): ERROR: " + e.getMessage());
returnOptional.empty();
 }
 }

/**
 * Moves the curser within the file.
 *
 * @param id The FID of the file.
 * @param to The distance to move the curser.
 */
publicvoidseek(intid, intto) {
dbMes("Seek()");
try{
files[id].seek(to);
dbMes("Seeked.");
 }
catch(Exceptione){
dbMes("Seek(): ERROR: " + e.getMessage());
 }
 }

/**
 * Writes to the desired File.
 *
 * @param id The FID of the desired File.
 * @param data The data to be writen to the File.
 */
publicOptional<Integer> write(intid, byte[] data) {
dbMes("Write() \"" + newString(data) + "\"");

try{
files[id].write(data);
returnOptional.of(data.length);
 }
catch(Exceptione){
dbMes("Write(): ERROR: " + e.getMessage());
returnOptional.empty();
 }
 }

/**
 * Closes the desired File.
 *
 * @param id The FID of the desired File.
 */
publicvoidclose(intid) {
dbMes("Close()");
if(files[id] == null){
dbMes("Close(): ERROR: Null device");
 }
else{
try{
files[id].close();
 }
catch (Exceptione){
dbMes("Close(): ERROR: " + e.getMessage());
 }

files[id] = null;
 }
 }

/**
 * EXTRA METHOD!!! Prints a message to the terminal to help bebugging.
 *
 * @param message The message printed to the terminal.
 */
privatevoiddbMes(Stringmessage){
OS.dbMes("|||FAKE_FILE_SYS: " + message);
 }
}