/**
* Creates a <code>File</code> and places it into FAT32, the <code>File</code> list.
* Pre-condition: size must be greater than 0 Post-condition: creates a <code>File</code> with
* appropriate number of blocks and places it into internal <code>File</code> list (FAT32)
*
* @param filename the name of the <code>File</code>
* @param size bytes in the <code>File</code>
* @return successful creation message
* @throws InSufficientDiskSpaceException if there are not enough blocks to create <code>File
* </code>
* @throws DuplicateFileException if a <code>File</code> with given filename already exists
*/
public String create(String filename, int size)
throws InsufficientDiskSpaceException, DuplicateFileException {
Iterator<File> findDuplicates = FAT32.iterator();
// Go through file list to find duplicates first
while (findDuplicates.hasNext()) {
if (findDuplicates.next().getName().equalsIgnoreCase(filename)) {
throw new DuplicateFileException();
}
}
// Check for available space
if (size > (freeBlocks.size() * blockSize)) {
throw new InsufficientDiskSpaceException("Not enough disk space to create new file.\n");
} else {
File file = new File(size, blockSize, filename);
Iterator<Block> itr = freeBlocks.iterator();
// Iterate through list of available blocks, adding them to the new file as needed
for (int i = 0; i < bytesBlocks(size); i++) {
if (itr.hasNext()) {
file.add(itr.next());
// After block is added to file, it's removed from available blocks
itr.remove();
}
}
// Add file to file table
FAT32.add(file);
return filename + " created successfully!\n";
}
}
/**
* Extends a <code>File</code> by the given size in bytes. Pre-condition: size must be greater
* than 0 Post-condition: <code>File</code> with the given filename will be extended by passed in
* amount of bytes, and additional <code>Blocks</code> will be allocated to it as needed
*
* @param filename the name of the <code>File</code>
* @param size number of bytes to increase the <code>File</code> by
* @return successful extension message
* @throws InSufficientDiskSpaceException if there are not enough blocks to extend <code>File
* </code>
* @throws NoSuchFileException if the filename does not match any existing <code>File</code>
*/
public String extend(String filename, int size)
throws InsufficientDiskSpaceException, NoSuchFileException {
Iterator<File> findFile = FAT32.iterator();
boolean fileFound = false;
// Check if file exists
while (findFile.hasNext()) {
if (findFile.next().getName().equalsIgnoreCase(filename)) {
fileFound = true;
}
}
// Throw exception if it doesn't
if (fileFound == false) {
throw new NoSuchFileException(filename + " does not exist!");
}
// Check there is enough space to extend file
if (size > (freeBlocks.size() * blockSize)) {
throw new InsufficientDiskSpaceException(
"Not enough disk space to extend " + filename + " \n");
} else {
Iterator<File> itr = FAT32.iterator();
// Iterate through list of files to find filename
while (itr.hasNext()) {
File file = itr.next();
if (file.getName().equals(filename)) {
// Calculate the extended size and how many blocks need to be added
int newSize = file.getBytes() + size;
int blocksToAdd = bytesBlocks(newSize) - bytesBlocks(file.getBytes());
// Take blocks from available blocks and add them to the file
for (int i = 0; i < blocksToAdd; i++) {
file.add(freeBlocks.remove(0));
}
file.addBytes(size);
}
}
// Throw exception or return appropriate message
if (fileFound == false) {
throw new NoSuchFileException(filename + " does not exist!");
} else {
return filename + " extended successfully!\n";
}
}
}
