public void InsertVariableLengthFile(string path, string source)
{
uint entryIndex = RomFsNameTable.GetFatEntryIndex(_underlyingStreamReader, _nameTableStartOffset, path);
var originalInsertDestinationEntry = RomFsFileAllocationTable.GetEntry(_underlyingStreamReader, _fatStartOffset, entryIndex);
byte[] sourceData = File.ReadAllBytes(source);
var oldEntryLength = originalInsertDestinationEntry.GetLength();
if (oldEntryLength == sourceData.Length)
{
// Is still the same length so just process as fixed length file.
_underlyingStreamReader.BaseStream.Position = originalInsertDestinationEntry.Start;
_underlyingStreamReader.BaseStream.Write(sourceData, 0, oldEntryLength);
return;
}
// Create new entry
var newInsertDestinationEntry = new Fat32.Entry(originalInsertDestinationEntry.Start, originalInsertDestinationEntry.Start + (uint)sourceData.Length);
int change = newInsertDestinationEntry.GetLength() - oldEntryLength;
// Update entry value
RomFsFileAllocationTable.SetEntry(_underlyingStreamWriter, _fatStartOffset, entryIndex, newInsertDestinationEntry);
// Update entry values after changed one with change
var currentEntryId = entryIndex + 1;
var previousEntry = newInsertDestinationEntry;
var currentEntry = RomFsFileAllocationTable.GetEntry(_underlyingStreamReader, _fatStartOffset, currentEntryId);
while (!currentEntry.IsDefault)
{
uint newStart = (uint)(currentEntry.Start + change);
uint newEnd = (uint)(currentEntry.End + change);
RomFsFileAllocationTable.SetEntry(_underlyingStreamWriter, _fatStartOffset, currentEntryId++, new Fat32.Entry(newStart, newEnd));
previousEntry = currentEntry;
currentEntry = RomFsFileAllocationTable.GetEntry(_underlyingStreamReader, _fatStartOffset, currentEntryId);
}
// Shift data
// last edited entry is the final non-default entry which will store the end of the data
byte[] buffer = new byte[previousEntry.End - originalInsertDestinationEntry.End];
// read the data from the original position
_underlyingStream.Position = originalInsertDestinationEntry.End;
_underlyingStream.Read(buffer, 0, buffer.Length);
// write the data into the new position
_underlyingStream.Position = newInsertDestinationEntry.End;
_underlyingStream.Write(buffer, 0, buffer.Length);
// Write file data in newly created space
_underlyingStream.Position = newInsertDestinationEntry.Start;
_underlyingStream.Write(sourceData, 0, sourceData.Length);
}
private void ExtractCopyOfFileFromEntry(Fat32.Entry entry, string destinationFile)
{
_underlyingStreamReader.BaseStream.Position = entry.Start;
byte[] bytes = _underlyingStreamReader.ReadBytes(entry.GetLength());
File.WriteAllBytes(destinationFile, bytes);
}