Question

I was wondering if It is possible to write to freespace in C#? I mean something like FreeSpace.WriteAllBytes() or like what some shredder apps do?

How can I do so?

Answer 1

If your intention is simply to overwrite all the free space available on a hard drive, you can use the GetDiskFreeSpaceEx API to determine how many bytes are available and write a file that large (or spread it out among several files).

P/Invoke for C#:

[DllImport("kernel32")]
public static extern int GetDiskFreeSpaceExW(string dir, ref ulong freeBytesAvailable,
    ref ulong totalNumBytes, ref ulong totalFreeBytes);

You can use a class like System.Random to fill an array of bytes with random values before writing them, if that might interest you.

Edit: Wasn’t aware of the System.IO.DriveInfo class, which could be simpler than using the mentioned API.