// Writes zeros to a file stream, with space advantage on compressed and sparse files.
public static void WriteZeros(System.IO.FileStream fs, long begin, long end)
{
#if NETSTANDARD2_0
if (fs.Length < end)
{
fs.SetLength(end); // Just extend the length of the file
}
#else
// Hopefully this works as expected, it's hard to get this working right over the .NET framework
fs.Flush(); // So that ALL of the buffers are cleared and written to the file.
zeroinfo zi = new zeroinfo();
int retd;
// Get the file handle
IntPtr hndl = fs.SafeFileHandle.DangerousGetHandle();
if (end > fs.Length)
{
while (end > fs.Length)
{
long pos = fs.Length;
long write = Math.Min(0x100000, end - pos);
fs.SetLength(pos + write);
zi.begin = pos;
zi.end = pos + write;
SetZeroData(hndl, FSCTL_SET_ZERO_DATA, ref zi, 16, IntPtr.Zero, 0, out retd, IntPtr.Zero);
}
}
zi.begin = begin;
zi.end = end;
SetZeroData(hndl, FSCTL_SET_ZERO_DATA, ref zi, 16, IntPtr.Zero, 0, out retd, IntPtr.Zero);
fs.Position = end;
#endif
}
private static extern bool SetZeroData(IntPtr hDevice, uint dwControlCode, ref zeroinfo zi, int i16, IntPtr zero1, int zero, out int bytesretd, IntPtr zero2);
