public static void CreateSparse(string filename, long length)
{
if (!supportsSparse)
{
return;
}
// Ensure we have the full path
filename = Path.GetFullPath(filename);
try
{
if (!CanCreateSparse(filename))
{
return;
}
// Create a file with the sparse flag enabled
uint bytesReturned = 0;
uint sharing = 0; // none
uint attributes = 0x00000080; // Normal
uint creation = 1; // Only create if new
using (
SafeFileHandle handle = CreateFileW(filename, GENERIC_WRITE_ACCESS, sharing, IntPtr.Zero, creation, attributes,
IntPtr.Zero))
{
// If we couldn't create the file, bail out
if (handle.IsInvalid)
{
return;
}
// If we can't set the sparse bit, bail out
if (
!DeviceIoControl(handle, FSCTL_SET_SPARSE, IntPtr.Zero, 0, IntPtr.Zero, 0, ref bytesReturned,
IntPtr.Zero))
{
return;
}
// Tell the filesystem to mark bytes 0 -> length as sparse zeros
var data = new FileZeroDataInformation(0, length);
var structSize = (uint)Marshal.SizeOf(data);
IntPtr ptr = Marshal.AllocHGlobal((int)structSize);
try
{
Marshal.StructureToPtr(data, ptr, false);
DeviceIoControl(handle, FSCTL_SET_ZERO_DATA, ptr,
structSize, IntPtr.Zero, 0, ref bytesReturned, IntPtr.Zero);
}
finally
{
Marshal.FreeHGlobal(ptr);
}
}
}
catch (DllNotFoundException)
{
supportsSparse = false;
}
catch (EntryPointNotFoundException)
{
supportsSparse = false;
}
catch
{
// Ignore for now. Maybe if i keep hitting this i should abort future attemts
}
}
public static void CreateSparse(string filename, long length)
{
if (!supportsSparse)
return;
// Ensure we have the full path
filename = Path.GetFullPath(filename);
try
{
if (!CanCreateSparse(filename))
return;
// Create a file with the sparse flag enabled
uint bytesReturned = 0;
uint sharing = 0; // none
uint attributes = 0x00000080; // Normal
uint creation = 1; // Only create if new
using (
SafeFileHandle handle = CreateFileW(filename, GENERIC_WRITE_ACCESS, sharing, IntPtr.Zero, creation, attributes,
IntPtr.Zero))
{
// If we couldn't create the file, bail out
if (handle.IsInvalid)
return;
// If we can't set the sparse bit, bail out
if (
!DeviceIoControl(handle, FSCTL_SET_SPARSE, IntPtr.Zero, 0, IntPtr.Zero, 0, ref bytesReturned,
IntPtr.Zero))
return;
// Tell the filesystem to mark bytes 0 -> length as sparse zeros
var data = new FileZeroDataInformation(0, length);
var structSize = (uint)Marshal.SizeOf(data);
IntPtr ptr = Marshal.AllocHGlobal((int)structSize);
try
{
Marshal.StructureToPtr(data, ptr, false);
DeviceIoControl(handle, FSCTL_SET_ZERO_DATA, ptr,
structSize, IntPtr.Zero, 0, ref bytesReturned, IntPtr.Zero);
}
finally
{
Marshal.FreeHGlobal(ptr);
}
}
}
catch (DllNotFoundException)
{
supportsSparse = false;
}
catch (EntryPointNotFoundException)
{
supportsSparse = false;
}
catch
{
// Ignore for now. Maybe if i keep hitting this i should abort future attemts
}
}
