public void SparseFile()
{
byte[] randomData = new byte[35 * 4096];
_random.NextBytes(randomData);
// Clear the 16 * 4096 -> 32 * 4096 range
Array.Clear(randomData, 16 * 4096, 16 * 4096);
using (TempFile tmpFile = new TempFile())
{
// Create a file
File.WriteAllBytes(tmpFile.File.FullName, randomData);
using (FilesystemDeviceWrapper wrapper = Win32.GetFileWrapper(tmpFile.File.FullName))
{
wrapper.FileSystemSetSparseFile(true);
wrapper.FileSystemSetZeroData(16 * 4096, 16 * 4096);
FILE_ALLOCATED_RANGE_BUFFER[] rangesData = wrapper.FileSystemQueryAllocatedRanges(0, randomData.Length);
// We should have 2 ranges on non-zero data
Assert.AreEqual(2, rangesData.Length);
}
// Discover it via the NTFS lib
char driveLetter = tmpFile.File.FullName[0];
RawDisk disk = new RawDisk(driveLetter);
NTFSDiskProvider provider = new NTFSDiskProvider(disk);
NTFSWrapper ntfsWrapper = new NTFSWrapper(provider, 0);
NtfsDirectory ntfsDir = NTFSHelpers.OpenDir(ntfsWrapper, tmpFile.File.DirectoryName);
NtfsFile ntfsFile = NTFSHelpers.OpenFile(ntfsDir, tmpFile.File.Name);
Assert.IsNotNull(ntfsFile);
Assert.IsTrue(tmpFile.File.Attributes.HasFlag(FileAttributes.SparseFile));
AttributeData attributeData = ntfsFile.MFTRecord.Attributes.OfType <AttributeData>().Single();
Assert.IsTrue(attributeData.DataFragments.Length > 1);
Assert.IsTrue(attributeData.DataFragments.Any(s => s.IsSparseFragment));
// Read it
using (Stream actualStream = File.OpenRead(tmpFile.File.FullName))
using (Stream ntfsStream = ntfsFile.OpenRead())
{
bool equal = StreamUtils.CompareStreams(actualStream, ntfsStream);
Assert.IsTrue(equal);
}
}
}
private static void ExampleSparseFile()
{
string file = Path.GetTempFileName();
try
{
// Write file data
const int length = 1 * 1024 * 1024; // 1 MB
const int sparseLength = 512 * 1024; // 0.5 MB
using (FileStream fs = File.OpenWrite(file))
{
byte[] data = new byte[length];
for (int i = 0; i < data.Length; i++)
data[i] = 1; // Set the data to non-zero
fs.Write(data, 0, data.Length);
}
Console.WriteLine(@"## Exmaple with {0} ##", file);
SafeFileHandle fileHandle = CreateFile(file, FileAccess.ReadWrite, FileShare.ReadWrite, IntPtr.Zero, FileMode.Open, FileAttributes.Normal, IntPtr.Zero);
if (fileHandle.IsInvalid)
{
int lastError = Marshal.GetLastWin32Error();
Console.WriteLine(@"!! Invalid {0}; Error ({1}): {2}", file, lastError, new Win32Exception(lastError).Message);
Console.WriteLine();
return;
}
using (FilesystemDeviceWrapper fileIo = new FilesystemDeviceWrapper(fileHandle, true))
{
FileInfo fileInfo = new FileInfo(file);
Console.WriteLine("File size: " + fileInfo.Length);
Console.WriteLine("Sparse: " + fileInfo.Attributes.HasFlag(FileAttributes.SparseFile));
// Enable sparse ranges
Console.WriteLine("Enabling Sparse file");
fileIo.FileSystemSetSparseFile(true);
fileInfo.Refresh();
Console.WriteLine("Sparse: " + fileInfo.Attributes.HasFlag(FileAttributes.SparseFile));
// Set sparse range
Console.WriteLine(" Setting sparse range: " + sparseLength + " (length: " + ((fileInfo.Length - sparseLength) / 2) + ")");
fileIo.FileSystemSetZeroData(sparseLength, (fileInfo.Length - sparseLength) / 2);
// Query sparse range
fileInfo.Refresh();
FILE_ALLOCATED_RANGE_BUFFER[] ranges = fileIo.FileSystemQueryAllocatedRanges(0, length);
Console.WriteLine("File size: " + fileInfo.Length);
Console.WriteLine("Sparse ranges (" + ranges.Length + "):");
foreach (FILE_ALLOCATED_RANGE_BUFFER range in ranges)
{
Console.WriteLine(" Non-sparse range: " + range.FileOffset + " (length: " + range.Length + ")");
}
}
}
finally
{
if (File.Exists(file))
File.Delete(file);
}
}
private static void ExampleSparseFile()
{
string file = Path.GetTempFileName();
try
{
// Write file data
const int length = 1 * 1024 * 1024; // 1 MB
const int sparseLength = 512 * 1024; // 0.5 MB
using (FileStream fs = File.OpenWrite(file))
{
byte[] data = new byte[length];
for (int i = 0; i < data.Length; i++)
{
data[i] = 1; // Set the data to non-zero
}
fs.Write(data, 0, data.Length);
}
Console.WriteLine(@"## Exmaple with {0} ##", file);
SafeFileHandle fileHandle = CreateFile(file, FileAccess.ReadWrite, FileShare.ReadWrite, IntPtr.Zero, FileMode.Open, FileAttributes.Normal, IntPtr.Zero);
if (fileHandle.IsInvalid)
{
int lastError = Marshal.GetLastWin32Error();
Console.WriteLine(@"!! Invalid {0}; Error ({1}): {2}", file, lastError, new Win32Exception(lastError).Message);
Console.WriteLine();
return;
}
using (FilesystemDeviceWrapper fileIo = new FilesystemDeviceWrapper(fileHandle, true))
{
FileInfo fileInfo = new FileInfo(file);
Console.WriteLine("File size: " + fileInfo.Length);
Console.WriteLine("Sparse: " + fileInfo.Attributes.HasFlag(FileAttributes.SparseFile));
// Enable sparse ranges
Console.WriteLine("Enabling Sparse file");
fileIo.FileSystemSetSparseFile(true);
fileInfo.Refresh();
Console.WriteLine("Sparse: " + fileInfo.Attributes.HasFlag(FileAttributes.SparseFile));
// Set sparse range
Console.WriteLine(" Setting sparse range: " + sparseLength + " (length: " + ((fileInfo.Length - sparseLength) / 2) + ")");
fileIo.FileSystemSetZeroData(sparseLength, (fileInfo.Length - sparseLength) / 2);
// Query sparse range
fileInfo.Refresh();
FILE_ALLOCATED_RANGE_BUFFER[] ranges = fileIo.FileSystemQueryAllocatedRanges(0, length);
Console.WriteLine("File size: " + fileInfo.Length);
Console.WriteLine("Sparse ranges (" + ranges.Length + "):");
foreach (FILE_ALLOCATED_RANGE_BUFFER range in ranges)
{
Console.WriteLine(" Non-sparse range: " + range.FileOffset + " (length: " + range.Length + ")");
}
}
}
finally
{
if (File.Exists(file))
{
File.Delete(file);
}
}
}