I am trying to use DeviceIoControl
with FSCTL_SET_ZERO_DATA
control code in C#.
I created the file C:\tmp\test.txt
and inside it I put the text "aaaa".
I ran the code and I received error number: 87
According to MSDN: "The parameter is incorrect."
I supposed that the problem is because I am sending input buffer (parameter number 3 in DeviceIoControl
) without any data.
The DeviceIoControl
returns false
.
How can I insert valid parameters to DeviceIoControl
with FSCTL_SET_ZERO_DATA
which will make it return true
?
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication1
{
class Program2
{
[DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
static extern bool DeviceIoControl(IntPtr hDevice, uint dwIoControlCode,
IntPtr lpInBuffer, uint nInBufferSize,
IntPtr lpOutBuffer, uint nOutBufferSize,
out uint lpBytesReturned, IntPtr lpOverlapped);
[Flags]
public enum EMethod : uint
{
Buffered = 0,
InDirect = 1,
OutDirect = 2,
Neither = 3
}
[Flags]
public enum EFileDevice : uint
{
FileSystem = 0x00000009
}
[Flags]
public enum EIOControlCode : uint
{
FsctlSetZeroData = (EFileDevice.FileSystem << 16) | (50 << 2) | EMethod.Buffered | (FileAccess.Write << 14),
}
[StructLayout(LayoutKind.Sequential)]
struct FILE_ZERO_DATA_INFORMATION
{
public FILE_ZERO_DATA_INFORMATION(long offset, long count)
{
FileOffset = offset;
BeyondFinalZero = offset + count;
}
public long FileOffset;
public long BeyondFinalZero;
}
[DllImport("kernel32.dll")]
public static extern uint GetLastError();
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern IntPtr CreateFile(
[MarshalAs(UnmanagedType.LPTStr)] string filename,
[MarshalAs(UnmanagedType.U4)] FileAccess access,
[MarshalAs(UnmanagedType.U4)] FileShare share,
IntPtr securityAttributes, // optional SECURITY_ATTRIBUTES struct or IntPtr.Zero
[MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
uint flagsAndAttributes,
IntPtr templateFile);
static void Main(string[] args)
{
IntPtr handle = CreateFile(@"C:\tmp\test.txt", FileAccess.ReadWrite, FileShare.ReadWrite, IntPtr.Zero, FileMode.Open, (int)FileAttributes.Normal, IntPtr.Zero);
long length = 2;
FILE_ZERO_DATA_INFORMATION data = new FILE_ZERO_DATA_INFORMATION(0, length);
uint structSize = (uint)Marshal.SizeOf(data);
IntPtr pBuffer = Marshal.AllocHGlobal((int)structSize);
uint bytesReturned = 0;
bool succeed = DeviceIoControl(handle, (uint)EIOControlCode.FsctlSetZeroData, pBuffer, 5, IntPtr.Zero, 5, out bytesReturned, IntPtr.Zero);
// bool succeed = DeviceIoControl(handle, (uint)EIOControlCode.FsctlSetZeroData, IntPtr.Zero, 0, IntPtr.Zero, 0, out bytesReturned, IntPtr.Zero);
if (succeed)
{
Console.WriteLine("Works fine");
}
else
{
uint err = GetLastError();
Console.WriteLine("Error number: {0}", err);
}
}
}
}
Credit to @Aybe.
The fix is:
uint pBufferSize = 16;
Marshal.StructureToPtr(data, pBuffer, false);
bool succeed = DeviceIoControl(handle, (uint)EIOControlCode.FsctlSetZeroData, pBuffer, pBufferSize, IntPtr.Zero, 0, out bytesReturned, IntPtr.Zero);
Marshal.StructureToPtr(data, pBuffer, false);
If you won't add it, sometimes the function will return true and sometime false.
Here is a reference to code that also uses FSCTL with C#.
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