Related
I want to use a c++ dll in c#. I'm using [DllImport] to call the method. I'm having trouble passing struct to a method.
I have a C struct:
typedef struct
{
DWORD TopPoint;
DWORD EndPoint;
WORD dwCount;
MYFUNC_NUMERIC11 *pGetData;
} MYFUNC_BUFFERNORMAL;
MYFUNC_NYMERIC11 is another struct.
typedef struct
{
BYTE Sign; // Sign ("±")
BYTE Integer[3]; // 3-digit integer (no zero suppression)
BYTE Period; // Decimal point (".")
BYTE Decimal[6]; // 6-digit decimal number
} MYFUNC_NUMERIC11;
I have written a C# struct to mimic this.
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public unsafe struct MYFUNC_BUFFERNORMAL
{
public uint TopPoint;
public uint EndPoint;
public ushort Count;
public IntPtr pGetData;
}
A pointer to the struct is an argument in a method. C# function is:
[DllImport("MYFUNC_DLL.dll", EntryPoint = "MYFUNC_GetData", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall, ThrowOnUnmappableChar = true)]
public static extern int MYFUNC_GetData(IntPtr myfuncHandle, UInt32 dwIO, ref IntPtr pBufferNormal, Byte bccFlg);
This is the method in C:
MYFUNC_STATUS MYFUNC_GetData(MYFUNC_HANDLE myfuncHandle, DWORD dwOut, MYFUNC_BUFFERNORMAL *pBufferNormal , BYTE bccFlg)
The return type is cast to an enum, which has an interpretation. The struct parameter is invalid. I've tried to allocate memory using Marshal.AllocHGlobal(...), but the parameter is still invalid, i.e. there is no error during compilation but the value returned is incorrect.
I've spent quite a few hours on this, still unable to figure out what to do. A lot of similar questions exist already, like here: How do I convert c struct from dll to C# or here: How to pass C# array to C++ and return it back to C# with additional items?, but I, somehow, still haven't figured out a way.
Something like this should work, at least with one element in the array (is it an array?). For an array, you will have to allocate sizeof * count of elements and marshal (StructureToPtr) each element at its offset.
var num = new MYFUNC_NUMERIC11();
num.Integer = new byte[] { 1, 2, 3 };
num.Decimal = new byte[] { 4, 5, 6, 7, 8, 9 };
num.Sign = 10;
num.Period = 11;
var buffer = new MYFUNC_BUFFERNORMAL();
buffer.Count = 1234;
buffer.EndPoint = 5678;
buffer.TopPoint = 9;
buffer.pGetData = Marshal.AllocCoTaskMem(Marshal.SizeOf(num));
try
{
Marshal.StructureToPtr(num, buffer.pGetData, false);
MYFUNC_GetData(Whatever, 0, ref buffer, 0);
}
finally
{
Marshal.FreeCoTaskMem(buffer.pGetData);
}
With these definitions.
[StructLayout(LayoutKind.Sequential)]
public struct MYFUNC_BUFFERNORMAL
{
public uint TopPoint;
public uint EndPoint;
public ushort Count;
public IntPtr pGetData;
}
[StructLayout(LayoutKind.Sequential)]
public struct MYFUNC_NUMERIC11
{
public byte Sign;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
public byte[] Integer;
public byte Period;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)]
public byte[] Decimal;
}
// check calling convention
[DllImport(#"MYFUNC_DLL.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern MYFUNC_STATUS MYFUNC_GetData(IntPtr myfuncHandle, uint dwIO, ref MYFUNC_BUFFERNORMAL pBufferNormal, byte bccFlg);
I'm trying to use the Windows multimedia MIDI functions from C#. Specifically:
MMRESULT midiOutPrepareHeader( HMIDIOUT hmo, LPMIDIHDR lpMidiOutHdr, UINT cbMidiOutHdr );
MMRESULT midiOutUnprepareHeader( HMIDIOUT hmo, LPMIDIHDR lpMidiOutHdr, UINT cbMidiOutHdr );
MMRESULT midiStreamOut( HMIDISTRM hMidiStream, LPMIDIHDR lpMidiHdr, UINT cbMidiHdr );
MMRESULT midiStreamRestart( HMIDISTRM hms );
/* MIDI data block header */
typedef struct midihdr_tag {
LPSTR lpData; /* pointer to locked data block */
DWORD dwBufferLength; /* length of data in data block */
DWORD dwBytesRecorded; /* used for input only */
DWORD_PTR dwUser; /* for client's use */
DWORD dwFlags; /* assorted flags (see defines) */
struct midihdr_tag far *lpNext; /* reserved for driver */
DWORD_PTR reserved; /* reserved for driver */
#if (WINVER >= 0x0400)
DWORD dwOffset; /* Callback offset into buffer */
DWORD_PTR dwReserved[8]; /* Reserved for MMSYSTEM */
#endif
} MIDIHDR, *PMIDIHDR, NEAR *NPMIDIHDR, FAR *LPMIDIHDR;
From a C program, I can successfully use these functions, by doing the following:
HMIDISTRM hms;
midiStreamOpen(&hms, ...);
MIDIHDR hdr;
hdr.this = that; ...
midiStreamRestart(hms);
midiOutPrepareHeader(hms, &hdr, sizeof(MIDIHDR)); // sizeof(MIDIHDR) == 64
midiStreamOut(hms, &hdr, sizeof(MIDIHDR));
// wait for an event that is set from the midi callback when the playback has finished
WaitForSingleObject(...);
midiOutUnprepareHeader(hms, &hdr, sizeof(MIDIHDR));
The above calling sequence works and produces no errors (error checks have been omitted for readability).
For the purpose of using those in C#, I have created some P/Invoke code:
[DllImport("winmm.dll")]
public static extern int midiOutPrepareHeader(IntPtr handle, ref MidiHeader header, uint headerSize);
[DllImport("winmm.dll")]
public static extern int midiOutUnprepareHeader(IntPtr handle, ref MidiHeader header, uint headerSize);
[DllImport("winmm.dll")]
public static extern int midiStreamOut(IntPtr handle, ref MidiHeader header, uint headerSize);
[DllImport("winmm.dll")]
public static extern int midiStreamRestart(IntPtr handle);
[StructLayout(LayoutKind.Sequential)]
public struct MidiHeader
{
public IntPtr Data;
public uint BufferLength;
public uint BytesRecorded;
public IntPtr UserData;
public uint Flags;
public IntPtr Next;
public IntPtr Reserved;
public uint Offset;
//[MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
//public IntPtr[] Reserved2;
public IntPtr Reserved0;
public IntPtr Reserved1;
public IntPtr Reserved2;
public IntPtr Reserved3;
public IntPtr Reserved4;
public IntPtr Reserved5;
public IntPtr Reserved6;
public IntPtr Reserved7;
}
The call sequence is the same as in C:
var hdr = new MidiHeader();
hdr.this = that;
midiStreamRestart(handle);
midiOutPrepareHeader(handle, ref header, headerSize); // headerSize == 64
midiStreamOut(handle, ref header, headerSize);
mre.WaitOne(); // wait until the midi playback has finished.
midiOutUnprepareHeader(handle, ref header, headerSize);
MIDI output works and the code produces no error (error checks are again omitted).
As soon as I uncomment the two lines with the array in MidiHeader, and instead remove the Reserved0 to Reserved7 fields, it doesn't work anymore. What happens is the following:
Everything is normal until and including midiStreamOut. I can hear the midi output. The playback length is correct. However, the event callback is never called when the playback ends.
At this point the value of MidiHeader.Flags is 0xe, indicating that the stream is still playing (even though the callback has been notified with the message that playback has finished). The value of MidiHeader.Flags should be 9, indicating that the stream has finished playing.
The call to midiOutUnprepareHeader fails with the error code 0x41 ("Cannot perform this operation while media data is still playing. Reset the device, or wait until the data is finished playing."). Note that resetting the device, as suggested in the error message, does in fact not fix the problem (neither does waiting or trying it multiple times).
Another variant that works correctly is if I use IntPtr instead of ref MidiHeader in the signatures of the C# declarations, and then manually allocate unmanaged memory, copying my MidiHeader structure onto that memory, and then using the allocated memory to call the functions.
Furthermore, I tried decreasing the size I'm passing to the headerSize argument to 32. Since the fields are reserved (and, in fact, didn't exist in previous version of the Windows API), they seemed to have no particular purpose anyway. However, this does not fix the problem, even though Windows should not even know that the array exists, and therefore it should not do anything. Commenting out the array entirely yet again fixes the problem (i.e., both the array as well as the 8 Reserved* fields are commented out, and the headerSize is 32).
This hints to me that the IntPtr[] Reserved2 cannot be marshaled correctly, and attempting to do so is corrupting other values. To verify that, I have created a Platform Invoke test project:
WIN32PROJECT1_API void __stdcall test_function(struct test_struct_t *s)
{
printf("%u %u %u %u %u %u %u %u\n", s->test0, s->test1, s->test2, s->test3, s->test4, s->test5, s->test6, s->test7);
for (int i = 0; i < sizeof(s->pointer_array) / sizeof(s->pointer_array[0]); ++i)
{
printf("%u ", ((uint32_t)s->pointer_array[i]) >> 16);
}
printf("\n");
}
typedef int32_t *test_ptr;
struct test_struct_t
{
test_ptr test0;
uint32_t test1;
uint32_t test2;
test_ptr test3;
uint32_t test4;
test_ptr test5;
uint32_t test6;
uint32_t test7;
test_ptr pointer_array[8];
};
Which is called from C#:
[StructLayout(LayoutKind.Sequential)]
struct TestStruct
{
public IntPtr test0;
public uint test1;
public uint test2;
public IntPtr test3;
public uint test4;
public IntPtr test5;
public uint test6;
public uint test7;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
public IntPtr[] pointer_array;
}
[DllImport("Win32Project1.dll")]
static extern void test_function(ref TestStruct s);
static void Main(string[] args)
{
TestStruct s = new TestStruct();
s.test0 = IntPtr.Zero;
s.test1 = 1;
s.test2 = 2;
s.test3 = IntPtr.Add(IntPtr.Zero, 3);
s.test4 = 4;
s.test5 = IntPtr.Add(IntPtr.Zero, 5);
s.test6 = 6;
s.test7 = 7;
s.pointer_array = new IntPtr[8];
for (int i = 0; i < s.pointer_array.Length; ++i)
{
s.pointer_array[i] = IntPtr.Add(IntPtr.Zero, i << 16);
}
test_function(ref s);
Console.ReadLine();
}
And the output is as expected, hence the marshaling of the IntPtr[] pointer_array worked in this program.
I am aware that not using SafeHandle is suboptimal, however, when using that, the behavior of the MIDI functions when using the array is even weirder, so I chose to maybe tackle one problem at a time.
Why does using IntPtr[] Reserved2 cause an error?
Here is some more code to produce a complete example:
C Code
/*
* example9.c
*
* Created on: Dec 21, 2011
* Author: David J. Rager
* Email: djrager#fourthwoods.com
*
* This code is hereby released into the public domain per the Creative Commons
* Public Domain dedication.
*
* http://http://creativecommons.org/publicdomain/zero/1.0/
*/
#include <windows.h>
#include <mmsystem.h>
#include <stdio.h>
HANDLE event;
static void CALLBACK example9_callback(HMIDIOUT out, UINT msg, DWORD dwInstance, DWORD dwParam1, DWORD dwParam2)
{
switch (msg)
{
case MOM_DONE:
SetEvent(event);
break;
case MOM_POSITIONCB:
case MOM_OPEN:
case MOM_CLOSE:
break;
}
}
int main()
{
unsigned int streambufsize = 24;
char* streambuf = NULL;
HMIDISTRM out;
MIDIPROPTIMEDIV prop;
MIDIHDR mhdr;
unsigned int device = 0;
streambuf = (char*)malloc(streambufsize);
if (streambuf == NULL)
goto error2;
memset(streambuf, 0, streambufsize);
if ((event = CreateEvent(0, FALSE, FALSE, 0)) == NULL)
goto error3;
memset(&mhdr, 0, sizeof(mhdr));
mhdr.lpData = streambuf;
mhdr.dwBufferLength = mhdr.dwBytesRecorded = streambufsize;
mhdr.dwFlags = 0;
// flags and event code
mhdr.lpData[8] = (char)0x90;
mhdr.lpData[9] = 63;
mhdr.lpData[10] = 0x55;
mhdr.lpData[11] = 0;
// next event
mhdr.lpData[12] = 96; // delta time?
mhdr.lpData[20] = (char)0x80;
mhdr.lpData[21] = 63;
mhdr.lpData[22] = 0x55;
mhdr.lpData[23] = 0;
if (midiStreamOpen(&out, &device, 1, (DWORD)example9_callback, 0, CALLBACK_FUNCTION) != MMSYSERR_NOERROR)
goto error4;
//printf("sizeof midiheader = %d\n", sizeof(MIDIHDR));
if (midiOutPrepareHeader((HMIDIOUT)out, &mhdr, sizeof(MIDIHDR)) != MMSYSERR_NOERROR)
goto error5;
if (midiStreamRestart(out) != MMSYSERR_NOERROR)
goto error6;
if (midiStreamOut(out, &mhdr, sizeof(MIDIHDR)) != MMSYSERR_NOERROR)
goto error7;
WaitForSingleObject(event, INFINITE);
error7:
//midiOutReset((HMIDIOUT)out);
error6:
MMRESULT blah = midiOutUnprepareHeader((HMIDIOUT)out, &mhdr, sizeof(MIDIHDR));
printf("stuff: %d\n", blah);
error5:
midiStreamClose(out);
error4:
CloseHandle(event);
error3:
free(streambuf);
error2:
//free(tracks);
error1:
//free(hdr);
return(0);
}
C# Code
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
namespace MidiOutTest
{
class Program
{
[DllImport("winmm.dll")]
public static extern int midiStreamOpen(out IntPtr handle, ref uint deviceId, uint cMidi, MidiCallback callback, IntPtr userData, uint flags);
[DllImport("winmm.dll")]
public static extern int midiStreamOut(IntPtr handle, ref MidiHeader header, uint headerSize);
[DllImport("winmm.dll")]
public static extern int midiStreamRestart(IntPtr handle);
[DllImport("winmm.dll")]
public static extern int midiOutPrepareHeader(IntPtr handle, ref MidiHeader header, uint headerSize);
[DllImport("winmm.dll")]
public static extern int midiOutUnprepareHeader(IntPtr handle, ref MidiHeader header, uint headerSize);
[DllImport("winmm.dll", CharSet = CharSet.Unicode)]
public static extern int midiOutGetErrorText(int mmsyserr, StringBuilder errMsg, int capacity);
[DllImport("winmm.dll")]
public static extern int midiStreamClose(IntPtr handle);
public delegate void MidiCallback(IntPtr handle, uint msg, IntPtr instance, IntPtr param1, IntPtr param2);
private static readonly ManualResetEvent mre = new ManualResetEvent(false);
private static void TestMidiCallback(IntPtr handle, uint msg, IntPtr instance, IntPtr param1, IntPtr param2)
{
Debug.WriteLine(msg.ToString());
if (msg == MOM_DONE)
{
Debug.WriteLine("MOM_DONE");
mre.Set();
}
}
public const uint MOM_DONE = 0x3C9;
public const int MMSYSERR_NOERROR = 0;
public const int MAXERRORLENGTH = 256;
public const uint CALLBACK_FUNCTION = 0x30000;
public const uint MidiHeaderSize = 64;
public static void CheckMidiOutMmsyserr(int mmsyserr)
{
if (mmsyserr != MMSYSERR_NOERROR)
{
var sb = new StringBuilder(MAXERRORLENGTH);
var errorResult = midiOutGetErrorText(mmsyserr, sb, sb.Capacity);
if (errorResult != MMSYSERR_NOERROR)
{
throw new /*Midi*/Exception("An error occurred and there was another error while attempting to retrieve the error message."/*, mmsyserr*/);
}
throw new /*Midi*/Exception(sb.ToString()/*, mmsyserr*/);
}
}
static void Main(string[] args)
{
IntPtr handle;
uint deviceId = 0;
CheckMidiOutMmsyserr(midiStreamOpen(out handle, ref deviceId, 1, TestMidiCallback, IntPtr.Zero, CALLBACK_FUNCTION));
try
{
var bytes = new byte[24];
IntPtr buffer = Marshal.AllocHGlobal(bytes.Length);
try
{
MidiHeader header = new MidiHeader();
header.Data = buffer;
header.BufferLength = 24;
header.BytesRecorded = 24;
header.UserData = IntPtr.Zero;
header.Flags = 0;
header.Next = IntPtr.Zero;
header.Reserved = IntPtr.Zero;
header.Offset = 0;
#warning uncomment if using array
//header.Reserved2 = new IntPtr[8];
// flags and event code
bytes[8] = 0x90;
bytes[9] = 63;
bytes[10] = 0x55;
bytes[11] = 0;
// next event
bytes[12] = 96;
bytes[20] = 0x80;
bytes[21] = 63;
bytes[22] = 0x55;
bytes[23] = 0;
Marshal.Copy(bytes, 0, buffer, bytes.Length);
CheckMidiOutMmsyserr(midiStreamRestart(handle));
CheckMidiOutMmsyserr(midiOutPrepareHeader(handle, ref header, MidiHeaderSize));
CheckMidiOutMmsyserr(midiStreamOut(handle, ref header, MidiHeaderSize));
mre.WaitOne();
CheckMidiOutMmsyserr(midiOutUnprepareHeader(handle, ref header, MidiHeaderSize));
}
finally
{
Marshal.FreeHGlobal(buffer);
}
}
finally
{
midiStreamClose(handle);
}
}
}
[StructLayout(LayoutKind.Sequential)]
public struct MidiHeader
{
public IntPtr Data;
public uint BufferLength;
public uint BytesRecorded;
public IntPtr UserData;
public uint Flags;
public IntPtr Next;
public IntPtr Reserved;
public uint Offset;
#if false
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
public IntPtr[] Reserved2;
#else
public IntPtr Reserved0;
public IntPtr Reserved1;
public IntPtr Reserved2;
public IntPtr Reserved3;
public IntPtr Reserved4;
public IntPtr Reserved5;
public IntPtr Reserved6;
public IntPtr Reserved7;
#endif
}
}
From the documentation of midiOutPrepareHeader:
Before you pass a MIDI data block to a device driver, you must prepare the buffer by passing it to the midiOutPrepareHeader function. After the header has been prepared, do not modify the buffer. After the driver is done using the buffer, call the midiOutUnprepareHeader function.
You are not adhering to this. The marshaller creates a temporary native version of your struct which lives for the duration of the call to midiOutPrepareHeader. Once midiOutPrepareHeader returns, the temporary native struct is destroyed. But the MIDI code still has a reference to it. And that's the key point, the MIDI code holds a reference to your struct and needs to be able to access it.
The version with the separately written fields works because that struct is blittable. And so the p/invoke marshaller optimises the call by pinning the managed structure which is binary compatible with the native structure. There's still a window of opportunity for the GC to relocate the struct before you call midiOutUnprepareHeader but it seems that you've not been caught out by that yet. Were you to persevere with the bittable struct you would need to pin it until you called midiOutUnprepareHeader.
So, the bottom line is that you need to provide a structure that lives until you call midiOutUnprepareHeader. Personally, I suggest that you use Marshal.AllocHGlobal, Marshal.StructureToPtr, and then Marshal.FreeHGlobal once midiOutUnprepareHeader returns. And obviously switch the parameters from ref MidiHeader to IntPtr.
I don't think I need to show you any code because it is clear from your question that you know how to do this stuff. Indeed the solution I propose is one that you've already tried and observed work. But now you know why!
I am calling into native code from managed code and I am having a bit of trouble figuring out how to properly marshal my code. In C, I have the following:
struct cHandle {
unsigned long handleLo;
unsigned long handleHi;
}
struct cBuffer {
unsigned long bufferSize;
unsigned long bufferType;
__field_bcount(bufferSize) void *bufferPtr;
}
struct cBufferDesc {
unsigned long bufferVersion;
unsigned long bufferCount;
_field_ecount(bufferCount) cBuffer *buffers;
}
uint __stdcall CMethod(
__in_opt cHandle* handle1,
__in_opt cHandle* handle2,
__in_opt wchar_t* wstr,
__in unsigned long long1,
__in unsigned long resevered1, // Reserved, always 0
__in unsigned long long2,
__in_opt cBufferDesc* inputBufferPtr,
__in unsigned long reserved2, // Reserved, always 0
__inout_opt cHandle* outHandle,
__inout_opt cBufferDesc* outputBufferPtr,
__out unsigned long * outLong,
__out_opt TimeStampStruct* timeStamp);
The behaviour of CMethod is as follows. outputBufferPtr will always output a value. If inputBufferPtr is NULL, handle2 should also be null and CMethod should follow different logic to give an initial output buffer, and if not CMethod should calculate the output buffer based on the data in the input buffer. I am having trouble getting my initial call to work. Additionally, I don't care about the timestamp, so I will not detail that struct, or make a C# equivalent. I have tried the following marshalling in C#:
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct Handle {
private IntPtr HandleLo;
private IntPtr HandleHi;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct Buffer {
public uint Size; // Possibly unknown
public uint Type; // Always set.
public IntPtr Buffer; // Possibly unknown
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct BufferDesc {
public uint Count; // Always 1 for my purposes
public uint Version; // Always set
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 1)]
public Buffer[] BufferArray; // Will always be a size 1 array.
}
// Used for calling when we have an existing input buffer
[DllImport("mylib.dll", ExactSpelling = "true", CharSet = CharSet.Unicode, SetLastError = true)]
uint CMethod(
[In] ref Handle handle1,
[In] ref Handle handle2,
[In] IntPtr wstr,
[In] uint long1, // C# uint == C ulong
[In] uint reserved1,
[In] uint long2,
[In] ref BufferDesc inputBufferPtr,
[In] uint reserved2,
[In, Out] ref Handle outHandle,
[In, Out] ref BufferDesc outputBufferPtr,
[Out] out IntPtr outLong,
[Out] out IntPtr timestamp);
// Used for calling when we do not have an existing input buffer
// Here IntPtr.Zero will be passed in for handle2 and inputBufferPtr
[DllImport("mylib.dll", ExactSpelling = "true", CharSet = CharSet.Unicode, SetLastError = true)]
private static extern uint CMethod(
[In] ref Handle handle1,
[In] IntPtr handle2,
[In] IntPtr wstr,
[In] uint long1, // C# uint == C ulong
[In] uint reserved1,
[In] uint long2,
[In] IntPtr inputBufferPtr,
[In] uint reserved2,
[In, Out] ref Handle outHandle,
[In, Out] ref BufferDesc outputBufferPtr,
[Out] out IntPtr outLong,
[Out] out IntPtr timestamp);
public static void WrapperMethod(
ref Handle handle1,
ref Handle handle2,
string wstr,
byte[] inputBuffer,
ref Handle outHandle,
out byte[] outputBuffer)
{
BufferDesc inputBufferDesc;
BufferDesc outputBufferDesc;
outputBufferDesc.Count = 1;
outputBufferDesc.Version = 0; // Real data not shown
outputBufferDesc.BufferArray = new Buffer[0];
outputBufferDesc.BufferArray[0].Count = 0;
outputBufferDesc.BufferArray[0].Type = 2; // Real data not shown
outputBufferDesc.BufferArray[0].Buffer = IntPtr.Zero;
IntPtr wstrPtr = Marshal.StringToCoTaskMemUni(wstr);
IntPtr ignoredOutLong;
IntPtr ignoredTimestamp;
if (null != inputBuffer)
{
inputBufferDesc.Count = 1;
inputBufferDesc.Version = 0; // Real data not shown
inputBufferDesc.BufferArray = new Buffer[1];
inputBufferDesc.BufferArray[0].Size = inputBuffer.Length;
inputBufferDesc.BufferArray[0].Type = 2; // Real data not shown
inputBufferDesc.BufferArray[0].Buffer = GCHandle.Alloc(inputBuffer, GCHandleType.Pinned).AddrOfPinnedObject();
CMethod(
ref handle1,
ref handle2,
wstrPtr,
0, // Real data not shown
0,
0, // Real data not shown
ref inputBufferDesc,
0,
ref outHandle,
ref outputBufferDesc,
out ignoreOutLong,
out ignoreTimestamp);
}
else
{ ///////////////////////////////////////////////////////////////////////
// This is the call I am taking and also where the code is crashing. //
CMethod( //
ref handle1, //
IntPtr.Zero, //
wstrPtr, //
0, // Real data not shown //
0, //
0, // Real data not shown //
IntPtr.Zero, //
0, //
ref outHandle, //
ref outputBufferDesc, //
out ignoreOutLong, //
out ignoreTimestamp); //
///////////////////////////////////////////////////////////////////////
}
// Do Cleanup. Not reached at this point.
}
The error that I am getting is that I am trying to access read or write protected memory. If there is anything you can see which is obviously wrong with how I am marshalling or if I am pinning wrong, or just not pinning where I should be please, or if you can see any other issues let me know.
The issue was with my output buffer. I wasn't assigning an empty array of size one to outputBufferDesc.Buffers, and the native code tried to write to memory that wasn't allocated for that purpose. I also couldn't marshal it as a byvalue array. Instead my struct looks like this:
[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct BufferDesc
{
public uint Version;
public uint Count;
public IntPtr Buffers;
}
And I pin an empty SecurityBuffer array of size 1 and give the address to Buffers.
I am working on WIN CE platform, developing windows forms in C#.Net.
The DeviceIoControl API is working fine with the parameters (mentioned below) in c++ console application.
PNIC_STATISTICS structure in nuiouser.h
global declarations :
TCHAR PCI1_NAME[] = _T("PCI\\ManiXX1");
TCHAR *AUB_NAME = NULL;
AUB_NAME = PCI1_NAME;
pNICStat = (PNIC_STATISTICS)malloc(sizeof(NIC_STATISTICS)) ;
pNICStat->ptcDeviceName = AUB_NAME ; //wchar_t* ptcDeviceName
DeviceIoControl( hUB94Port, //void*
IOCTL_NDISUIO_NIC_STATISTICS,
pNICStat, //PNIC_STATISTICS
0,
pNICStat, //PNIC_STATISTICS
sizeof(NIC_STATISTICS),
&dwReturnedBytes,
NULL
);
<==============================================================================>
But I'm getting problems in implementing the same with C#.Net CF for WIN-CE7
My WIN-CE Code is as follows:
Modified Structure in C#:
[StructLayout(LayoutKind.Sequential,CharSet = CharSet.Unicode)]
public struct __NIC_STAT
{
ulong Size; // Of this structure.
public Char[] ptcDeviceName; // The device name to be queried..
ulong DeviceState; // DEVICE_STATE_XXX above
ulong DeviceState; // DEVICE_STATE_XXX above
ulong MediaType; // NdisMediumXXX
ulong MediaState; // MEDIA_STATE_XXX above
ulong PhysicalMediaType;
ulong LinkSpeed; // In 100bits/s. 10Mb/s = 100000
UInt64 PacketsSent;
UInt64 PacketsReceived;
ulong InitTime; // In milliseconds
ulong ConnectTime; // In seconds
UInt64 BytesSent; // 0 - Unknown (or not supported)
UInt64 BytesReceived; // 0 - Unknown (or not supported)
UInt64 DirectedBytesReceived;
UInt64 DirectedPacketsReceived;
ulong PacketsReceiveErrors;
ulong PacketsSendErrors;
ulong ResetCount;
ulong MediaSenseConnectCount;
ulong MediaSenseDisconnectCount;
} ;
From this Structure I am just filling ptcDeviceName and trying to send.
__NIC_STAT NIC_STAT = new __NIC_STAT();
Char[] toBytes = {'P','C','I','\\','M','a','n','i','X','X','1','\0'}
NIC_STAT.ptcDeviceName = toBytes; //public Char[] ptcDeviceName; in structure
// __NIC_STAT this is the same structure as
//in nuiouser.h
int sz = Marshal.SizeOf(NIC_STAT.GetType());//sometimes Getting exception here
intptr ptr = Marshal.AllocHGlobal(sz);
Marshal.StructureToPtr((__NIC_STAT)NIC_STAT, ptr, false);
unsafe
{
DeviceIoControl(hFileHandle,
IOCTL_NDISUIO_NIC_STATISTICS,
ref ptr,
0,
ref ptr,
sz,
ref dwReturnedBytes,
0);
}//unsafe
It's corresponding prototype
[DllImport("coredll.dll", CharSet = CharSet.Auto, SetLastError = true)]
unsafe public static extern bool DeviceIoControl(
int hDevice,
int dwIoControlCode,
ref intptr InBuffer,
int nInBufferSize,
ref intptr OutBuffer,
int nOutputBufferSize,
ref int pBytesReturned,
int pOverlapped
);
In Win-CE DeviceIoControl() is getting failed, with exception and not displaying any error codes. and sometimes getting error code as 87 (INVALID PARAMETERS).
I feel ptcDeviceName is creating the problem or may be because of allocating memory for pointer (ptr) ?
In Console application we are sending ptcDeviceName as Wchar_t* but in WIN-CE so I used
public Char[] ptcDeviceName;
Can anybody tell me where I am doing wrong.?
You have a couple problems going on here.
First is that you seem to think a ulong is 32-bits in C#, but it's not. It'64 bits, so your struct is totally mapped wrong.
Second, I'm sure you need to be setting the struct Size member before passing it to the call.
Third, that ptcDeviceName member is a pointer to a wide character string. That means that in the struct itself it's 4 bytes. I'd likely make it an IntPtr. You then need to separately allocate the string, pin it, and put the pointer to it into that member slot. Since `StringToHGlobal doesn't exist in the CF, it would look something like this:
public struct __NIC_STAT
{
public uint Size;
public IntPtr ptcDeviceName;
public uint DeviceState;
public uint DeviceState;
public uint MediaType;
public uint MediaState;
public uint PhysicalMediaType;
public uint LinkSpeed;
public ulong PacketsSent;
public ulong PacketsReceived;
public uint InitTime;
public uint ConnectTime;
public ulong BytesSent;
public ulong BytesReceived;
public ulong DirectedBytesReceived;
public ulong DirectedPacketsReceived;
public uint PacketsReceiveErrors;
public uint PacketsSendErrors;
public uint ResetCount;
public uint MediaSenseConnectCount;
public uint MediaSenseDisconnectCount;
};
....
var myStruct = new __NIC_STAT();
myStruct.Size = (15 * 4) + (6 * 8);
var name = "PCI\\Manixx1\0";
var nameBytes = Encoding.Unicode.GetBytes(name);
myStruct.ptcDeviceName = Marshal.AllocHGlobal(nameBytes.Length);
try
{
Marshal.Copy(nameBytes, 0, myStruct.ptcDeviceName, nameBytes.Length);
// make the IOCTL call, a-la
NativeMethods.DeviceIoControl(...., ref myStruct, ....);
}
finally
{
Marshal.FreeHGlobal(myStruct.ptcDeviceName);
}
I am trying to conver a C SDK to C# and am running into a "Illegal Parameter" error on the conversion of a C function.
The details of the C SDK function are listed below
#ifndef LLONG
#ifdef WIN32
#define LLONG LONG
#else //WIN64
#define LLONG INT64
#endif
#endif
#ifndef CLIENT_API
#define CLIENT_API __declspec(dllexport)
#endif
#else
#ifndef CLIENT_API
#define CLIENT_API __declspec(dllimport)
#endif
#endif
#define CALLBACK __stdcall
#define CALL_METHOD __stdcall //__cdecl
// Configuration type,corresponding to CLIENT_GetDevConfig and CLIENT_SetDevConfig
#define DH_DEV_DEVICECFG 0x0001 // Device property setup
#define DH_DEV_NETCFG 0x0002 // Network setup
#define DH_DEV_CHANNELCFG 0x0003 // Video channel setup
#define DH_DEV_PREVIEWCFG 0x0004 // Preview parameter setup
#define DH_DEV_RECORDCFG 0x0005 // Record setup
#define DH_DEV_COMMCFG 0x0006 // COM property setup
#define DH_DEV_ALARMCFG 0x0007 // Alarm property setup
#define DH_DEV_TIMECFG 0x0008 // DVR time setup
#define DH_DEV_TALKCFG 0x0009 // Audio talk parameter setup
#define DH_DEV_AUTOMTCFG 0x000A // Auto matrix setup
#define DH_DEV_VEDIO_MARTIX 0x000B // Local matrix control strategy setup
#define DH_DEV_MULTI_DDNS 0x000C // Multiple ddns setup
#define DH_DEV_SNAP_CFG 0x000D // Snapshot corresponding setup
#define DH_DEV_WEB_URL_CFG 0x000E // HTTP path setup
#define DH_DEV_FTP_PROTO_CFG 0x000F // FTP upload setup
#define DH_DEV_INTERVIDEO_CFG 0x0010 // Plaform embedded setup. Now the channel parameter represents the platform type.
// Search configuration information
CLIENT_API BOOL CALL_METHOD CLIENT_GetDevConfig(LLONG lLoginID, DWORD dwCommand, LONG lChannel, LPVOID lpOutBuffer, DWORD dwOutBufferSize, LPDWORD lpBytesReturned,int waittime=500);
The C# info is as follows:
// [DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.StdCall)]
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
// [DllImport("dhnetsdk.dll")]
public static extern bool CLIENT_GetDevConfig(long lLoginID,
uint dwCommand,
long lChannel,
IntPtr lpBuffer,
uint dwOutBufferSize,
uint lpBytesReturned,
int waittime = 500);
And I am calling the method as follows:
int t = 500;
uint BytesReturned = 0;
uint c = 8;
var lpOutBuffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(NET_TIME)));
if (CLIENT_GetDevConfig(lLogin, c, 0, lpOutBuffer, (uint)Marshal.SizeOf(typeof(NET_TIME)), BytesReturned, t) == false)
{
Console.WriteLine("GetDevConfig FAILED");
}
[StructLayout(LayoutKind.Sequential)]
public struct NET_TIME
{
// [FieldOffset(0)]
uint dwYear;
// [FieldOffset(4)]
uint dwMonth;
// [FieldOffset(4)]
uint dwDay;
// [FieldOffset(4)]
uint dwHour;
// [FieldOffset(4)]
uint dwMinute;
// [FieldOffset(4)]
uint dwSecond;
}
I am positive the lLogin is correct since I successfully logged into the device using it.
But when I check GetLastError immediately after the call to GetDevConfig fails, it indicates a illegal parameter. So, can anybody point out the illegal parameter in the above code?
The following is my C# code with the illegal parameter issues...
using System;
using System.Runtime.InteropServices;
class PlatformInvokeTest
{
static public int lLogin;
public delegate void fDisConnect(long lLoginID, IntPtr pchDVRIP, long nDVRPort, uint dwUser);
public delegate void fHaveReConnect(long lLoginID, IntPtr pchDVRIP, long nDVRPort, uint dwUser);
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern bool CLIENT_Init(fDisConnect cbDisConnect, uint dwUser);
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern void CLIENT_SetAutoReconnect(fHaveReConnect cbHaveReconnt, uint dwUser);
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern int CLIENT_Login(string pchDVRIP, ushort wDVRPort, string pchUserName, string pchPassword, NET_DEVICEINFO lpDeviceInfo, IntPtr error);
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CLIENT_GetDevConfig(
int loginId,
uint command,
int channel,
out NET_TIME buffer,
out uint bufferSize,
IntPtr lpBytesReturned,
int waittime = 500);
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern bool CLIENT_Logout(long lID);
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern void CLIENT_Cleanup();
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern uint CLIENT_GetLastError();
public static void fDisConnectMethod(long lLoginID, IntPtr pchDVRIP, long nDVRPort, uint dwUser)
{
System.Console.WriteLine("Disconnect");
return;
}
public static void fHaveReConnectMethod(long lLoginID, IntPtr pchDVRIP, long nDVRPort, uint dwUser)
{
System.Console.WriteLine("Reconnect success");
return;
}
[StructLayout(LayoutKind.Sequential)]
public class NET_DEVICEINFO
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 48)]
public byte[] sSerialNumber;
public byte byAlarmInPortNum;
public byte byAlarmOutPortNum;
public byte byDiskNum;
public byte byDVRType;
public byte byChanNum;
}
[StructLayout(LayoutKind.Sequential)]
public struct NET_TIME
{
uint dwYear;
uint dwMonth;
uint dwDay;
uint dwHour;
uint dwMinute;
uint dwSecond;
}
public static void Main()
{
fDisConnect fDisConnecthandler = fDisConnectMethod;
fHaveReConnect fHaveReConnecthandler = fHaveReConnectMethod;
NET_DEVICEINFO deviceinfo = new NET_DEVICEINFO();
IntPtr iRet = new IntPtr(0);
CLIENT_Init(fDisConnectMethod, 0);
CLIENT_SetAutoReconnect(fHaveReConnecthandler, 0);
lLogin = CLIENT_Login("192.168.1.198", 31111, "user", "password", deviceinfo, iRet);
if (lLogin <= 0)
Console.WriteLine("Login device failed");
else
{
Console.WriteLine("Login device successful");
byte[] byteout = new byte[20];
const int t = 500;
IntPtr BytesReturned;
BytesReturned = IntPtr.Zero;
const uint c = 8;
NET_TIME nt;
uint sizeofnt = (uint)Marshal.SizeOf(typeof(NET_TIME));
if (CLIENT_GetDevConfig(lLogin, c, 0, out nt, out sizeofnt, BytesReturned, t) == false)
{
uint gle = CLIENT_GetLastError();
Console.WriteLine("getDevConfig failed");
}
CLIENT_Logout(lLogin);
CLIENT_Cleanup();
}
}
}
And here is my C code that I'm trying to port to C#. It works without any issues..
#pragma comment(lib,"dhnetsdk.lib")
#include <Windows.h>
#include <stdio.h>
#include <conio.h>
#include "dhnetsdk.h"
void CALLBACK DisConnectFunc(LONG lLoginID, char *pchDVRIP, LONG nDVRPort, DWORD dwUser)
{
printf("Disconnect.");
return;
}
void CALLBACK AutoConnectFunc(LONG lLoginID,char *pchDVRIP,LONG nDVRPort,DWORD dwUser)
{
printf("Reconnect success.");
return;
}
int main(void)
{
NET_TIME nt = {0};
NET_DEVICEINFO deviceInfo = {0};
unsigned long lLogin = 0;
LPVOID OutBuffer;
int iRet = 0;
DWORD dwRet = 0;
//Initialize the SDK, set the disconnection callback functions
CLIENT_Init(DisConnectFunc,0);
//Setting disconnection reconnection success of callback functions. If don't call this interface, the SDK will not break reconnection.
CLIENT_SetAutoReconnect(AutoConnectFunc,0);
lLogin = CLIENT_Login("192.168.1.108",31111,"user","password",&deviceInfo, &iRet);
if(lLogin <= 0)
{
printf("Login device failed");
}
else
{
OutBuffer = (LPVOID)malloc(sizeof(NET_TIME));
memset(OutBuffer, 0, sizeof(NET_TIME));
if(CLIENT_GetDevConfig( lLogin, 8 /* DH_DEV_TIMECFG */, 0, OutBuffer, sizeof(NET_TIME), &dwRet, 500) == FALSE)
{
printf("Failed\n");
}
else
{
memcpy(&nt, OutBuffer, sizeof(nt));
printf("Time %d %d %d %d %d %d\n", nt.dwYear,nt.dwMonth,nt.dwDay, nt.dwHour,nt.dwMinute, nt.dwSecond);
}
_getch();
}
CLIENT_Logout(lLogin);
CLIENT_Cleanup();
return 0;
}
Your extern function is wrongly defined. Let's take your C call example.
// Search configuration information
CLIENT_API BOOL CALL_METHOD CLIENT_GetDevConfig(LLONG lLoginID, DWORD dwCommand, LONG lChannel, LPVOID lpOutBuffer, DWORD dwOutBufferSize, LPDWORD lpBytesReturned,int waittime=500);
As stated in comment of your post, the length of LONG is 32-bit in Win32, so you have to use an int. You can also use the keyword out to get your structure without manually use the Mashaller. I would define your function as that.
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CLIENT_GetDevConfig(int loginId, uint command, int channel, out NET_TIME buffer, out uint bufferSize, IntPtr lpBytesReturned, int waittime = 500);
Note the presence of the additional attribute MarshalAs. It indicates how the managed code should consider the return value of the pinvoke'd function.
Here are the differences that I can see:
The C++ code:
CLIENT_API BOOL CALL_METHOD CLIENT_GetDevConfig(
LLONG lLoginID,
DWORD dwCommand,
LONG lChannel,
LPVOID lpOutBuffer,
DWORD dwOutBufferSize,
LPDWORD lpBytesReturned,
int waittime
);
Now, LLONG is pointer sized, 32 bit under x86, 64 bit under x64. That translates to IntPtr for C#. I'd declare the p/invoke like this:
[DllImport("dhnetsdk.dll", CallingConvention = CallingConvention.Cdecl)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CLIENT_GetDevConfig(
IntPtr lLoginID,
uint dwCommand,
int lChannel,
out NET_TIME lpOutBuffer,
uint dwOutBufferSize,
out uint lpBytesReturned,
int waittime
);
The main problems that I can see are that:
You are translated dwOutBufferSize incorrectly. It's an IN parameter but you are passing it by reference. This is the most likely explanation for the failure.
In the C++ code you pass a pointer to a DWORD variable for lpBytesReturned. In your C# code you pass IntPtr.Zero which is the null pointer.
So, I'd have the call to CLIENT_GetDevConfig looking like this:
NET_TIME nt;
uint sizeofnt = (uint)Marshal.SizeOf(typeof(NET_TIME));
uint BytesReturned;
if (!CLIENT_GetDevConfig(lLogin, 8, 0, out nt, sizeofnt, out BytesReturned, 500))
....
It may be that you can indeed pass IntPtr.Zero to the BytesReturned parameter. Perhaps it's an optional parameter. But I cannot tell that from here. However, for sure the dwOutBufferSize mis-declaration is an error.