I have a (C/C++) DLL which I am calling by DLLImport to a C# project.
This DLL has this method:
int __stdcall Connect(OUT int *p_sessionID, IN BYTE mode, IN BYTE comport, IN char *servername, IN DWORD serverport);
I tried several ways to "translate" it to C# but one that I find is closer is:
[DllImport("UnmanagedDLL.dll", EntryPoint = "Connect", CallingConvention = CallingConvention.StdCall)]
private static extern unsafe int CS1_Connect(out IntPtr p_sessionID, byte mode, byte comport, string servername, int serverport);
I am trying to invoke like this:
IntPtr connection;
var i = Connect(out connection, 1, 0, "192.0.0.1", 1982);
But I always get the following error:
Additional information: A call to PInvoke function 'DllImportTest!DllImportTest.Program::Connect' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.
I know I can reach the DLL because I have another method that worked fine.
What am I doing wrong?
Thanks.
Your first parameter is translated incorrectly.
OUT int *p_sessionID
Here OUT is a macro that indicates semantics to the reader. The macro expands it to nothing. And so after pre-processing you have:
int *p_sessionID
That translates as
out int sessionID
in your C#.
You don't need to declare the function as unsafe, remove that. And the final parameter is unsigned. You might want to switch to uint.
The correct translation would therefore be:
[DllImport("UnmanagedDLL.dll", EntryPoint = "Connect",
CallingConvention = CallingConvention.StdCall)]
private static extern int CS1_Connect(
out int sessionID,
byte mode,
byte comport,
string servername,
uint serverport
);
If you still receive the stack imbalanced message then you would know that the unmanaged function does not have the signature that you have quoted in the question.
Related
I have a C# project where I need to use an external dll.
The dll was built using C++. I have only the c++ header file (.hpp) that describes functions interfaces (signatures), and the .dll (binary code).
I want to load the dll dynamically in my C# project and use two functions :
void OpenService(long &handle);
int GetCode(long handle, const char* pin, char* passcode, char* nextPasscode, char* tokencode, char* nextTokencode);
I am able to load the dll using DllImport from System.Runtime.InteropServices and it works for the first function using the code bellow :
[DllImport(#"C:\Program Files\Path to my dll\myDll.dll")]
public static extern void OpenService(ref long handle);
But for the second one, I tried the code bellow :
[DllImport(#"C:\Program Files\Path to my dll\myDll.dll")]
unsafe public static extern int GetCode (long handle, string* pin, string* passcode, string* nextPasscode, string* tokencode, string* nextTokencode);
But the compiler is complaining that I should use the unsafe mode while compiling to be able to use C# pointers which is something I cannot do due to rules imposed by the Tech lead.
So, my question is how can I call the second function without using C# pointers ?
I tried to use references as bellow :
[DllImport(#"C:\Program Files\Path to my dll\myDll.dll")]
public static extern int GetCode (long handle, ref string pin, ref string passcode, ref string nextPasscode, ref string tokencode, ref string nextTokencode);
But the program crashes whenever I call GetCode.
Any idea on how can I solve this problem ?
Thank you in advance.
Instead of using unsafe and pointers you can marshal (transform) the string to a char* type using the MarshalAs method:
[DllImport(#"C:\Program Files\Path to my dll\myDll.dll")]
public static extern int GetCode (long handle, [MarshalAs(UnmanagedType.LPStr)]string pin, [MarshalAs(UnmanagedType.LPStr)]string passcode, [MarshalAs(UnmanagedType.LPStr)]string nextPasscode, [MarshalAs(UnmanagedType.LPStr)]string tokencode, [MarshalAs(UnmanagedType.LPStr)]string nextTokencode);
UnmanagedType.LPStr means that the string will be marshalled as
A pointer to a null-terminated array of ANSI characters.
If you need unicode you can use UnmanagedType.LPWStr
Here is more info:
https://learn.microsoft.com/en-us/dotnet/framework/interop/default-marshaling-for-strings
I would like to call a function inside MediaInfo.dll.
The function is:
const wchar_t* __stdcall MediaInfo_Option (void* Handle, const
wchar_t* Option, const wchar_t* Value);
I have declared it in the c# code in this way:
[DllImport("MediaInfo.dll", CharSet = CharSet.Unicode)] internal
static extern string MediaInfo_Option(IntPtr Handle, string OptionString, string Value);
here is the code in which it's called:
MediaInfo.MediaInfo_Open(this.h, path);
MediaInfo.MediaInfo_Option(this.Handle, "Complete", "1");
myTextBox.Text = MediaInfo.MediaInfo_Inform(this.h, 0);
MediaInfo.MediaInfo_Close(this.h);
The problem is that any c# application compiled with .NET Framework equal or greater than the version 4 crash when calling that function.
How can I solve it?
Thanks in advance.
You did not Marshall the wchar_t* of both input and output, you'll get random errors.
There is a C# binding of MediaInfo which takes care of all the ugly stuff.
You can use it with a C# example of MediaInfo.
You may be interested in downloading the DLL package with a C# example project.
I am using the Hardware ID Extractor library (written in Delphi) from http://www.soft.tahionic.com/download-hdd_id/index.html with the purpose of generating unique system fingerprints.
The library is really good and unlike anything else I have seen on the market, but the main issue with it is that it's unstable when running with .NET applications, meaning that it sometimes works, other times it works for a few function calls then the main application crashes, or most of the time the application instantly crashes when a dll function is being called.
As the developer of the library pointed out (in the last support e-mail that I have received), the fault is with ntdll.dll, as I have seen that for myself:
Following is a link to a demo project I have created with the purpose of testing the dll functions (so to make sure that nothing else interferes, the demo app does that and only that- it calls the dll functions).
http://www.mediafire.com/download/1jws7zh9218v88a/HardwareIdExtractDllTest.zip
The archive contains the Visual Studio 2013 project with source code and a compiled demo application which looks like this:
The list of functions contained by the dll can be found here:
http://www.soft.tahionic.com/download-hdd_id/hardware%20id%20programming%20source%20code/exported%20functions%20for%20non-Delphi.html
If anyone has the knowledge and is willing to test the demo project/application to make tests or personal opinions in regard to the issue, and then share a possible solution with me, I would be grateful.
Please let me know if there's anything I can do to further assist in solving this issue if you think there's anything that can be done about it.
EDIT: This is how I am declaring the dll functions
[DllImport("HardwareIDExtractorC.dll")]
private static extern bool EnterKey(int key);
[DllImport("HardwareIDExtractorC.dll")]
private static extern bool IsCPUIDAvailable();
[DllImport("HardwareIDExtractorC.dll")]
private static extern int GetCPUCount();
[DllImport("HardwareIDExtractorC.dll")]
private static extern byte CoreNumber2CoreMask(byte cpuCore);
[DllImport("HardwareIDExtractorC.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, EntryPoint = "GetCPUID")]
[return: MarshalAs(UnmanagedType.LPStr)]
private static extern string GetCPUID(byte cpuCore);
[DllImport("HardwareIDExtractorC.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, EntryPoint = "GetCpuIdNow")]
[return: MarshalAs(UnmanagedType.LPStr)]
private static extern string GetCpuIdNow();
[DllImport("HardwareIDExtractorC.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, EntryPoint = "GetIDESerialNumber")]
[return: MarshalAs(UnmanagedType.LPStr)]
private static extern string GetIDESerialNumber(byte driveNumber);
The functions that fail are the ones that return string. Such a p/invoke marshals the return value as a pointer to null terminated character array, and then calls CoTaskMemFree on the raw pointer returned by the unmanaged code.
With probability close to 1 that string was not allocated on the COM heap and so the error is likely in the C# p/invoke declarations. That an access violation then arises in ntdll is quite plausible.
So, to make progress you need to fix the p/invoke calls. I cannot tell you how to do so because you have not shown the unmanaged function declarations. Or, more importantly, how the memory is allocated.
There are some clues at the documentation
procedure ReleaseMemory (P: PAnsiChar); stdcall;
I think this tells us that the strings returned by the DLL must be deallocated by the DLL, by calling this function. Presumably because they were allocated by the DLL's heap allocator.
So, use IntPtr for the return type of the functions that return text. Call Marshal.PtrToStringAnsi to convert to a C# string. And then pass the pointer to ReleaseMemory.
For example:
[DllImport(DllPath, CallingConvention = CallingConvention.StdCall)]
private static extern IntPtr GetCPUID(ushort CoreMask);
[DllImport(DllPath, CallingConvention = CallingConvention.StdCall)]
private static extern void ReleaseMemory(IntPtr P);
....
IntPtr ptr = GetCPUID(CoreMask);
string cpuid = Marshal.PtrToStringAnsi(ptr);
ReleaseMemory(ptr);
I am receiving this error while using a dllimport Attempted to read or write protected memory. This is often an indication that other memory is corrupt
private const string dir2 = #"C:\NBioBSP.dll";
[System.Runtime.InteropServices.DllImport(dir2, SetLastError = true, CallingConvention = System.Runtime.InteropServices.CallingConvention.Cdecl)]
public static extern uint NBioAPI_FreeFIRHandle(IntPtr hHandle, IntPtr hFIR);
I call it like this
uint resultado = NBioAPI_FreeFIRHandle(handle, handle);
Anyone know what the issue can be
Two problems.
First, the calling convention is wrong. Per the header file that defines the function (as well as the supporting file that defines NBioAPI as __stdcall on the Win32 platform), you should be using CallingConvention.StdCall.
Second, in the header that defines the types used by the API, NBioAPI_HANDLE and NBioAPI_FIR_HANDLE are typedef'd to UINT, which is always 32 bits (four bytes) long. You're using IntPtr, which has a platform-dependent size (it will be 64 bits in a 64-bit process.) Change the function parameters to uint.
I'm encountering this error while using one of method in my .dll reference.
When I call MyRef.SetDbaseId method I'm returned to VS with this error. I've tried to add CallingConvention enum parameters, but all of them does not work for me. I've also opened dll in DependencyWalker to check entry point and param (ulong), which fits in my app. It's confusing because other methods works fine. Any ideas how to solve this problem?
[DllImport("my.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "?setdbaseid##YGHK#Z")]
public static extern int SetDbaseID(ulong dbase_id);
ulong tmid = ulong.Parse(p_6);
i = MyRef.SetDbaseID(tmid);
The mangled name, ?setdbaseid##YGHK#Z, demangles to:
int __stdcall setdbaseid(unsigned long);
Which makes your declaration wrong, an unsigned long in native code is 32-bits. And the calling convention is wrong. Fix:
[DllImport("my.dll", EntryPoint = "?setdbaseid##YGHK#Z"))]
public static extern int SetDbaseID(uint dbase_id);