I have a DLL that was developed in Visual C++, and I've started importing it's functionality to a c# project using DllImport. I've already implemented a few methods and they work well.
For that specific method I'm getting the following error:
Additional information: A call to PInvoke function 'SdkTest!SdkTest.Program::CLIENT_RealPlay' 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.
The c++ method I'm trying to implement has this signature:
CLIENT_NET_API LLONG CALL_METHOD CLIENT_RealPlay(LLONG lLoginID, int nChannelID, HWND hWnd);
With the following definitions:
#define CLIENT_NET_API __declspec(dllimport)
#define CALL_METHOD __stdcall
#define LLONG LONG
My c# impelmentation is the following:
[DllImport("dhnetsdk.dll")]
public static extern long CLIENT_RealPlay(long lLoginID, int nChannelID, IntPtr hWnd);
(I've read that HWND equivalent in c# is IntPtr, but I've also tried to put int, long, object...)
I also tried doing DllImport in the following way (As suggested in some posts and worked for some other methods I'm using):
[DllImport("dhnetsdk.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
No matter what I try I'm getting the same error. What am I miss understanding? If an internal exception in the c++ code is thrown, what kind of exception will I get in my code?
#define LLONG LONG
Now, LONG maps to long, which is a signed 32 bit type on Windows. Therefore, using long in your C# code is wrong because C# long is a 64 bit type. You need to use int instead. Like this:
[DllImport("dhnetsdk.dll")]
public static extern int CLIENT_RealPlay(int lLoginID, int nChannelID, IntPtr hWnd);
The c++ function is declared with calling convention stdcall, but you are calling it with cdecl.
In my experience, call stack corruptions are mostly caused by using the wrong calling convention.
Related
I am using DLL runtime which is made with C language into C#.
I came across below statement.
typedef void *JCCP_PROPERTY_HANDLE;
In function it is being used as:
JCCP_RESULT __JCCP_FUNCTION__ jccpGetProperty(
JCCP_HANDLE hjccp,
const char *name,
JCCP_PROPERTY_HANDLE *phproperty);
Now I want to call jccpGetProperty() method in my C# code.
Can anybody tell how can I pass third parameter(JCCP_PROPERTY_HANDLE *phproperty) to function from C#.
I tried with below code but not working.
Extern Method:
[DllImport(DLL_NAME, EntryPoint = "_jccpGetProperty", CallingConvention = CallingConvention.Cdecl)]
public static extern IntPtr jccpGetProperty(IntPtr hjccp, string name, ref IntPtr JCCP_PROPERTY_HANDLE);
Usage
IntPtr handle = IntPtr.Zero;
string tag = "server.version";
var result = jccpGetProperty(hjccp, tag, ref handle);
Can anybody help me in this?
IntPtr is the correct type mapping for void*. The native type void* is generally used for an opaque pointer, and that is mapped to IntPtr in C#.
Those parts of the p/invoke declaration that we can verify are correct. The unverifible parts are:
The calling convention. You believe that it is cdecl, but we can't check.
The return type. You believe it to be pointer sized. Again we cannot check. My guess is that a 32 bit integer, int or uint is more likely. That would make a difference in a 64 bit process.
The values passed to the function. It's perfectly possible that the function is declared correctly, but you are passing invalid values.
Because you only showed partial code and details, it's hard to say much more. You will have to verify all the parts of the program that we cannot.
I suggest that you start with working C or C++ code and translate that, looking for the first point of deviation in behaviour between that code and your C# translation.
I have below function on C++ (header)
string __declspec(dllexport) *GetReaders(int& readerCount);
I wrote below method on C# for invoking
[DllImport("ABC.dll", CharSet = CharSet.Auto )]
extern static string[] GetReaders(out IntPtr readercount);
But after run I can got readercount but the app got below error:
Cannot marshal 'return value': Invalid managed/unmanaged type combination.
What is wrong?
I did it by java and work perfectly. But I have problem with .Net.
It's impossible to call that method with p/invoke. That's because you cannot marshal C++ classes using p/invoke. And string is, presumably, std::string.
You'll need to either use a C++/CLI wrapper, or re-design the C++ interface to be p/invoke friendly.
I'm trying to call an external .dll function from c#. The doc for the dll defines the function:
int funcName(int *retVal)
I've tried various configurations and always the unbalanced stack error from p/invoke; My c# code currently looks like this:
[DLLImport("dllName");
unsafe static extern int funcName(ref IntPtr retVal);
unsafe IntPtr retNum;
int status = funcName(ref retNum);
Any ideas are appreciated!
Your p/invoke declaration has the wrong parameter type.
ref Int32 is the correct match for int*.
IntPtr can also work.
ref IntPtr would be int**. Definitely not what you want.
Use
[DLLImport("dllName")]
static extern int funcName(ref Int32 retVal);
Also make sure that the calling convention matches. You should never use a dllexport in C or C++ without also using an explicit calling convention, and then the C# DllImport needs to have the matching convention.
Generally the prototype in C++ should be
extern "C" int __stdcall funcName(int* arg);
Is there a header file provided for C and C++ clients that you could check to verify the signature?
I am trying to call an existing C dll from a C# application, using System.Runtime.InteropServices, and am having difficulty matching the signatures between the PInvoke function and the Target function.
The target function is
__declspec(dllexport) DWORD GetSomeString(char* strOut);
And my PInvoke function is
[DllImport("Existing.dll")]
public static extern uint GetSomeString([MarshalAs(UnmanagedType.LPWStr)]
string strDisplay);
I make the function call
string tempStr = "My Output String";
uint retVal = GetSomeString(tempStr);
But I get the message
Managed Debugging Assistant 'PInvokeStackImbalance' has detected a problem...
...A call to PInvoke function 'GetSomeString' 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 have also tried implementing the PInvoke function as
[DllImport("Existing.dll")]
public static extern uint GetSomeString([MarshalAs(UnmanagedType.LPWStr)]
StringBuilder strDisplay);
But to no avail.
Does anyone out there have an idea what I could be doing wrong?
Please let me know if further info is required or my question is unclear.
Thanks in advance.
You need to specify the calling convention. By default, PInvoke uses StdCall, but your method is (likely) Cdecl.
[DllImport("Existing.dll", CallingConvention=CallingConvention.Cdecl)]
In addition to the incorrect calling convention mentioned by Reed Copsey, the matching type for char* is UnmanagedType.LPStr.
i have the following method signature on my c++ dll:
extern char *bpStringCalc(char *bpDirectory, char *issString);
And i'm trying to call it from c# using this:
[DllImport(#"C:\MuniAxis\Bp\BpDLL.dll", CharSet = CharSet.Ansi)]
[return: MarshalAs(UnmanagedType.LPStr)]
public static extern string bpStringCalc([MarshalAs(UnmanagedType.LPStr)] string bpDirectory,
[MarshalAs(UnmanagedType.LPStr)] string issString);
But it keep getting this exception:
'ConsoleApplication1!ConsoleApplication1.Program::bpStringCalc'
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.
Any ideas?
Thanks
Try specifying a Cdecl calling convention on import or __stdcall on export. See this almost similar question.
Unbalancing the stack probably has more to do with calling convention than it does the actual arguments. C++, by default, uses the __cdecl calling convention. C# defaults to __stdcall because __stdcall is the convention used by Win32. You need to either set calling convention on your import statement in C#, or you need to specify __stdcall in your C++ binary.
EDIT: The above was edited to fix the fact that __cdecl and __stdcall had only one leading underscore each ;)