CODEWITHSUNDEEP
c#.netdllpinvoke
kevp
kevp

Reputation: 377

DLLImport in C# has incorrect call

I am getting a PInvokeStackImbalance: 'PInvokeStackImbalance was detected Message: A call to PInvoke function 'ConvertedClass::MapViewOfFile' 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 am fairly new to DLL use, and just managed to work out a few tutorials today.

Any help would be appreciated.

using System.Runtime.InteropServices;     

//dll
[DllImport("kernel32", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Auto)]

public static extern IntPtr MapViewOfFile(IntPtr hFileMappingObject, FileMapAccessRights dwDesiredAccess, uint dwFileOffsetHigh, uint dwFileOffsetLow, ulong dwNumberOfBytesToMap;)

string szSharedMemory = "FUNKY_BUSINESS";

//other dll call is successful and returns value
IntPtr hMem = OpenFileMapping(FileMapAccessRights.Write, FALSE, szSharedMemory);

///BOOM.. not this one
IntPtr pvHead = MapViewOfFile(hMem, FileMapAccessRights.Write, 0, 0, 0);

Edit: It was a bad argument.. The 5th arg should be UIntPtr instead of ulong. this is how i feel right now

Upvotes: 2

Views: 1041

Answers (2)

David Heffernan
David Heffernan

Reputation: 612794

The final parameter is SIZE_T. That's unsigned, and 32 bits in a 32 bit process and 64 bits in a 64 bit process. So the best solution is to use UIntPtr for the final parameter.

I would use the following:

[DllImport("kernel32")]
public static extern IntPtr MapViewOfFile(
    IntPtr hFileMappingObject,
    FileMapAccessRights dwDesiredAccess, 
    uint dwFileOffsetHigh, 
    uint dwFileOffsetLow, 
    UIntPtr dwNumberOfBytesToMap
);

Your code uses ulong which is always 64 bits wide. And your process is a 32 bit process which explains why the P/invoke marshaller has detected a stack imbalance.

Upvotes: 3

MichelZ
MichelZ

Reputation: 4394

The 5th parameter should be an uint, not ulong.

public static extern IntPtr MapViewOfFile(IntPtr hFileMappingObject, FileMapAccessRights dwDesiredAccess, uint dwFileOffsetHigh, uint dwFileOffsetLow, uint dwNumberOfBytesToMap;)

For P/Invoke, you can use sample code from pinvoke.net. http://www.pinvoke.net/default.aspx/kernel32.mapviewoffile

Upvotes: 0

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