MSOCAF Verification - P/Invoke should be portable

Question

I have this MSOCAF error's :

As it is declared in your code, parameter 'fDeleteOnRelease' of P/Invoke 'CompoundDocument.CreateILockBytesOnHGlobal(IntPtr, bool, out CompoundDocument.ILockBytes)' will be 1 bytes wide on 32-bit platforms. This is not correct, as the actual native declaration of this API indicates it should be 4 bytes wide on 32-bit platforms. Consult the MSDN Platform SDK documentation for help determining what data type should be used instead of 'bool'.

and this is the code :

 [DllImport("ole32.dll")]
 static extern IntPtr CreateILockBytesOnHGlobal (
    IntPtr hGlobal,
    [MarshalAs(UnmanagedType.U1)] bool fDeleteOnRelease,
    out ILockBytes ppLkbyt);

I search for a data type to use instead of bool but I fail. What's an alternative that is 4 bytes wide?

Answer 1

The native signature for this function, as found on MSDN is:

WINOLEAPI CreateILockBytesOnHGlobal(
  _In_   HGLOBAL hGlobal,
  _In_   BOOL fDeleteOnRelease,
  _Out_  ILockBytes **ppLkbyt
);

You have translated this as:

[DllImport("ole32.dll")]
static extern IntPtr CreateILockBytesOnHGlobal (
    IntPtr hGlobal,
    [MarshalAs(UnmanagedType.U1)] bool fDeleteOnRelease,
    out ILockBytes ppLkbyt
);

I see the following problems:

1. The return value is an HRESULT. That maps to int.
2. The BOOL parameter is 4 bytes wide. That's the subject of the warning you quote.

Now, the default marshalling for a bool is as a 4 byte Windows BOOL. So you can fix the declaration like so:

[DllImport("ole32.dll")]
static extern int CreateILockBytesOnHGlobal (
    IntPtr hGlobal,
    bool fDeleteOnRelease,
    out ILockBytes ppLkbyt
);