[Mono-list] Problems with DllImport attribute and calling libuser32.so

[Steinar Herland]

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I'm trying to call the MessageBox function in the WineLib libuser32.so

The attached Class1.cs file works on WinXP (using native user32.dll),
but fails on mono (linux)

I found that if I compile Class1.cs on mono (linux) it does not create
the same method-definition.
There seems to be problems (at least) with the DllImport.CharSet and
DllImport.ExactSpelling attributes.

From my Class1.cs-file:

class Win32Methods{
//mcs & csc il: .method public hidebysig static pinvokeimpl("user32"
ansi)=20
[DllImport("user32",
CharSet=3DCharSet.Ansi,ExactSpelling=3Dfalse,CallingConvention=3DCallingC=
onven
tion.StdCall)]
public extern static int MessageBox(IntPtr hWnd, string text, string
caption, int type);

//csc il: .method public hidebysig static pinvokeimpl("user32" unicode)
//mcs il: .method public hidebysig static pinvokeimpl("user32" nomangle
ansi)=20
[DllImport("user32",
CharSet=3DCharSet.Unicode,ExactSpelling=3Dfalse,CallingConvention=3DCalli=
ngCon
vention.StdCall)]
public extern static int MessageBoxW(IntPtr hWnd, string text, string
caption, int type);

//mcs & csc il: .method public hidebysig static pinvokeimpl("user32"
ansi)=20
[DllImport("user32",
CharSet=3DCharSet.Ansi,ExactSpelling=3Dfalse,CallingConvention=3DCallingC=
onven
tion.StdCall)]
public extern static int MessageBoxA(IntPtr hWnd, string text, string
caption, int type);
}
class Win32Methods2{
//csc: .method public hidebysig static pinvokeimpl("user32" nomangle
ansi)=20
//mcs: .method public hidebysig static pinvokeimpl("user32" ansi)=20
[DllImport("user32",
CharSet=3DCharSet.Ansi,ExactSpelling=3Dtrue,CallingConvention=3DCallingCo=
nvent
ion.StdCall)]
public extern static int MessageBox(IntPtr hWnd, string text, string
caption, int type);
}

-----------------------------
Output running mono on linux:
-----------------------------
** (process:11827): WARNING **: Failed to load function MessageBox from
user32

** (process:11827): WARNING **: Failed to load function MessageBox from
user32
err:heap:HEAP_GetPtr Invalid heap 00000000!
err:heap:HEAP_GetPtr Invalid heap 00000000!
Failure calling Win32Methods.MessageBoxW System.NullReferenceException
A null value was found where an object instance was
requiredSystem.NullReference
Exceptionin (unmanaged) Win32Api.Win32Methods:MessageBoxW ()
in <0x0004a> Win32Api.Class1:Main (string[])

Failure calling Win32Methods.MessageBoxA System.NullReferenceException
A null value was found where an object instance was
requiredSystem.NullReference
Exceptionin (unmanaged) Win32Api.Win32Methods:MessageBoxA ()
in <0x000bf> Win32Api.Class1:Main (string[])

Failure calling Win32Methods.MessageBox System.NotImplementedException
The requested feature is not yet
implementedSystem.NotImplementedExceptionin (un
managed) Win32Api.Win32Methods:MessageBox ()
in <0x00134> Win32Api.Class1:Main (string[])

Failure calling Win32Methods2.MessageBox System.NotImplementedException
The requested feature is not yet
implementedSystem.NotImplementedExceptionin (un
managed) Win32Api.Win32Methods2:MessageBox ()
in <0x001a9> Win32Api.Class1:Main (string[])


------------------------
Output running on WinXP:
------------------------
Failure calling Win32Methods2.MessageBox
System.EntryPointNotFoundException: Unable to find an entry point named
MessageBox in DLL user32.
   at Win32Api.Win32Methods2.MessageBox(IntPtr hWnd, String text, String
caption
, Int32 type)
   at Win32Api.Class1.Main(String[] args) in
d:\dev\steinar\forms\winforms\class
1.cs:line 46
------------------------
This failure is expected because DllImport.ExactSpelling =3D true

Any help appreciated.

Steinar Herland

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