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How to compile a shared library on Windows such that it can be used with NativeCall in raku?

Tags:

windows

dll

raku

I am trying to compile a DLL library on Windows that can be used with NativeCall in Raku. Here is a minimal C code (my_c_dll.c):

#include <stdio.h>
#define EXPORTED __declspec(dllexport)
extern __declspec(dllexport) void foo();

void foo()
{
  printf("Hello from C\n");
}

I am on Windows 10 and have installed Build Tools for Visual Studio 2019. To compile the DLL I open a "Developer Command Prompt for VS 2019" and run:

> cl.exe /c my_c_dll.c
> link /DLL /OUT:my_c_dll.dll my_c_dll.obj

This creates a DLL my_c_dll.dll, then I try to use this from Raku (test-dll.raku):

use v6.d;
use NativeCall;
sub foo() is native("./my_c_dll.dll"){ * }
foo();

but when I run this (I have installed Rakudo version 2020.05.1) I get:

> raku test-dll.raku
Cannot locate native library '(null)': error 0xc1
  in method setup at C:\rakudo\share\perl6\core\sources\947BDAB9F96E0E5FCCB383124F923A6BF6F8D76B (NativeCall) line 298
  in block foo at C:\rakudo\share\perl6\core\sources\947BDAB9F96E0E5FCCB383124F923A6BF6F8D76B (NativeCall) line 594
  in block <unit> at test-dll.raku line 9

What can be the problem here?

like image 615
Håkon Hægland Avatar asked Mar 06 '21 21:03

Håkon Hægland


1 Answers

Cannot locate native library '(null)': error 0xc1

The error code 0xc1 is a Windows system error code :

ERROR_BAD_EXE_FORMAT
193 (0xC1)
%1 is not a valid Win32 application.

By inspecting the header of the DLL using dumpbin

> dumpbin /headers my_c_dll.dll
Microsoft (R) COFF/PE Dumper Version 14.26.28806.0
Copyright (C) Microsoft Corporation.  All rights reserved.


Dump of file my_c_dll.dll

PE signature found

File Type: DLL

FILE HEADER VALUES
             14C machine (x86)
               4 number of sections
        6043A8CB time date stamp Sat Mar  6 17:07:39 2021
               0 file pointer to symbol table
               0 number of symbols
              E0 size of optional header
            2102 characteristics
                   Executable
                   32 bit word machine
                   DLL

I observe that it says machine (x86) and 32 bit word machine, so I suspect the DLL is a 32-bit DLL. However, I am on a 64 bit machine:

> PowerShell -Command "systeminfo | perl -nE 'say if /System Type/'"
System Type:               x64-based PC

It turns out that the Build Tools for Visual Studio 2019 installed some more developer prompts in addition to the "Developer Command Prompt for VS 2019", namely:

  • x64 Native Tools Command Prompt for VS 2019
  • x64_x86 Cross Tools Command Prompt for VS 2019
  • x86 Native Tools Command Prompt for VS 2019
  • x86_x64 Cross Tools Command Prompt for VS 2019

By opening a "x64 Native Tools Command Prompt for VS 2019" and recompiling the DLL here, I now get:

> dumpbin /headers my_c_dll.dll
Microsoft (R) COFF/PE Dumper Version 14.26.28806.0
Copyright (C) Microsoft Corporation.  All rights reserved.


Dump of file my_c_dll.dll

PE signature found

File Type: DLL

FILE HEADER VALUES
            8664 machine (x64)
               6 number of sections
        6043AAA2 time date stamp Sat Mar  6 17:15:30 2021
               0 file pointer to symbol table
               0 number of symbols
              F0 size of optional header
            2022 characteristics
                   Executable
                   Application can handle large (>2GB) addresses
                   DLL

Notice that the output now says machine (x64) and Application can handle large (>2GB) addresses, and this also seems to fix the problem:

> raku test-dll.raku
Hello from C
like image 92
Håkon Hægland Avatar answered Oct 25 '22 19:10

Håkon Hægland