为什么 Ada DLL 在通过 FFI 接口从 Rust 调用时会卡在 adainit？

Question

快乐案例

我使用 Mingw 在 Ada 中成功编译了一个最小的 hello world windows DLL 并通过 FFI 接口使用它：

package MY_FFI is
    procedure Hello_World
        with
            Export => True,
            Convention => C,
            External_Name => "hello_world";
end MY_FFI;

package body MY_FFI is
    procedure Hello_World is
    begin
        Ada.Text_IO.Put_Line("Hello world!");
    end Send_Request;
end MY_FFI;

#[link(name = "my_ffi")]
extern "C" {
    #[link_name = "hello_world"]
    fn ada_hello_world();
    fn my_ffiinit(); // same as adainit just renamed by gprbuild
    fn my_ffifinal(); // same as adafinal just renamed by gprbuild
}

pub fn initialize_my_ffi() {
    unsafe {
        println!("step 1");
        my_ffiinit();
        println!("step 2");
        ada_hello_world();
        println!("step 3");
    }
}

这导致：

step 1
step 2
Hello world!
step 3

真正的问题

当我的 Ada 库变得更加复杂并且需要以下额外的系统 DLL 时：

libgnarl-7.dll
libgnat-7.dll
libgcc_s_seh-1.dll (mingw posix)
libwinpthreadthread-1.dll (mingw posix)

我无法准确地挑出需要那些额外 DLL 的代码，但是一旦代码变得复杂到需要这些 DLL，它就会在 my_ffiinit 函数处停滞不前，输出仅：

step 1

x64 Linux 上的相同代码可以正常工作。其他 Linux 平台（powerpc、arm64）的交叉编译也有效。

当我使用 Library_Auto_Init="true" 时，wine64 输出：

0009:err:module:LdrInitializeThunk "libmy_ffi.dll" failed to initialize, aborting
0009:err:module:LdrInitializeThunk Initializing dlls for L"Z:\test.exe" failed, status 20474343

主项目gpr：

with "/opt/libA/a_lib.gpr";
with "/opt/libB/b_lib.gpr";

library project MY_FFI is
  for Languages    use ("Ada");
  for Library_Name use "my_ffi";
  for Library_Kind use "dynamic";
  for Library_Standalone use "encapsulated";
  for Source_Dirs  use ("src/**");
  for Library_Interface use (
    "my_ffi",
  );

  type Target_Type is ("windows64", "windows32", "linux64", "armhf", "powerpc", "arm64");
  Target : Target_Type := external ("target", "linux64");
  for Library_Dir use "lib/" & external ("target", "linux64");
  for Object_Dir   use  "obj/" & external ("target", "linux64");
end MY_FFI;

预编译共享库 A 的 gpr:

library project a_lib is
  for Languages    use ("Ada");
  for Library_Name use "a";
  for Library_Kind use "dynamic";
  for Source_Dirs  use ("src/**");

  type Target_Type is ("windows64", "windows32", "linux64", "armhf", "powerpc", "arm64");
  Target : Target_Type := external ("target", "linux64");
  for Library_Dir use "lib/" & external ("target", "linux64");
  for Object_Dir   use  "obj/" & external ("target", "linux64");

  package Naming is
      for Spec_Suffix ("ada") use ".ads";
      for Body_Suffix ("ada") use ".adb";
      for Separate_Suffix use ".adb";
      for Casing use "MixedCase";
      for Dot_Replacement use "-";
   end Naming;

  package Compiler is
    for Default_Switches ("ada") use ("-fPIC");
  end Compiler;

  for Externally_Built use "true";
end a_lib;

从源代码编译的库 B 的 gpr：

library project b_lib is
   for Source_Dirs use ("src");
   for Library_Name use "b";
   for Library_Dir use "lib";
   for Object_Dir use "obj";
   for Languages use ("Ada");

   package Compiler is
      for Switches ("ada") use ("-O2", "-ffunction-sections", "-gnatQ", "-fdata-sections", "-fPIC", "-gnatf", "-gnatwa");
   end Compiler;

   package Builder is
      for Switches ("ada") use ("-j0", "-k", "-s");
   end Builder;

   type Target_Type is ("windows64", "windows32", "linux64", "armhf", "powerpc", "arm64");
   Target : Target_Type := external ("target", "linux64");
   for Library_Dir use "lib/" & external ("target", "linux64");
   for Object_Dir   use  "obj/" & external ("target", "linux64");
end b_lib;

Answer 1

对Ada不是很了解，但是它没有自己的ABI吗？这个 document 建议你需要用 Convention => C 标记一个函数以便从 C 调用它，类似于你在 Rust 中使用 extern "C" 的方式。

Answer 2

问题是在主项目配置文件中使用 for Library_Standalone use "encapsulated";，当它被替换为默认值 standard 项目编译失败并出现以下错误：

shared library project "my_ffi" cannot import static library project "b"

将行 for Library_Kind use "relocatable"; 添加到库 B 项目配置后，编译错误消失并且 libmy_ffi.dll 编译成功。更重要的是，生成的 DLL 在从 Rust 调用时按预期工作。

尚未解决的怪癖：

为什么这对 Linux 平台来说不是问题
为什么 gprbuild 在编译项目时不强制执行或警告唯一的静态策略

Answer 3

您是否正在 DLL:s 中创建图书馆级别的任务？这行不通，因为动态库中的初始化代码在 Windows.

上严格是单线程的

为什么 Ada DLL 在通过 FFI 接口从 Rust 调用时会卡在 adainit？

Why does Ada DLL get stuck at adainit when called from Rust over FFI interface?

windows

dll

ada

ffi

rust

快乐案例

真正的问题

尚未解决的怪癖：