Haskell DLL 函数上的外部导入 stdcall

Question

这可能是一个非常容易回答的问题，但出于某种原因我真的很难回答。

我有一个用 C 编写的 DLL，用于在协议级别访问硬件，并且我想编写一个调用其中一些 C 函数的 Haskell 程序。 下面是相关 C 头文件的片段（由于可能存在版权问题，名称略有混淆）：

#ifdef HWDRIVER_EXPORTS
#define HWDRIVER_API __declspec(dllexport)
#else
#define HWDRIVER_API __declspec(dllimport)
#endif
HWDRIVER_API int HW_Init(void);

这已在 Visual Studio 2003 中编译为 DLL，并且我已成功从 C 和 C# 加载了 DLL，因此我有信心DLL 工作正常。 该 DLL 名为“hw-driver.dll”。

接下来，这是 Haskell 源代码，只是为了测试我是否可以正确加载 DLL 并调用其中最简单的函数：

{-# LANGUAGE ForeignFunctionInterface #-}
module Main
    where
import Foreign
import Foreign.C

foreign import stdcall "hw-driver" "HW_Init"  hwInit :: IO (CInt)

main = do
    x <- hwInit
    if x == 0 
        then putStr "Successfully initialized"
        else putStr "Could not initialize"

给我带来麻烦的行是foreign import 行。 据我了解，语法是外来的（导入/导出）（ccall/stdcall）库名称 C函数名称 haskell-函数名称< /em> :: Haskell 类型声明。 所以我的应该是foreign import stdcall（因为在Win32中加载DLL时使用stdcall）“hw-driver”（因为该文件名为“hw-driver.dll”并且与dlltest.hs位于同一目录中） “HW_Init”（C 中函数的名称） hwInit :: IO (Cint)（空参数，返回 int）。

但是，当我尝试运行 ghci dlltest.hs 时，我得到以下输出：

[1 of 1] Compiling Main             ( dlltest.hs, interpreted )

dlltest.hs:8:43: parse error on input `"'
Failed, modules loaded: none.

第 8 行，第 43 列是 HW_Init 上的第一个引号。 好吧，也许我必须将库名称和函数名称都放在一个字符串中，我在一些地方看到过这种情况。 如果我尝试运行它，则会得到：

[1 of 1] Compiling Main             ( dlltest.hs, interpreted )

dlltest.hs:8:23: Malformed entity string
Failed, modules loaded: none.

8:23 是新字符串“hw-driver HW_Init”的第一个引号。

我不认为我的 ghc 设置（6.10.3）有什么问题，因为我可以运行以下从 Real World Haskell 复制粘贴到 ghci 的代码：

{-- snippet pragma --}
{-# LANGUAGE ForeignFunctionInterface #-}
{-- /snippet pragma --}

{-- snippet imports --}
import Foreign
import Foreign.C.Types
{-- /snippet imports --}

{-- snippet binding --}
foreign import ccall "math.h sin"
     c_sin :: CDouble -> CDouble
{-- /snippet binding --}

{-- snippet highlevel --}
fastsin :: Double -> Double
fastsin x = realToFrac (c_sin (realToFrac x))
{-- /snippet highlevel --}

{-- snippet use --}
main = mapM_ (print . fastsin) [0/10, 1/10 .. 10/10]
{-- /snippet use --}

问题很长，我如何正确声明外部导入在 Win32 DLL 上？ 我在 Google 上找不到任何内容。

为了解决这个问题，我是否能够使用像 c2hs 或 hsc2hs 这样的程序来解析头文件 hw-driver.h 这样我就不必手动编写外部文件import 调用该 DLL 中包含的所有 20-25 个函数？ 我也找不到任何合适的例子。

---

编辑：ephemient 指出外部导入行的正确语法是：

foreign import stdcall "hw-driver.h HW_Init" hwInit :: IO CInt

有了这个，我就可以调用 ghci dlltest.hs -lhw-driver 并正确调用主函数并成功返回代码。 但是，命令 ghc --make dlltest.hs -lhw-driver 失败并出现链接器错误。 因此，这是该命令的详细输出（请注意，我在工作目录中拥有所有 hw-driver.{dll,h,lib} ）：

Glasgow Haskell Compiler, Version 6.10.3, for Haskell 98, stage 2 booted by GHC version 6.10.1
Using package config file: C:\ghc\ghc-6.10.3\package.conf
hiding package base-3.0.3.1 to avoid conflict with later version base-4.1.0.0
wired-in package ghc-prim mapped to ghc-prim-0.1.0.0
wired-in package integer mapped to integer-0.1.0.1
wired-in package base mapped to base-4.1.0.0
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0.1.0
wired-in package syb mapped to syb-0.1.0.1
wired-in package template-haskell mapped to template-haskell-2.3.0.1
wired-in package dph-seq mapped to dph-seq-0.3
wired-in package dph-par mapped to dph-par-0.3
Hsc static flags: -static
*** Chasing dependencies:
Chasing modules from: *dlltest.hs
Stable obj: [Main]
Stable BCO: []
Ready for upsweep
  [NONREC
      ModSummary {
         ms_hs_date = Mon Jun 22 13:20:05 Eastern Daylight Time 2009
         ms_mod = main:Main,
         ms_imps = [Foreign.C, Foreign]
         ms_srcimps = []
      }]
compile: input file dlltest.hs
Created temporary directory: C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0
*** Checking old interface for main:Main:
[1 of 1] Skipping  Main             ( dlltest.hs, dlltest.o )
*** Deleting temp files:
Deleting: C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.s
Warning: deleting non-existent C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.s
Upsweep completely successful.
*** Deleting temp files:
Deleting: 
link: linkables are ...
LinkableM (Mon Jun 22 13:22:26 Eastern Daylight Time 2009) main:Main
   [DotO dlltest.o]
Linking dlltest.exe ...
*** Windres:
C:\ghc\ghc-6.10.3\bin/windres --preprocessor="C:\ghc\ghc-6.10.3\gcc" "-BC:\ghc\ghc-6.10.3\gcc-lib/" "-IC:\ghc\ghc-6.10.3\include/mingw" "-E" "-xc" "-DRC_INVOKED" --use-temp-file --input=C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.rc --output=C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.o --output-format=coff
*** Linker:
C:\ghc\ghc-6.10.3\gcc -BC:\ghc\ghc-6.10.3\gcc-lib/ -IC:\ghc\ghc-6.10.3\include/mingw -v -o dlltest.exe -DDONT_WANT_WIN32_DLL_SUPPORT dlltest.o -lhw-driver C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.o -LC:\ghc\ghc-6.10.3\base-4.1.0.0 -LC:\ghc\ghc-6.10.3\integer-0.1.0.1 -LC:\ghc\ghc-6.10.3\ghc-prim-0.1.0.0 -LC:\ghc\ghc-6.10.3 -LC:\ghc\ghc-6.10.3/gcc-lib -lHSbase-4.1.0.0 -lwsock32 -lmsvcrt -lkernel32 -luser32 -lshell32 -lHSinteger-0.1.0.1 -lHSghc-prim-0.1.0.0 -lHSrts -lm -lffi -lgmp -lwsock32 -u _ghczmprim_GHCziTypes_Izh_static_info -u _ghczmprim_GHCziTypes_Czh_static_info -u _ghczmprim_GHCziTypes_Fzh_static_info -u _ghczmprim_GHCziTypes_Dzh_static_info -u _base_GHCziPtr_Ptr_static_info -u _base_GHCziWord_Wzh_static_info -u _base_GHCziInt_I8zh_static_info -u _base_GHCziInt_I16zh_static_info -u _base_GHCziInt_I32zh_static_info -u _base_GHCziInt_I64zh_static_info -u _base_GHCziWord_W8zh_static_info -u _base_GHCziWord_W16zh_static_info -u _base_GHCziWord_W32zh_static_info -u _base_GHCziWord_W64zh_static_info -u _base_GHCziStable_StablePtr_static_info -u _ghczmprim_GHCziTypes_Izh_con_info -u _ghczmprim_GHCziTypes_Czh_con_info -u _ghczmprim_GHCziTypes_Fzh_con_info -u _ghczmprim_GHCziTypes_Dzh_con_info -u _base_GHCziPtr_Ptr_con_info -u _base_GHCziPtr_FunPtr_con_info -u _base_GHCziStable_StablePtr_con_info -u _ghczmprim_GHCziBool_False_closure -u _ghczmprim_GHCziBool_True_closure -u _base_GHCziPack_unpackCString_closure -u _base_GHCziIOBase_stackOverflow_closure -u _base_GHCziIOBase_heapOverflow_closure -u _base_ControlziExceptionziBase_nonTermination_closure -u _base_GHCziIOBase_blockedOnDeadMVar_closure -u _base_GHCziIOBase_blockedIndefinitely_closure -u _base_ControlziExceptionziBase_nestedAtomically_closure -u _base_GHCziWeak_runFinalizzerBatch_closure -u _base_GHCziTopHandler_runIO_closure -u _base_GHCziTopHandler_runNonIO_closure -u _base_GHCziConc_runHandlers_closure -u _base_GHCziConc_ensureIOManagerIsRunning_closure
Reading specs from C:/ghc/ghc-6.10.3/gcc-lib/specs
Configured with: ../gcc-3.4.5-20060117-3/configure --with-gcc --with-gnu-ld --with-gnu-as --host=mingw32 --target=mingw32 --prefix=/mingw --enable-threads --disable-nls --enable-languages=c,c++,f77,ada,objc,java --disable-win32-registry --disable-shared --enable-sjlj-exceptions --enable-libgcj --disable-java-awt --without-x --enable-java-gc=boehm --disable-libgcj-debug --enable-interpreter --enable-hash-synchronization --enable-libstdcxx-debug
Thread model: win32
gcc version 3.4.5 (mingw-vista special r3)
 C:/ghc/ghc-6.10.3/gcc-lib/collect2.exe -Bdynamic -o dlltest.exe -u _ghczmprim_GHCziTypes_Izh_static_info -u _ghczmprim_GHCziTypes_Czh_static_info -u _ghczmprim_GHCziTypes_Fzh_static_info -u _ghczmprim_GHCziTypes_Dzh_static_info -u _base_GHCziPtr_Ptr_static_info -u _base_GHCziWord_Wzh_static_info -u _base_GHCziInt_I8zh_static_info -u _base_GHCziInt_I16zh_static_info -u _base_GHCziInt_I32zh_static_info -u _base_GHCziInt_I64zh_static_info -u _base_GHCziWord_W8zh_static_info -u _base_GHCziWord_W16zh_static_info -u _base_GHCziWord_W32zh_static_info -u _base_GHCziWord_W64zh_static_info -u _base_GHCziStable_StablePtr_static_info -u _ghczmprim_GHCziTypes_Izh_con_info -u _ghczmprim_GHCziTypes_Czh_con_info -u _ghczmprim_GHCziTypes_Fzh_con_info -u _ghczmprim_GHCziTypes_Dzh_con_info -u _base_GHCziPtr_Ptr_con_info -u _base_GHCziPtr_FunPtr_con_info -u _base_GHCziStable_StablePtr_con_info -u _ghczmprim_GHCziBool_False_closure -u _ghczmprim_GHCziBool_True_closure -u _base_GHCziPack_unpackCString_closure -u _base_GHCziIOBase_stackOverflow_closure -u _base_GHCziIOBase_heapOverflow_closure -u _base_ControlziExceptionziBase_nonTermination_closure -u _base_GHCziIOBase_blockedOnDeadMVar_closure -u _base_GHCziIOBase_blockedIndefinitely_closure -u _base_ControlziExceptionziBase_nestedAtomically_closure -u _base_GHCziWeak_runFinalizzerBatch_closure -u _base_GHCziTopHandler_runIO_closure -u _base_GHCziTopHandler_runNonIO_closure -u _base_GHCziConc_runHandlers_closure -u _base_GHCziConc_ensureIOManagerIsRunning_closure C:/ghc/ghc-6.10.3/gcc-lib/crt2.o C:/ghc/ghc-6.10.3/gcc-lib/crtbegin.o -LC:\ghc\ghc-6.10.3\base-4.1.0.0 -LC:\ghc\ghc-6.10.3\integer-0.1.0.1 -LC:\ghc\ghc-6.10.3\ghc-prim-0.1.0.0 -LC:\ghc\ghc-6.10.3 -LC:\ghc\ghc-6.10.3/gcc-lib -LC:/ghc/ghc-6.10.3/gcc-lib dlltest.o -lhw-driver C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.o -lHSbase-4.1.0.0 -lwsock32 -lmsvcrt -lkernel32 -luser32 -lshell32 -lHSinteger-0.1.0.1 -lHSghc-prim-0.1.0.0 -lHSrts -lm -lffi -lgmp -lwsock32 -lmingw32 -lgcc -lmoldname -lmingwex -lmsvcrt -luser32 -lkernel32 -ladvapi32 -lshell32 -lmingw32 -lgcc -lmoldname -lmingwex -lmsvcrt C:/ghc/ghc-6.10.3/gcc-lib/crtend.o
C:\ghc\ghc-6.10.3\gcc-lib\ld.exe: cannot find -lhw-driver
collect2: ld returned 1 exit status
*** Deleting temp files:
Deleting: C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.o C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0/ghc4428_0.rc
*** Deleting temp dirs:
Deleting: C:\DOCUME~1\CHRISC~1\LOCALS~1\Temp\/ghc4428_0

---

As it turns out, the actual linking wasn't as difficult as I was making it out to be. I was using foreign import stdcall which I believed to be correct with a DLL built in Visual Studio 2003. I had to download the pexports tool for MinGW, which lists the functions exported from a DLL. The linker had been looking for HWInit@0 the whole time, but pexports said the DLL was exporting just HWInit.

我将行更改为 foreign import ccall，并且我成功地使用 ghc --make 之一链接了程序dlltest.hs hw-driver.lib 或 ghc --make dlltest.hs -L。 -lhw-driver 由于工作目录中同时存在 .lib 和 .dll 文件。

Answer 1

FFI 规范 # 4.1。 1 进口报关,

impent → " [static] [chname] [&] [cid] "
         | “动态”
         | “包装”

其中 chname 是“C 标头名称”，而不是“库名称”。

FFI 规范 # 4.1。 4 头文件规范

导入声明中指定的 AC 标头始终包含在 #include "chname" 中。 没有明确支持 #include <chname> 样式包含。 ISO C99 [3 ] 标准保证用于 #include <chname> 的任何搜索路径也用于 #include "chname" 并且保证在 #include " 特有的所有路径之后搜索这些路径chname". 此外，我们要求 chname 以 .h 结尾，以使外部实体规范的解析明确。

尝试使用正确的标头名称，

foreign import stdcall "hw-driver.h HW_Init" hwInit :: IO CInt

或者根本不使用标头名称。

foreign import stdcall "HW_Init" hwInit :: IO CInt

---

您的命令行似乎不包含 . 作为库搜索路径。 这很可能就是问题所在。 GHCi 神奇地在库搜索路径中包含 .。

ghc --make dlltest.hs -L. -lhwdriver

如果仍然失败，则可能是静态库引起了问题。 不太可能，但是...

Windows 上的 GHC 默认使用动态链接。 由于您有一个.lib，它是一个静态库，请尝试通知链接器您想要静态链接。

ghc --make dlltest.hs -L. -optl-Bstatic -lhwdriver -optl-Bdynamic

---

至于自动生成的绑定，有

• 绿卡
• C->Haskell
• hsc2hs

我发现 c2hs 是最容易使用的，但我从未尝试过它适用于任何需要 stdcall 的地方。

如果只有 25 次左右的调用，那么手动编写所有外部内容并不是那么繁重。 几年前，为了一些小项目，我设法手动编写到 libvlc 的绑定......

Answer 2

下面是一个调用 GetComputerNamekernel32.dll 的 a>：

{-# LANGUAGE ForeignFunctionInterface #-}

module Main where

import Control.Monad
import Foreign.C
import Foreign.Marshal.Alloc
import Foreign.Marshal.Array
import System.Win32.Types

foreign import stdcall "GetComputerNameW"
  win32_getComputerName :: LPTSTR -> LPDWORD -> IO Bool

getComputerName :: IO String
getComputerName = do
  withTString maxBuf $
    \buf -> do
      alloca $ \len -> do
        pokeArray len [fromIntegral maxLength]

        success <- win32_getComputerName buf len
        when (not success) $ fail "GetComputerName failed"

        [len'] <- peekArray 1 len
        peekTStringLen (buf, (fromIntegral len'))
  where
    maxBuf = take maxLength $ repeat 'x'
    maxLength = 15  -- cheating

main :: IO ()
main = getComputerName >>= putStrLn

使用以下命令构建它

ghc --make compname.hs -lkernel32