Question

这可能是一个非常容易回答的问题，但出于某种原因，我真的很难接受它。

我有一个用C语言编写的DLL来访问协议级别的硬件，我想写一个调用其中一些C函数的Haskell程序。这是相关C标题的片段（由于可能的版权问题，名称只是略微混淆）：

#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DLL，因此我确信DLL工作正常。该DLL名为“hw-driver.dll”。

接下来，这里是Haskell源代码，用于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"

给我带来麻烦的是外国进口线。据我了解，语法是外来的（导入/导出）（ccall / stdcall） library-name C-function-name haskell-function-name < / em> :: Haskell类型声明。所以我的应该是外部导入stdcall（因为你在Win32中加载DLL时使用stdcall）“hw-driver”（因为该文件名为“hw-driver.dll”，它与dlltest.hs位于同一目录中） “HW_Init”（C中函数的名称）hwInit :: IO（Cint）（void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，也许我必须将库名和函数名都放在一个字符串中，我在一些地方看到过。如果我尝试运行它，那么我得到：

[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。

我不相信我的ghc设置（6.10.3）有任何问题，因为我可以运行以下代码，这些代码是从ghci中的Real World Haskell复制粘贴的：

{-- 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 --}

这么久的问题简介，如何在Win32 DLL上正确声明外部导入？我无法在Google上找到任何。

对于那个问题上的那种标记，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，这样我就不必为所有人手动编写外部导入调用了该DLL包含20-25个函数？我也找不到任何合适的例子。

编辑：ephemient指出外国导入行的正确语法是：

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

通过这个，我可以调用ghci dlltest.hs -lhw-driver并使用成功的返回代码正确调用main函数。但是，命令ghc --make dlltest.hs -lhw-driver失败并出现链接器错误。所以，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

<小时/> 事实证明，实际链接并不像我想要的那样困难。我正在使用foreign import stdcall ，我认为这对于使用Visual Studio 2003内置的DLL是正确的。我必须为MinGW下载pexports工具，列出从DLL导出的函数。链接器一直在寻找HWInit @ 0，但pexports表示DLL只导出HWInit。

我改为将我的行改为foreign import ccall ，我成功地使用ghc --make dlltest.hs hw-driver.lib或ghc --make dlltest.hs -L. -lhw-driver之一链接了该计划由于.lib和.dll文件都在工作目录中可用。

Answer 1

FFI spec # 4.1.1 Import Declarations，


迫切→“[static] [ chname ] [＆amp;] [ cid ]”
  | “dynamic”
  | “wrapper”

其中 chname 是“C header name”，而不是“library name”。

FFI spec # 4.1.4 Specification of Header Files

导入声明中指定的C标头始终包含在#include " chname "中。对#include < chname >样式包含没有明确的支持。 ISO C99 [3]标准保证用于#include < chname >的任何搜索路径也用于#include " < em> chname "并保证在#include " chname "的所有路径之后搜索这些路径。此外，我们要求 chname 在.h上结束，以便明确解析外部实体的规范。

尝试使用正确的标题名称

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

或根本没有标题名称。

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，可能是导致问题的静态库。不太可能，但是......

Windows上的GHC默认使用动态链接。由于您有一个静态库.lib，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

对于自动生成的绑定，有

我发现c2hs最容易使用，但我从未尝试过需要stdcall的任何内容。

如果只有25个电话左右，手动写入所有foreign内容并不是。几年前，我设法手动将绑定写入libvlc，用于一些小项目......

Answer 2

以下是从[{1}}调用[GetComputerName]（http://msdn.microsoft.com/en-us/library/ms724295(VS.85).aspx)）的工作示例：

kernel32.dll

使用

构建它

{-# 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

Haskell外部导入stdcall对DLL函数

2 个答案: