11

这可能是一个非常容易回答的问题，但出于某种原因，我真的很挣扎。

我有一个用 C 语言编写的 DLL，用于在协议级别访问硬件，我想编写一个 Haskell 程序来调用其中一些 C 函数。这是相关 C 标头的片段（由于可能的版权问题，名称只是稍微混淆了）：

#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 可以正常工作。该 DLL 被命名为“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 并在其中调用最简单的函数：

{-# 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"

给我带来麻烦的线是外国进口线。据我了解，语法是 foreign (import/export) (ccall/stdcall) library-name C-function-name haskell-function-name :: Haskell type declaration。所以我的应该是foreign import stdcall（因为你在Win32中加载DLL时使用stdcall）“hw-driver”（因为文件名为“hw-driver.dll”并且它与dlltest.hs位于同一目录中） “HW_Init”（C 中函数的名称） hwInit :: IO (Cint)（无效参数，返回一个 int）。

但是，当我尝试运行时ghci dlltest.hs，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。好的，所以也许我必须将库名称和函数名称放在一个字符串中，我已经在几个地方看到过。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，因为我可以在 ghci 中运行从 Real World Haskell 复制粘贴的以下代码：

{-- 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 --}

这么长的问题，我如何正确地在 Win32 DLL 上声明一个外部导入？我在谷歌上找不到任何东西。

为了解决这个问题，我是否能够使用 c2hs 或 hsc2hs 之类的程序来解析头文件hw-driver.h，这样我就不必为该 DLL 中包含的所有 20-25 函数手动编写外部导入调用? 我也找不到任何像样的例子。

编辑： ehemient 指出，外国进口行的正确语法是：

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

有了这个，我可以调用ghci dlltest.hs -lhw-driver并正确调用主函数并返回成功的代码。但是，该命令ghc --make dlltest.hs -lhw-driver因链接器错误而失败。因此，这是该命令的详细输出（请注意，我在工作目录中有所有 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

事实证明，实际的链接并不像我想象的那么困难。我正在使用foreign import stdcall我认为在 Visual Studio 2003 中构建的 DLL 是正确的。我必须下载pexportsMinGW 的工具，其中列出了从 DLL 导出的函数。链接器一直在寻找 HWInit@0，但pexports说 DLL 只导出了 HWInit。

我将我的行改为，并且由于工作目录中同时存在 .lib 和 .dll 文件，foreign import ccall我能够成功地链接程序。ghc --make dlltest.hs hw-driver.libghc --make dlltest.hs -L. -lhw-driver

4

2 回答 2

5

FFI 规范#4.1.1 进口声明，

impent → " [ static] [ chname ] [&] [ cid ] "
            | " dynamic"
            | " wrapper"

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 ] 标准保证将用于#include <chname>的任何搜索路径也用于#include "chname"，并保证在所有#include "chname"唯一的路径之后搜索这些路径。此外，我们要求chname结束.h以使外部实体规范的解析明确。

尝试使用正确的标题名称，

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

或者根本没有标题名称。

foreign import stdcall "HW_Init" hwInit :: IO CInt

您的命令行似乎没有包含.在库搜索路径中。这很可能是问题所在。GHCi 神奇地包含.在库搜索路径中。

ghc --make dlltest.hs -L。-lhwdriver

如果仍然失败，则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.lib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

我发现 c2hs 是最容易使用的，但我从未在任何需要stdcalls.

如果只有 25 个左右的调用，手动编写所有的东西并不是那么繁重。几年前，foreign我设法手动编写绑定，用于一些小项目......libvlc

于 2009-06-22T16:10:24.463 回答
3

下面是一个调用 [GetComputerName]( http://msdn.microsoft.com/en-us/library/ms724295(VS.85).aspx)的工作示例kernel32.dll：

{-# 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

构建它

ghc --make compname.hs -lkernel32
于 2009-06-22T17:21:21.297 回答