AccessViolation從Delphi使用C++ DLL時

Question

我有一個奇怪的問題，試圖使用Delphi（Turbo Delphi 2006）程序中使用C++編寫的DLL。

當我從命令行運行Delphi程序（見下文）時，一切正常。另外，當我從Delphi環境運行而不進行調試時（CTRL + SHIFT + F9），一切都很好。然而，隨着調試（F9）運行時，它，我得到以下錯誤：

Project Z:\test.exe faulted with message: 'access violation at 0x00403fdf: read of address 0x00a14e74'. Process stopped. Use Step or Run to continue.

奇怪的是，在執行最後一次出現的錯誤「結束」。的代碼。德爾福的CPU顯示說，這是在某處「UnsetExceptionHandler」，四大行前「FinalizeUnits」，更具體，在

00403FDF 3901 cmp [ecx],eax

我在這裏損失是有點; Delphi不是我的領域（我是編寫DLL的人，現在我需要提供一個使用它的示例程序）。所以在這個問題上的任何幫助感激:)

這裏的Delphi代碼：

program libiup_integration; 
{$APPTYPE CONSOLE} 

uses 
    SysUtils, 
    WinProcs; 

type 
    T_F_GetError = function() : pchar; stdcall; 

    T_F_SetPath = function(path: pchar) : integer; stdcall; 

    T_F_GetStrat = function(date: integer;time: single;lat: single;lon: single) : single; cdecl; 

var 
    F_GetError : T_F_GetError; 
    PF_GetError : TFarProc; 
    F_SetPath : T_F_SetPath; 
    PF_SetPath : TFarProc; 
    F_GetStrat : T_F_GetStrat; 
    PF_GetStrat : TFarProc; 
    DLLHandle : THandle; 
    errormsg : pchar; 
    h5path : pchar; 
    h5err  : integer; 
    date  : integer; 
    time  : single; 
    lat  : single; 
    lon  : single; 
    strat  : single; 
    i   : integer; 

begin 
    DLLHandle := LoadLibrary('libiup.dll'); 
    if DLLHandle <> 0 then 
    begin 
     { construct the function pointers } 
     PF_GetError := GetProcAddress(DLLHandle, 'getError'); 
     PF_SetPath := GetProcAddress(DLLHandle, 'setPath'); 
     PF_GetStrat := GetProcAddress(DLLHandle, 'getStrat'); 

     { If the function pointer is valid ... } 
     if (PF_GetError <> nil) and (PF_SetPath <> nil) and (PF_GetStrat <> nil) then 
     begin 
      { Assign the function pointer to the function handle } 
      @F_GetError := PF_GetError; 
      @F_SetPath := PF_SetPath; 
      @F_GetStrat := PF_GetStrat; 

      errormsg := StrAlloc(4096); 

      h5path := StrAlloc(256); 
      StrCopy(h5path, 'z:\data\%Y%m.h5'); 
      h5err := F_SetPath(h5path); 
      if h5err < 0 then 
      begin 
       errormsg := F_GetError(); 
       WriteLn(errormsg); 
      end; 

      for i := 1 to 10 do 
      begin 
       date := 4745; 
       time := 12.34 + i/10; 
       lat := -35.321 + i*i; 
       lon := 115.67 - i*i; 

       strat := F_GetStrat(date, time, lat, lon); 
       if strat < 0. then 
       begin 
        errormsg := F_GetError(); 
        WriteLn(errormsg); 
       end; 

       WriteLn('Value returned by getStrat call no. ' + IntToStr(i) + ': ' + FloatToStr(strat)); 
      end; 

      { and finally, delete the function pointers ...} 
      PF_SetPath := nil; 
      PF_GetStrat := nil; 
      PF_GetError := nil; 
      FreeLibrary(DLLHandle); 
      WriteLn('Press ENTER to continue ...'); 
      ReadLn; 
     end 

     else 
     { The function pointer was not valid, so this means that the function was not found in the dll. } 
     begin 
      WriteLn('Function not found'); 
      RaiseLastOSError; 
     end; 
    end 

    else 
    { The LoadLibrary function did not return a valid DLL handle. } 
    begin 
     WriteLn('DLL not loaded'); 
     FreeLibrary(DLLHandle); 
     WriteLn('Press ENTER to continue ...'); 
     ReadLn; 
    end; 
end. 

dll.h

#ifndef LIBIUP_DLL_H_ 
#define LIBIUP_DLL_H_ 
#ifdef BUILD_DLL 
#define WIN32DLL_API __declspec(dllexport) 
#else 
#define WIN32DLL_API __declspec(dllimport) 
#endif 

#include "stratcalc/SimpleStratosphericColumnCalculator.h" 
#include <iostream> 
#include <string> 
#include "boost/date_time/posix_time/posix_time.hpp" 

#ifdef __cplusplus 
extern "C" {   /* Assume C declarations for C++ */ 
#endif 
    WIN32DLL_API BOOL __stdcall DllMain(HANDLE, DWORD, LPVOID); 
    WIN32DLL_API int setPath(char*); 
    WIN32DLL_API const char* getError(); 
    WIN32DLL_API float getStrat(int, float, float, float); 
    std::string errormsg; 
    SimpleStratosphericColumnCalculator* calc; 
#ifdef __cplusplus 
}      /* End of extern "C" */ 
#endif 

#endif 

dll.cpp

#ifdef BUILD_DLL 
#include "windows.h" 
#include "dll.h" 
#include <iostream> 
// different functions of this library 
= new SimpleStratosphericColumnCalculator(); 


WIN32DLL_API BOOL __stdcall DllMain(HANDLE hModule, 
         DWORD ul_reason_for_call, 
         LPVOID lpReserved 
        ) 
{ 
    switch (ul_reason_for_call) 
    { 
     case DLL_PROCESS_ATTACH: 
      calc = new SimpleStratosphericColumnCalculator(); 
      break; 
     case DLL_THREAD_ATTACH: 
      calc = new SimpleStratosphericColumnCalculator(); 
      break; 
     case DLL_THREAD_DETACH: 
      delete calc; 
      break; 
     case DLL_PROCESS_DETACH: 
      delete calc; 
      break; 
    } 

    return TRUE; 
} 


WIN32DLL_API int setPath(char* Path) 
{ 
    errormsg = ""; 
    return calc->setPath(Path); 
} 

WIN32DLL_API const char* getError() 
{ 
    std::cout << errormsg << std::endl; 
    return errormsg.c_str(); 
} 

WIN32DLL_API float getStrat(int Date, float Time, float Lat, float Lon) 
{ 
    errormsg = ""; 
    if (Lat < -90. || Lat > 90.) 
     errormsg += "Latitude value out of bounds.\n"; 
    if (Lon < 0. || Lon > 360.) 
     errormsg += "Longitude value out of bounds.\n"; 
    if (errormsg != "") 
     return -1.; 
    return (float)calc->getStrat(Date, Time, Lat, Lon); 
} 
#else 
#endif 

Answer 1

檢查調用約定。我在一個函數中看到了2個函數的stdcall和cdecl。嘗試改變一切，以stdcall或cdecl，看看它是否工作

Answer 2

我認爲無論DLL_THREAD_DETACH和DLL_PROCESS_DETACH將被調用。所以你會雙重刪除你的計算對象。

的Try ...

if (calc != NULL) 
{ 
    delete calc; 
    calc = NULL; 
} 

Answer 3

我調用LoadLibrary加載DLL時，也有類似的問題。

我通過在FreeLibrary之前調用Application.ProcessMessages得到了它。