请高手们看看这段代码有什么问题

Question

 function MouseHookProc(iCode:LongInt;wParam:WPARAM;lParam:LPARAM):LRESULT;stdcall;
  begin
       Result:=0;       if iCode<0 then Result:=CallNextHookEx(NextHook,iCode,wParam,lParam);
       if wParam=WM_MOUSEMOVE then begin
          pShare^.MouseInfoStruct:=PMOUSEHOOKSTRUCT(lParam)^;
          GetWindowText(pShare^.MouseInfoStruct.hwnd, pShare^.WindowText,1024);
          SendMessage(pShare^.Data[1],pShare^.Data[2],wParam,lParam); //单步执行到这里出错
          //错误信息为:Project project1.exeraised exception class exteranl 'sigsegv'
          //请前辈们指点，谢谢！
       end;
  end; pShare的数据类型定义在:unit MemoryShare;
{$mode objfpc}{$H+}
interface
uses
  Classes, SysUtils,Windows;
const MappingFileName='MouseHookMappingFile';
type
    TMemoryShare=record
       {Sender:DWORD;
       MessageID:DWORD;}
       Data:array[1..2] of DWORD;
       MouseInfoStruct:TMOUSEHOOKSTRUCT;
       WindowText:array[0..1024] of char;
    end;
    PMemoryShare =^TMemoryShare;
implementation
end.             

Answer 1

下面是完整工程
MouseHook.Dll工程unit MouseHookDll;{$mode delphi}{$H+}interfaceuses
  Classes, SysUtils,Windows,Messages,MemoryShare;
  var
     pShare:PMemoryShare;
     NextHook:LRESULT;
     FileMappingHandle:HANDLE;
  function StartHook(sender:HWND;MessageID:DWORD):BOOL;stdcall;
  function StopHook():BOOL;stdcall;
  function MouseHookProc(iCode:LongInt;wParam:WPARAM;lParam:LPARAM):LRESULT;stdcall;
  procedure CreateOfOpenMaping();
implementation
  function MouseHookProc(iCode:LongInt;wParam:WPARAM;lParam:LPARAM):LRESULT;stdcall;
  begin
       Result:=0;       if iCode<0 then Result:=CallNextHookEx(NextHook,iCode,wParam,lParam);
       if wParam=WM_MOUSEMOVE then begin
          pShare^.MouseInfoStruct:=PMOUSEHOOKSTRUCT(lParam)^;
          GetWindowText(pShare^.MouseInfoStruct.hwnd, pShare^.WindowText,1024);
          SendMessage(pShare^.Data[1],pShare^.Data[2],wParam,lParam);
       end;
  end;
  {挂钩,参数说明sender为调用本Dll的窗口句柄，MessageID为自定义消息}
  function StartHook(sender:HWND;MessageID:DWORD):BOOL;stdcall;begin
      CreateOfOpenMaping();
      Result:=False;
      pShare^.Data[1]:=sender;
      pShare^.Data[2]:=MessageID;
      NextHook:=SetWindowsHookEx(WH_MOUSE,MouseHookProc,GetModuleHandle(nil),0);
      Result:=NextHook<>0;
  end;
  {脱钩}
  function StopHook():BOOL;stdcall;begin
      if NextHook<>0 then begin
         UnHookWindowsHookEx(NextHook);
         NextHook:=0;
      end;
      Result:=NextHook=0;
  end;
  procedure CreateOfOpenMaping();begin
    NextHook:=0;
    FileMappingHandle:=OpenFileMapping(FILE_MAP_WRITE,False,MappingFileName);
    if FileMappingHandle=0 then begin
       FileMappingHandle:=CreateFileMapping($FFFFFFFF,nil,PAGE_READWRITE,0,SizeOf(TMemoryShare),MappingFileName);
    end else begin
       Exception.Create('不能创建共享内存');
    end;
    pShare:=MapViewOFFile(FileMappingHandle,FILE_MAP_READ or FILE_MAP_WRITE,0,0,0);
    if pShare=nil then begin
       CloseHandle(FileMappingHandle);
       Exception.Create('不能映射共享内存');
    end;
  end;{DLL初始化时候执行的动作}
initialization
    {NextHook:=0;
    FileMappingHandle:=OpenFileMapping(FILE_MAP_WRITE,False,MappingFileName);
    if FileMappingHandle=0 then begin
       FileMappingHandle:=CreateFileMapping($FFFFFFFF,nil,PAGE_READWRITE,0,SizeOf(TMemoryShare),MappingFileName);
    end else begin
       Exception.Create('不能创建共享内存');
    end;
    pShare:=MapViewOFFile(FileMappingHandle,FILE_MAP_READ or FILE_MAP_WRITE,0,0,0);
    if pShare=nil then begin
       CloseHandle(FileMappingHandle);
       Exception.Create('不能映射共享内存');
    end;}
{DLL释放时候执行的动作}
finalization
    UnMapViewOfFile(pShare);
    CloseHandle(FileMappingHandle);
end.
unit MemoryShare;{$mode objfpc}{$H+}interfaceuses
  Classes, SysUtils,Windows;
const MappingFileName='MouseHookMappingFile';
type
    TMemoryShare=record
       {Sender:DWORD;
       MessageID:DWORD;}
       Data:array[1..2] of DWORD;
       MouseInfoStruct:TMOUSEHOOKSTRUCT;
       WindowText:array[0..1024] of char;
    end;
    PMemoryShare =^TMemoryShare;
implementationend.主程序:
[code=Delphi(Pascal)]
unit MouseHookMain;{$mode delphi}{$H+}interfaceuses
  Classes,Windows,Messages, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
  StdCtrls,MemoryShare;type  { TForm1 }  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Edit1: TEdit;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
    procedure WndProc(var TheMessage : TMessage); override;
  end; var
  Form1: TForm1;
  pShare:PMemoryShare;
  FileMappingHandle:HANDLE;
  const MessageID=WM_USER+100;
implementation
    function StartHook(sender:HWND;MessageID:DWORD):BOOL;stdcall;external 'MouseHook.DLL';
    function StopHook():BOOL;stdcall;external  'MouseHook.DLL';    procedure TForm1.Button1Click(Sender: TObject);begin
        StartHook(Form1.Handle,MessageID);
    end;    procedure TForm1.Button2Click(Sender: TObject);begin
        StopHook();
    end;    procedure TForm1.FormCreate(Sender: TObject);begin
        pShare:=nil;
    end;    procedure TForm1.WndProc(var TheMessage : TMessage);begin
        FileMappingHandle:=OpenFileMapping(FILE_MAP_WRITE,False,MappingFileName);
        if FileMappingHandle=0 then begin
           Exception.Create('不能打开共享内存');
        end;
        pShare:=MapViewOfFile(FileMappingHandle,FILE_MAP_READ OR FILE_MAP_WRITE,0,SizeOf(TMemoryShare),0);
        if pShare=nil then begin
           Exception.Create('不能映射共享内存');
        end;
        if TheMessage.Msg=MessageID then begin
            Edit1.Text:=string(pShare^.WindowText);
        end else begin
            inherited;
        end;
    end;initialization
  {$I MouseHookMain.lrs}end.
[/code]

Answer 2

SIGSEGV --- Segment Fault. The possible cases of your encountering this error are: 
1.buffer overflow --- usually caused by a pointer reference out of range. 
2.stack overflow --- please keep in mind that the default stack size is 8192K. 
3.illegal file access --- file operations are forbidden on our judge system.SIGSEGV(Segment fault)意味着指针所对应的地址是无效地址，没有物理内存对应该地址。

Answer 3

问题就在这一句SendMessage(pShare^.Data[1],pShare^.Data[2],wParam,lParam);
实在想不透了，请前辈们帮帮忙吧。
我修改成这样样子又没有问题，可以确定是pShare^.Data[1]的问题，可是我又找不到是什么原因。
SendMessage(0,pShare^.Data[2],wParam,lParam);

Answer 4

pShare:PMemoryShare;是指针吧？你在
procedure TForm1.FormCreate(Sender: TObject);begin
   pShare:=nil;
end;
没有分配内存，导致指针非法。#include <iostream.h>
typedef struct test 
{
int a;
int b;
}*PTEST,TEST;void main()
{
//   PTEST p = new TEST;
PTEST p;
   p->a = 2;
   p->b = 3;
   cout<<p->a<<"==="<<p->b<<endl;
//   delete p;
}你的和如上C++代码类似,不new不行

Answer 5

本质的问题我找出来了，是这一句Edit1.Text:=string(pShare^.WindowText);
想不明白为什么出错了。

Answer 6

pShare没分配内存吧？指针合法？

Answer 7

pShare是指向一个共享内存的，其它的值都可以读得到。