delphi - 当系统文件实际存在时找不到它

Question

系统找不到alg.exe，但它确实存在 - “c:\windows\system32\alg.exe”。

我最近从 Win 7 x86 迁移到 x64，当我使用 x86 时，我对此没有任何问题，尝试了 Delphi 7 和 XE2。

我正在使用的代码:

if FileExists('c:\windows\system32\alg.exe') then
  ShowMessage('fe') else ShowMessage('fne');

尝试使用管理员权限获取文件+我的应用程序的所有权 - 同样的问题。

伙计们，检查一下是否是 x64..

function IsWow64Process(Handle:THandle; var IsWow64 : BOOL) : BOOL; stdcall; external 'kernel32.dll';

function IS64 : Boolean;
var
 xIS64 : Bool;
begin
 if IsWow64Process(GetCurrentProcess, xIS64) then
  Result := xIS64 else RaiseLastOSError;
end;

Answer 1

这是因为WOW64 file system redirection ，如果您的32位应用程序想要访问 native system32目录，则必须使用Wow64DisableWow64FsRedirection函数或 Sysnative 别名。

Wow64禁用Wow64Fs重定向

尝试这个示例

{$APPTYPE CONSOLE}

uses
  SysUtils,
  Windows;

Function Wow64DisableWow64FsRedirection(Var Wow64FsEnableRedirection: LongBool): LongBool; StdCall;
  External 'Kernel32.dll' Name 'Wow64DisableWow64FsRedirection';
Function Wow64EnableWow64FsRedirection(Wow64FsEnableRedirection: LongBool): LongBool; StdCall;
  External 'Kernel32.dll' Name 'Wow64EnableWow64FsRedirection';

Var
  Wow64FsEnableRedirection: LongBool;
begin
 try
    if Wow64DisableWow64FsRedirection(Wow64FsEnableRedirection) then
    begin
      if FileExists('c:\windows\system32\alg.exe') then
       Writeln('fe')
      else
       Writeln('fne');

      if not Wow64EnableWow64FsRedirection(Wow64FsEnableRedirection) then
       RaiseLastOSError;
    end
    else
    RaiseLastOSError;
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;

end.
end.

另外，请查看此主题的 MSDN 文档。

Applications can control the WOW64 file system redirector using the Wow64DisableWow64FsRedirection, Wow64EnableWow64FsRedirection, and Wow64RevertWow64FsRedirection functions. Disabling file system redirection affects all file operations performed by the calling thread, so it should be disabled only when necessary for a single CreateFile call and re-enabled again immediately after the function returns. Disabling file system redirection for longer periods can prevent 32-bit applications from loading system DLLs, causing the applications to fail.

Sysnative

32-bit applications can access the native system directory by substituting %windir%\Sysnative for %windir%\System32. WOW64 recognizes Sysnative as a special alias used to indicate that the file system should not redirect the access. This mechanism is flexible and easy to use, therefore, it is the recommended mechanism to bypass file system redirection. Note that 64-bit applications cannot use the Sysnative alias as it is a virtual directory not a real one.

{$APPTYPE CONSOLE}

{$R *.res}

uses
  SysUtils,
  Windows;

begin
 try
    if FileExists('c:\windows\SysNative\alg.exe') then
     Writeln('fe')
    else
     Writeln('fne');
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;

end.