如何检查用户是否具有使用windows api访问文件的权限

我正试图为windows编写一个简单的函数来回答以下问题。

哪里
R是(泛型读、泛型写、泛型执行)的某种组合

我编写的代码如下所示。应用程序调用显示的第一个UserHasPermission。

我的问题有两个:
1.有更好的方法吗?

function UserHasPermission(APermission: Longword; out HasPermission: Boolean; AFileName: WideString; AUserName: String; ADomainName: String): Boolean;
    var
      SID: PSID;
      ACL: PACL;
    begin
      SID := nil;
      ACL := nil;
      try
        Result := GetUserSID(SID, AUserNAme, ADomainName);
        Result := Result and GetFileDACL(AFileName, ACL);
        Result := Result and UserHasPermission(APermission, HasPermission, ACL, SID);
      finally
        Dispose(SID);
      end;
    end;

    function UserHasPermission(APermission: Longword; out HasPermission: Boolean; AACL: PACL; AUserSID: PSID): Boolean;
    var
      T: TRUSTEE;
      Rights: ACCESS_MASK;
    begin
      BuildTrusteeWithSid(@T, AUserSID);
      Result := GetEffectiveRightsFromAcl(AACL, @T, @Rights) = ERROR_SUCCESS;
      HasPermission := (Rights and APermission) = APermission;
    end;

    function GetUserSID(out ASID: PSID; AUserName: WideString; const ADomainName: WideString): Boolean;
    var
      NSID, NDomain: Longword;
      Use: SID_NAME_USE;
      DomainName: WideString;
    begin
      Result := False;
      if Length(AUserName) > 0 then
        begin
          if Length(ADomainName) > 0 then
            AUserName := ADomainName + '\' + AUserName;

          // determine memory requirements
          NSID := 0;
          NDomain := 0;
          LookupAccountNameW(nil, PWideChar(AUserName), nil, NSID, nil, NDomain, Use);

          // allocate memory
          GetMem(ASID, NSID);
          SetLength(DomainName, NDomain);

          Result := LookupAccountNameW(nil, PWideChar(AUserName), ASID, NSID, PWideChar(DomainName), NDomain, Use);
        end;
    end;

    function GetFileDACL(AFileName: WideString; out AACL: PACL): Boolean;
    var
      SD: PSecurityDescriptor;
      NSD, NNeeded: Longword;
      Present, Defualted: Longbool;
    begin
      GetFileSecurityW(PWideChar(AFileName), DACL_SECURITY_INFORMATION, nil, 0, NNeeded);
      GetMem(SD, NNeeded);
      try
        NSD := NNeeded;
        Result := GetFileSecurityW(PWideChar(AFileName), DACL_SECURITY_INFORMATION, SD, NSD, NNeeded);
        Result := Result and GetSecurityDescriptorDacl(SD, Present, AACL, Defualted);
        Result := Result and Present;
      finally
        Dispose(SD);
      end;
    end;