Step to UEFI (25） ----- 命令行参数为什么是Unicode

之前的文章【参考1】，提出了一个问题：为什么 CLIB 下面收到的参数 IN char **Argv 实际上是一个 Unicode ?

为了回答这个问题，还要在代码中寻找答案。同样，追踪一下当我们使用 CLIB 的时候，编译过程中程序被添加了什么。分析方法和之前的类似，我们最终得到下面这个结果：

_ModuleEntryPoint:\MdePkg\Library\UefiApplicationEntryPoint\ApplicationEntryPoint.c 入口还是他

框架没变

ProcessLibraryConstructorList (1)
ProcessModuleEntryPointList (2)
ProcessLibraryDestructorList (3)

(1) ProcessLibraryConstructorList:\Build\AppPkg\DEBUG_VS2008\IA32\AppPkg\Applications\ArgTest\ArgTest\DEBUG\AutoGen.c

  Status = UefiRuntimeServicesTableLibConstructor (ImageHandle, SystemTable);  (1.1)
  Status = UefiBootServicesTableLibConstructor (ImageHandle, SystemTable);(1.2)
  Status = UefiLibConstructor (ImageHandle, SystemTable);	(1.3)
  Status = ShellLibConstructor (ImageHandle, SystemTable);	(1.4)
  Status = UefiHiiServicesLibConstructor (ImageHandle, SystemTable); 	(1.5)
  Status = __wchar_construct (ImageHandle, SystemTable);	(1.6)

 

(1.1) UefiRuntimeServicesTableLibConstructor :\MdePkg\Library\UefiRuntimeServicesTableLib\UefiRuntimeServicesTableLib.c

(1.2) UefiBootServicesTableLibConstructor :\MdePkg\Library\UefiBootServicesTableLib\UefiBootServicesTableLib.c

(1.3) UefiLibConstructor :\MdePkg\Library\UefiLib\UefiLib.c

(1.4) ShellLibConstructor :\ShellPkg\Library\UefiShellLib\UefiShellLib.c

ShellLibConstructorWorker //加载一些 Shell Protocol

(1.5) UefiHiiServicesLibConstructor :\MdeModulePkg\Library\UefiHiiServicesLib\UefiHiiServicesLib.c

(1.6) __wchar_construct :\StdLib\LibC\Wchar\ConsDecons.c

(2) ProcessModuleEntryPointList :\Build\AppPkg\DEBUG_VS2008\IA32\AppPkg\Applications\ArgTest\ArgTest\DEBUG\AutoGen.c

	return ShellCEntryLib (ImageHandle, SystemTable); (2.1)

 

(2.1) ShellCEntryLib : \ShellPkg\Library\UefiShellCEntryLib\UefiShellCEntryLib.c

ReturnFromMain = ShellAppMain (
                       EfiShellParametersProtocol->Argc,
                       EfiShellParametersProtocol->Argv
                      );  

 

(2.1.1) ShellAppMain : \StdLib\LibC\Main\Main.c

	ExitVal = (INTN)main( (int)Argc, (wchar_t **)Argv);

 

对照 map 文件可以看到这个main就是我们写的 ArgTest中的Main

0001:000007d0 _ShellGetEnvironmentVariable 00000a50 f UefiShellLib:UefiShellLib.obj
0001:000007eb _ShellIsFile 00000a6b f UefiShellLib:UefiShellLib.obj
0001:00000830 _UefiHiiServicesLibConstructor 00000ab0 f UefiHiiServicesLib:UefiHiiServicesLib.obj
0001:000008a8 _main 00000b28 f ArgTest:ArgTest.obj
0001:00000962 _GetPerformanceCounter 00000be2 f BaseTimerLibNullTemplate:TimerLibNull.obj
0001:00000967 _GetPerformanceCounterProperties 00000be7 f BaseTimerLibNullTemplate:TimerLibNull.obj

(3) ProcessLibraryDestructorList :\Build\AppPkg\DEBUG_VS2008\IA32\AppPkg\Applications\ArgTest\ArgTest\DEBUG\AutoGen.c

	  Status = __wchar_deconstruct (ImageHandle, SystemTable); (3.1)
	  Status = ShellLibDestructor (ImageHandle, SystemTable);  (3.2)

 

(3.1) __wchar_deconstruct :\StdLib\LibC\Wchar\ConsDecons.c
(3.2) ShellLibDestructor :\ShellPkg\Library\UefiShellLib\UefiShellLib.c

上面的调用关系可以用下面的图来简单总结一下

====================================分割线====================================

我们在运行期确定是下面的代码来取得参数的

    //
    // try to get shell 1.0 interface instead.
    //
    Status = SystemTable->BootServices->OpenProtocol(ImageHandle,
                               &gEfiShellInterfaceGuid,
                               (VOID **)&EfiShellInterface,
                               ImageHandle,
                               NULL,
                               EFI_OPEN_PROTOCOL_GET_PROTOCOL
                              );
    if (!EFI_ERROR(Status)) {
      //
      // use shell 1.0 interface
      //
      ReturnFromMain = ShellAppMain (
                         EfiShellInterface->Argc,
                         EfiShellInterface->Argv
                        );
    } else {
      ASSERT(FALSE);
    }

 

对于这个EfiShellInterface ，我们可以在 《EFI Shell Developer’s Guide》 找到。

因此，可以看到，取出来的Argc就是CHAR16.

参考：

1.http://www.lab-z.com/step-to-uefi-15%EF%BC%89-%E5%91%BD%E4%BB%A4%E8%A1%8C%E5%8F%82%E6%95%B0-again/