Re: UEFI Shell Lib Constructor and Shell Parameters Protocol

[<Jim.Dailey@dell.com>]

Thanks, Jaben. That makes sense.

Now I see the real issue is with the "app" I ran across.  It is a driver,
and it was trying to access command line args.  The driver crashed when
it tried to access the command line, but it had been loaded in memory via
the "load" command.

So, it seems "load" has no mechanism to pass command line arguments to a
driver, and as a result, it apparently doesn't load the shell parameters
protocol on the driver's handle, which caused the crash.

Regards,
Jim

-----Original Message-----
From: Carsey, Jaben [mailto:jaben.carsey@intel.com] 
Sent: Wednesday, April 5, 2017 10:08 AM
To: Dailey, Jim <Jim_Dailey@Dell.com>; Ni, Ruiyu <ruiyu.ni@intel.com>
Cc: edk2-devel@lists.01.org
Subject: RE: UEFI Shell Lib Constructor and Shell Parameters Protocol

Jim,

That protocol must be installed on your applications own image handle for it to be valid.  Locating the protocol on some other image would result with finding the other image's command line parameters and the like...

-Jaben


> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Jim.Dailey@dell.com
> Sent: Wednesday, April 05, 2017 7:07 AM
> To: Carsey, Jaben <jaben.carsey@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>
> Cc: edk2-devel@lists.01.org
> Subject: [edk2] UEFI Shell Lib Constructor and Shell Parameters Protocol
> Importance: High
> 
> 
> A question or two for all shell experts:
> 
> In the UEFI Shell Lib constructor code, if the Shell protocol cannot
> be opened, then an attempt is made to locate it before "giving up".
> 
> However, if the Shell parameters protocol cannot be opened, no attempt
> is made to locate it---the code simply leaves the parameters protocol
> pointer set to NULL. Can anyone explain why this is?
> 
> I came across an app that crashes because of this behavior, but if I
> add code to try and locate the parameters protocol, then the app works
> as designed WRT accessing command line parameters.  Is there some
> lurking issue if an attempt to locate the parameters protocol is made
> and is successful?
> 
> Thanks,
> Jim
> 
> -------
> Here is the relevant code:
> 
> EFI_STATUS
> ShellLibConstructorWorker (
>   IN EFI_HANDLE        ImageHandle,
>   IN EFI_SYSTEM_TABLE  *SystemTable
>   )
> {
>   EFI_STATUS  Status;
> 
>   //
>   // UEFI 2.0 shell interfaces (used preferentially)
>   //
>   Status = gBS->OpenProtocol(
>     ImageHandle,
>     &gEfiShellProtocolGuid,
>     (VOID **)&gEfiShellProtocol,
>     ImageHandle,
>     NULL,
>     EFI_OPEN_PROTOCOL_GET_PROTOCOL
>    );
>   if (EFI_ERROR(Status)) {
>     //
>     // Search for the shell protocol
>     //
>     Status = gBS->LocateProtocol(
>       &gEfiShellProtocolGuid,
>       NULL,
>       (VOID **)&gEfiShellProtocol
>      );
>     if (EFI_ERROR(Status)) {
>       gEfiShellProtocol = NULL;
>     }
>   }
>   Status = gBS->OpenProtocol(
>     ImageHandle,
>     &gEfiShellParametersProtocolGuid,
>     (VOID **)&gEfiShellParametersProtocol,
>     ImageHandle,
>     NULL,
>     EFI_OPEN_PROTOCOL_GET_PROTOCOL
>    );
>   if (EFI_ERROR(Status)) {
> #if 1 // _Dell_ : Search for the parameters protocol too!
>     //
>     // Search for the shell parameters protocol
>     //
>     Status = gBS->LocateProtocol(
>       &gEfiShellParametersProtocolGuid,
>       NULL,
>       (VOID **)&gEfiShellParametersProtocol
>      );
>     if (EFI_ERROR(Status)) {
>       gEfiShellParametersProtocol = NULL;
>     }
> #else
>     gEfiShellParametersProtocol = NULL;
> #endif
>   }
> ...
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