Re: LocateHandle for gEfiShellProtocolGuid is failing in my application

[GN Keshava <keshava.gn@gmail.com>]

Thanks a lot, Andrew and Jaben.
I will check these and get back...

Thanks again. :)

Regards,
Keshava

On ಗುರು, ಡಿಸೆಂ 22, 2016 12:43 ಪೂರ್ವಾಹ್ನ Andrew Fish <afish@apple.com> wrote:

> On Dec 20, 2016, at 11:32 PM, GN Keshava <keshava.gn@gmail.com> wrote:
>
> Hi,
>
> I'm developing a shell application. A call to LocateHandle for
> gEfiShellProtocolGuid is failing with Status 0x0E.
>
> Below is my code. Please let me know what I'm doing wrong.
>
>
> Assuming this is your entire code fragment you are passing 2 uninitialized
> values
>
> If you want to probe the size you need to:
> BufferSize = 0;
>
> Status = gBS->LocateHandle(ByProtocol, &gEfiShellProtocolGuid, NULL,
> &BufferSize, Buffer); // Get BufferSize
> if (EFI_ERROR(Status))
>
>
> Per the spec you would expect to get Status = EFI_BUFFER_TOO_SMALL if you
> need to grow the size. You should only allocate the buffer and retry if you
> get EFI_BUFFER_TOO_SMALL.
>
> You don't handle the case of  EFI_NOT_FOUND.
>
> FYI the error codes are defined in the UEFI Spec and exist here in the
> code:
> https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Base.h
>
>
> ///
> /// The buffer was not large enough to hold the requested data.
> /// The required buffer size is returned in the appropriate
> /// parameter when this error occurs.
> ///
> #define RETURN_BUFFER_TOO_SMALL ENCODE_ERROR (5)
>
>
> ...
>
> ///
> /// The item was not found.
> ///
> #define RETURN_NOT_FOUND ENCODE_ERROR (14)
>
>
> #define ENCODE_ERROR(StatusCode) ((RETURN_STATUS)(MAX_BIT | (StatusCode)))
>
>
> MAX_BIT is going to be defined as BIT63 or BIT31 depending on the CPU
> architecture you are using.
>
>
> Print(L"LocateHandle Status 0x%x\n",Status);
>
> Status = gBS->AllocatePool(EfiBootServicesData, BufferSize,
> (void**)&Buffer);
> if (EFI_ERROR(Status))
> Print(L"AllocatePool Status 0x%x\n",Status);
>
>
> I mentioned in the other mail that you can use %r to get a string for the
> error.
>
> Thanks,
>
> Andrew Fish
>
>
> Status = gBS->LocateHandle(ByProtocol, &gEfiShellProtocolGuid, NULL,
> &BufferSize, Buffer);
> if (EFI_ERROR(Status))
> Print(L"LocateHandle Status 0x%x\n",Status);
>
> All calls failing with Status being 0x0E. Please help me to solve this. Is
> there any special requirement for using this protocol?
>
> Thanks.
> Regards,
> Keshava
>
> ___________________________________
>
>
>