How to open a file on it the full path in UEFI

Question

I am new to UEFI. I am trying to open a file from my UEFI application. File path

fs1:/myfolder/myfile.txt

Code (using this answer ):

efiStatus = bs->LocateHandleBuffer(ByProtocol, 
                                   &sfspGuid, 
                                   NULL, 
                                   &handleCount, 
                                   &handles);

for (index = 0; index < (int)handleCount; ++ index)
{
    EFI_SIMPLE_FILE_SYSTEM_PROTOCOL* fs = NULL;

    efiStatus = bs->HandleProtocol(
        handles[index],
        &sfspGuid,
        (void**)&fs);

    EFI_FILE_PROTOCOL* root = NULL;
    ...
    efiStatus = fs->OpenVolume(fs, &root);

    EFI_FILE_PROTOCOL* token = NULL;

    efiStatus = root->Open(
        root, 
        &token,
        L"myfolder\\myfile.txt",
        EFI_FILE_MODE_READ,
        EFI_FILE_READ_ONLY | EFI_FILE_HIDDEN | EFI_FILE_SYSTEM);
}

But using this method, I can go through all the file system descriptors and open each volume and try to open the file.

But I want to give the full path to my file and open it in it.

How can I understand that?

---

EDIT:

I tried using the Shell API to open the file, as suggested by @Alex in the comments. Below is the code. But it freezes in function OpenFileByName.

What is the error in this code? (argv [1] will be my file path fs1:\myfile.txt)

EFI_STATUS
EFIAPI
main (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{

    EFI_STATUS      status;
    UINTN           argc;
    CHAR16          **argv;
    SHELL_FILE_HANDLE Handle;

    status = get_args(&argc, &argv);
    if (EFI_ERROR(status)) {
       Print(L"ERROR: Parsing command line arguments: %d\n", status);
       return status;
    }

    if (argc <= 1){
        Print(L"No file name to open\n");
        return (EFI_UNSUPPORTED);  //need to have at least one parameter
    }

    Print(L"File to open is: %s\n", argv[1]);

    status = gEfiShellProtocol->OpenFileByName (argv[1], &Handle, 
        EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE | EFI_FILE_MODE_CREATE);

    if (EFI_ERROR(status)) {
        Print(L"\nFile Open did not work %s\n", argv[1]);
        return (status);
    }else{
        Print(L"\nFile Open worked %s\n", argv[1]);
        gEfiShellProtocol->CloseFile(Handle);
    }

    return EFI_SUCCESS;
}

And the code freezes even if I try the GetCurDirfunction.

Print(L"Dir: %s \n",gEfiShellProtocol->GetCurDir(NULL));

Any pointers would be helpful.

Answer 1

, EFI_SHELL_PROTOCOL: , Efi. :

UINTN BufferSize;
EFI_HANDLE* Buffer;
Status = bs->LocateHandle(ByProtocol, &gEfiShellProtocolGuid, NULL, &BufferSize, Buffer);

:

    Status = bs->AllocatePool(EfiBootServicesData, BufferSize, &Buffer);

    Status = bs->LocateHandle(ByProtocol, &gEfiShellProtocolGuid, NULL, &BufferSize, Buffer);

. , EFI ! . , , SHELL:

 UINTN HandleCounter;
 for (HandleCounter = 0 ; HandleCounter < (BufferSize/sizeof(EFI_HANDLE)) ; HandleCounter++)
 {
    Status = bs->OpenProtocol(Buffer[HandleCounter],
                              &gEfiShellProtocolGuid,
                              (VOID**)&gEfiShellProtocol,
                              imageHandle, 
                              NULL,
                              EFI_OPEN_PROTOCOL_GET_PROTOCOL);

!

, , :

bs->FreePool(buffer);

, . EFI, 2.31, .