Starts a device controller or a bus controller

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/**
  Starts a device controller or a bus controller.

  The Start() function is designed to be invoked from the EFI boot service ConnectController().
  As a result, much of the error checking on the parameters to Start() has been moved into this
  common boot service. It is legal to call Start() from other locations,
  but the following calling restrictions must be followed, or the system behavior will not be deterministic.
  1. ControllerHandle must be a valid EFI_HANDLE.
  2. If RemainingDevicePath is not NULL, then it must be a pointer to a naturally aligned
     EFI_DEVICE_PATH_PROTOCOL.
  3. Prior to calling Start(), the Supported() function for the driver specified by This must
     have been called with the same calling parameters, and Supported() must have returned EFI_SUCCESS.

  @param[in]  This                 A pointer to the EFI_DRIVER_BINDING_PROTOCOL instance.
  @param[in]  ControllerHandle     The handle of the controller to start. This handle
                                   must support a protocol interface that supplies
                                   an I/O abstraction to the driver.
  @param[in]  RemainingDevicePath  A pointer to the remaining portion of a device path.  This
                                   parameter is ignored by device drivers, and is optional for bus
                                   drivers. For a bus driver, if this parameter is NULL, then handles
                                   for all the children of Controller are created by this driver.
                                   If this parameter is not NULL and the first Device Path Node is
                                   not the End of Device Path Node, then only the handle for the
                                   child device specified by the first Device Path Node of
                                   RemainingDevicePath is created by this driver.
                                   If the first Device Path Node of RemainingDevicePath is
                                   the End of Device Path Node, no child handle is created by this
                                   driver.

  @retval EFI_SUCCESS              The device was started.
  @retval EFI_DEVICE_ERROR         The device could not be started due to a device error.Currently not implemented.
  @retval EFI_OUT_OF_RESOURCES     The request could not be completed due to a lack of resources.
  @retval Others                   The driver failded to start the device.

**/
EFI_STATUS
EFIAPI
EmuBlockIoDriverBindingStart (
  IN  EFI_DRIVER_BINDING_PROTOCOL   *This,
  IN  EFI_HANDLE                    Handle,
  IN  EFI_DEVICE_PATH_PROTOCOL      *RemainingDevicePath
  )
{
  EFI_STATUS                  Status;
  EMU_IO_THUNK_PROTOCOL       *EmuIoThunk;
  EMU_BLOCK_IO_PRIVATE        *Private = NULL;

  //
  // Grab the protocols we need
  //

  Status = gBS->OpenProtocol (
                  Handle,
                  &gEmuIoThunkProtocolGuid,
                  (void *)&EmuIoThunk,
                  This->DriverBindingHandle,
                  Handle,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  if (!CompareGuid (EmuIoThunk->Protocol, &gEmuBlockIoProtocolGuid)) {
    Status = EFI_UNSUPPORTED;
    goto Done;
  }

  Status = EmuIoThunk->Open (EmuIoThunk);
  if (EFI_ERROR (Status)) {
    goto Done;
  }

  Private = AllocatePool (sizeof (EMU_BLOCK_IO_PRIVATE));
  if (Private == NULL) {
    goto Done;
  }

  Private->Signature = EMU_BLOCK_IO_PRIVATE_SIGNATURE;
  Private->IoThunk   = EmuIoThunk;
  Private->Io        = EmuIoThunk->Interface;
  Private->EfiHandle = Handle;

  Private->BlockIo.Revision    = EFI_BLOCK_IO_PROTOCOL_REVISION2;
  Private->BlockIo.Media       = &Private->Media;
  Private->BlockIo.Reset       = EmuBlockIoReset;
  Private->BlockIo.ReadBlocks  = EmuBlockIoReadBlocks;
  Private->BlockIo.WriteBlocks = EmuBlockIoWriteBlocks;
  Private->BlockIo.FlushBlocks = EmuBlockIoFlushBlocks;

  Private->BlockIo2.Media         = &Private->Media;
  Private->BlockIo2.Reset         = EmuBlockIo2Reset;
  Private->BlockIo2.ReadBlocksEx  = EmuBlockIo2ReadBlocksEx;
  Private->BlockIo2.WriteBlocksEx = EmuBlockIo2WriteBlocksEx;
  Private->BlockIo2.FlushBlocksEx = EmuBlockIo2Flush;

  Private->ControllerNameTable = NULL;

  Status = Private->Io->CreateMapping (Private->Io, &Private->Media);
  if (EFI_ERROR (Status)) {
    goto Done;
  }

  AddUnicodeString2 (
    "eng",
    gEmuBlockIoComponentName.SupportedLanguages,
    &Private->ControllerNameTable,
    EmuIoThunk->ConfigString,
    TRUE
    );

  AddUnicodeString2 (
    "en",
    gEmuBlockIoComponentName2.SupportedLanguages,
    &Private->ControllerNameTable,
    EmuIoThunk->ConfigString,
    FALSE
    );

  Status = gBS->InstallMultipleProtocolInterfaces (
                  &Handle,
                  &gEfiBlockIoProtocolGuid,    &Private->BlockIo,
                  &gEfiBlockIo2ProtocolGuid,   &Private->BlockIo2,
                  NULL
                  );

Done:
  if (EFI_ERROR (Status)) {
    if (Private != NULL) {
      if (Private->ControllerNameTable != NULL) {
        FreeUnicodeStringTable (Private->ControllerNameTable);
      }

      gBS->FreePool (Private);

    }

    gBS->CloseProtocol (
          Handle,
          &gEmuIoThunkProtocolGuid,
          This->DriverBindingHandle,
          Handle
          );
  }

  return Status;
}

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