MdePkg/Library/UefiDevicePathLib/DevicePathUtilitiesDxeSmm.c

   1 /** @file
   2   Device Path services. The thing to remember is device paths are built out of
   3   nodes. The device path is terminated by an end node that is length
   4   sizeof(EFI_DEVICE_PATH_PROTOCOL). That would be why there is sizeof(EFI_DEVICE_PATH_PROTOCOL)
   5   all over this file.
   6
   7   The only place where multi-instance device paths are supported is in
   8   environment varibles. Multi-instance device paths should never be placed
   9   on a Handle.
  10
  11   Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
  12   Copyright (c) Microsoft Corporation.
  13   SPDX-License-Identifier: BSD-2-Clause-Patent
  14
  15 **/
  16
  17 #include "UefiDevicePathLib.h"
  18
  19
  20 /**
  21   Retrieves the device path protocol from a handle.
  22
  23   This function returns the device path protocol from the handle specified by Handle.
  24   If Handle is NULL or Handle does not contain a device path protocol, then NULL
  25   is returned.
  26
  27   @param  Handle                     The handle from which to retrieve the device
  28                                      path protocol.
  29
  30   @return The device path protocol from the handle specified by Handle.
  31
  32 **/
  33 EFI_DEVICE_PATH_PROTOCOL *
  34 EFIAPI
  35 DevicePathFromHandle (
  36   IN EFI_HANDLE                      Handle
  37   )
  38 {
  39   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
  40   EFI_STATUS                Status;
  41
  42   Status = gBS->HandleProtocol (
  43                   Handle,
  44                   &gEfiDevicePathProtocolGuid,
  45                   (VOID *) &DevicePath
  46                   );
  47   if (EFI_ERROR (Status)) {
  48     DevicePath = NULL;
  49   }
  50   return DevicePath;
  51 }