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)
7 The only place where multi-instance device paths are supported is in
8 environment varibles. Multi-instance device paths should never be placed
11 Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
12 This program and the accompanying materials
13 are licensed and made available under the terms and conditions of the BSD License
14 which accompanies this distribution. The full text of the license may be found at
15 http://opensource.org/licenses/bsd-license.php.
17 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
18 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
22 #include "UefiDevicePathLib.h"
25 // Template for an end-of-device path node.
27 GLOBAL_REMOVE_IF_UNREFERENCED CONST EFI_DEVICE_PATH_PROTOCOL mUefiDevicePathLibEndDevicePath
= {
29 END_ENTIRE_DEVICE_PATH_SUBTYPE
,
31 END_DEVICE_PATH_LENGTH
,
37 Determine whether a given device path is valid.
38 If DevicePath is NULL, then ASSERT().
40 @param DevicePath A pointer to a device path data structure.
41 @param MaxSize The maximum size of the device path data structure.
43 @retval TRUE DevicePath is valid.
44 @retval FALSE The length of any node node in the DevicePath is less
45 than sizeof (EFI_DEVICE_PATH_PROTOCOL).
46 @retval FALSE If MaxSize is not zero, the size of the DevicePath
48 @retval FALSE If PcdMaximumDevicePathNodeCount is not zero, the node
49 count of the DevicePath exceeds PcdMaximumDevicePathNodeCount.
54 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
,
62 ASSERT (DevicePath
!= NULL
);
64 for (Count
= 0, Size
= 0; !IsDevicePathEnd (DevicePath
); DevicePath
= NextDevicePathNode (DevicePath
)) {
65 NodeLength
= DevicePathNodeLength (DevicePath
);
66 if (NodeLength
< sizeof (EFI_DEVICE_PATH_PROTOCOL
)) {
72 if (Size
+ END_DEVICE_PATH_LENGTH
> MaxSize
) {
77 if (PcdGet32 (PcdMaximumDevicePathNodeCount
) > 0) {
79 if (Count
>= PcdGet32 (PcdMaximumDevicePathNodeCount
)) {
86 // Only return TRUE when the End Device Path node is valid.
88 return (BOOLEAN
) (DevicePathNodeLength (DevicePath
) == END_DEVICE_PATH_LENGTH
);
93 Returns the Type field of a device path node.
95 Returns the Type field of the device path node specified by Node.
97 If Node is NULL, then ASSERT().
99 @param Node A pointer to a device path node data structure.
101 @return The Type field of the device path node specified by Node.
110 ASSERT (Node
!= NULL
);
111 return ((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->Type
;
115 Returns the SubType field of a device path node.
117 Returns the SubType field of the device path node specified by Node.
119 If Node is NULL, then ASSERT().
121 @param Node A pointer to a device path node data structure.
123 @return The SubType field of the device path node specified by Node.
132 ASSERT (Node
!= NULL
);
133 return ((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->SubType
;
137 Returns the 16-bit Length field of a device path node.
139 Returns the 16-bit Length field of the device path node specified by Node.
140 Node is not required to be aligned on a 16-bit boundary, so it is recommended
141 that a function such as ReadUnaligned16() be used to extract the contents of
144 If Node is NULL, then ASSERT().
146 @param Node A pointer to a device path node data structure.
148 @return The 16-bit Length field of the device path node specified by Node.
153 DevicePathNodeLength (
157 ASSERT (Node
!= NULL
);
158 return ReadUnaligned16 ((UINT16
*)&((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->Length
[0]);
162 Returns a pointer to the next node in a device path.
164 Returns a pointer to the device path node that follows the device path node
167 If Node is NULL, then ASSERT().
169 @param Node A pointer to a device path node data structure.
171 @return a pointer to the device path node that follows the device path node
175 EFI_DEVICE_PATH_PROTOCOL
*
181 ASSERT (Node
!= NULL
);
182 return (EFI_DEVICE_PATH_PROTOCOL
*)((UINT8
*)(Node
) + DevicePathNodeLength(Node
));
186 Determines if a device path node is an end node of a device path.
187 This includes nodes that are the end of a device path instance and nodes that
188 are the end of an entire device path.
190 Determines if the device path node specified by Node is an end node of a device path.
191 This includes nodes that are the end of a device path instance and nodes that are the
192 end of an entire device path. If Node represents an end node of a device path,
193 then TRUE is returned. Otherwise, FALSE is returned.
195 If Node is NULL, then ASSERT().
197 @param Node A pointer to a device path node data structure.
199 @retval TRUE The device path node specified by Node is an end node of a
201 @retval FALSE The device path node specified by Node is not an end node of
207 IsDevicePathEndType (
211 ASSERT (Node
!= NULL
);
212 return (BOOLEAN
) (DevicePathType (Node
) == END_DEVICE_PATH_TYPE
);
216 Determines if a device path node is an end node of an entire device path.
218 Determines if a device path node specified by Node is an end node of an entire
219 device path. If Node represents the end of an entire device path, then TRUE is
220 returned. Otherwise, FALSE is returned.
222 If Node is NULL, then ASSERT().
224 @param Node A pointer to a device path node data structure.
226 @retval TRUE The device path node specified by Node is the end of an entire
228 @retval FALSE The device path node specified by Node is not the end of an
238 ASSERT (Node
!= NULL
);
239 return (BOOLEAN
) (IsDevicePathEndType (Node
) && DevicePathSubType(Node
) == END_ENTIRE_DEVICE_PATH_SUBTYPE
);
243 Determines if a device path node is an end node of a device path instance.
245 Determines if a device path node specified by Node is an end node of a device
246 path instance. If Node represents the end of a device path instance, then TRUE
247 is returned. Otherwise, FALSE is returned.
249 If Node is NULL, then ASSERT().
251 @param Node A pointer to a device path node data structure.
253 @retval TRUE The device path node specified by Node is the end of a device
255 @retval FALSE The device path node specified by Node is not the end of a
256 device path instance.
261 IsDevicePathEndInstance (
265 ASSERT (Node
!= NULL
);
266 return (BOOLEAN
) (IsDevicePathEndType (Node
) && DevicePathSubType(Node
) == END_INSTANCE_DEVICE_PATH_SUBTYPE
);
270 Sets the length, in bytes, of a device path node.
272 Sets the length of the device path node specified by Node to the value specified
273 by NodeLength. NodeLength is returned. Node is not required to be aligned on
274 a 16-bit boundary, so it is recommended that a function such as WriteUnaligned16()
275 be used to set the contents of the Length field.
277 If Node is NULL, then ASSERT().
278 If NodeLength >= SIZE_64KB, then ASSERT().
279 If NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL), then ASSERT().
281 @param Node A pointer to a device path node data structure.
282 @param Length The length, in bytes, of the device path node.
289 SetDevicePathNodeLength (
294 ASSERT (Node
!= NULL
);
295 ASSERT ((Length
>= sizeof (EFI_DEVICE_PATH_PROTOCOL
)) && (Length
< SIZE_64KB
));
296 return WriteUnaligned16 ((UINT16
*)&((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->Length
[0], (UINT16
)(Length
));
300 Fills in all the fields of a device path node that is the end of an entire device path.
302 Fills in all the fields of a device path node specified by Node so Node represents
303 the end of an entire device path. The Type field of Node is set to
304 END_DEVICE_PATH_TYPE, the SubType field of Node is set to
305 END_ENTIRE_DEVICE_PATH_SUBTYPE, and the Length field of Node is set to
306 END_DEVICE_PATH_LENGTH. Node is not required to be aligned on a 16-bit boundary,
307 so it is recommended that a function such as WriteUnaligned16() be used to set
308 the contents of the Length field.
310 If Node is NULL, then ASSERT().
312 @param Node A pointer to a device path node data structure.
317 SetDevicePathEndNode (
321 ASSERT (Node
!= NULL
);
322 CopyMem (Node
, &mUefiDevicePathLibEndDevicePath
, sizeof (mUefiDevicePathLibEndDevicePath
));
326 Returns the size of a device path in bytes.
328 This function returns the size, in bytes, of the device path data structure
329 specified by DevicePath including the end of device path node.
330 If DevicePath is NULL or invalid, then 0 is returned.
332 @param DevicePath A pointer to a device path data structure.
334 @retval 0 If DevicePath is NULL or invalid.
335 @retval Others The size of a device path in bytes.
340 UefiDevicePathLibGetDevicePathSize (
341 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
344 CONST EFI_DEVICE_PATH_PROTOCOL
*Start
;
346 if (DevicePath
== NULL
) {
350 if (!IsDevicePathValid (DevicePath
, 0)) {
355 // Search for the end of the device path structure
358 while (!IsDevicePathEnd (DevicePath
)) {
359 DevicePath
= NextDevicePathNode (DevicePath
);
363 // Compute the size and add back in the size of the end device path structure
365 return ((UINTN
) DevicePath
- (UINTN
) Start
) + DevicePathNodeLength (DevicePath
);
369 Creates a new copy of an existing device path.
371 This function allocates space for a new copy of the device path specified by DevicePath.
372 If DevicePath is NULL, then NULL is returned. If the memory is successfully
373 allocated, then the contents of DevicePath are copied to the newly allocated
374 buffer, and a pointer to that buffer is returned. Otherwise, NULL is returned.
375 The memory for the new device path is allocated from EFI boot services memory.
376 It is the responsibility of the caller to free the memory allocated.
378 @param DevicePath A pointer to a device path data structure.
380 @retval NULL DevicePath is NULL or invalid.
381 @retval Others A pointer to the duplicated device path.
384 EFI_DEVICE_PATH_PROTOCOL
*
386 UefiDevicePathLibDuplicateDevicePath (
387 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
395 Size
= GetDevicePathSize (DevicePath
);
401 // Allocate space for duplicate device path
404 return AllocateCopyPool (Size
, DevicePath
);
408 Creates a new device path by appending a second device path to a first device path.
410 This function creates a new device path by appending a copy of SecondDevicePath
411 to a copy of FirstDevicePath in a newly allocated buffer. Only the end-of-device-path
412 device node from SecondDevicePath is retained. The newly created device path is
413 returned. If FirstDevicePath is NULL, then it is ignored, and a duplicate of
414 SecondDevicePath is returned. If SecondDevicePath is NULL, then it is ignored,
415 and a duplicate of FirstDevicePath is returned. If both FirstDevicePath and
416 SecondDevicePath are NULL, then a copy of an end-of-device-path is returned.
418 If there is not enough memory for the newly allocated buffer, then NULL is returned.
419 The memory for the new device path is allocated from EFI boot services memory.
420 It is the responsibility of the caller to free the memory allocated.
422 @param FirstDevicePath A pointer to a device path data structure.
423 @param SecondDevicePath A pointer to a device path data structure.
425 @retval NULL If there is not enough memory for the newly allocated buffer.
426 @retval NULL If FirstDevicePath or SecondDevicePath is invalid.
427 @retval Others A pointer to the new device path if success.
428 Or a copy an end-of-device-path if both FirstDevicePath and SecondDevicePath are NULL.
431 EFI_DEVICE_PATH_PROTOCOL
*
433 UefiDevicePathLibAppendDevicePath (
434 IN CONST EFI_DEVICE_PATH_PROTOCOL
*FirstDevicePath
, OPTIONAL
435 IN CONST EFI_DEVICE_PATH_PROTOCOL
*SecondDevicePath OPTIONAL
441 EFI_DEVICE_PATH_PROTOCOL
*NewDevicePath
;
442 EFI_DEVICE_PATH_PROTOCOL
*DevicePath2
;
445 // If there's only 1 path, just duplicate it.
447 if (FirstDevicePath
== NULL
) {
448 return DuplicateDevicePath ((SecondDevicePath
!= NULL
) ? SecondDevicePath
: &mUefiDevicePathLibEndDevicePath
);
451 if (SecondDevicePath
== NULL
) {
452 return DuplicateDevicePath (FirstDevicePath
);
455 if (!IsDevicePathValid (FirstDevicePath
, 0) || !IsDevicePathValid (SecondDevicePath
, 0)) {
460 // Allocate space for the combined device path. It only has one end node of
461 // length EFI_DEVICE_PATH_PROTOCOL.
463 Size1
= GetDevicePathSize (FirstDevicePath
);
464 Size2
= GetDevicePathSize (SecondDevicePath
);
465 Size
= Size1
+ Size2
- END_DEVICE_PATH_LENGTH
;
467 NewDevicePath
= AllocatePool (Size
);
469 if (NewDevicePath
!= NULL
) {
470 NewDevicePath
= CopyMem (NewDevicePath
, FirstDevicePath
, Size1
);
472 // Over write FirstDevicePath EndNode and do the copy
474 DevicePath2
= (EFI_DEVICE_PATH_PROTOCOL
*) ((CHAR8
*) NewDevicePath
+
475 (Size1
- END_DEVICE_PATH_LENGTH
));
476 CopyMem (DevicePath2
, SecondDevicePath
, Size2
);
479 return NewDevicePath
;
483 Creates a new path by appending the device node to the device path.
485 This function creates a new device path by appending a copy of the device node
486 specified by DevicePathNode to a copy of the device path specified by DevicePath
487 in an allocated buffer. The end-of-device-path device node is moved after the
488 end of the appended device node.
489 If DevicePathNode is NULL then a copy of DevicePath is returned.
490 If DevicePath is NULL then a copy of DevicePathNode, followed by an end-of-device
491 path device node is returned.
492 If both DevicePathNode and DevicePath are NULL then a copy of an end-of-device-path
493 device node is returned.
494 If there is not enough memory to allocate space for the new device path, then
496 The memory is allocated from EFI boot services memory. It is the responsibility
497 of the caller to free the memory allocated.
499 @param DevicePath A pointer to a device path data structure.
500 @param DevicePathNode A pointer to a single device path node.
502 @retval NULL If there is not enough memory for the new device path.
503 @retval Others A pointer to the new device path if success.
504 A copy of DevicePathNode followed by an end-of-device-path node
505 if both FirstDevicePath and SecondDevicePath are NULL.
506 A copy of an end-of-device-path node if both FirstDevicePath
507 and SecondDevicePath are NULL.
510 EFI_DEVICE_PATH_PROTOCOL
*
512 UefiDevicePathLibAppendDevicePathNode (
513 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
, OPTIONAL
514 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePathNode OPTIONAL
517 EFI_DEVICE_PATH_PROTOCOL
*TempDevicePath
;
518 EFI_DEVICE_PATH_PROTOCOL
*NextNode
;
519 EFI_DEVICE_PATH_PROTOCOL
*NewDevicePath
;
522 if (DevicePathNode
== NULL
) {
523 return DuplicateDevicePath ((DevicePath
!= NULL
) ? DevicePath
: &mUefiDevicePathLibEndDevicePath
);
526 // Build a Node that has a terminator on it
528 NodeLength
= DevicePathNodeLength (DevicePathNode
);
530 TempDevicePath
= AllocatePool (NodeLength
+ END_DEVICE_PATH_LENGTH
);
531 if (TempDevicePath
== NULL
) {
534 TempDevicePath
= CopyMem (TempDevicePath
, DevicePathNode
, NodeLength
);
536 // Add and end device path node to convert Node to device path
538 NextNode
= NextDevicePathNode (TempDevicePath
);
539 SetDevicePathEndNode (NextNode
);
541 // Append device paths
543 NewDevicePath
= AppendDevicePath (DevicePath
, TempDevicePath
);
545 FreePool (TempDevicePath
);
547 return NewDevicePath
;
551 Creates a new device path by appending the specified device path instance to the specified device
554 This function creates a new device path by appending a copy of the device path
555 instance specified by DevicePathInstance to a copy of the device path specified
556 by DevicePath in a allocated buffer.
557 The end-of-device-path device node is moved after the end of the appended device
558 path instance and a new end-of-device-path-instance node is inserted between.
559 If DevicePath is NULL, then a copy if DevicePathInstance is returned.
560 If DevicePathInstance is NULL, then NULL is returned.
561 If DevicePath or DevicePathInstance is invalid, then NULL is returned.
562 If there is not enough memory to allocate space for the new device path, then
564 The memory is allocated from EFI boot services memory. It is the responsibility
565 of the caller to free the memory allocated.
567 @param DevicePath A pointer to a device path data structure.
568 @param DevicePathInstance A pointer to a device path instance.
570 @return A pointer to the new device path.
573 EFI_DEVICE_PATH_PROTOCOL
*
575 UefiDevicePathLibAppendDevicePathInstance (
576 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
, OPTIONAL
577 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePathInstance OPTIONAL
580 EFI_DEVICE_PATH_PROTOCOL
*NewDevicePath
;
581 EFI_DEVICE_PATH_PROTOCOL
*TempDevicePath
;
585 if (DevicePath
== NULL
) {
586 return DuplicateDevicePath (DevicePathInstance
);
589 if (DevicePathInstance
== NULL
) {
593 if (!IsDevicePathValid (DevicePath
, 0) || !IsDevicePathValid (DevicePathInstance
, 0)) {
597 SrcSize
= GetDevicePathSize (DevicePath
);
598 InstanceSize
= GetDevicePathSize (DevicePathInstance
);
600 NewDevicePath
= AllocatePool (SrcSize
+ InstanceSize
);
601 if (NewDevicePath
!= NULL
) {
603 TempDevicePath
= CopyMem (NewDevicePath
, DevicePath
, SrcSize
);;
605 while (!IsDevicePathEnd (TempDevicePath
)) {
606 TempDevicePath
= NextDevicePathNode (TempDevicePath
);
609 TempDevicePath
->SubType
= END_INSTANCE_DEVICE_PATH_SUBTYPE
;
610 TempDevicePath
= NextDevicePathNode (TempDevicePath
);
611 CopyMem (TempDevicePath
, DevicePathInstance
, InstanceSize
);
614 return NewDevicePath
;
618 Creates a copy of the current device path instance and returns a pointer to the next device path
621 This function creates a copy of the current device path instance. It also updates
622 DevicePath to point to the next device path instance in the device path (or NULL
623 if no more) and updates Size to hold the size of the device path instance copy.
624 If DevicePath is NULL, then NULL is returned.
625 If DevicePath points to a invalid device path, then NULL is returned.
626 If there is not enough memory to allocate space for the new device path, then
628 The memory is allocated from EFI boot services memory. It is the responsibility
629 of the caller to free the memory allocated.
630 If Size is NULL, then ASSERT().
632 @param DevicePath On input, this holds the pointer to the current
633 device path instance. On output, this holds
634 the pointer to the next device path instance
635 or NULL if there are no more device path
636 instances in the device path pointer to a
637 device path data structure.
638 @param Size On output, this holds the size of the device
639 path instance, in bytes or zero, if DevicePath
642 @return A pointer to the current device path instance.
645 EFI_DEVICE_PATH_PROTOCOL
*
647 UefiDevicePathLibGetNextDevicePathInstance (
648 IN OUT EFI_DEVICE_PATH_PROTOCOL
**DevicePath
,
652 EFI_DEVICE_PATH_PROTOCOL
*DevPath
;
653 EFI_DEVICE_PATH_PROTOCOL
*ReturnValue
;
656 ASSERT (Size
!= NULL
);
658 if (DevicePath
== NULL
|| *DevicePath
== NULL
) {
663 if (!IsDevicePathValid (*DevicePath
, 0)) {
668 // Find the end of the device path instance
670 DevPath
= *DevicePath
;
671 while (!IsDevicePathEndType (DevPath
)) {
672 DevPath
= NextDevicePathNode (DevPath
);
676 // Compute the size of the device path instance
678 *Size
= ((UINTN
) DevPath
- (UINTN
) (*DevicePath
)) + sizeof (EFI_DEVICE_PATH_PROTOCOL
);
681 // Make a copy and return the device path instance
683 Temp
= DevPath
->SubType
;
684 DevPath
->SubType
= END_ENTIRE_DEVICE_PATH_SUBTYPE
;
685 ReturnValue
= DuplicateDevicePath (*DevicePath
);
686 DevPath
->SubType
= Temp
;
689 // If DevPath is the end of an entire device path, then another instance
690 // does not follow, so *DevicePath is set to NULL.
692 if (DevicePathSubType (DevPath
) == END_ENTIRE_DEVICE_PATH_SUBTYPE
) {
695 *DevicePath
= NextDevicePathNode (DevPath
);
702 Creates a device node.
704 This function creates a new device node in a newly allocated buffer of size
705 NodeLength and initializes the device path node header with NodeType and NodeSubType.
706 The new device path node is returned.
707 If NodeLength is smaller than a device path header, then NULL is returned.
708 If there is not enough memory to allocate space for the new device path, then
710 The memory is allocated from EFI boot services memory. It is the responsibility
711 of the caller to free the memory allocated.
713 @param NodeType The device node type for the new device node.
714 @param NodeSubType The device node sub-type for the new device node.
715 @param NodeLength The length of the new device node.
717 @return The new device path.
720 EFI_DEVICE_PATH_PROTOCOL
*
722 UefiDevicePathLibCreateDeviceNode (
724 IN UINT8 NodeSubType
,
728 EFI_DEVICE_PATH_PROTOCOL
*DevicePath
;
730 if (NodeLength
< sizeof (EFI_DEVICE_PATH_PROTOCOL
)) {
732 // NodeLength is less than the size of the header.
737 DevicePath
= AllocateZeroPool (NodeLength
);
738 if (DevicePath
!= NULL
) {
739 DevicePath
->Type
= NodeType
;
740 DevicePath
->SubType
= NodeSubType
;
741 SetDevicePathNodeLength (DevicePath
, NodeLength
);
748 Determines if a device path is single or multi-instance.
750 This function returns TRUE if the device path specified by DevicePath is
752 Otherwise, FALSE is returned.
753 If DevicePath is NULL or invalid, then FALSE is returned.
755 @param DevicePath A pointer to a device path data structure.
757 @retval TRUE DevicePath is multi-instance.
758 @retval FALSE DevicePath is not multi-instance, or DevicePath
764 UefiDevicePathLibIsDevicePathMultiInstance (
765 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
768 CONST EFI_DEVICE_PATH_PROTOCOL
*Node
;
770 if (DevicePath
== NULL
) {
774 if (!IsDevicePathValid (DevicePath
, 0)) {
779 while (!IsDevicePathEnd (Node
)) {
780 if (IsDevicePathEndInstance (Node
)) {
784 Node
= NextDevicePathNode (Node
);
792 Retrieves the device path protocol from a handle.
794 This function returns the device path protocol from the handle specified by Handle.
795 If Handle is NULL or Handle does not contain a device path protocol, then NULL
798 @param Handle The handle from which to retrieve the device
801 @return The device path protocol from the handle specified by Handle.
804 EFI_DEVICE_PATH_PROTOCOL
*
806 DevicePathFromHandle (
810 EFI_DEVICE_PATH_PROTOCOL
*DevicePath
;
813 Status
= gBS
->HandleProtocol (
815 &gEfiDevicePathProtocolGuid
,
818 if (EFI_ERROR (Status
)) {
825 Allocates a device path for a file and appends it to an existing device path.
827 If Device is a valid device handle that contains a device path protocol, then a device path for
828 the file specified by FileName is allocated and appended to the device path associated with the
829 handle Device. The allocated device path is returned. If Device is NULL or Device is a handle
830 that does not support the device path protocol, then a device path containing a single device
831 path node for the file specified by FileName is allocated and returned.
832 The memory for the new device path is allocated from EFI boot services memory. It is the responsibility
833 of the caller to free the memory allocated.
835 If FileName is NULL, then ASSERT().
836 If FileName is not aligned on a 16-bit boundary, then ASSERT().
838 @param Device A pointer to a device handle. This parameter
839 is optional and may be NULL.
840 @param FileName A pointer to a Null-terminated Unicode string.
842 @return The allocated device path.
845 EFI_DEVICE_PATH_PROTOCOL
*
848 IN EFI_HANDLE Device
, OPTIONAL
849 IN CONST CHAR16
*FileName
853 FILEPATH_DEVICE_PATH
*FilePath
;
854 EFI_DEVICE_PATH_PROTOCOL
*DevicePath
;
855 EFI_DEVICE_PATH_PROTOCOL
*FileDevicePath
;
859 Size
= StrSize (FileName
);
860 FileDevicePath
= AllocatePool (Size
+ SIZE_OF_FILEPATH_DEVICE_PATH
+ END_DEVICE_PATH_LENGTH
);
861 if (FileDevicePath
!= NULL
) {
862 FilePath
= (FILEPATH_DEVICE_PATH
*) FileDevicePath
;
863 FilePath
->Header
.Type
= MEDIA_DEVICE_PATH
;
864 FilePath
->Header
.SubType
= MEDIA_FILEPATH_DP
;
865 CopyMem (&FilePath
->PathName
, FileName
, Size
);
866 SetDevicePathNodeLength (&FilePath
->Header
, Size
+ SIZE_OF_FILEPATH_DEVICE_PATH
);
867 SetDevicePathEndNode (NextDevicePathNode (&FilePath
->Header
));
869 if (Device
!= NULL
) {
870 DevicePath
= DevicePathFromHandle (Device
);
873 DevicePath
= AppendDevicePath (DevicePath
, FileDevicePath
);
874 FreePool (FileDevicePath
);