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
);
69 // Validate the input size big enough to touch the first node.
71 if (MaxSize
< sizeof (EFI_DEVICE_PATH_PROTOCOL
)) {
75 for (Count
= 0, Size
= 0; !IsDevicePathEnd (DevicePath
); DevicePath
= NextDevicePathNode (DevicePath
)) {
76 NodeLength
= DevicePathNodeLength (DevicePath
);
77 if (NodeLength
< sizeof (EFI_DEVICE_PATH_PROTOCOL
)) {
81 if (NodeLength
> MAX_UINTN
- Size
) {
87 // Validate next node before touch it.
89 if (Size
> MaxSize
- END_DEVICE_PATH_LENGTH
) {
93 if (PcdGet32 (PcdMaximumDevicePathNodeCount
) > 0) {
95 if (Count
>= PcdGet32 (PcdMaximumDevicePathNodeCount
)) {
102 // Only return TRUE when the End Device Path node is valid.
104 return (BOOLEAN
) (DevicePathNodeLength (DevicePath
) == END_DEVICE_PATH_LENGTH
);
109 Returns the Type field of a device path node.
111 Returns the Type field of the device path node specified by Node.
113 If Node is NULL, then ASSERT().
115 @param Node A pointer to a device path node data structure.
117 @return The Type field of the device path node specified by Node.
126 ASSERT (Node
!= NULL
);
127 return ((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->Type
;
131 Returns the SubType field of a device path node.
133 Returns the SubType field of the device path node specified by Node.
135 If Node is NULL, then ASSERT().
137 @param Node A pointer to a device path node data structure.
139 @return The SubType field of the device path node specified by Node.
148 ASSERT (Node
!= NULL
);
149 return ((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->SubType
;
153 Returns the 16-bit Length field of a device path node.
155 Returns the 16-bit Length field of the device path node specified by Node.
156 Node is not required to be aligned on a 16-bit boundary, so it is recommended
157 that a function such as ReadUnaligned16() be used to extract the contents of
160 If Node is NULL, then ASSERT().
162 @param Node A pointer to a device path node data structure.
164 @return The 16-bit Length field of the device path node specified by Node.
169 DevicePathNodeLength (
173 ASSERT (Node
!= NULL
);
174 return ReadUnaligned16 ((UINT16
*)&((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->Length
[0]);
178 Returns a pointer to the next node in a device path.
180 Returns a pointer to the device path node that follows the device path node
183 If Node is NULL, then ASSERT().
185 @param Node A pointer to a device path node data structure.
187 @return a pointer to the device path node that follows the device path node
191 EFI_DEVICE_PATH_PROTOCOL
*
197 ASSERT (Node
!= NULL
);
198 return (EFI_DEVICE_PATH_PROTOCOL
*)((UINT8
*)(Node
) + DevicePathNodeLength(Node
));
202 Determines if a device path node is an end node of a device path.
203 This includes nodes that are the end of a device path instance and nodes that
204 are the end of an entire device path.
206 Determines if the device path node specified by Node is an end node of a device path.
207 This includes nodes that are the end of a device path instance and nodes that are the
208 end of an entire device path. If Node represents an end node of a device path,
209 then TRUE is returned. Otherwise, FALSE is returned.
211 If Node is NULL, then ASSERT().
213 @param Node A pointer to a device path node data structure.
215 @retval TRUE The device path node specified by Node is an end node of a
217 @retval FALSE The device path node specified by Node is not an end node of
223 IsDevicePathEndType (
227 ASSERT (Node
!= NULL
);
228 return (BOOLEAN
) (DevicePathType (Node
) == END_DEVICE_PATH_TYPE
);
232 Determines if a device path node is an end node of an entire device path.
234 Determines if a device path node specified by Node is an end node of an entire
235 device path. If Node represents the end of an entire device path, then TRUE is
236 returned. Otherwise, FALSE is returned.
238 If Node is NULL, then ASSERT().
240 @param Node A pointer to a device path node data structure.
242 @retval TRUE The device path node specified by Node is the end of an entire
244 @retval FALSE The device path node specified by Node is not the end of an
254 ASSERT (Node
!= NULL
);
255 return (BOOLEAN
) (IsDevicePathEndType (Node
) && DevicePathSubType(Node
) == END_ENTIRE_DEVICE_PATH_SUBTYPE
);
259 Determines if a device path node is an end node of a device path instance.
261 Determines if a device path node specified by Node is an end node of a device
262 path instance. If Node represents the end of a device path instance, then TRUE
263 is returned. Otherwise, FALSE is returned.
265 If Node is NULL, then ASSERT().
267 @param Node A pointer to a device path node data structure.
269 @retval TRUE The device path node specified by Node is the end of a device
271 @retval FALSE The device path node specified by Node is not the end of a
272 device path instance.
277 IsDevicePathEndInstance (
281 ASSERT (Node
!= NULL
);
282 return (BOOLEAN
) (IsDevicePathEndType (Node
) && DevicePathSubType(Node
) == END_INSTANCE_DEVICE_PATH_SUBTYPE
);
286 Sets the length, in bytes, of a device path node.
288 Sets the length of the device path node specified by Node to the value specified
289 by NodeLength. NodeLength is returned. Node is not required to be aligned on
290 a 16-bit boundary, so it is recommended that a function such as WriteUnaligned16()
291 be used to set the contents of the Length field.
293 If Node is NULL, then ASSERT().
294 If NodeLength >= SIZE_64KB, then ASSERT().
295 If NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL), then ASSERT().
297 @param Node A pointer to a device path node data structure.
298 @param Length The length, in bytes, of the device path node.
305 SetDevicePathNodeLength (
310 ASSERT (Node
!= NULL
);
311 ASSERT ((Length
>= sizeof (EFI_DEVICE_PATH_PROTOCOL
)) && (Length
< SIZE_64KB
));
312 return WriteUnaligned16 ((UINT16
*)&((EFI_DEVICE_PATH_PROTOCOL
*)(Node
))->Length
[0], (UINT16
)(Length
));
316 Fills in all the fields of a device path node that is the end of an entire device path.
318 Fills in all the fields of a device path node specified by Node so Node represents
319 the end of an entire device path. The Type field of Node is set to
320 END_DEVICE_PATH_TYPE, the SubType field of Node is set to
321 END_ENTIRE_DEVICE_PATH_SUBTYPE, and the Length field of Node is set to
322 END_DEVICE_PATH_LENGTH. Node is not required to be aligned on a 16-bit boundary,
323 so it is recommended that a function such as WriteUnaligned16() be used to set
324 the contents of the Length field.
326 If Node is NULL, then ASSERT().
328 @param Node A pointer to a device path node data structure.
333 SetDevicePathEndNode (
337 ASSERT (Node
!= NULL
);
338 CopyMem (Node
, &mUefiDevicePathLibEndDevicePath
, sizeof (mUefiDevicePathLibEndDevicePath
));
342 Returns the size of a device path in bytes.
344 This function returns the size, in bytes, of the device path data structure
345 specified by DevicePath including the end of device path node.
346 If DevicePath is NULL or invalid, then 0 is returned.
348 @param DevicePath A pointer to a device path data structure.
350 @retval 0 If DevicePath is NULL or invalid.
351 @retval Others The size of a device path in bytes.
356 UefiDevicePathLibGetDevicePathSize (
357 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
360 CONST EFI_DEVICE_PATH_PROTOCOL
*Start
;
362 if (DevicePath
== NULL
) {
366 if (!IsDevicePathValid (DevicePath
, 0)) {
371 // Search for the end of the device path structure
374 while (!IsDevicePathEnd (DevicePath
)) {
375 DevicePath
= NextDevicePathNode (DevicePath
);
379 // Compute the size and add back in the size of the end device path structure
381 return ((UINTN
) DevicePath
- (UINTN
) Start
) + DevicePathNodeLength (DevicePath
);
385 Creates a new copy of an existing device path.
387 This function allocates space for a new copy of the device path specified by DevicePath.
388 If DevicePath is NULL, then NULL is returned. If the memory is successfully
389 allocated, then the contents of DevicePath are copied to the newly allocated
390 buffer, and a pointer to that buffer is returned. Otherwise, NULL is returned.
391 The memory for the new device path is allocated from EFI boot services memory.
392 It is the responsibility of the caller to free the memory allocated.
394 @param DevicePath A pointer to a device path data structure.
396 @retval NULL DevicePath is NULL or invalid.
397 @retval Others A pointer to the duplicated device path.
400 EFI_DEVICE_PATH_PROTOCOL
*
402 UefiDevicePathLibDuplicateDevicePath (
403 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
411 Size
= GetDevicePathSize (DevicePath
);
417 // Allocate space for duplicate device path
420 return AllocateCopyPool (Size
, DevicePath
);
424 Creates a new device path by appending a second device path to a first device path.
426 This function creates a new device path by appending a copy of SecondDevicePath
427 to a copy of FirstDevicePath in a newly allocated buffer. Only the end-of-device-path
428 device node from SecondDevicePath is retained. The newly created device path is
429 returned. If FirstDevicePath is NULL, then it is ignored, and a duplicate of
430 SecondDevicePath is returned. If SecondDevicePath is NULL, then it is ignored,
431 and a duplicate of FirstDevicePath is returned. If both FirstDevicePath and
432 SecondDevicePath are NULL, then a copy of an end-of-device-path is returned.
434 If there is not enough memory for the newly allocated buffer, then NULL is returned.
435 The memory for the new device path is allocated from EFI boot services memory.
436 It is the responsibility of the caller to free the memory allocated.
438 @param FirstDevicePath A pointer to a device path data structure.
439 @param SecondDevicePath A pointer to a device path data structure.
441 @retval NULL If there is not enough memory for the newly allocated buffer.
442 @retval NULL If FirstDevicePath or SecondDevicePath is invalid.
443 @retval Others A pointer to the new device path if success.
444 Or a copy an end-of-device-path if both FirstDevicePath and SecondDevicePath are NULL.
447 EFI_DEVICE_PATH_PROTOCOL
*
449 UefiDevicePathLibAppendDevicePath (
450 IN CONST EFI_DEVICE_PATH_PROTOCOL
*FirstDevicePath
, OPTIONAL
451 IN CONST EFI_DEVICE_PATH_PROTOCOL
*SecondDevicePath OPTIONAL
457 EFI_DEVICE_PATH_PROTOCOL
*NewDevicePath
;
458 EFI_DEVICE_PATH_PROTOCOL
*DevicePath2
;
461 // If there's only 1 path, just duplicate it.
463 if (FirstDevicePath
== NULL
) {
464 return DuplicateDevicePath ((SecondDevicePath
!= NULL
) ? SecondDevicePath
: &mUefiDevicePathLibEndDevicePath
);
467 if (SecondDevicePath
== NULL
) {
468 return DuplicateDevicePath (FirstDevicePath
);
471 if (!IsDevicePathValid (FirstDevicePath
, 0) || !IsDevicePathValid (SecondDevicePath
, 0)) {
476 // Allocate space for the combined device path. It only has one end node of
477 // length EFI_DEVICE_PATH_PROTOCOL.
479 Size1
= GetDevicePathSize (FirstDevicePath
);
480 Size2
= GetDevicePathSize (SecondDevicePath
);
481 Size
= Size1
+ Size2
- END_DEVICE_PATH_LENGTH
;
483 NewDevicePath
= AllocatePool (Size
);
485 if (NewDevicePath
!= NULL
) {
486 NewDevicePath
= CopyMem (NewDevicePath
, FirstDevicePath
, Size1
);
488 // Over write FirstDevicePath EndNode and do the copy
490 DevicePath2
= (EFI_DEVICE_PATH_PROTOCOL
*) ((CHAR8
*) NewDevicePath
+
491 (Size1
- END_DEVICE_PATH_LENGTH
));
492 CopyMem (DevicePath2
, SecondDevicePath
, Size2
);
495 return NewDevicePath
;
499 Creates a new path by appending the device node to the device path.
501 This function creates a new device path by appending a copy of the device node
502 specified by DevicePathNode to a copy of the device path specified by DevicePath
503 in an allocated buffer. The end-of-device-path device node is moved after the
504 end of the appended device node.
505 If DevicePathNode is NULL then a copy of DevicePath is returned.
506 If DevicePath is NULL then a copy of DevicePathNode, followed by an end-of-device
507 path device node is returned.
508 If both DevicePathNode and DevicePath are NULL then a copy of an end-of-device-path
509 device node is returned.
510 If there is not enough memory to allocate space for the new device path, then
512 The memory is allocated from EFI boot services memory. It is the responsibility
513 of the caller to free the memory allocated.
515 @param DevicePath A pointer to a device path data structure.
516 @param DevicePathNode A pointer to a single device path node.
518 @retval NULL If there is not enough memory for the new device path.
519 @retval Others A pointer to the new device path if success.
520 A copy of DevicePathNode followed by an end-of-device-path node
521 if both FirstDevicePath and SecondDevicePath are NULL.
522 A copy of an end-of-device-path node if both FirstDevicePath
523 and SecondDevicePath are NULL.
526 EFI_DEVICE_PATH_PROTOCOL
*
528 UefiDevicePathLibAppendDevicePathNode (
529 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
, OPTIONAL
530 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePathNode OPTIONAL
533 EFI_DEVICE_PATH_PROTOCOL
*TempDevicePath
;
534 EFI_DEVICE_PATH_PROTOCOL
*NextNode
;
535 EFI_DEVICE_PATH_PROTOCOL
*NewDevicePath
;
538 if (DevicePathNode
== NULL
) {
539 return DuplicateDevicePath ((DevicePath
!= NULL
) ? DevicePath
: &mUefiDevicePathLibEndDevicePath
);
542 // Build a Node that has a terminator on it
544 NodeLength
= DevicePathNodeLength (DevicePathNode
);
546 TempDevicePath
= AllocatePool (NodeLength
+ END_DEVICE_PATH_LENGTH
);
547 if (TempDevicePath
== NULL
) {
550 TempDevicePath
= CopyMem (TempDevicePath
, DevicePathNode
, NodeLength
);
552 // Add and end device path node to convert Node to device path
554 NextNode
= NextDevicePathNode (TempDevicePath
);
555 SetDevicePathEndNode (NextNode
);
557 // Append device paths
559 NewDevicePath
= AppendDevicePath (DevicePath
, TempDevicePath
);
561 FreePool (TempDevicePath
);
563 return NewDevicePath
;
567 Creates a new device path by appending the specified device path instance to the specified device
570 This function creates a new device path by appending a copy of the device path
571 instance specified by DevicePathInstance to a copy of the device path specified
572 by DevicePath in a allocated buffer.
573 The end-of-device-path device node is moved after the end of the appended device
574 path instance and a new end-of-device-path-instance node is inserted between.
575 If DevicePath is NULL, then a copy if DevicePathInstance is returned.
576 If DevicePathInstance is NULL, then NULL is returned.
577 If DevicePath or DevicePathInstance is invalid, then NULL is returned.
578 If there is not enough memory to allocate space for the new device path, then
580 The memory is allocated from EFI boot services memory. It is the responsibility
581 of the caller to free the memory allocated.
583 @param DevicePath A pointer to a device path data structure.
584 @param DevicePathInstance A pointer to a device path instance.
586 @return A pointer to the new device path.
589 EFI_DEVICE_PATH_PROTOCOL
*
591 UefiDevicePathLibAppendDevicePathInstance (
592 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
, OPTIONAL
593 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePathInstance OPTIONAL
596 EFI_DEVICE_PATH_PROTOCOL
*NewDevicePath
;
597 EFI_DEVICE_PATH_PROTOCOL
*TempDevicePath
;
601 if (DevicePath
== NULL
) {
602 return DuplicateDevicePath (DevicePathInstance
);
605 if (DevicePathInstance
== NULL
) {
609 if (!IsDevicePathValid (DevicePath
, 0) || !IsDevicePathValid (DevicePathInstance
, 0)) {
613 SrcSize
= GetDevicePathSize (DevicePath
);
614 InstanceSize
= GetDevicePathSize (DevicePathInstance
);
616 NewDevicePath
= AllocatePool (SrcSize
+ InstanceSize
);
617 if (NewDevicePath
!= NULL
) {
619 TempDevicePath
= CopyMem (NewDevicePath
, DevicePath
, SrcSize
);;
621 while (!IsDevicePathEnd (TempDevicePath
)) {
622 TempDevicePath
= NextDevicePathNode (TempDevicePath
);
625 TempDevicePath
->SubType
= END_INSTANCE_DEVICE_PATH_SUBTYPE
;
626 TempDevicePath
= NextDevicePathNode (TempDevicePath
);
627 CopyMem (TempDevicePath
, DevicePathInstance
, InstanceSize
);
630 return NewDevicePath
;
634 Creates a copy of the current device path instance and returns a pointer to the next device path
637 This function creates a copy of the current device path instance. It also updates
638 DevicePath to point to the next device path instance in the device path (or NULL
639 if no more) and updates Size to hold the size of the device path instance copy.
640 If DevicePath is NULL, then NULL is returned.
641 If DevicePath points to a invalid device path, then NULL is returned.
642 If there is not enough memory to allocate space for the new device path, then
644 The memory is allocated from EFI boot services memory. It is the responsibility
645 of the caller to free the memory allocated.
646 If Size is NULL, then ASSERT().
648 @param DevicePath On input, this holds the pointer to the current
649 device path instance. On output, this holds
650 the pointer to the next device path instance
651 or NULL if there are no more device path
652 instances in the device path pointer to a
653 device path data structure.
654 @param Size On output, this holds the size of the device
655 path instance, in bytes or zero, if DevicePath
658 @return A pointer to the current device path instance.
661 EFI_DEVICE_PATH_PROTOCOL
*
663 UefiDevicePathLibGetNextDevicePathInstance (
664 IN OUT EFI_DEVICE_PATH_PROTOCOL
**DevicePath
,
668 EFI_DEVICE_PATH_PROTOCOL
*DevPath
;
669 EFI_DEVICE_PATH_PROTOCOL
*ReturnValue
;
672 ASSERT (Size
!= NULL
);
674 if (DevicePath
== NULL
|| *DevicePath
== NULL
) {
679 if (!IsDevicePathValid (*DevicePath
, 0)) {
684 // Find the end of the device path instance
686 DevPath
= *DevicePath
;
687 while (!IsDevicePathEndType (DevPath
)) {
688 DevPath
= NextDevicePathNode (DevPath
);
692 // Compute the size of the device path instance
694 *Size
= ((UINTN
) DevPath
- (UINTN
) (*DevicePath
)) + sizeof (EFI_DEVICE_PATH_PROTOCOL
);
697 // Make a copy and return the device path instance
699 Temp
= DevPath
->SubType
;
700 DevPath
->SubType
= END_ENTIRE_DEVICE_PATH_SUBTYPE
;
701 ReturnValue
= DuplicateDevicePath (*DevicePath
);
702 DevPath
->SubType
= Temp
;
705 // If DevPath is the end of an entire device path, then another instance
706 // does not follow, so *DevicePath is set to NULL.
708 if (DevicePathSubType (DevPath
) == END_ENTIRE_DEVICE_PATH_SUBTYPE
) {
711 *DevicePath
= NextDevicePathNode (DevPath
);
718 Creates a device node.
720 This function creates a new device node in a newly allocated buffer of size
721 NodeLength and initializes the device path node header with NodeType and NodeSubType.
722 The new device path node is returned.
723 If NodeLength is smaller than a device path header, then NULL is returned.
724 If there is not enough memory to allocate space for the new device path, then
726 The memory is allocated from EFI boot services memory. It is the responsibility
727 of the caller to free the memory allocated.
729 @param NodeType The device node type for the new device node.
730 @param NodeSubType The device node sub-type for the new device node.
731 @param NodeLength The length of the new device node.
733 @return The new device path.
736 EFI_DEVICE_PATH_PROTOCOL
*
738 UefiDevicePathLibCreateDeviceNode (
740 IN UINT8 NodeSubType
,
744 EFI_DEVICE_PATH_PROTOCOL
*DevicePath
;
746 if (NodeLength
< sizeof (EFI_DEVICE_PATH_PROTOCOL
)) {
748 // NodeLength is less than the size of the header.
753 DevicePath
= AllocateZeroPool (NodeLength
);
754 if (DevicePath
!= NULL
) {
755 DevicePath
->Type
= NodeType
;
756 DevicePath
->SubType
= NodeSubType
;
757 SetDevicePathNodeLength (DevicePath
, NodeLength
);
764 Determines if a device path is single or multi-instance.
766 This function returns TRUE if the device path specified by DevicePath is
768 Otherwise, FALSE is returned.
769 If DevicePath is NULL or invalid, then FALSE is returned.
771 @param DevicePath A pointer to a device path data structure.
773 @retval TRUE DevicePath is multi-instance.
774 @retval FALSE DevicePath is not multi-instance, or DevicePath
780 UefiDevicePathLibIsDevicePathMultiInstance (
781 IN CONST EFI_DEVICE_PATH_PROTOCOL
*DevicePath
784 CONST EFI_DEVICE_PATH_PROTOCOL
*Node
;
786 if (DevicePath
== NULL
) {
790 if (!IsDevicePathValid (DevicePath
, 0)) {
795 while (!IsDevicePathEnd (Node
)) {
796 if (IsDevicePathEndInstance (Node
)) {
800 Node
= NextDevicePathNode (Node
);
808 Retrieves the device path protocol from a handle.
810 This function returns the device path protocol from the handle specified by Handle.
811 If Handle is NULL or Handle does not contain a device path protocol, then NULL
814 @param Handle The handle from which to retrieve the device
817 @return The device path protocol from the handle specified by Handle.
820 EFI_DEVICE_PATH_PROTOCOL
*
822 DevicePathFromHandle (
826 EFI_DEVICE_PATH_PROTOCOL
*DevicePath
;
829 Status
= gBS
->HandleProtocol (
831 &gEfiDevicePathProtocolGuid
,
834 if (EFI_ERROR (Status
)) {
841 Allocates a device path for a file and appends it to an existing device path.
843 If Device is a valid device handle that contains a device path protocol, then a device path for
844 the file specified by FileName is allocated and appended to the device path associated with the
845 handle Device. The allocated device path is returned. If Device is NULL or Device is a handle
846 that does not support the device path protocol, then a device path containing a single device
847 path node for the file specified by FileName is allocated and returned.
848 The memory for the new device path is allocated from EFI boot services memory. It is the responsibility
849 of the caller to free the memory allocated.
851 If FileName is NULL, then ASSERT().
852 If FileName is not aligned on a 16-bit boundary, then ASSERT().
854 @param Device A pointer to a device handle. This parameter
855 is optional and may be NULL.
856 @param FileName A pointer to a Null-terminated Unicode string.
858 @return The allocated device path.
861 EFI_DEVICE_PATH_PROTOCOL
*
864 IN EFI_HANDLE Device
, OPTIONAL
865 IN CONST CHAR16
*FileName
869 FILEPATH_DEVICE_PATH
*FilePath
;
870 EFI_DEVICE_PATH_PROTOCOL
*DevicePath
;
871 EFI_DEVICE_PATH_PROTOCOL
*FileDevicePath
;
875 Size
= StrSize (FileName
);
876 FileDevicePath
= AllocatePool (Size
+ SIZE_OF_FILEPATH_DEVICE_PATH
+ END_DEVICE_PATH_LENGTH
);
877 if (FileDevicePath
!= NULL
) {
878 FilePath
= (FILEPATH_DEVICE_PATH
*) FileDevicePath
;
879 FilePath
->Header
.Type
= MEDIA_DEVICE_PATH
;
880 FilePath
->Header
.SubType
= MEDIA_FILEPATH_DP
;
881 CopyMem (&FilePath
->PathName
, FileName
, Size
);
882 SetDevicePathNodeLength (&FilePath
->Header
, Size
+ SIZE_OF_FILEPATH_DEVICE_PATH
);
883 SetDevicePathEndNode (NextDevicePathNode (&FilePath
->Header
));
885 if (Device
!= NULL
) {
886 DevicePath
= DevicePathFromHandle (Device
);
889 DevicePath
= AppendDevicePath (DevicePath
, FileDevicePath
);
890 FreePool (FileDevicePath
);