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audk/MdePkg/Library/UefiDevicePathLib/DevicePathUtilities.c

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/** @file
Device Path services. The thing to remember is device paths are built out of
nodes. The device path is terminated by an end node that is length
sizeof(EFI_DEVICE_PATH_PROTOCOL). That would be why there is sizeof(EFI_DEVICE_PATH_PROTOCOL)
all over this file.
The only place where multi-instance device paths are supported is in
environment varibles. Multi-instance device paths should never be placed
on a Handle.
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "UefiDevicePathLib.h"
//
// Template for an end-of-device path node.
//
GLOBAL_REMOVE_IF_UNREFERENCED CONST EFI_DEVICE_PATH_PROTOCOL mUefiDevicePathLibEndDevicePath = {
END_DEVICE_PATH_TYPE,
END_ENTIRE_DEVICE_PATH_SUBTYPE,
{
END_DEVICE_PATH_LENGTH,
0
}
};
/**
Determine whether a given device path is valid.
@param DevicePath A pointer to a device path data structure.
@param MaxSize The maximum size of the device path data structure.
@retval TRUE DevicePath is valid.
@retval FALSE DevicePath is NULL.
@retval FALSE Maxsize is less than sizeof(EFI_DEVICE_PATH_PROTOCOL).
@retval FALSE The length of any node node in the DevicePath is less
than sizeof (EFI_DEVICE_PATH_PROTOCOL).
@retval FALSE If MaxSize is not zero, the size of the DevicePath
exceeds MaxSize.
@retval FALSE If PcdMaximumDevicePathNodeCount is not zero, the node
count of the DevicePath exceeds PcdMaximumDevicePathNodeCount.
**/
BOOLEAN
EFIAPI
IsDevicePathValid (
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath,
IN UINTN MaxSize
)
{
UINTN Count;
UINTN Size;
UINTN NodeLength;
//
//Validate the input whether exists and its size big enough to touch the first node
//
if (DevicePath == NULL || (MaxSize > 0 && MaxSize < END_DEVICE_PATH_LENGTH)) {
return FALSE;
}
if (MaxSize == 0) {
MaxSize = MAX_UINTN;
}
for (Count = 0, Size = 0; !IsDevicePathEnd (DevicePath); DevicePath = NextDevicePathNode (DevicePath)) {
NodeLength = DevicePathNodeLength (DevicePath);
if (NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
return FALSE;
}
if (NodeLength > MAX_UINTN - Size) {
return FALSE;
}
Size += NodeLength;
//
// Validate next node before touch it.
//
if (Size > MaxSize - END_DEVICE_PATH_LENGTH ) {
return FALSE;
}
if (PcdGet32 (PcdMaximumDevicePathNodeCount) > 0) {
Count++;
if (Count >= PcdGet32 (PcdMaximumDevicePathNodeCount)) {
return FALSE;
}
}
//
// FilePath must be a NULL-terminated string.
//
if (DevicePathType (DevicePath) == MEDIA_DEVICE_PATH &&
DevicePathSubType (DevicePath) == MEDIA_FILEPATH_DP &&
*(CHAR16 *)((UINT8 *)DevicePath + NodeLength - 2) != 0) {
return FALSE;
}
}
//
// Only return TRUE when the End Device Path node is valid.
//
return (BOOLEAN) (DevicePathNodeLength (DevicePath) == END_DEVICE_PATH_LENGTH);
}
/**
Returns the Type field of a device path node.
Returns the Type field of the device path node specified by Node.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
@return The Type field of the device path node specified by Node.
**/
UINT8
EFIAPI
DevicePathType (
IN CONST VOID *Node
)
{
ASSERT (Node != NULL);
return ((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Type;
}
/**
Returns the SubType field of a device path node.
Returns the SubType field of the device path node specified by Node.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
@return The SubType field of the device path node specified by Node.
**/
UINT8
EFIAPI
DevicePathSubType (
IN CONST VOID *Node
)
{
ASSERT (Node != NULL);
return ((EFI_DEVICE_PATH_PROTOCOL *)(Node))->SubType;
}
/**
Returns the 16-bit Length field of a device path node.
Returns the 16-bit Length field of the device path node specified by Node.
Node is not required to be aligned on a 16-bit boundary, so it is recommended
that a function such as ReadUnaligned16() be used to extract the contents of
the Length field.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
@return The 16-bit Length field of the device path node specified by Node.
**/
UINTN
EFIAPI
DevicePathNodeLength (
IN CONST VOID *Node
)
{
ASSERT (Node != NULL);
return ReadUnaligned16 ((UINT16 *)&((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Length[0]);
}
/**
Returns a pointer to the next node in a device path.
Returns a pointer to the device path node that follows the device path node
specified by Node.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
@return a pointer to the device path node that follows the device path node
specified by Node.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
NextDevicePathNode (
IN CONST VOID *Node
)
{
ASSERT (Node != NULL);
return (EFI_DEVICE_PATH_PROTOCOL *)((UINT8 *)(Node) + DevicePathNodeLength(Node));
}
/**
Determines if a device path node is an end node of a device path.
This includes nodes that are the end of a device path instance and nodes that
are the end of an entire device path.
Determines if the device path node specified by Node is an end node of a device path.
This includes nodes that are the end of a device path instance and nodes that are the
end of an entire device path. If Node represents an end node of a device path,
then TRUE is returned. Otherwise, FALSE is returned.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
@retval TRUE The device path node specified by Node is an end node of a
device path.
@retval FALSE The device path node specified by Node is not an end node of
a device path.
**/
BOOLEAN
EFIAPI
IsDevicePathEndType (
IN CONST VOID *Node
)
{
ASSERT (Node != NULL);
return (BOOLEAN) (DevicePathType (Node) == END_DEVICE_PATH_TYPE);
}
/**
Determines if a device path node is an end node of an entire device path.
Determines if a device path node specified by Node is an end node of an entire
device path. If Node represents the end of an entire device path, then TRUE is
returned. Otherwise, FALSE is returned.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
@retval TRUE The device path node specified by Node is the end of an entire
device path.
@retval FALSE The device path node specified by Node is not the end of an
entire device path.
**/
BOOLEAN
EFIAPI
IsDevicePathEnd (
IN CONST VOID *Node
)
{
ASSERT (Node != NULL);
return (BOOLEAN) (IsDevicePathEndType (Node) && DevicePathSubType(Node) == END_ENTIRE_DEVICE_PATH_SUBTYPE);
}
/**
Determines if a device path node is an end node of a device path instance.
Determines if a device path node specified by Node is an end node of a device
path instance. If Node represents the end of a device path instance, then TRUE
is returned. Otherwise, FALSE is returned.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
@retval TRUE The device path node specified by Node is the end of a device
path instance.
@retval FALSE The device path node specified by Node is not the end of a
device path instance.
**/
BOOLEAN
EFIAPI
IsDevicePathEndInstance (
IN CONST VOID *Node
)
{
ASSERT (Node != NULL);
return (BOOLEAN) (IsDevicePathEndType (Node) && DevicePathSubType(Node) == END_INSTANCE_DEVICE_PATH_SUBTYPE);
}
/**
Sets the length, in bytes, of a device path node.
Sets the length of the device path node specified by Node to the value specified
by NodeLength. NodeLength is returned. Node is not required to be aligned on
a 16-bit boundary, so it is recommended that a function such as WriteUnaligned16()
be used to set the contents of the Length field.
If Node is NULL, then ASSERT().
If NodeLength >= SIZE_64KB, then ASSERT().
If NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL), then ASSERT().
@param Node A pointer to a device path node data structure.
@param Length The length, in bytes, of the device path node.
@return Length
**/
UINT16
EFIAPI
SetDevicePathNodeLength (
IN OUT VOID *Node,
IN UINTN Length
)
{
ASSERT (Node != NULL);
ASSERT ((Length >= sizeof (EFI_DEVICE_PATH_PROTOCOL)) && (Length < SIZE_64KB));
return WriteUnaligned16 ((UINT16 *)&((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Length[0], (UINT16)(Length));
}
/**
Fills in all the fields of a device path node that is the end of an entire device path.
Fills in all the fields of a device path node specified by Node so Node represents
the end of an entire device path. The Type field of Node is set to
END_DEVICE_PATH_TYPE, the SubType field of Node is set to
END_ENTIRE_DEVICE_PATH_SUBTYPE, and the Length field of Node is set to
END_DEVICE_PATH_LENGTH. Node is not required to be aligned on a 16-bit boundary,
so it is recommended that a function such as WriteUnaligned16() be used to set
the contents of the Length field.
If Node is NULL, then ASSERT().
@param Node A pointer to a device path node data structure.
**/
VOID
EFIAPI
SetDevicePathEndNode (
OUT VOID *Node
)
{
ASSERT (Node != NULL);
CopyMem (Node, &mUefiDevicePathLibEndDevicePath, sizeof (mUefiDevicePathLibEndDevicePath));
}
/**
Returns the size of a device path in bytes.
This function returns the size, in bytes, of the device path data structure
specified by DevicePath including the end of device path node.
If DevicePath is NULL or invalid, then 0 is returned.
@param DevicePath A pointer to a device path data structure.
@retval 0 If DevicePath is NULL or invalid.
@retval Others The size of a device path in bytes.
**/
UINTN
EFIAPI
UefiDevicePathLibGetDevicePathSize (
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath
)
{
CONST EFI_DEVICE_PATH_PROTOCOL *Start;
if (DevicePath == NULL) {
return 0;
}
if (!IsDevicePathValid (DevicePath, 0)) {
return 0;
}
//
// Search for the end of the device path structure
//
Start = DevicePath;
while (!IsDevicePathEnd (DevicePath)) {
DevicePath = NextDevicePathNode (DevicePath);
}
//
// Compute the size and add back in the size of the end device path structure
//
return ((UINTN) DevicePath - (UINTN) Start) + DevicePathNodeLength (DevicePath);
}
/**
Creates a new copy of an existing device path.
This function allocates space for a new copy of the device path specified by DevicePath.
If DevicePath is NULL, then NULL is returned. If the memory is successfully
allocated, then the contents of DevicePath are copied to the newly allocated
buffer, and a pointer to that buffer is returned. Otherwise, NULL is returned.
The memory for the new device path is allocated from EFI boot services memory.
It is the responsibility of the caller to free the memory allocated.
@param DevicePath A pointer to a device path data structure.
@retval NULL DevicePath is NULL or invalid.
@retval Others A pointer to the duplicated device path.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
UefiDevicePathLibDuplicateDevicePath (
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath
)
{
UINTN Size;
//
// Compute the size
//
Size = GetDevicePathSize (DevicePath);
if (Size == 0) {
return NULL;
}
//
// Allocate space for duplicate device path
//
return AllocateCopyPool (Size, DevicePath);
}
/**
Creates a new device path by appending a second device path to a first device path.
This function creates a new device path by appending a copy of SecondDevicePath
to a copy of FirstDevicePath in a newly allocated buffer. Only the end-of-device-path
device node from SecondDevicePath is retained. The newly created device path is
returned. If FirstDevicePath is NULL, then it is ignored, and a duplicate of
SecondDevicePath is returned. If SecondDevicePath is NULL, then it is ignored,
and a duplicate of FirstDevicePath is returned. If both FirstDevicePath and
SecondDevicePath are NULL, then a copy of an end-of-device-path is returned.
If there is not enough memory for the newly allocated buffer, then NULL is returned.
The memory for the new device path is allocated from EFI boot services memory.
It is the responsibility of the caller to free the memory allocated.
@param FirstDevicePath A pointer to a device path data structure.
@param SecondDevicePath A pointer to a device path data structure.
@retval NULL If there is not enough memory for the newly allocated buffer.
@retval NULL If FirstDevicePath or SecondDevicePath is invalid.
@retval Others A pointer to the new device path if success.
Or a copy an end-of-device-path if both FirstDevicePath and SecondDevicePath are NULL.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
UefiDevicePathLibAppendDevicePath (
IN CONST EFI_DEVICE_PATH_PROTOCOL *FirstDevicePath, OPTIONAL
IN CONST EFI_DEVICE_PATH_PROTOCOL *SecondDevicePath OPTIONAL
)
{
UINTN Size;
UINTN Size1;
UINTN Size2;
EFI_DEVICE_PATH_PROTOCOL *NewDevicePath;
EFI_DEVICE_PATH_PROTOCOL *DevicePath2;
//
// If there's only 1 path, just duplicate it.
//
if (FirstDevicePath == NULL) {
return DuplicateDevicePath ((SecondDevicePath != NULL) ? SecondDevicePath : &mUefiDevicePathLibEndDevicePath);
}
if (SecondDevicePath == NULL) {
return DuplicateDevicePath (FirstDevicePath);
}
if (!IsDevicePathValid (FirstDevicePath, 0) || !IsDevicePathValid (SecondDevicePath, 0)) {
return NULL;
}
//
// Allocate space for the combined device path. It only has one end node of
// length EFI_DEVICE_PATH_PROTOCOL.
//
Size1 = GetDevicePathSize (FirstDevicePath);
Size2 = GetDevicePathSize (SecondDevicePath);
Size = Size1 + Size2 - END_DEVICE_PATH_LENGTH;
NewDevicePath = AllocatePool (Size);
if (NewDevicePath != NULL) {
NewDevicePath = CopyMem (NewDevicePath, FirstDevicePath, Size1);
//
// Over write FirstDevicePath EndNode and do the copy
//
DevicePath2 = (EFI_DEVICE_PATH_PROTOCOL *) ((CHAR8 *) NewDevicePath +
(Size1 - END_DEVICE_PATH_LENGTH));
CopyMem (DevicePath2, SecondDevicePath, Size2);
}
return NewDevicePath;
}
/**
Creates a new path by appending the device node to the device path.
This function creates a new device path by appending a copy of the device node
specified by DevicePathNode to a copy of the device path specified by DevicePath
in an allocated buffer. The end-of-device-path device node is moved after the
end of the appended device node.
If DevicePathNode is NULL then a copy of DevicePath is returned.
If DevicePath is NULL then a copy of DevicePathNode, followed by an end-of-device
path device node is returned.
If both DevicePathNode and DevicePath are NULL then a copy of an end-of-device-path
device node is returned.
If there is not enough memory to allocate space for the new device path, then
NULL is returned.
The memory is allocated from EFI boot services memory. It is the responsibility
of the caller to free the memory allocated.
@param DevicePath A pointer to a device path data structure.
@param DevicePathNode A pointer to a single device path node.
@retval NULL If there is not enough memory for the new device path.
@retval Others A pointer to the new device path if success.
A copy of DevicePathNode followed by an end-of-device-path node
if both FirstDevicePath and SecondDevicePath are NULL.
A copy of an end-of-device-path node if both FirstDevicePath
and SecondDevicePath are NULL.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
UefiDevicePathLibAppendDevicePathNode (
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath, OPTIONAL
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePathNode OPTIONAL
)
{
EFI_DEVICE_PATH_PROTOCOL *TempDevicePath;
EFI_DEVICE_PATH_PROTOCOL *NextNode;
EFI_DEVICE_PATH_PROTOCOL *NewDevicePath;
UINTN NodeLength;
if (DevicePathNode == NULL) {
return DuplicateDevicePath ((DevicePath != NULL) ? DevicePath : &mUefiDevicePathLibEndDevicePath);
}
//
// Build a Node that has a terminator on it
//
NodeLength = DevicePathNodeLength (DevicePathNode);
TempDevicePath = AllocatePool (NodeLength + END_DEVICE_PATH_LENGTH);
if (TempDevicePath == NULL) {
return NULL;
}
TempDevicePath = CopyMem (TempDevicePath, DevicePathNode, NodeLength);
//
// Add and end device path node to convert Node to device path
//
NextNode = NextDevicePathNode (TempDevicePath);
SetDevicePathEndNode (NextNode);
//
// Append device paths
//
NewDevicePath = AppendDevicePath (DevicePath, TempDevicePath);
FreePool (TempDevicePath);
return NewDevicePath;
}
/**
Creates a new device path by appending the specified device path instance to the specified device
path.
This function creates a new device path by appending a copy of the device path
instance specified by DevicePathInstance to a copy of the device path specified
by DevicePath in a allocated buffer.
The end-of-device-path device node is moved after the end of the appended device
path instance and a new end-of-device-path-instance node is inserted between.
If DevicePath is NULL, then a copy if DevicePathInstance is returned.
If DevicePathInstance is NULL, then NULL is returned.
If DevicePath or DevicePathInstance is invalid, then NULL is returned.
If there is not enough memory to allocate space for the new device path, then
NULL is returned.
The memory is allocated from EFI boot services memory. It is the responsibility
of the caller to free the memory allocated.
@param DevicePath A pointer to a device path data structure.
@param DevicePathInstance A pointer to a device path instance.
@return A pointer to the new device path.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
UefiDevicePathLibAppendDevicePathInstance (
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath, OPTIONAL
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePathInstance OPTIONAL
)
{
EFI_DEVICE_PATH_PROTOCOL *NewDevicePath;
EFI_DEVICE_PATH_PROTOCOL *TempDevicePath;
UINTN SrcSize;
UINTN InstanceSize;
if (DevicePath == NULL) {
return DuplicateDevicePath (DevicePathInstance);
}
if (DevicePathInstance == NULL) {
return NULL;
}
if (!IsDevicePathValid (DevicePath, 0) || !IsDevicePathValid (DevicePathInstance, 0)) {
return NULL;
}
SrcSize = GetDevicePathSize (DevicePath);
InstanceSize = GetDevicePathSize (DevicePathInstance);
NewDevicePath = AllocatePool (SrcSize + InstanceSize);
if (NewDevicePath != NULL) {
TempDevicePath = CopyMem (NewDevicePath, DevicePath, SrcSize);;
while (!IsDevicePathEnd (TempDevicePath)) {
TempDevicePath = NextDevicePathNode (TempDevicePath);
}
TempDevicePath->SubType = END_INSTANCE_DEVICE_PATH_SUBTYPE;
TempDevicePath = NextDevicePathNode (TempDevicePath);
CopyMem (TempDevicePath, DevicePathInstance, InstanceSize);
}
return NewDevicePath;
}
/**
Creates a copy of the current device path instance and returns a pointer to the next device path
instance.
This function creates a copy of the current device path instance. It also updates
DevicePath to point to the next device path instance in the device path (or NULL
if no more) and updates Size to hold the size of the device path instance copy.
If DevicePath is NULL, then NULL is returned.
If DevicePath points to a invalid device path, then NULL is returned.
If there is not enough memory to allocate space for the new device path, then
NULL is returned.
The memory is allocated from EFI boot services memory. It is the responsibility
of the caller to free the memory allocated.
If Size is NULL, then ASSERT().
@param DevicePath On input, this holds the pointer to the current
device path instance. On output, this holds
the pointer to the next device path instance
or NULL if there are no more device path
instances in the device path pointer to a
device path data structure.
@param Size On output, this holds the size of the device
path instance, in bytes or zero, if DevicePath
is NULL.
@return A pointer to the current device path instance.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
UefiDevicePathLibGetNextDevicePathInstance (
IN OUT EFI_DEVICE_PATH_PROTOCOL **DevicePath,
OUT UINTN *Size
)
{
EFI_DEVICE_PATH_PROTOCOL *DevPath;
EFI_DEVICE_PATH_PROTOCOL *ReturnValue;
UINT8 Temp;
ASSERT (Size != NULL);
if (DevicePath == NULL || *DevicePath == NULL) {
*Size = 0;
return NULL;
}
if (!IsDevicePathValid (*DevicePath, 0)) {
return NULL;
}
//
// Find the end of the device path instance
//
DevPath = *DevicePath;
while (!IsDevicePathEndType (DevPath)) {
DevPath = NextDevicePathNode (DevPath);
}
//
// Compute the size of the device path instance
//
*Size = ((UINTN) DevPath - (UINTN) (*DevicePath)) + sizeof (EFI_DEVICE_PATH_PROTOCOL);
//
// Make a copy and return the device path instance
//
Temp = DevPath->SubType;
DevPath->SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE;
ReturnValue = DuplicateDevicePath (*DevicePath);
DevPath->SubType = Temp;
//
// If DevPath is the end of an entire device path, then another instance
// does not follow, so *DevicePath is set to NULL.
//
if (DevicePathSubType (DevPath) == END_ENTIRE_DEVICE_PATH_SUBTYPE) {
*DevicePath = NULL;
} else {
*DevicePath = NextDevicePathNode (DevPath);
}
return ReturnValue;
}
/**
Creates a device node.
This function creates a new device node in a newly allocated buffer of size
NodeLength and initializes the device path node header with NodeType and NodeSubType.
The new device path node is returned.
If NodeLength is smaller than a device path header, then NULL is returned.
If there is not enough memory to allocate space for the new device path, then
NULL is returned.
The memory is allocated from EFI boot services memory. It is the responsibility
of the caller to free the memory allocated.
@param NodeType The device node type for the new device node.
@param NodeSubType The device node sub-type for the new device node.
@param NodeLength The length of the new device node.
@return The new device path.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
UefiDevicePathLibCreateDeviceNode (
IN UINT8 NodeType,
IN UINT8 NodeSubType,
IN UINT16 NodeLength
)
{
EFI_DEVICE_PATH_PROTOCOL *DevicePath;
if (NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
//
// NodeLength is less than the size of the header.
//
return NULL;
}
DevicePath = AllocateZeroPool (NodeLength);
if (DevicePath != NULL) {
DevicePath->Type = NodeType;
DevicePath->SubType = NodeSubType;
SetDevicePathNodeLength (DevicePath, NodeLength);
}
return DevicePath;
}
/**
Determines if a device path is single or multi-instance.
This function returns TRUE if the device path specified by DevicePath is
multi-instance.
Otherwise, FALSE is returned.
If DevicePath is NULL or invalid, then FALSE is returned.
@param DevicePath A pointer to a device path data structure.
@retval TRUE DevicePath is multi-instance.
@retval FALSE DevicePath is not multi-instance, or DevicePath
is NULL or invalid.
**/
BOOLEAN
EFIAPI
UefiDevicePathLibIsDevicePathMultiInstance (
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath
)
{
CONST EFI_DEVICE_PATH_PROTOCOL *Node;
if (DevicePath == NULL) {
return FALSE;
}
if (!IsDevicePathValid (DevicePath, 0)) {
return FALSE;
}
Node = DevicePath;
while (!IsDevicePathEnd (Node)) {
if (IsDevicePathEndInstance (Node)) {
return TRUE;
}
Node = NextDevicePathNode (Node);
}
return FALSE;
}
/**
Retrieves the device path protocol from a handle.
This function returns the device path protocol from the handle specified by Handle.
If Handle is NULL or Handle does not contain a device path protocol, then NULL
is returned.
@param Handle The handle from which to retrieve the device
path protocol.
@return The device path protocol from the handle specified by Handle.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
DevicePathFromHandle (
IN EFI_HANDLE Handle
)
{
EFI_DEVICE_PATH_PROTOCOL *DevicePath;
EFI_STATUS Status;
Status = gBS->HandleProtocol (
Handle,
&gEfiDevicePathProtocolGuid,
(VOID *) &DevicePath
);
if (EFI_ERROR (Status)) {
DevicePath = NULL;
}
return DevicePath;
}
/**
Allocates a device path for a file and appends it to an existing device path.
If Device is a valid device handle that contains a device path protocol, then a device path for
the file specified by FileName is allocated and appended to the device path associated with the
handle Device. The allocated device path is returned. If Device is NULL or Device is a handle
that does not support the device path protocol, then a device path containing a single device
path node for the file specified by FileName is allocated and returned.
The memory for the new device path is allocated from EFI boot services memory. It is the responsibility
of the caller to free the memory allocated.
If FileName is NULL, then ASSERT().
If FileName is not aligned on a 16-bit boundary, then ASSERT().
@param Device A pointer to a device handle. This parameter
is optional and may be NULL.
@param FileName A pointer to a Null-terminated Unicode string.
@return The allocated device path.
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
FileDevicePath (
IN EFI_HANDLE Device, OPTIONAL
IN CONST CHAR16 *FileName
)
{
UINTN Size;
FILEPATH_DEVICE_PATH *FilePath;
EFI_DEVICE_PATH_PROTOCOL *DevicePath;
EFI_DEVICE_PATH_PROTOCOL *FileDevicePath;
DevicePath = NULL;
Size = StrSize (FileName);
FileDevicePath = AllocatePool (Size + SIZE_OF_FILEPATH_DEVICE_PATH + END_DEVICE_PATH_LENGTH);
if (FileDevicePath != NULL) {
FilePath = (FILEPATH_DEVICE_PATH *) FileDevicePath;
FilePath->Header.Type = MEDIA_DEVICE_PATH;
FilePath->Header.SubType = MEDIA_FILEPATH_DP;
CopyMem (&FilePath->PathName, FileName, Size);
SetDevicePathNodeLength (&FilePath->Header, Size + SIZE_OF_FILEPATH_DEVICE_PATH);
SetDevicePathEndNode (NextDevicePathNode (&FilePath->Header));
if (Device != NULL) {
DevicePath = DevicePathFromHandle (Device);
}
DevicePath = AppendDevicePath (DevicePath, FileDevicePath);
FreePool (FileDevicePath);
}
return DevicePath;
}
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