uefidevicepathlib.c

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/*++

Copyright (c) 2004 - 2006, Intel Corporation                                                         
All rights reserved. This program and the accompanying materials                          
are licensed and made available under the terms and conditions of the BSD License         
which accompanies this distribution.  The full text of the license may be found at        
http://opensource.org/licenses/bsd-license.php                                            
                                                                                          
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.  


Module Name:

  UefiDevicePathLib.c
  
Abstract: 

  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.

--*/

#include "EdkIIGlueUefi.h"
#include "Library\EdkIIGlueMemoryAllocationLib.h"

/**
  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, then 0 is returned.

  @param  DevicePath                 A pointer to a device path data structure.

  @return The size of a device path in bytes.

**/
UINTN
EFIAPI
GlueGetDevicePathSize (
  IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
  )
{
  CONST EFI_DEVICE_PATH_PROTOCOL  *Start;

  if (DevicePath == NULL) {
    return 0;
  }

  //
  // Search for the end of the device path structure
  //
  Start = DevicePath;
  while (!EfiIsDevicePathEnd (DevicePath)) {
    DevicePath = EfiNextDevicePathNode (DevicePath);
  }

  //
  // Compute the size and add back in the size of the end device path structure
  //
  return ((UINTN) DevicePath - (UINTN) Start) + sizeof (EFI_DEVICE_PATH_PROTOCOL);
}

/**
  Creates a new device path by appending a second device path to a first 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.  
  
  @param  DevicePath                 A pointer to a device path data structure.

  @return A pointer to the duplicated device path.

**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
GlueDuplicateDevicePath (
  IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
  )
{
  EFI_DEVICE_PATH_PROTOCOL  *NewDevicePath;
  UINTN                     Size;

  //
  // Compute the size
  //
  Size = GetDevicePathSize (DevicePath);
  if (Size == 0) {
    return NULL;
  }

  //
  // Allocate space for duplicate device path
  //
  NewDevicePath = AllocateCopyPool (Size, DevicePath);

  return NewDevicePath;
}

/**
  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 NULL 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.

  @return A pointer to the new device path.

**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
GlueAppendDevicePath (
  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);
  }

  if (SecondDevicePath == NULL) {
    return DuplicateDevicePath (FirstDevicePath);
  }

  //
  // 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 - sizeof (EFI_DEVICE_PATH_PROTOCOL);

  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 - sizeof (EFI_DEVICE_PATH_PROTOCOL)));
    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 DevicePath is NULL, then NULL is returned.
  If DevicePathNode is NULL, 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  DevicePathNode             A pointer to a single device path node.

  @return A pointer to the new device path.

**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
GlueAppendDevicePathNode (
  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 (DevicePath == NULL || DevicePathNode == NULL) {
    return NULL;
  }
  //
  // Build a Node that has a terminator on it
  //
  NodeLength = DevicePathNodeLength (DevicePathNode);

  TempDevicePath = AllocatePool (NodeLength + sizeof (EFI_DEVICE_PATH_PROTOCOL));
  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 secified 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 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
GlueAppendDevicePathInstance (
  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);
  }