rtdevicepath.c

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/*++

Copyright (c) 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:

  RtDevicePath.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 "Tiano.h"
#include "EfiRuntimeLib.h"
#include "RtDevicePath.h"
#include EFI_GUID_DEFINITION (FrameworkDevicePath)
#include EFI_PROTOCOL_DEFINITION (DevicePath)

STATIC
VOID *
InternalAllocatePool (
  IN  UINTN   AllocationSize
  )
/*++

Routine Description:

  Allocate BootServicesData pool.

Arguments:

  AllocationSize  - The size to allocate

Returns:

  Pointer of the buffer allocated.

--*/
{
  VOID  *Memory;

  Memory = NULL;
  gBS->AllocatePool (EfiBootServicesData, AllocationSize, &Memory);
  return Memory;
}

STATIC
VOID *
InternalAllocateCopyPool (
  IN  UINTN   AllocationSize,
  IN  VOID    *Buffer
  )
/*++

Routine Description:

  Allocate BootServicesData pool and use a buffer provided by 
  caller to fill it.

Arguments:

  AllocationSize  - The size to allocate
  
  Buffer          - Buffer that will be filled into the buffer allocated

Returns:

  Pointer of the buffer allocated.

--*/
{
  VOID  *Memory;

  Memory = NULL;
  gBS->AllocatePool (EfiBootServicesData, AllocationSize, &Memory);
  if (Memory != NULL) {
    gBS->CopyMem (Memory, Buffer, AllocationSize);
  }

  return Memory;
}

STATIC
VOID *
InternalAllocateZeroPool (
  IN  UINTN   AllocationSize
  )
/*++

Routine Description:

  Allocate BootServicesData pool and zero it.

Arguments:

  AllocationSize  - The size to allocate

Returns:

  Pointer of the buffer allocated.

--*/
{
  VOID  *Memory;

  Memory = InternalAllocatePool (AllocationSize);
  if (Memory != NULL) {
    gBS->SetMem (Memory, AllocationSize, 0);
  }

  return Memory;
}

EFI_DEVICE_PATH_PROTOCOL *
RtEfiDevicePathInstance (
  IN OUT EFI_DEVICE_PATH_PROTOCOL   **DevicePath,
  OUT UINTN                         *Size
  )
/*++

Routine Description:
  Function retrieves the next device path instance from a device path data structure.

Arguments:
  DevicePath           - A pointer to a device path data structure.

  Size                 - A pointer to the size of a device path instance in bytes.

Returns:

  This function returns a pointer to the current device path instance.
  In addition, it returns the size in bytes of the current device path instance in Size,
  and a pointer to the next device path instance in DevicePath.
  If there are no more device path instances in DevicePath, then DevicePath will be set to NULL.

--*/
{
  EFI_DEVICE_PATH_PROTOCOL  *DevPath;
  EFI_DEVICE_PATH_PROTOCOL  *ReturnValue;
  UINT8                     Temp;

  if (*DevicePath == NULL) {
    if (Size != NULL) {
      *Size = 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
  //
  if (Size != NULL) {
    *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       = RtEfiDuplicateDevicePath (*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;
}

BOOLEAN
RtEfiIsDevicePathMultiInstance (
  IN EFI_DEVICE_PATH_PROTOCOL  *DevicePath
  )
/*++

Routine Description:
  Return TRUE is this is a multi instance device path.

Arguments:
  DevicePath  - A pointer to a device path data structure.


Returns:
  TRUE - If DevicePath is multi instance. FALSE - If DevicePath is not multi
  instance.

--*/
{
  EFI_DEVICE_PATH_PROTOCOL  *Node;

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

  Node = DevicePath;
  while (!EfiIsDevicePathEnd (Node)) {
    if (EfiIsDevicePathEndInstance (Node)) {
      return TRUE;
    }

    Node = EfiNextDevicePathNode (Node);
  }

  return FALSE;
}

UINTN
RtEfiDevicePathSize (
  IN EFI_DEVICE_PATH_PROTOCOL  *DevicePath
  )
/*++

Routine Description:

  Calculate the space size of a device path.

Arguments:

  DevicePath  - A specified device path

Returns:

  The size.

--*/
{
  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);
}

EFI_DEVICE_PATH_PROTOCOL *
RtEfiDevicePathFromHandle (
  IN EFI_HANDLE  Handle
  )
/*++

Routine Description:

  Get the device path protocol interface installed on a specified handle.

Arguments:

  Handle  - a specified handle

Returns:

  The device path protocol interface installed on that handle.

--*/
{
  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;

  DevicePath = NULL;
  gBS->HandleProtocol (
        Handle,
        &gEfiDevicePathProtocolGuid,
        (VOID *) &DevicePath
        );
  return DevicePath;
}

EFI_DEVICE_PATH_PROTOCOL *
RtEfiDuplicateDevicePath (
  IN EFI_DEVICE_PATH_PROTOCOL   *DevicePath
  )
/*++

Routine Description:

  Duplicate a device path structure.

Arguments:

  DevicePath  - The device path to duplicated.

Returns:

  The duplicated device path.

--*/
{
  EFI_DEVICE_PATH_PROTOCOL  *NewDevicePath;
  UINTN                     Size;

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

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

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

  return NewDevicePath;
}

EFI_DEVICE_PATH_PROTOCOL *