MdePkg/Include/Library/DevicePathLib.h

   1 /** @file
   2   Provides library functions to construct and parse UEFI Device Paths.
   3
   4   This library provides defines, macros, and functions to help create and parse
   5   EFI_DEVICE_PATH_PROTOCOL structures.  The macros that help create and parse device
   6   path nodes make use of the ReadUnaligned16() and WriteUnaligned16() functions from
   7   the Base Library, so this library class has an implied dependency on the Base Library.
   8
   9 Copyright (c) 2006 - 2008, Intel Corporation<BR>
  10 All rights reserved. This program and the accompanying materials
  11 are licensed and made available under the terms and conditions of the BSD License
  12 which accompanies this distribution.  The full text of the license may be found at
  13 http://opensource.org/licenses/bsd-license.php
  14
  15 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  16 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  17
  18 **/
  19
  20 #ifndef __DEVICE_PATH_LIB_H__
  21 #define __DEVICE_PATH_LIB_H__
  22
  23 #include <Library/BaseLib.h>
  24
  25 #define END_DEVICE_PATH_LENGTH               (sizeof (EFI_DEVICE_PATH_PROTOCOL))
  26
  27 /**
  28   Macro that returns the Type field of a device path node.
  29
  30   Returns the Type field of the device path node specified by Node.
  31
  32   @param  Node      A pointer to a device path node data structure.
  33
  34   @return The Type field of the device path node specified by Node.
  35
  36 **/
  37 #define DevicePathType(Node)                 (((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Type)
  38
  39 /**
  40   Macro that returns the SubType field of a device path node.
  41
  42   Returns the SubType field of the device path node specified by Node.
  43
  44   @param  Node      A pointer to a device path node data structure.
  45
  46   @return The SubType field of the device path node specified by Node.
  47
  48 **/
  49 #define DevicePathSubType(Node)              (((EFI_DEVICE_PATH_PROTOCOL *)(Node))->SubType)
  50
  51 /**
  52   Macro that returns the 16-bit Length field of a device path node.
  53
  54   Returns the 16-bit Length field of the device path node specified by Node.
  55
  56   @param  Node      A pointer to a device path node data structure.
  57
  58   @return The 16-bit Length field of the device path node specified by Node.
  59
  60 **/
  61 #define DevicePathNodeLength(Node)           ReadUnaligned16 ((UINT16 *)&((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Length[0])
  62
  63 /**
  64   Macro that returns a pointer to the next node in a device path.
  65
  66   Returns a pointer to the device path node that follows the device path node specified by Node.
  67
  68   @param  Node      A pointer to a device path node data structure.
  69
  70   @return a pointer to the device path node that follows the device path node specified by Node.
  71
  72 **/
  73 #define NextDevicePathNode(Node)             ((EFI_DEVICE_PATH_PROTOCOL *)((UINT8 *)(Node) + DevicePathNodeLength(Node)))
  74
  75 /**
  76   Macro that determines if a device path node is an end node of a device path.
  77   This includes nodes that are the end of a device path instance and nodes that are the end of an entire device path.
  78
  79   Determines if the device path node specified by Node is an end node of a device path.
  80   This includes nodes that are the end of a device path instance and nodes that are the
  81   end of an entire device path.  If Node represents an end node of a device path,
  82   then TRUE is returned.  Otherwise, FALSE is returned.
  83
  84   @param  Node      A pointer to a device path node data structure.
  85
  86   @retval TRUE      The device path node specified by Node is an end node of a device path.
  87   @retval FALSE     The device path node specified by Node is not an end node of a device path.
  88
  89 **/
  90 #define IsDevicePathEndType(Node)            ((DevicePathType (Node) & 0x7f) == END_DEVICE_PATH_TYPE)
  91
  92 /**
  93   Macro that determines if a device path node is an end node of an entire device path.
  94
  95   Determines if a device path node specified by Node is an end node of an entire device path.
  96   If Node represents the end of an entire device path, then TRUE is returned.  Otherwise, FALSE is returned.
  97
  98   @param  Node      A pointer to a device path node data structure.
  99
 100   @retval TRUE      The device path node specified by Node is the end of an entire device path.
 101   @retval FALSE     The device path node specified by Node is not the end of an entire device path.
 102
 103 **/
 104 #define IsDevicePathEnd(Node)                (IsDevicePathEndType (Node) && DevicePathSubType(Node) == END_ENTIRE_DEVICE_PATH_SUBTYPE)
 105
 106 /**
 107   Macro that determines if a device path node is an end node of a device path instance.
 108
 109   Determines if a device path node specified by Node is an end node of a device path instance.
 110   If Node represents the end of a device path instance, then TRUE is returned.  Otherwise, FALSE is returned.
 111
 112   @param  Node      A pointer to a device path node data structure.
 113
 114   @retval TRUE      The device path node specified by Node is the end of a device path instance.
 115   @retval FALSE     The device path node specified by Node is not the end of a device path instance.
 116
 117 **/
 118 #define IsDevicePathEndInstance(Node)        (IsDevicePathEndType (Node) && DevicePathSubType(Node) == END_INSTANCE_DEVICE_PATH_SUBTYPE)
 119
 120 /**
 121   Macro that sets the length, in bytes, of a device path node.
 122
 123   Sets the length of the device path node specified by Node to the value specified by Length. Length is returned.
 124
 125   @param  Node      A pointer to a device path node data structure.
 126   @param  Length    The length, in bytes, of the device path node.
 127
 128   @return Length
 129
 130 **/
 131 #define SetDevicePathNodeLength(Node,NodeLength)  WriteUnaligned16 ((UINT16 *)&((EFI_DEVICE_PATH_PROTOCOL *)(Node))->Length[0], (UINT16)(NodeLength))
 132
 133 /**
 134   Macro that fills in all the fields of a device path node that is the end of an entire device path.
 135
 136   Fills in all the fields of a device path node specified by Node so Node represents the end of an entire device path.
 137
 138   @param  Node      A pointer to a device path node data structure.
 139
 140 **/
 141 #define SetDevicePathEndNode(Node)  {                                   \
 142           DevicePathType (Node)    = END_DEVICE_PATH_TYPE;              \
 143           DevicePathSubType (Node) = END_ENTIRE_DEVICE_PATH_SUBTYPE;    \
 144           SetDevicePathNodeLength ((Node), END_DEVICE_PATH_LENGTH);     \
 145           }
 146
 147 /**
 148   Returns the size of a device path in bytes.
 149
 150   This function returns the size, in bytes, of the device path data structure specified by
 151   DevicePath including the end of device path node.  If DevicePath is NULL, then 0 is returned.
 152
 153   @param  DevicePath                 A pointer to a device path data structure.
 154
 155   @retval 0       If DevicePath is NULL.
 156   @retval Others  The size of a device path in bytes.
 157
 158 **/
 159 UINTN
 160 EFIAPI
 161 GetDevicePathSize (
 162   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
 163   );
 164
 165 /**
 166   Creates a new device path by appending a second device path to a first device path.
 167
 168   This function allocates space for a new copy of the device path specified by DevicePath.  If
 169   DevicePath is NULL, then NULL is returned.  If the memory is successfully allocated, then the
 170   contents of DevicePath are copied to the newly allocated buffer, and a pointer to that buffer
 171   is returned.  Otherwise, NULL is returned.
 172   The memory for the new device path is allocated from EFI boot services memory.
 173   It is the responsibility of the caller to free the memory allocated.
 174
 175   @param  DevicePath                 A pointer to a device path data structure.
 176
 177   @retval NULL    If DevicePath is NULL.
 178   @retval Others  A pointer to the duplicated device path.
 179
 180 **/
 181 EFI_DEVICE_PATH_PROTOCOL *
 182 EFIAPI
 183 DuplicateDevicePath (
 184   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
 185   );
 186
 187 /**
 188   Creates a new device path by appending a second device path to a first device path.
 189
 190   This function creates a new device path by appending a copy of SecondDevicePath to a copy of
 191   FirstDevicePath in a newly allocated buffer.  Only the end-of-device-path device node from
 192   SecondDevicePath is retained. The newly created device path is returned.
 193   If FirstDevicePath is NULL, then it is ignored, and a duplicate of SecondDevicePath is returned.
 194   If SecondDevicePath is NULL, then it is ignored, and a duplicate of FirstDevicePath is returned.
 195   If both FirstDevicePath and SecondDevicePath are NULL, then a copy of an end-of-device-path is
 196   returned.
 197   If there is not enough memory for the newly allocated buffer, then NULL is returned.
 198   The memory for the new device path is allocated from EFI boot services memory. It is the
 199   responsibility of the caller to free the memory allocated.
 200
 201   @param  FirstDevicePath            A pointer to a device path data structure.
 202   @param  SecondDevicePath           A pointer to a device path data structure.
 203
 204   @retval NULL      If there is not enough memory for the newly allocated buffer.
 205   @retval Others    A pointer to the new device path if success.
 206                     Or a copy an end-of-device-path if both FirstDevicePath and SecondDevicePath are NULL.
 207
 208 **/
 209 EFI_DEVICE_PATH_PROTOCOL *
 210 EFIAPI
 211 AppendDevicePath (
 212   IN CONST EFI_DEVICE_PATH_PROTOCOL  *FirstDevicePath,  OPTIONAL
 213   IN CONST EFI_DEVICE_PATH_PROTOCOL  *SecondDevicePath  OPTIONAL
 214   );
 215
 216 /**
 217   Creates a new path by appending the device node to the device path.
 218
 219   This function creates a new device path by appending a copy of the device node specified by
 220   DevicePathNode to a copy of the device path specified by DevicePath in an allocated buffer.
 221   The end-of-device-path device node is moved after the end of the appended device node.
 222   If DevicePathNode is NULL then a copy of DevicePath is returned.
 223   If DevicePath is NULL then a copy of DevicePathNode, followed by an end-of-device path device
 224   node is returned.
 225   If both DevicePathNode and DevicePath are NULL then a copy of an end-of-device-path device node
 226   is returned.
 227   If there is not enough memory to allocate space for the new device path, then NULL is returned.
 228   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
 229   free the memory allocated.
 230
 231   @param  DevicePath                 A pointer to a device path data structure.
 232   @param  DevicePathNode             A pointer to a single device path node.
 233
 234   @retval NULL      If there is not enough memory for the new device path.
 235   @retval Others    A pointer to the new device path if success.
 236                     A copy of DevicePathNode followed by an end-of-device-path node
 237                     if both FirstDevicePath and SecondDevicePath are NULL.
 238                     A copy of an end-of-device-path node if both FirstDevicePath and SecondDevicePath are NULL.
 239
 240 **/
 241 EFI_DEVICE_PATH_PROTOCOL *
 242 EFIAPI
 243 AppendDevicePathNode (
 244   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath,     OPTIONAL
 245   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePathNode  OPTIONAL
 246   );
 247
 248 /**
 249   Creates a new device path by appending the specified device path instance to the specified device
 250   path.
 251
 252   This function creates a new device path by appending a copy of the device path instance specified
 253   by DevicePathInstance to a copy of the device path secified by DevicePath in a allocated buffer.
 254   The end-of-device-path device node is moved after the end of the appended device path instance
 255   and a new end-of-device-path-instance node is inserted between.
 256   If DevicePath is NULL, then a copy if DevicePathInstance is returned.
 257   If DevicePathInstance is NULL, then NULL is returned.
 258   If there is not enough memory to allocate space for the new device path, then NULL is returned.
 259   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
 260   free the memory allocated.
 261
 262   @param  DevicePath                 A pointer to a device path data structure.
 263   @param  DevicePathInstance         A pointer to a device path instance.
 264
 265   @return A pointer to the new device path.
 266
 267 **/
 268 EFI_DEVICE_PATH_PROTOCOL *
 269 EFIAPI
 270 AppendDevicePathInstance (
 271   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath,        OPTIONAL
 272   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePathInstance OPTIONAL
 273   );
 274
 275 /**
 276   Creates a copy of the current device path instance and returns a pointer to the next device path
 277   instance.
 278
 279   This function creates a copy of the current device path instance. It also updates DevicePath to
 280   point to the next device path instance in the device path (or NULL if no more) and updates Size
 281   to hold the size of the device path instance copy.
 282   If DevicePath is NULL, then NULL is returned.
 283   If there is not enough memory to allocate space for the new device path, then NULL is returned.
 284   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
 285   free the memory allocated.
 286   If Size is NULL, then ASSERT().
 287
 288   @param  DevicePath                 On input, this holds the pointer to the current device path
 289                                      instance. On output, this holds the pointer to the next device
 290                                      path instance or NULL if there are no more device path
 291                                      instances in the device path pointer to a device path data
 292                                      structure.
 293   @param  Size                       On output, this holds the size of the device path instance, in
 294                                      bytes or zero, if DevicePath is NULL.
 295
 296   @return A pointer to the current device path instance.
 297
 298 **/
 299 EFI_DEVICE_PATH_PROTOCOL *
 300 EFIAPI
 301 GetNextDevicePathInstance (
 302   IN OUT EFI_DEVICE_PATH_PROTOCOL    **DevicePath,
 303   OUT UINTN                          *Size
 304   );
 305
 306 /**
 307   Creates a device node.
 308
 309   This function creates a new device node in a newly allocated buffer of size NodeLength and
 310   initializes the device path node header with NodeType and NodeSubType.  The new device path node
 311   is returned.
 312   If NodeLength is smaller than a device path header, then NULL is returned.
 313   If there is not enough memory to allocate space for the new device path, then NULL is returned.
 314   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
 315   free the memory allocated.
 316
 317   @param  NodeType                   The device node type for the new device node.
 318   @param  NodeSubType                The device node sub-type for the new device node.
 319   @param  NodeLength                 The length of the new device node.
 320
 321   @return The new device path.
 322
 323 **/
 324 EFI_DEVICE_PATH_PROTOCOL *
 325 EFIAPI
 326 CreateDeviceNode (
 327   IN UINT8                           NodeType,
 328   IN UINT8                           NodeSubType,
 329   IN UINT16                          NodeLength
 330   );
 331
 332 /**
 333   Determines if a device path is single or multi-instance.
 334
 335   This function returns TRUE if the device path specified by DevicePath is multi-instance.
 336   Otherwise, FALSE is returned.  If DevicePath is NULL, then FALSE is returned.
 337
 338   @param  DevicePath                 A pointer to a device path data structure.
 339
 340   @retval  TRUE                      DevicePath is multi-instance.
 341   @retval  FALSE                     DevicePath is not multi-instance or DevicePath is NULL.
 342
 343 **/
 344 BOOLEAN
 345 EFIAPI
 346 IsDevicePathMultiInstance (
 347   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
 348   );
 349
 350 /**
 351   Retrieves the device path protocol from a handle.
 352
 353   This function returns the device path protocol from the handle specified by Handle.  If Handle is
 354   NULL or Handle does not contain a device path protocol, then NULL is returned.
 355
 356   @param  Handle                     The handle from which to retrieve the device path protocol.
 357
 358   @return The device path protocol from the handle specified by Handle.
 359
 360 **/
 361 EFI_DEVICE_PATH_PROTOCOL *
 362 EFIAPI
 363 DevicePathFromHandle (
 364   IN EFI_HANDLE                      Handle
 365   );
 366
 367 /**
 368   Allocates a device path for a file and appends it to an existing device path.
 369
 370   If Device is a valid device handle that contains a device path protocol, then a device path for
 371   the file specified by FileName  is allocated and appended to the device path associated with the
 372   handle Device.  The allocated device path is returned.  If Device is NULL or Device is a handle
 373   that does not support the device path protocol, then a device path containing a single device
 374   path node for the file specified by FileName is allocated and returned.
 375   The memory for the new device path is allocated from EFI boot services memory. It is the responsibility
 376   of the caller to free the memory allocated.
 377
 378   If FileName is NULL, then ASSERT().
 379   If FileName is not aligned on a 16-bit boundary, then ASSERT().
 380
 381   @param  Device                     A pointer to a device handle.  This parameter is optional and
 382                                      may be NULL.
 383   @param  FileName                   A pointer to a Null-terminated Unicode string.
 384
 385   @return The allocated device path.
 386
 387 **/
 388 EFI_DEVICE_PATH_PROTOCOL *
 389 EFIAPI
 390 FileDevicePath (
 391   IN EFI_HANDLE                      Device,     OPTIONAL
 392   IN CONST CHAR16                    *FileName
 393   );
 394
 395 #endif